/* Support routines for Value Range Propagation (VRP).
- Copyright (C) 2005 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>.
This file is part of GCC.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+Boston, MA 02110-1301, USA. */
#include "config.h"
#include "system.h"
#include "tree-dump.h"
#include "timevar.h"
#include "diagnostic.h"
+#include "toplev.h"
+#include "intl.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-propagate.h"
#include "tree-chrec.h"
/* Set of SSA names found during the dominator traversal of a
- sub-graph in maybe_add_assert_expr. */
-static sbitmap found;
-
-/* Loop structure of the program. Used to analyze scalar evolutions
- inside adjust_range_with_scev. */
-static struct loops *cfg_loops;
+ sub-graph in find_assert_locations. */
+static sbitmap found_in_subgraph;
/* Local functions. */
static int compare_values (tree val1, tree val2);
+static int compare_values_warnv (tree val1, tree val2, bool *);
+static void vrp_meet (value_range_t *, value_range_t *);
+static tree vrp_evaluate_conditional_warnv (tree, bool, bool *);
+
+/* Location information for ASSERT_EXPRs. Each instance of this
+ structure describes an ASSERT_EXPR for an SSA name. Since a single
+ SSA name may have more than one assertion associated with it, these
+ locations are kept in a linked list attached to the corresponding
+ SSA name. */
+struct assert_locus_d
+{
+ /* Basic block where the assertion would be inserted. */
+ basic_block bb;
+
+ /* Some assertions need to be inserted on an edge (e.g., assertions
+ generated by COND_EXPRs). In those cases, BB will be NULL. */
+ edge e;
+
+ /* Pointer to the statement that generated this assertion. */
+ block_stmt_iterator si;
+
+ /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
+ enum tree_code comp_code;
+
+ /* Value being compared against. */
+ tree val;
+
+ /* Next node in the linked list. */
+ struct assert_locus_d *next;
+};
+
+typedef struct assert_locus_d *assert_locus_t;
+
+/* If bit I is present, it means that SSA name N_i has a list of
+ assertions that should be inserted in the IL. */
+static bitmap need_assert_for;
+
+/* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
+ holds a list of ASSERT_LOCUS_T nodes that describe where
+ ASSERT_EXPRs for SSA name N_I should be inserted. */
+static assert_locus_t *asserts_for;
+
+/* Set of blocks visited in find_assert_locations. Used to avoid
+ visiting the same block more than once. */
+static sbitmap blocks_visited;
+
+/* Value range array. After propagation, VR_VALUE[I] holds the range
+ of values that SSA name N_I may take. */
+static value_range_t **vr_value;
+
+
+/* Return whether TYPE should use an overflow infinity distinct from
+ TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
+ represent a signed overflow during VRP computations. An infinity
+ is distinct from a half-range, which will go from some number to
+ TYPE_{MIN,MAX}_VALUE. */
+
+static inline bool
+needs_overflow_infinity (tree type)
+{
+ return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type);
+}
+
+/* Return whether TYPE can support our overflow infinity
+ representation: we use the TREE_OVERFLOW flag, which only exists
+ for constants. If TYPE doesn't support this, we don't optimize
+ cases which would require signed overflow--we drop them to
+ VARYING. */
-/* Given a conditional predicate COND that has WHICH as one of its
- operands, return the other operand. No error checking is done.
- This helper assumes that COND is a comparison and WHICH is one of
- its operands. */
+static inline bool
+supports_overflow_infinity (tree type)
+{
+#ifdef ENABLE_CHECKING
+ gcc_assert (needs_overflow_infinity (type));
+#endif
+ return (TYPE_MIN_VALUE (type) != NULL_TREE
+ && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type))
+ && TYPE_MAX_VALUE (type) != NULL_TREE
+ && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type)));
+}
+
+/* VAL is the maximum or minimum value of a type. Return a
+ corresponding overflow infinity. */
static inline tree
-get_opposite_operand (tree cond, tree which)
+make_overflow_infinity (tree val)
{
- if (TREE_OPERAND (cond, 0) == which)
- return TREE_OPERAND (cond, 1);
- else
- return TREE_OPERAND (cond, 0);
+#ifdef ENABLE_CHECKING
+ gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val));
+#endif
+ val = copy_node (val);
+ TREE_OVERFLOW (val) = 1;
+ return val;
}
+/* Return a negative overflow infinity for TYPE. */
-/* Given a comparison code, return its opposite. Note that this is *not*
- the same as inverting its truth value (invert_tree_comparison). Here we
- just want to literally flip the comparison around.
-
- So, '<' gets '>', '<=' gets '>='. Both '==' and '!=' are returned
- unchanged. */
-
-static enum tree_code
-opposite_comparison (enum tree_code code)
-{
- switch (code)
- {
- case EQ_EXPR:
- case NE_EXPR:
- case ORDERED_EXPR:
- case UNORDERED_EXPR:
- case LTGT_EXPR:
- case UNEQ_EXPR:
- return code;
- case GT_EXPR:
- return LT_EXPR;
- case GE_EXPR:
- return LE_EXPR;
- case LT_EXPR:
- return GT_EXPR;
- case LE_EXPR:
- return GE_EXPR;
- case UNGT_EXPR:
- return UNLT_EXPR;
- case UNGE_EXPR:
- return UNLE_EXPR;
- case UNLT_EXPR:
- return UNGT_EXPR;
- case UNLE_EXPR:
- return UNGE_EXPR;
- default:
- gcc_unreachable ();
+static inline tree
+negative_overflow_infinity (tree type)
+{
+#ifdef ENABLE_CHECKING
+ gcc_assert (supports_overflow_infinity (type));
+#endif
+ return make_overflow_infinity (TYPE_MIN_VALUE (type));
+}
+
+/* Return a positive overflow infinity for TYPE. */
+
+static inline tree
+positive_overflow_infinity (tree type)
+{
+#ifdef ENABLE_CHECKING
+ gcc_assert (supports_overflow_infinity (type));
+#endif
+ return make_overflow_infinity (TYPE_MAX_VALUE (type));
+}
+
+/* Return whether VAL is a negative overflow infinity. */
+
+static inline bool
+is_negative_overflow_infinity (tree val)
+{
+ return (needs_overflow_infinity (TREE_TYPE (val))
+ && CONSTANT_CLASS_P (val)
+ && TREE_OVERFLOW (val)
+ && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0));
+}
+
+/* Return whether VAL is a positive overflow infinity. */
+
+static inline bool
+is_positive_overflow_infinity (tree val)
+{
+ return (needs_overflow_infinity (TREE_TYPE (val))
+ && CONSTANT_CLASS_P (val)
+ && TREE_OVERFLOW (val)
+ && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0));
+}
+
+/* Return whether VAL is a positive or negative overflow infinity. */
+
+static inline bool
+is_overflow_infinity (tree val)
+{
+ return (needs_overflow_infinity (TREE_TYPE (val))
+ && CONSTANT_CLASS_P (val)
+ && TREE_OVERFLOW (val)
+ && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)
+ || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)));
+}
+
+
+/* Return true if ARG is marked with the nonnull attribute in the
+ current function signature. */
+
+static bool
+nonnull_arg_p (tree arg)
+{
+ tree t, attrs, fntype;
+ unsigned HOST_WIDE_INT arg_num;
+
+ gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
+
+ /* The static chain decl is always non null. */
+ if (arg == cfun->static_chain_decl)
+ return true;
+
+ fntype = TREE_TYPE (current_function_decl);
+ attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
+
+ /* If "nonnull" wasn't specified, we know nothing about the argument. */
+ if (attrs == NULL_TREE)
+ return false;
+
+ /* If "nonnull" applies to all the arguments, then ARG is non-null. */
+ if (TREE_VALUE (attrs) == NULL_TREE)
+ return true;
+
+ /* Get the position number for ARG in the function signature. */
+ for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
+ t;
+ t = TREE_CHAIN (t), arg_num++)
+ {
+ if (t == arg)
+ break;
+ }
+
+ gcc_assert (t == arg);
+
+ /* Now see if ARG_NUM is mentioned in the nonnull list. */
+ for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
+ {
+ if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
+ return true;
}
+
+ return false;
}
-/* Set value range VR to {T, MIN, MAX}. */
+/* Set value range VR to {T, MIN, MAX, EQUIV}. */
-static inline void
-set_value_range (value_range *vr, enum value_range_type t, tree min, tree max)
+static void
+set_value_range (value_range_t *vr, enum value_range_type t, tree min,
+ tree max, bitmap equiv)
{
#if defined ENABLE_CHECKING
+ /* Check the validity of the range. */
if (t == VR_RANGE || t == VR_ANTI_RANGE)
{
int cmp;
gcc_assert (min && max);
if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
- gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
- || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
+ gcc_assert ((min != TYPE_MIN_VALUE (TREE_TYPE (min))
+ && !is_negative_overflow_infinity (min))
+ || (max != TYPE_MAX_VALUE (TREE_TYPE (max))
+ && !is_positive_overflow_infinity (max)));
cmp = compare_values (min, max);
gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
}
+
+ if (t == VR_UNDEFINED || t == VR_VARYING)
+ gcc_assert (min == NULL_TREE && max == NULL_TREE);
+
+ if (t == VR_UNDEFINED || t == VR_VARYING)
+ gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
#endif
- if (t == VR_RANGE
- && INTEGRAL_TYPE_P (TREE_TYPE (min))
- && min == TYPE_MIN_VALUE (TREE_TYPE (min))
- && max == TYPE_MAX_VALUE (TREE_TYPE (max)))
+ vr->type = t;
+ vr->min = min;
+ vr->max = max;
+
+ /* Since updating the equivalence set involves deep copying the
+ bitmaps, only do it if absolutely necessary. */
+ if (vr->equiv == NULL)
+ vr->equiv = BITMAP_ALLOC (NULL);
+
+ if (equiv != vr->equiv)
+ {
+ if (equiv && !bitmap_empty_p (equiv))
+ bitmap_copy (vr->equiv, equiv);
+ else
+ bitmap_clear (vr->equiv);
+ }
+}
+
+
+/* Copy value range FROM into value range TO. */
+
+static inline void
+copy_value_range (value_range_t *to, value_range_t *from)
+{
+ set_value_range (to, from->type, from->min, from->max, from->equiv);
+}
+
+
+/* Set value range VR to VR_VARYING. */
+
+static inline void
+set_value_range_to_varying (value_range_t *vr)
+{
+ vr->type = VR_VARYING;
+ vr->min = vr->max = NULL_TREE;
+ if (vr->equiv)
+ bitmap_clear (vr->equiv);
+}
+
+/* Set value range VR to a non-negative range of type TYPE.
+ OVERFLOW_INFINITY indicates whether to use a overflow infinity
+ rather than TYPE_MAX_VALUE; this should be true if we determine
+ that the range is nonnegative based on the assumption that signed
+ overflow does not occur. */
+
+static inline void
+set_value_range_to_nonnegative (value_range_t *vr, tree type,
+ bool overflow_infinity)
+{
+ tree zero;
+
+ if (overflow_infinity && !supports_overflow_infinity (type))
{
- /* Ranges that cover all the possible values for the type decay
- to VARYING. */
- vr->type = VR_VARYING;
- vr->min = NULL_TREE;
- vr->max = NULL_TREE;
+ set_value_range_to_varying (vr);
return;
}
- vr->type = t;
- vr->min = min;
- vr->max = max;
+ zero = build_int_cst (type, 0);
+ set_value_range (vr, VR_RANGE, zero,
+ (overflow_infinity
+ ? positive_overflow_infinity (type)
+ : TYPE_MAX_VALUE (type)),
+ vr->equiv);
+}
+
+/* Set value range VR to a non-NULL range of type TYPE. */
+
+static inline void
+set_value_range_to_nonnull (value_range_t *vr, tree type)
+{
+ tree zero = build_int_cst (type, 0);
+ set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
}
-/* Similar to set_value_range but return true if any field of VR
- changed from its previous value. */
+/* Set value range VR to a NULL range of type TYPE. */
-static inline bool
-update_value_range (value_range *vr, enum value_range_type t, tree min,
- tree max)
+static inline void
+set_value_range_to_null (value_range_t *vr, tree type)
{
- bool is_new = vr->type != t || vr->min != min || vr->max != max;
- if (is_new)
- set_value_range (vr, t, min, max);
+ tree zero = build_int_cst (type, 0);
+ set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
+}
- return is_new;
+
+/* Set value range VR to a range of a truthvalue of type TYPE. */
+
+static inline void
+set_value_range_to_truthvalue (value_range_t *vr, tree type)
+{
+ if (TYPE_PRECISION (type) == 1)
+ set_value_range_to_varying (vr);
+ else
+ set_value_range (vr, VR_RANGE,
+ build_int_cst (type, 0), build_int_cst (type, 1),
+ vr->equiv);
}
-/* Return value range information for VAR. Create an empty range if
- none existed. */
+/* Set value range VR to VR_UNDEFINED. */
+
+static inline void
+set_value_range_to_undefined (value_range_t *vr)
+{
+ vr->type = VR_UNDEFINED;
+ vr->min = vr->max = NULL_TREE;
+ if (vr->equiv)
+ bitmap_clear (vr->equiv);
+}
+
+
+/* Return value range information for VAR.
+
+ If we have no values ranges recorded (ie, VRP is not running), then
+ return NULL. Otherwise create an empty range if none existed for VAR. */
-value_range *
+static value_range_t *
get_value_range (tree var)
{
- value_range *vr;
+ value_range_t *vr;
tree sym;
+ unsigned ver = SSA_NAME_VERSION (var);
- vr = SSA_NAME_VALUE_RANGE (var);
+ /* If we have no recorded ranges, then return NULL. */
+ if (! vr_value)
+ return NULL;
+
+ vr = vr_value[ver];
if (vr)
return vr;
/* Create a default value range. */
- vr = ggc_alloc (sizeof (*vr));
- memset ((void *) vr, 0, sizeof (*vr));
- SSA_NAME_VALUE_RANGE (var) = vr;
+ vr_value[ver] = vr = XCNEW (value_range_t);
+
+ /* Allocate an equivalence set. */
+ vr->equiv = BITMAP_ALLOC (NULL);
- /* If VAR is a default definition for a PARM_DECL, then we have to
- assume a VARYING range for it. */
+ /* If VAR is a default definition, the variable can take any value
+ in VAR's type. */
sym = SSA_NAME_VAR (var);
- if (TREE_CODE (sym) == PARM_DECL && var == var_ann (sym)->default_def)
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ if (SSA_NAME_IS_DEFAULT_DEF (var))
+ {
+ /* Try to use the "nonnull" attribute to create ~[0, 0]
+ anti-ranges for pointers. Note that this is only valid with
+ default definitions of PARM_DECLs. */
+ if (TREE_CODE (sym) == PARM_DECL
+ && POINTER_TYPE_P (TREE_TYPE (sym))
+ && nonnull_arg_p (sym))
+ set_value_range_to_nonnull (vr, TREE_TYPE (sym));
+ else
+ set_value_range_to_varying (vr);
+ }
return vr;
}
+/* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
-/* Return true if value range VR involves at least one symbol. */
+static inline bool
+vrp_operand_equal_p (tree val1, tree val2)
+{
+ if (val1 == val2)
+ return true;
+ if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
+ return false;
+ if (is_overflow_infinity (val1))
+ return is_overflow_infinity (val2);
+ return true;
+}
+
+/* Return true, if the bitmaps B1 and B2 are equal. */
static inline bool
-symbolic_range_p (value_range *vr)
+vrp_bitmap_equal_p (bitmap b1, bitmap b2)
{
- return (!is_gimple_min_invariant (vr->min)
- || !is_gimple_min_invariant (vr->max));
+ return (b1 == b2
+ || (b1 && b2
+ && bitmap_equal_p (b1, b2)));
}
+/* Update the value range and equivalence set for variable VAR to
+ NEW_VR. Return true if NEW_VR is different from VAR's previous
+ value.
-/* Return true if EXPR computes a non-zero value. */
+ NOTE: This function assumes that NEW_VR is a temporary value range
+ object created for the sole purpose of updating VAR's range. The
+ storage used by the equivalence set from NEW_VR will be freed by
+ this function. Do not call update_value_range when NEW_VR
+ is the range object associated with another SSA name. */
-bool
-expr_computes_nonzero (tree expr)
+static inline bool
+update_value_range (tree var, value_range_t *new_vr)
{
- /* Type casts won't change anything, so just strip it. */
- STRIP_NOPS (expr);
+ value_range_t *old_vr;
+ bool is_new;
- /* Calling alloca, guarantees that the value is non-NULL. */
- if (alloca_call_p (expr))
- return true;
+ /* Update the value range, if necessary. */
+ old_vr = get_value_range (var);
+ is_new = old_vr->type != new_vr->type
+ || !vrp_operand_equal_p (old_vr->min, new_vr->min)
+ || !vrp_operand_equal_p (old_vr->max, new_vr->max)
+ || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
- /* The address of a non-weak symbol is never NULL, unless the user
- has requested not to remove NULL pointer checks. */
- if (flag_delete_null_pointer_checks
- && TREE_CODE (expr) == ADDR_EXPR
- && DECL_P (TREE_OPERAND (expr, 0))
- && !DECL_WEAK (TREE_OPERAND (expr, 0)))
- return true;
+ if (is_new)
+ set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
+ new_vr->equiv);
- /* IOR of any value with a nonzero value will result in a nonzero
- value. */
- if (TREE_CODE (expr) == BIT_IOR_EXPR
- && integer_nonzerop (TREE_OPERAND (expr, 1)))
- return true;
+ BITMAP_FREE (new_vr->equiv);
+ new_vr->equiv = NULL;
- return false;
+ return is_new;
+}
+
+
+/* Add VAR and VAR's equivalence set to EQUIV. */
+
+static void
+add_equivalence (bitmap equiv, tree var)
+{
+ unsigned ver = SSA_NAME_VERSION (var);
+ value_range_t *vr = vr_value[ver];
+
+ bitmap_set_bit (equiv, ver);
+ if (vr && vr->equiv)
+ bitmap_ior_into (equiv, vr->equiv);
}
/* Return true if VR is ~[0, 0]. */
static inline bool
-range_is_nonnull (value_range *vr)
+range_is_nonnull (value_range_t *vr)
{
return vr->type == VR_ANTI_RANGE
&& integer_zerop (vr->min)
/* Return true if VR is [0, 0]. */
static inline bool
-range_is_null (value_range *vr)
+range_is_null (value_range_t *vr)
{
return vr->type == VR_RANGE
&& integer_zerop (vr->min)
}
-/* Set value range VR to a non-NULL range of type TYPE. */
+/* Return true if value range VR involves at least one symbol. */
-static void
-set_value_range_to_nonnull (value_range *vr, tree type)
+static inline bool
+symbolic_range_p (value_range_t *vr)
{
- tree zero = build_int_cst (type, 0);
- set_value_range (vr, VR_ANTI_RANGE, zero, zero);
+ return (!is_gimple_min_invariant (vr->min)
+ || !is_gimple_min_invariant (vr->max));
}
+/* Return true if value range VR uses a overflow infinity. */
-/* Set value range VR to a NULL range of type TYPE. */
+static inline bool
+overflow_infinity_range_p (value_range_t *vr)
+{
+ return (vr->type == VR_RANGE
+ && (is_overflow_infinity (vr->min)
+ || is_overflow_infinity (vr->max)));
+}
-static void
-set_value_range_to_null (value_range *vr, tree type)
+/* Return false if we can not make a valid comparison based on VR;
+ this will be the case if it uses an overflow infinity and overflow
+ is not undefined (i.e., -fno-strict-overflow is in effect).
+ Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
+ uses an overflow infinity. */
+
+static bool
+usable_range_p (value_range_t *vr, bool *strict_overflow_p)
{
- tree zero = build_int_cst (type, 0);
- set_value_range (vr, VR_RANGE, zero, zero);
+ gcc_assert (vr->type == VR_RANGE);
+ if (is_overflow_infinity (vr->min))
+ {
+ *strict_overflow_p = true;
+ if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min)))
+ return false;
+ }
+ if (is_overflow_infinity (vr->max))
+ {
+ *strict_overflow_p = true;
+ if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max)))
+ return false;
+ }
+ return true;
+}
+
+
+/* Like tree_expr_nonnegative_warnv_p, but this function uses value
+ ranges obtained so far. */
+
+static bool
+vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
+{
+ return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p);
+}
+
+/* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
+ obtained so far. */
+
+static bool
+vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p)
+{
+ if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p))
+ return true;
+
+ /* If we have an expression of the form &X->a, then the expression
+ is nonnull if X is nonnull. */
+ if (TREE_CODE (expr) == ADDR_EXPR)
+ {
+ tree base = get_base_address (TREE_OPERAND (expr, 0));
+
+ if (base != NULL_TREE
+ && TREE_CODE (base) == INDIRECT_REF
+ && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
+ {
+ value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
+ if (range_is_nonnull (vr))
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/* Returns true if EXPR is a valid value (as expected by compare_values) --
+ a gimple invariant, or SSA_NAME +- CST. */
+
+static bool
+valid_value_p (tree expr)
+{
+ if (TREE_CODE (expr) == SSA_NAME)
+ return true;
+
+ if (TREE_CODE (expr) == PLUS_EXPR
+ || TREE_CODE (expr) == MINUS_EXPR)
+ return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
+ && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
+
+ return is_gimple_min_invariant (expr);
}
+/* Return
+ 1 if VAL < VAL2
+ 0 if !(VAL < VAL2)
+ -2 if those are incomparable. */
+static inline int
+operand_less_p (tree val, tree val2)
+{
+ /* LT is folded faster than GE and others. Inline the common case. */
+ if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
+ {
+ if (TYPE_UNSIGNED (TREE_TYPE (val)))
+ return INT_CST_LT_UNSIGNED (val, val2);
+ else
+ {
+ if (INT_CST_LT (val, val2))
+ return 1;
+ }
+ }
+ else
+ {
+ tree tcmp;
+
+ fold_defer_overflow_warnings ();
+
+ tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
+
+ fold_undefer_and_ignore_overflow_warnings ();
+
+ if (!tcmp)
+ return -2;
+
+ if (!integer_zerop (tcmp))
+ return 1;
+ }
+
+ /* val >= val2, not considering overflow infinity. */
+ if (is_negative_overflow_infinity (val))
+ return is_negative_overflow_infinity (val2) ? 0 : 1;
+ else if (is_positive_overflow_infinity (val2))
+ return is_positive_overflow_infinity (val) ? 0 : 1;
+
+ return 0;
+}
/* Compare two values VAL1 and VAL2. Return
+2 if VAL1 != VAL2
This is similar to tree_int_cst_compare but supports pointer values
- and values that cannot be compared at compile time. */
+ and values that cannot be compared at compile time.
+
+ If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
+ true if the return value is only valid if we assume that signed
+ overflow is undefined. */
static int
-compare_values (tree val1, tree val2)
+compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
{
if (val1 == val2)
return 0;
gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
== POINTER_TYPE_P (TREE_TYPE (val2)));
- /* Do some limited symbolic comparisons. */
- if (!POINTER_TYPE_P (TREE_TYPE (val1)))
- {
- /* We can determine some comparisons against +INF and -INF even
- if the other value is an expression. */
- if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
- && TREE_CODE (val2) == MINUS_EXPR)
- {
- /* +INF > NAME - CST. */
- return 1;
- }
- else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
- && TREE_CODE (val2) == PLUS_EXPR)
- {
- /* -INF < NAME + CST. */
- return -1;
- }
- else if (TREE_CODE (val1) == MINUS_EXPR
- && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
- {
- /* NAME - CST < +INF. */
- return -1;
- }
- else if (TREE_CODE (val1) == PLUS_EXPR
- && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
- {
- /* NAME + CST > -INF. */
- return 1;
- }
- }
-
if ((TREE_CODE (val1) == SSA_NAME
|| TREE_CODE (val1) == PLUS_EXPR
|| TREE_CODE (val1) == MINUS_EXPR)
|| TREE_CODE (val2) == MINUS_EXPR))
{
tree n1, c1, n2, c2;
+ enum tree_code code1, code2;
/* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
same name, return -2. */
if (TREE_CODE (val1) == SSA_NAME)
{
+ code1 = SSA_NAME;
n1 = val1;
c1 = NULL_TREE;
}
else
{
+ code1 = TREE_CODE (val1);
n1 = TREE_OPERAND (val1, 0);
c1 = TREE_OPERAND (val1, 1);
+ if (tree_int_cst_sgn (c1) == -1)
+ {
+ if (is_negative_overflow_infinity (c1))
+ return -2;
+ c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
+ if (!c1)
+ return -2;
+ code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
+ }
}
if (TREE_CODE (val2) == SSA_NAME)
{
+ code2 = SSA_NAME;
n2 = val2;
c2 = NULL_TREE;
}
else
{
+ code2 = TREE_CODE (val2);
n2 = TREE_OPERAND (val2, 0);
c2 = TREE_OPERAND (val2, 1);
+ if (tree_int_cst_sgn (c2) == -1)
+ {
+ if (is_negative_overflow_infinity (c2))
+ return -2;
+ c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
+ if (!c2)
+ return -2;
+ code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
+ }
}
/* Both values must use the same name. */
if (n1 != n2)
return -2;
- if (TREE_CODE (val1) == SSA_NAME)
+ if (code1 == SSA_NAME
+ && code2 == SSA_NAME)
+ /* NAME == NAME */
+ return 0;
+
+ /* If overflow is defined we cannot simplify more. */
+ if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
+ return -2;
+
+ if (strict_overflow_p != NULL)
+ *strict_overflow_p = true;
+
+ if (code1 == SSA_NAME)
{
- if (TREE_CODE (val2) == SSA_NAME)
- /* NAME == NAME */
- return 0;
- else if (TREE_CODE (val2) == PLUS_EXPR)
+ if (code2 == PLUS_EXPR)
/* NAME < NAME + CST */
return -1;
- else if (TREE_CODE (val2) == MINUS_EXPR)
+ else if (code2 == MINUS_EXPR)
/* NAME > NAME - CST */
return 1;
}
- else if (TREE_CODE (val1) == PLUS_EXPR)
+ else if (code1 == PLUS_EXPR)
{
- if (TREE_CODE (val2) == SSA_NAME)
+ if (code2 == SSA_NAME)
/* NAME + CST > NAME */
return 1;
- else if (TREE_CODE (val2) == PLUS_EXPR)
+ else if (code2 == PLUS_EXPR)
/* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
- return compare_values (c1, c2);
- else if (TREE_CODE (val2) == MINUS_EXPR)
+ return compare_values_warnv (c1, c2, strict_overflow_p);
+ else if (code2 == MINUS_EXPR)
/* NAME + CST1 > NAME - CST2 */
return 1;
}
- else if (TREE_CODE (val1) == MINUS_EXPR)
+ else if (code1 == MINUS_EXPR)
{
- if (TREE_CODE (val2) == SSA_NAME)
+ if (code2 == SSA_NAME)
/* NAME - CST < NAME */
return -1;
- else if (TREE_CODE (val2) == PLUS_EXPR)
+ else if (code2 == PLUS_EXPR)
/* NAME - CST1 < NAME + CST2 */
return -1;
- else if (TREE_CODE (val2) == MINUS_EXPR)
+ else if (code2 == MINUS_EXPR)
/* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
C1 and C2 are swapped in the call to compare_values. */
- return compare_values (c2, c1);
+ return compare_values_warnv (c2, c1, strict_overflow_p);
}
gcc_unreachable ();
return -2;
if (!POINTER_TYPE_P (TREE_TYPE (val1)))
- return tree_int_cst_compare (val1, val2);
+ {
+ /* We cannot compare overflowed values, except for overflow
+ infinities. */
+ if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
+ {
+ if (strict_overflow_p != NULL)
+ *strict_overflow_p = true;
+ if (is_negative_overflow_infinity (val1))
+ return is_negative_overflow_infinity (val2) ? 0 : -1;
+ else if (is_negative_overflow_infinity (val2))
+ return 1;
+ else if (is_positive_overflow_infinity (val1))
+ return is_positive_overflow_infinity (val2) ? 0 : 1;
+ else if (is_positive_overflow_infinity (val2))
+ return -1;
+ return -2;
+ }
+
+ return tree_int_cst_compare (val1, val2);
+ }
else
{
tree t;
return 0;
/* If VAL1 is a lower address than VAL2, return -1. */
- t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
- if (t == boolean_true_node)
+ if (operand_less_p (val1, val2) == 1)
return -1;
/* If VAL1 is a higher address than VAL2, return +1. */
- t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
- if (t == boolean_true_node)
+ if (operand_less_p (val2, val1) == 1)
return 1;
- /* If VAL1 is different than VAL2, return +2. */
- t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
- if (t == boolean_true_node)
- return 2;
+ /* If VAL1 is different than VAL2, return +2.
+ For integer constants we either have already returned -1 or 1
+ or they are equivalent. We still might succeed in proving
+ something about non-trivial operands. */
+ if (TREE_CODE (val1) != INTEGER_CST
+ || TREE_CODE (val2) != INTEGER_CST)
+ {
+ t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
+ if (t && tree_expr_nonzero_p (t))
+ return 2;
+ }
return -2;
}
}
+/* Compare values like compare_values_warnv, but treat comparisons of
+ nonconstants which rely on undefined overflow as incomparable. */
+
+static int
+compare_values (tree val1, tree val2)
+{
+ bool sop;
+ int ret;
+
+ sop = false;
+ ret = compare_values_warnv (val1, val2, &sop);
+ if (sop
+ && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
+ ret = -2;
+ return ret;
+}
+
/* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
0 if VAL is not inside VR,
- -2 if we cannot tell either way. */
+ -2 if we cannot tell either way.
+
+ FIXME, the current semantics of this functions are a bit quirky
+ when taken in the context of VRP. In here we do not care
+ about VR's type. If VR is the anti-range ~[3, 5] the call
+ value_inside_range (4, VR) will return 1.
+
+ This is counter-intuitive in a strict sense, but the callers
+ currently expect this. They are calling the function
+ merely to determine whether VR->MIN <= VAL <= VR->MAX. The
+ callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
+ themselves.
+
+ This also applies to value_ranges_intersect_p and
+ range_includes_zero_p. The semantics of VR_RANGE and
+ VR_ANTI_RANGE should be encoded here, but that also means
+ adapting the users of these functions to the new semantics.
+
+ Benchmark compile/20001226-1.c compilation time after changing this
+ function. */
static inline int
-value_inside_range (tree val, value_range *vr)
+value_inside_range (tree val, value_range_t * vr)
{
int cmp1, cmp2;
- cmp1 = compare_values (val, vr->min);
- if (cmp1 == -2 || cmp1 == 2)
+ cmp1 = operand_less_p (val, vr->min);
+ if (cmp1 == -2)
return -2;
+ if (cmp1 == 1)
+ return 0;
- cmp2 = compare_values (val, vr->max);
- if (cmp2 == -2 || cmp2 == 2)
+ cmp2 = operand_less_p (vr->max, val);
+ if (cmp2 == -2)
return -2;
- return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
+ return !cmp2;
}
/* Return true if value ranges VR0 and VR1 have a non-empty
- intersection. */
+ intersection.
+
+ Benchmark compile/20001226-1.c compilation time after changing this
+ function.
+ */
static inline bool
-value_ranges_intersect_p (value_range *vr0, value_range *vr1)
+value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
+{
+ /* The value ranges do not intersect if the maximum of the first range is
+ less than the minimum of the second range or vice versa.
+ When those relations are unknown, we can't do any better. */
+ if (operand_less_p (vr0->max, vr1->min) != 0)
+ return false;
+ if (operand_less_p (vr1->max, vr0->min) != 0)
+ return false;
+ return true;
+}
+
+
+/* Return true if VR includes the value zero, false otherwise. FIXME,
+ currently this will return false for an anti-range like ~[-4, 3].
+ This will be wrong when the semantics of value_inside_range are
+ modified (currently the users of this function expect these
+ semantics). */
+
+static inline bool
+range_includes_zero_p (value_range_t *vr)
+{
+ tree zero;
+
+ gcc_assert (vr->type != VR_UNDEFINED
+ && vr->type != VR_VARYING
+ && !symbolic_range_p (vr));
+
+ zero = build_int_cst (TREE_TYPE (vr->min), 0);
+ return (value_inside_range (zero, vr) == 1);
+}
+
+/* Return true if T, an SSA_NAME, is known to be nonnegative. Return
+ false otherwise or if no value range information is available. */
+
+bool
+ssa_name_nonnegative_p (tree t)
+{
+ value_range_t *vr = get_value_range (t);
+
+ if (!vr)
+ return false;
+
+ /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
+ which would return a useful value should be encoded as a VR_RANGE. */
+ if (vr->type == VR_RANGE)
+ {
+ int result = compare_values (vr->min, integer_zero_node);
+
+ return (result == 0 || result == 1);
+ }
+ return false;
+}
+
+/* Return true if T, an SSA_NAME, is known to be nonzero. Return
+ false otherwise or if no value range information is available. */
+
+bool
+ssa_name_nonzero_p (tree t)
{
- return (value_inside_range (vr1->min, vr0) == 1
- || value_inside_range (vr1->max, vr0) == 1
- || value_inside_range (vr0->min, vr1) == 1
- || value_inside_range (vr0->max, vr1) == 1);
+ value_range_t *vr = get_value_range (t);
+
+ if (!vr)
+ return false;
+
+ /* A VR_RANGE which does not include zero is a nonzero value. */
+ if (vr->type == VR_RANGE && !symbolic_range_p (vr))
+ return ! range_includes_zero_p (vr);
+
+ /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
+ if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
+ return range_includes_zero_p (vr);
+
+ return false;
}
it in *VR_P. */
static void
-extract_range_from_assert (value_range *vr_p, tree expr)
+extract_range_from_assert (value_range_t *vr_p, tree expr)
{
- tree var, cond, limit, type;
- value_range *var_vr;
+ tree var, cond, limit, min, max, type;
+ value_range_t *var_vr, *limit_vr;
+ enum tree_code cond_code;
var = ASSERT_EXPR_VAR (expr);
cond = ASSERT_EXPR_COND (expr);
gcc_assert (COMPARISON_CLASS_P (cond));
/* Find VAR in the ASSERT_EXPR conditional. */
- limit = get_opposite_operand (cond, var);
- type = TREE_TYPE (limit);
+ if (var == TREE_OPERAND (cond, 0))
+ {
+ /* If the predicate is of the form VAR COMP LIMIT, then we just
+ take LIMIT from the RHS and use the same comparison code. */
+ limit = TREE_OPERAND (cond, 1);
+ cond_code = TREE_CODE (cond);
+ }
+ else
+ {
+ /* If the predicate is of the form LIMIT COMP VAR, then we need
+ to flip around the comparison code to create the proper range
+ for VAR. */
+ limit = TREE_OPERAND (cond, 0);
+ cond_code = swap_tree_comparison (TREE_CODE (cond));
+ }
+ type = TREE_TYPE (limit);
gcc_assert (limit != var);
- /* For pointer arithmetic, we only keep track of anti-ranges
- (NE_EXPR). Notice that we don't need to handle EQ_EXPR in these
- cases because assertions with equalities are never generated.
- The assert pass generates straight assignments in those cases. */
- if (POINTER_TYPE_P (type) && TREE_CODE (cond) != NE_EXPR)
+ /* For pointer arithmetic, we only keep track of pointer equality
+ and inequality. */
+ if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
{
- set_value_range (vr_p, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr_p);
return;
}
- if (TREE_CODE (cond) == NE_EXPR)
- set_value_range (vr_p, VR_ANTI_RANGE, limit, limit);
- else if (TREE_CODE (cond) == LE_EXPR)
- set_value_range (vr_p, VR_RANGE, TYPE_MIN_VALUE (type), limit);
- else if (TREE_CODE (cond) == LT_EXPR)
+ /* If LIMIT is another SSA name and LIMIT has a range of its own,
+ try to use LIMIT's range to avoid creating symbolic ranges
+ unnecessarily. */
+ limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
+
+ /* LIMIT's range is only interesting if it has any useful information. */
+ if (limit_vr
+ && (limit_vr->type == VR_UNDEFINED
+ || limit_vr->type == VR_VARYING
+ || symbolic_range_p (limit_vr)))
+ limit_vr = NULL;
+
+ /* Initially, the new range has the same set of equivalences of
+ VAR's range. This will be revised before returning the final
+ value. Since assertions may be chained via mutually exclusive
+ predicates, we will need to trim the set of equivalences before
+ we are done. */
+ gcc_assert (vr_p->equiv == NULL);
+ vr_p->equiv = BITMAP_ALLOC (NULL);
+ add_equivalence (vr_p->equiv, var);
+
+ /* Extract a new range based on the asserted comparison for VAR and
+ LIMIT's value range. Notice that if LIMIT has an anti-range, we
+ will only use it for equality comparisons (EQ_EXPR). For any
+ other kind of assertion, we cannot derive a range from LIMIT's
+ anti-range that can be used to describe the new range. For
+ instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
+ then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
+ no single range for x_2 that could describe LE_EXPR, so we might
+ as well build the range [b_4, +INF] for it. */
+ if (cond_code == EQ_EXPR)
+ {
+ enum value_range_type range_type;
+
+ if (limit_vr)
+ {
+ range_type = limit_vr->type;
+ min = limit_vr->min;
+ max = limit_vr->max;
+ }
+ else
+ {
+ range_type = VR_RANGE;
+ min = limit;
+ max = limit;
+ }
+
+ set_value_range (vr_p, range_type, min, max, vr_p->equiv);
+
+ /* When asserting the equality VAR == LIMIT and LIMIT is another
+ SSA name, the new range will also inherit the equivalence set
+ from LIMIT. */
+ if (TREE_CODE (limit) == SSA_NAME)
+ add_equivalence (vr_p->equiv, limit);
+ }
+ else if (cond_code == NE_EXPR)
{
- tree one = build_int_cst (type, 1);
- set_value_range (vr_p, VR_RANGE, TYPE_MIN_VALUE (type),
- fold (build (MINUS_EXPR, type, limit, one)));
+ /* As described above, when LIMIT's range is an anti-range and
+ this assertion is an inequality (NE_EXPR), then we cannot
+ derive anything from the anti-range. For instance, if
+ LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
+ not imply that VAR's range is [0, 0]. So, in the case of
+ anti-ranges, we just assert the inequality using LIMIT and
+ not its anti-range.
+
+ If LIMIT_VR is a range, we can only use it to build a new
+ anti-range if LIMIT_VR is a single-valued range. For
+ instance, if LIMIT_VR is [0, 1], the predicate
+ VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
+ Rather, it means that for value 0 VAR should be ~[0, 0]
+ and for value 1, VAR should be ~[1, 1]. We cannot
+ represent these ranges.
+
+ The only situation in which we can build a valid
+ anti-range is when LIMIT_VR is a single-valued range
+ (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
+ build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
+ if (limit_vr
+ && limit_vr->type == VR_RANGE
+ && compare_values (limit_vr->min, limit_vr->max) == 0)
+ {
+ min = limit_vr->min;
+ max = limit_vr->max;
+ }
+ else
+ {
+ /* In any other case, we cannot use LIMIT's range to build a
+ valid anti-range. */
+ min = max = limit;
+ }
+
+ /* If MIN and MAX cover the whole range for their type, then
+ just use the original LIMIT. */
+ if (INTEGRAL_TYPE_P (type)
+ && (min == TYPE_MIN_VALUE (type)
+ || is_negative_overflow_infinity (min))
+ && (max == TYPE_MAX_VALUE (type)
+ || is_positive_overflow_infinity (max)))
+ min = max = limit;
+
+ set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
+ }
+ else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
+ {
+ min = TYPE_MIN_VALUE (type);
+
+ if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
+ max = limit;
+ else
+ {
+ /* If LIMIT_VR is of the form [N1, N2], we need to build the
+ range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
+ LT_EXPR. */
+ max = limit_vr->max;
+ }
+
+ /* If the maximum value forces us to be out of bounds, simply punt.
+ It would be pointless to try and do anything more since this
+ all should be optimized away above us. */
+ if ((cond_code == LT_EXPR
+ && compare_values (max, min) == 0)
+ || is_overflow_infinity (max))
+ set_value_range_to_varying (vr_p);
+ else
+ {
+ /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
+ if (cond_code == LT_EXPR)
+ {
+ tree one = build_int_cst (type, 1);
+ max = fold_build2 (MINUS_EXPR, type, max, one);
+ }
+
+ set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
+ }
}
- else if (TREE_CODE (cond) == GE_EXPR)
- set_value_range (vr_p, VR_RANGE, limit, TYPE_MAX_VALUE (type));
- else if (TREE_CODE (cond) == GT_EXPR)
+ else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
{
- tree one = build_int_cst (type, 1);
- set_value_range (vr_p, VR_RANGE,
- fold (build (PLUS_EXPR, type, limit, one)),
- TYPE_MAX_VALUE (type));
+ max = TYPE_MAX_VALUE (type);
+
+ if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
+ min = limit;
+ else
+ {
+ /* If LIMIT_VR is of the form [N1, N2], we need to build the
+ range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
+ GT_EXPR. */
+ min = limit_vr->min;
+ }
+
+ /* If the minimum value forces us to be out of bounds, simply punt.
+ It would be pointless to try and do anything more since this
+ all should be optimized away above us. */
+ if ((cond_code == GT_EXPR
+ && compare_values (min, max) == 0)
+ || is_overflow_infinity (min))
+ set_value_range_to_varying (vr_p);
+ else
+ {
+ /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
+ if (cond_code == GT_EXPR)
+ {
+ tree one = build_int_cst (type, 1);
+ min = fold_build2 (PLUS_EXPR, type, min, one);
+ }
+
+ set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
+ }
}
else
gcc_unreachable ();
- /* If VAR already has a known range and the two ranges have a
- non-empty intersection, we can refine the resulting range.
- Since the assert expression creates an equivalency and at the
- same time it asserts a predicate, we can take the intersection of
- the two ranges to get better precision. */
+ /* If VAR already had a known range, it may happen that the new
+ range we have computed and VAR's range are not compatible. For
+ instance,
+
+ if (p_5 == NULL)
+ p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
+ x_7 = p_6->fld;
+ p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
+
+ While the above comes from a faulty program, it will cause an ICE
+ later because p_8 and p_6 will have incompatible ranges and at
+ the same time will be considered equivalent. A similar situation
+ would arise from
+
+ if (i_5 > 10)
+ i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
+ if (i_5 < 5)
+ i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
+
+ Again i_6 and i_7 will have incompatible ranges. It would be
+ pointless to try and do anything with i_7's range because
+ anything dominated by 'if (i_5 < 5)' will be optimized away.
+ Note, due to the wa in which simulation proceeds, the statement
+ i_7 = ASSERT_EXPR <...> we would never be visited because the
+ conditional 'if (i_5 < 5)' always evaluates to false. However,
+ this extra check does not hurt and may protect against future
+ changes to VRP that may get into a situation similar to the
+ NULL pointer dereference example.
+
+ Note that these compatibility tests are only needed when dealing
+ with ranges or a mix of range and anti-range. If VAR_VR and VR_P
+ are both anti-ranges, they will always be compatible, because two
+ anti-ranges will always have a non-empty intersection. */
+
var_vr = get_value_range (var);
- if (var_vr->type == VR_RANGE
- && vr_p->type == VR_RANGE
- && value_ranges_intersect_p (var_vr, vr_p))
+
+ /* We may need to make adjustments when VR_P and VAR_VR are numeric
+ ranges or anti-ranges. */
+ if (vr_p->type == VR_VARYING
+ || vr_p->type == VR_UNDEFINED
+ || var_vr->type == VR_VARYING
+ || var_vr->type == VR_UNDEFINED
+ || symbolic_range_p (vr_p)
+ || symbolic_range_p (var_vr))
+ return;
+
+ if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
{
- tree min, max;
+ /* If the two ranges have a non-empty intersection, we can
+ refine the resulting range. Since the assert expression
+ creates an equivalency and at the same time it asserts a
+ predicate, we can take the intersection of the two ranges to
+ get better precision. */
+ if (value_ranges_intersect_p (var_vr, vr_p))
+ {
+ /* Use the larger of the two minimums. */
+ if (compare_values (vr_p->min, var_vr->min) == -1)
+ min = var_vr->min;
+ else
+ min = vr_p->min;
- /* Use the larger of the two minimums. */
- if (compare_values (vr_p->min, var_vr->min) == -1)
- min = var_vr->min;
- else
- min = vr_p->min;
+ /* Use the smaller of the two maximums. */
+ if (compare_values (vr_p->max, var_vr->max) == 1)
+ max = var_vr->max;
+ else
+ max = vr_p->max;
- /* Use the smaller of the two maximums. */
- if (compare_values (vr_p->max, var_vr->max) == 1)
- max = var_vr->max;
+ set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
+ }
+ else
+ {
+ /* The two ranges do not intersect, set the new range to
+ VARYING, because we will not be able to do anything
+ meaningful with it. */
+ set_value_range_to_varying (vr_p);
+ }
+ }
+ else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
+ || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
+ {
+ /* A range and an anti-range will cancel each other only if
+ their ends are the same. For instance, in the example above,
+ p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
+ so VR_P should be set to VR_VARYING. */
+ if (compare_values (var_vr->min, vr_p->min) == 0
+ && compare_values (var_vr->max, vr_p->max) == 0)
+ set_value_range_to_varying (vr_p);
else
- max = vr_p->max;
+ {
+ tree min, max, anti_min, anti_max, real_min, real_max;
+ int cmp;
+
+ /* We want to compute the logical AND of the two ranges;
+ there are three cases to consider.
+
+
+ 1. The VR_ANTI_RANGE range is completely within the
+ VR_RANGE and the endpoints of the ranges are
+ different. In that case the resulting range
+ should be whichever range is more precise.
+ Typically that will be the VR_RANGE.
+
+ 2. The VR_ANTI_RANGE is completely disjoint from
+ the VR_RANGE. In this case the resulting range
+ should be the VR_RANGE.
+
+ 3. There is some overlap between the VR_ANTI_RANGE
+ and the VR_RANGE.
+
+ 3a. If the high limit of the VR_ANTI_RANGE resides
+ within the VR_RANGE, then the result is a new
+ VR_RANGE starting at the high limit of the
+ the VR_ANTI_RANGE + 1 and extending to the
+ high limit of the original VR_RANGE.
+
+ 3b. If the low limit of the VR_ANTI_RANGE resides
+ within the VR_RANGE, then the result is a new
+ VR_RANGE starting at the low limit of the original
+ VR_RANGE and extending to the low limit of the
+ VR_ANTI_RANGE - 1. */
+ if (vr_p->type == VR_ANTI_RANGE)
+ {
+ anti_min = vr_p->min;
+ anti_max = vr_p->max;
+ real_min = var_vr->min;
+ real_max = var_vr->max;
+ }
+ else
+ {
+ anti_min = var_vr->min;
+ anti_max = var_vr->max;
+ real_min = vr_p->min;
+ real_max = vr_p->max;
+ }
+
- set_value_range (vr_p, vr_p->type, min, max);
+ /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
+ not including any endpoints. */
+ if (compare_values (anti_max, real_max) == -1
+ && compare_values (anti_min, real_min) == 1)
+ {
+ set_value_range (vr_p, VR_RANGE, real_min,
+ real_max, vr_p->equiv);
+ }
+ /* Case 2, VR_ANTI_RANGE completely disjoint from
+ VR_RANGE. */
+ else if (compare_values (anti_min, real_max) == 1
+ || compare_values (anti_max, real_min) == -1)
+ {
+ set_value_range (vr_p, VR_RANGE, real_min,
+ real_max, vr_p->equiv);
+ }
+ /* Case 3a, the anti-range extends into the low
+ part of the real range. Thus creating a new
+ low for the real range. */
+ else if (((cmp = compare_values (anti_max, real_min)) == 1
+ || cmp == 0)
+ && compare_values (anti_max, real_max) == -1)
+ {
+ gcc_assert (!is_positive_overflow_infinity (anti_max));
+ if (needs_overflow_infinity (TREE_TYPE (anti_max))
+ && anti_max == TYPE_MAX_VALUE (TREE_TYPE (anti_max)))
+ {
+ if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
+ {
+ set_value_range_to_varying (vr_p);
+ return;
+ }
+ min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
+ }
+ else
+ min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
+ anti_max,
+ build_int_cst (TREE_TYPE (var_vr->min), 1));
+ max = real_max;
+ set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
+ }
+ /* Case 3b, the anti-range extends into the high
+ part of the real range. Thus creating a new
+ higher for the real range. */
+ else if (compare_values (anti_min, real_min) == 1
+ && ((cmp = compare_values (anti_min, real_max)) == -1
+ || cmp == 0))
+ {
+ gcc_assert (!is_negative_overflow_infinity (anti_min));
+ if (needs_overflow_infinity (TREE_TYPE (anti_min))
+ && anti_min == TYPE_MIN_VALUE (TREE_TYPE (anti_min)))
+ {
+ if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
+ {
+ set_value_range_to_varying (vr_p);
+ return;
+ }
+ max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
+ }
+ else
+ max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
+ anti_min,
+ build_int_cst (TREE_TYPE (var_vr->min), 1));
+ min = real_min;
+ set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
+ }
+ }
}
}
always false. */
static void
-extract_range_from_ssa_name (value_range *vr, tree var)
+extract_range_from_ssa_name (value_range_t *vr, tree var)
{
- value_range *var_vr = get_value_range (var);
+ value_range_t *var_vr = get_value_range (var);
if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
- *vr = *var_vr;
+ copy_value_range (vr, var_vr);
else
- set_value_range (vr, VR_RANGE, var, var);
+ set_value_range (vr, VR_RANGE, var, var, NULL);
+
+ add_equivalence (vr->equiv, var);
+}
+
+
+/* Wrapper around int_const_binop. If the operation overflows and we
+ are not using wrapping arithmetic, then adjust the result to be
+ -INF or +INF depending on CODE, VAL1 and VAL2. This can return
+ NULL_TREE if we need to use an overflow infinity representation but
+ the type does not support it. */
+
+static tree
+vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
+{
+ tree res;
+
+ res = int_const_binop (code, val1, val2, 0);
+
+ /* If we are not using wrapping arithmetic, operate symbolically
+ on -INF and +INF. */
+ if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
+ {
+ int checkz = compare_values (res, val1);
+ bool overflow = false;
+
+ /* Ensure that res = val1 [+*] val2 >= val1
+ or that res = val1 - val2 <= val1. */
+ if ((code == PLUS_EXPR
+ && !(checkz == 1 || checkz == 0))
+ || (code == MINUS_EXPR
+ && !(checkz == 0 || checkz == -1)))
+ {
+ overflow = true;
+ }
+ /* Checking for multiplication overflow is done by dividing the
+ output of the multiplication by the first input of the
+ multiplication. If the result of that division operation is
+ not equal to the second input of the multiplication, then the
+ multiplication overflowed. */
+ else if (code == MULT_EXPR && !integer_zerop (val1))
+ {
+ tree tmp = int_const_binop (TRUNC_DIV_EXPR,
+ res,
+ val1, 0);
+ int check = compare_values (tmp, val2);
+
+ if (check != 0)
+ overflow = true;
+ }
+
+ if (overflow)
+ {
+ res = copy_node (res);
+ TREE_OVERFLOW (res) = 1;
+ }
+
+ }
+ else if ((TREE_OVERFLOW (res)
+ && !TREE_OVERFLOW (val1)
+ && !TREE_OVERFLOW (val2))
+ || is_overflow_infinity (val1)
+ || is_overflow_infinity (val2))
+ {
+ /* If the operation overflowed but neither VAL1 nor VAL2 are
+ overflown, return -INF or +INF depending on the operation
+ and the combination of signs of the operands. */
+ int sgn1 = tree_int_cst_sgn (val1);
+ int sgn2 = tree_int_cst_sgn (val2);
+
+ if (needs_overflow_infinity (TREE_TYPE (res))
+ && !supports_overflow_infinity (TREE_TYPE (res)))
+ return NULL_TREE;
+
+ /* We have to punt on adding infinities of different signs,
+ since we can't tell what the sign of the result should be.
+ Likewise for subtracting infinities of the same sign. */
+ if (((code == PLUS_EXPR && sgn1 != sgn2)
+ || (code == MINUS_EXPR && sgn1 == sgn2))
+ && is_overflow_infinity (val1)
+ && is_overflow_infinity (val2))
+ return NULL_TREE;
+
+ /* Don't try to handle division or shifting of infinities. */
+ if ((code == TRUNC_DIV_EXPR
+ || code == FLOOR_DIV_EXPR
+ || code == CEIL_DIV_EXPR
+ || code == EXACT_DIV_EXPR
+ || code == ROUND_DIV_EXPR
+ || code == RSHIFT_EXPR)
+ && (is_overflow_infinity (val1)
+ || is_overflow_infinity (val2)))
+ return NULL_TREE;
+
+ /* Notice that we only need to handle the restricted set of
+ operations handled by extract_range_from_binary_expr.
+ Among them, only multiplication, addition and subtraction
+ can yield overflow without overflown operands because we
+ are working with integral types only... except in the
+ case VAL1 = -INF and VAL2 = -1 which overflows to +INF
+ for division too. */
+
+ /* For multiplication, the sign of the overflow is given
+ by the comparison of the signs of the operands. */
+ if ((code == MULT_EXPR && sgn1 == sgn2)
+ /* For addition, the operands must be of the same sign
+ to yield an overflow. Its sign is therefore that
+ of one of the operands, for example the first. For
+ infinite operands X + -INF is negative, not positive. */
+ || (code == PLUS_EXPR
+ && (sgn1 >= 0
+ ? !is_negative_overflow_infinity (val2)
+ : is_positive_overflow_infinity (val2)))
+ /* For subtraction, non-infinite operands must be of
+ different signs to yield an overflow. Its sign is
+ therefore that of the first operand or the opposite of
+ that of the second operand. A first operand of 0 counts
+ as positive here, for the corner case 0 - (-INF), which
+ overflows, but must yield +INF. For infinite operands 0
+ - INF is negative, not positive. */
+ || (code == MINUS_EXPR
+ && (sgn1 >= 0
+ ? !is_positive_overflow_infinity (val2)
+ : is_negative_overflow_infinity (val2)))
+ /* We only get in here with positive shift count, so the
+ overflow direction is the same as the sign of val1.
+ Actually rshift does not overflow at all, but we only
+ handle the case of shifting overflowed -INF and +INF. */
+ || (code == RSHIFT_EXPR
+ && sgn1 >= 0)
+ /* For division, the only case is -INF / -1 = +INF. */
+ || code == TRUNC_DIV_EXPR
+ || code == FLOOR_DIV_EXPR
+ || code == CEIL_DIV_EXPR
+ || code == EXACT_DIV_EXPR
+ || code == ROUND_DIV_EXPR)
+ return (needs_overflow_infinity (TREE_TYPE (res))
+ ? positive_overflow_infinity (TREE_TYPE (res))
+ : TYPE_MAX_VALUE (TREE_TYPE (res)));
+ else
+ return (needs_overflow_infinity (TREE_TYPE (res))
+ ? negative_overflow_infinity (TREE_TYPE (res))
+ : TYPE_MIN_VALUE (TREE_TYPE (res)));
+ }
+
+ return res;
}
the ranges of each of its operands and the expression code. */
static void
-extract_range_from_binary_expr (value_range *vr, tree expr)
+extract_range_from_binary_expr (value_range_t *vr, tree expr)
{
enum tree_code code = TREE_CODE (expr);
+ enum value_range_type type;
tree op0, op1, min, max;
- value_range vr0, vr1;
int cmp;
+ value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+ value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
/* Not all binary expressions can be applied to ranges in a
meaningful way. Handle only arithmetic operations. */
&& code != CEIL_DIV_EXPR
&& code != EXACT_DIV_EXPR
&& code != ROUND_DIV_EXPR
+ && code != RSHIFT_EXPR
&& code != MIN_EXPR
- && code != MAX_EXPR)
+ && code != MAX_EXPR
+ && code != BIT_AND_EXPR
+ && code != TRUTH_ANDIF_EXPR
+ && code != TRUTH_ORIF_EXPR
+ && code != TRUTH_AND_EXPR
+ && code != TRUTH_OR_EXPR)
{
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
return;
}
op0 = TREE_OPERAND (expr, 0);
if (TREE_CODE (op0) == SSA_NAME)
vr0 = *(get_value_range (op0));
+ else if (is_gimple_min_invariant (op0))
+ set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
else
- {
- if (is_gimple_min_invariant (op0))
- set_value_range (&vr0, VR_RANGE, op0, op0);
- else
- set_value_range (&vr0, VR_VARYING, NULL_TREE, NULL_TREE);
- }
+ set_value_range_to_varying (&vr0);
op1 = TREE_OPERAND (expr, 1);
if (TREE_CODE (op1) == SSA_NAME)
vr1 = *(get_value_range (op1));
+ else if (is_gimple_min_invariant (op1))
+ set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
else
- {
- if (is_gimple_min_invariant (op1))
- set_value_range (&vr1, VR_RANGE, op1, op1);
- else
- set_value_range (&vr1, VR_VARYING, 0, 0);
- }
+ set_value_range_to_varying (&vr1);
/* If either range is UNDEFINED, so is the result. */
if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
{
- set_value_range (vr, VR_UNDEFINED, NULL_TREE, NULL_TREE);
- return;
- }
-
- /* If either range is VARYING, so is the result. */
- if (vr0.type == VR_VARYING || vr1.type == VR_VARYING)
- {
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
- }
-
- /* If the ranges are of different types, the result is VARYING. */
- if (vr0.type != vr1.type)
- {
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_undefined (vr);
return;
}
- /* TODO. Refuse to do any symbolic range operations for now. */
- if (symbolic_range_p (&vr0) || symbolic_range_p (&vr1))
+ /* The type of the resulting value range defaults to VR0.TYPE. */
+ type = vr0.type;
+
+ /* Refuse to operate on VARYING ranges, ranges of different kinds
+ and symbolic ranges. As an exception, we allow BIT_AND_EXPR
+ because we may be able to derive a useful range even if one of
+ the operands is VR_VARYING or symbolic range. TODO, we may be
+ able to derive anti-ranges in some cases. */
+ if (code != BIT_AND_EXPR
+ && code != TRUTH_AND_EXPR
+ && code != TRUTH_OR_EXPR
+ && (vr0.type == VR_VARYING
+ || vr1.type == VR_VARYING
+ || vr0.type != vr1.type
+ || symbolic_range_p (&vr0)
+ || symbolic_range_p (&vr1)))
{
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
return;
}
|| POINTER_TYPE_P (TREE_TYPE (op1)))
{
/* For pointer types, we are really only interested in asserting
- whether the expression evaluates to non-NULL. FIXME. We
- used to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR),
- but ivopts is generating expressions with pointer
- multiplication in them. */
+ whether the expression evaluates to non-NULL. FIXME, we used
+ to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
+ ivopts is generating expressions with pointer multiplication
+ in them. */
if (code == PLUS_EXPR)
{
- /* Assume that pointers can never wrap around. FIXME, Is
- this always safe? */
- tree zero = build_int_cst (TREE_TYPE (expr), 0);
- set_value_range (vr, VR_ANTI_RANGE, zero, zero);
+ if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
+ set_value_range_to_nonnull (vr, TREE_TYPE (expr));
+ else if (range_is_null (&vr0) && range_is_null (&vr1))
+ set_value_range_to_null (vr, TREE_TYPE (expr));
+ else
+ set_value_range_to_varying (vr);
}
else
{
/* Subtracting from a pointer, may yield 0, so just drop the
resulting range to varying. */
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
}
return;
/* For integer ranges, apply the operation to each end of the
range and see what we end up with. */
- if (code == PLUS_EXPR
- || code == MULT_EXPR
- || code == MIN_EXPR
- || code == MAX_EXPR)
+ if (code == TRUTH_ANDIF_EXPR
+ || code == TRUTH_ORIF_EXPR
+ || code == TRUTH_AND_EXPR
+ || code == TRUTH_OR_EXPR)
+ {
+ /* If one of the operands is zero, we know that the whole
+ expression evaluates zero. */
+ if (code == TRUTH_AND_EXPR
+ && ((vr0.type == VR_RANGE
+ && integer_zerop (vr0.min)
+ && integer_zerop (vr0.max))
+ || (vr1.type == VR_RANGE
+ && integer_zerop (vr1.min)
+ && integer_zerop (vr1.max))))
+ {
+ type = VR_RANGE;
+ min = max = build_int_cst (TREE_TYPE (expr), 0);
+ }
+ /* If one of the operands is one, we know that the whole
+ expression evaluates one. */
+ else if (code == TRUTH_OR_EXPR
+ && ((vr0.type == VR_RANGE
+ && integer_onep (vr0.min)
+ && integer_onep (vr0.max))
+ || (vr1.type == VR_RANGE
+ && integer_onep (vr1.min)
+ && integer_onep (vr1.max))))
+ {
+ type = VR_RANGE;
+ min = max = build_int_cst (TREE_TYPE (expr), 1);
+ }
+ else if (vr0.type != VR_VARYING
+ && vr1.type != VR_VARYING
+ && vr0.type == vr1.type
+ && !symbolic_range_p (&vr0)
+ && !overflow_infinity_range_p (&vr0)
+ && !symbolic_range_p (&vr1)
+ && !overflow_infinity_range_p (&vr1))
+ {
+ /* Boolean expressions cannot be folded with int_const_binop. */
+ min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
+ max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
+ }
+ else
+ {
+ /* The result of a TRUTH_*_EXPR is always true or false. */
+ set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
+ return;
+ }
+ }
+ else if (code == PLUS_EXPR
+ || code == MIN_EXPR
+ || code == MAX_EXPR)
{
+ /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
+ VR_VARYING. It would take more effort to compute a precise
+ range for such a case. For example, if we have op0 == 1 and
+ op1 == -1 with their ranges both being ~[0,0], we would have
+ op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
+ Note that we are guaranteed to have vr0.type == vr1.type at
+ this point. */
+ if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
/* For operations that make the resulting range directly
proportional to the original ranges, apply the operation to
the same end of each range. */
- min = int_const_binop (code, vr0.min, vr1.min, 0);
- max = int_const_binop (code, vr0.max, vr1.max, 0);
+ min = vrp_int_const_binop (code, vr0.min, vr1.min);
+ max = vrp_int_const_binop (code, vr0.max, vr1.max);
+ }
+ else if (code == MULT_EXPR
+ || code == TRUNC_DIV_EXPR
+ || code == FLOOR_DIV_EXPR
+ || code == CEIL_DIV_EXPR
+ || code == EXACT_DIV_EXPR
+ || code == ROUND_DIV_EXPR
+ || code == RSHIFT_EXPR)
+ {
+ tree val[4];
+ size_t i;
+ bool sop;
+
+ /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
+ drop to VR_VARYING. It would take more effort to compute a
+ precise range for such a case. For example, if we have
+ op0 == 65536 and op1 == 65536 with their ranges both being
+ ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
+ we cannot claim that the product is in ~[0,0]. Note that we
+ are guaranteed to have vr0.type == vr1.type at this
+ point. */
+ if (code == MULT_EXPR
+ && vr0.type == VR_ANTI_RANGE
+ && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
+ then drop to VR_VARYING. Outside of this range we get undefined
+ behaviour from the shift operation. We cannot even trust
+ SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
+ shifts, and the operation at the tree level may be widened. */
+ if (code == RSHIFT_EXPR)
+ {
+ if (vr1.type == VR_ANTI_RANGE
+ || !vrp_expr_computes_nonnegative (op1, &sop)
+ || (operand_less_p
+ (build_int_cst (TREE_TYPE (vr1.max),
+ TYPE_PRECISION (TREE_TYPE (expr)) - 1),
+ vr1.max) != 0))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+
+ /* Multiplications and divisions are a bit tricky to handle,
+ depending on the mix of signs we have in the two ranges, we
+ need to operate on different values to get the minimum and
+ maximum values for the new range. One approach is to figure
+ out all the variations of range combinations and do the
+ operations.
+
+ However, this involves several calls to compare_values and it
+ is pretty convoluted. It's simpler to do the 4 operations
+ (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
+ MAX1) and then figure the smallest and largest values to form
+ the new range. */
+
+ /* Divisions by zero result in a VARYING value. */
+ else if (code != MULT_EXPR
+ && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* Compute the 4 cross operations. */
+ sop = false;
+ val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
+ if (val[0] == NULL_TREE)
+ sop = true;
+
+ if (vr1.max == vr1.min)
+ val[1] = NULL_TREE;
+ else
+ {
+ val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
+ if (val[1] == NULL_TREE)
+ sop = true;
+ }
+
+ if (vr0.max == vr0.min)
+ val[2] = NULL_TREE;
+ else
+ {
+ val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
+ if (val[2] == NULL_TREE)
+ sop = true;
+ }
+
+ if (vr0.min == vr0.max || vr1.min == vr1.max)
+ val[3] = NULL_TREE;
+ else
+ {
+ val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
+ if (val[3] == NULL_TREE)
+ sop = true;
+ }
+
+ if (sop)
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* Set MIN to the minimum of VAL[i] and MAX to the maximum
+ of VAL[i]. */
+ min = val[0];
+ max = val[0];
+ for (i = 1; i < 4; i++)
+ {
+ if (!is_gimple_min_invariant (min)
+ || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
+ || !is_gimple_min_invariant (max)
+ || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
+ break;
+
+ if (val[i])
+ {
+ if (!is_gimple_min_invariant (val[i])
+ || (TREE_OVERFLOW (val[i])
+ && !is_overflow_infinity (val[i])))
+ {
+ /* If we found an overflowed value, set MIN and MAX
+ to it so that we set the resulting range to
+ VARYING. */
+ min = max = val[i];
+ break;
+ }
+
+ if (compare_values (val[i], min) == -1)
+ min = val[i];
+
+ if (compare_values (val[i], max) == 1)
+ max = val[i];
+ }
+ }
+ }
+ else if (code == MINUS_EXPR)
+ {
+ /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
+ VR_VARYING. It would take more effort to compute a precise
+ range for such a case. For example, if we have op0 == 1 and
+ op1 == 1 with their ranges both being ~[0,0], we would have
+ op0 - op1 == 0, so we cannot claim that the difference is in
+ ~[0,0]. Note that we are guaranteed to have
+ vr0.type == vr1.type at this point. */
+ if (vr0.type == VR_ANTI_RANGE)
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* For MINUS_EXPR, apply the operation to the opposite ends of
+ each range. */
+ min = vrp_int_const_binop (code, vr0.min, vr1.max);
+ max = vrp_int_const_binop (code, vr0.max, vr1.min);
+ }
+ else if (code == BIT_AND_EXPR)
+ {
+ if (vr0.type == VR_RANGE
+ && vr0.min == vr0.max
+ && TREE_CODE (vr0.max) == INTEGER_CST
+ && !TREE_OVERFLOW (vr0.max)
+ && tree_int_cst_sgn (vr0.max) >= 0)
+ {
+ min = build_int_cst (TREE_TYPE (expr), 0);
+ max = vr0.max;
+ }
+ else if (vr1.type == VR_RANGE
+ && vr1.min == vr1.max
+ && TREE_CODE (vr1.max) == INTEGER_CST
+ && !TREE_OVERFLOW (vr1.max)
+ && tree_int_cst_sgn (vr1.max) >= 0)
+ {
+ type = VR_RANGE;
+ min = build_int_cst (TREE_TYPE (expr), 0);
+ max = vr1.max;
+ }
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
}
else
+ gcc_unreachable ();
+
+ /* If either MIN or MAX overflowed, then set the resulting range to
+ VARYING. But we do accept an overflow infinity
+ representation. */
+ if (min == NULL_TREE
+ || !is_gimple_min_invariant (min)
+ || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
+ || max == NULL_TREE
+ || !is_gimple_min_invariant (max)
+ || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* We punt if:
+ 1) [-INF, +INF]
+ 2) [-INF, +-INF(OVF)]
+ 3) [+-INF(OVF), +INF]
+ 4) [+-INF(OVF), +-INF(OVF)]
+ We learn nothing when we have INF and INF(OVF) on both sides.
+ Note that we do accept [-INF, -INF] and [+INF, +INF] without
+ overflow. */
+ if ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
+ || is_overflow_infinity (min))
+ && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
+ || is_overflow_infinity (max)))
{
- /* For operations that make the resulting range inversely
- proportional to the original ranges (-, /), apply the
- operation to the opposite ends of each range. */
- min = int_const_binop (code, vr0.min, vr1.max, 0);
- max = int_const_binop (code, vr0.max, vr1.min, 0);
+ set_value_range_to_varying (vr);
+ return;
}
cmp = compare_values (min, max);
/* If the new range has its limits swapped around (MIN > MAX),
then the operation caused one of them to wrap around, mark
the new range VARYING. */
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
}
else
- set_value_range (vr, vr0.type, min, max);
+ set_value_range (vr, type, min, max, NULL);
}
the range of its operand and the expression code. */
static void
-extract_range_from_unary_expr (value_range *vr, tree expr)
+extract_range_from_unary_expr (value_range_t *vr, tree expr)
{
enum tree_code code = TREE_CODE (expr);
tree min, max, op0;
- value_range vr0;
int cmp;
+ value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+
+ /* Refuse to operate on certain unary expressions for which we
+ cannot easily determine a resulting range. */
+ if (code == FIX_TRUNC_EXPR
+ || code == FLOAT_EXPR
+ || code == BIT_NOT_EXPR
+ || code == NON_LVALUE_EXPR
+ || code == CONJ_EXPR)
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
/* Get value ranges for the operand. For constant operands, create
a new value range with the operand to simplify processing. */
op0 = TREE_OPERAND (expr, 0);
if (TREE_CODE (op0) == SSA_NAME)
vr0 = *(get_value_range (op0));
+ else if (is_gimple_min_invariant (op0))
+ set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
else
- {
- if (is_gimple_min_invariant (op0))
- set_value_range (&vr0, VR_RANGE, op0, op0);
- else
- set_value_range (&vr0, VR_VARYING, NULL_TREE, NULL_TREE);
- }
+ set_value_range_to_varying (&vr0);
/* If VR0 is UNDEFINED, so is the result. */
if (vr0.type == VR_UNDEFINED)
{
- set_value_range (vr, VR_UNDEFINED, NULL_TREE, NULL_TREE);
- return;
- }
-
- /* If VR0 is VARYING, so is the result. */
- if (vr0.type == VR_VARYING)
- {
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
- }
-
- /* TODO. Refuse to do any symbolic range operations for now. */
- if (symbolic_range_p (&vr0))
- {
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_undefined (vr);
return;
}
- /* If the operand is neither a pointer nor an integral type, set the
- range to VARYING. TODO, we may set the range to non-zero. */
- if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
- && !POINTER_TYPE_P (TREE_TYPE (op0)))
+ /* Refuse to operate on symbolic ranges, or if neither operand is
+ a pointer or integral type. */
+ if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
+ && !POINTER_TYPE_P (TREE_TYPE (op0)))
+ || (vr0.type != VR_VARYING
+ && symbolic_range_p (&vr0)))
{
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
return;
}
determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
{
- if (range_is_nonnull (&vr0) || expr_computes_nonzero (expr))
+ bool sop;
+
+ sop = false;
+ if (range_is_nonnull (&vr0)
+ || (tree_expr_nonzero_warnv_p (expr, &sop)
+ && !sop))
set_value_range_to_nonnull (vr, TREE_TYPE (expr));
else if (range_is_null (&vr0))
set_value_range_to_null (vr, TREE_TYPE (expr));
else
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
return;
}
/* Handle unary expressions on integer ranges. */
- if ((code == NOP_EXPR || code == CONVERT_EXPR)
- && (TYPE_SIZE (TREE_TYPE (vr0.min)) != TYPE_SIZE (TREE_TYPE (expr))))
+ if (code == NOP_EXPR || code == CONVERT_EXPR)
{
+ tree inner_type = TREE_TYPE (op0);
+ tree outer_type = TREE_TYPE (expr);
+
+ /* If VR0 represents a simple range, then try to convert
+ the min and max values for the range to the same type
+ as OUTER_TYPE. If the results compare equal to VR0's
+ min and max values and the new min is still less than
+ or equal to the new max, then we can safely use the newly
+ computed range for EXPR. This allows us to compute
+ accurate ranges through many casts. */
+ if ((vr0.type == VR_RANGE
+ && !overflow_infinity_range_p (&vr0))
+ || (vr0.type == VR_VARYING
+ && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
+ {
+ tree new_min, new_max, orig_min, orig_max;
+
+ /* Convert the input operand min/max to OUTER_TYPE. If
+ the input has no range information, then use the min/max
+ for the input's type. */
+ if (vr0.type == VR_RANGE)
+ {
+ orig_min = vr0.min;
+ orig_max = vr0.max;
+ }
+ else
+ {
+ orig_min = TYPE_MIN_VALUE (inner_type);
+ orig_max = TYPE_MAX_VALUE (inner_type);
+ }
+
+ new_min = fold_convert (outer_type, orig_min);
+ new_max = fold_convert (outer_type, orig_max);
+
+ /* Verify the new min/max values are gimple values and
+ that they compare equal to the original input's
+ min/max values. */
+ if (is_gimple_val (new_min)
+ && is_gimple_val (new_max)
+ && tree_int_cst_equal (new_min, orig_min)
+ && tree_int_cst_equal (new_max, orig_max)
+ && (cmp = compare_values (new_min, new_max)) <= 0
+ && cmp >= -1)
+ {
+ set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
+ return;
+ }
+ }
+
/* When converting types of different sizes, set the result to
VARYING. Things like sign extensions and precision loss may
change the range. For instance, if x_3 is of type 'long long
int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
is impossible to know at compile time whether y_5 will be
~[0, 0]. */
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
+ || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+
+ /* Conversion of a VR_VARYING value to a wider type can result
+ in a usable range. So wait until after we've handled conversions
+ before dropping the result to VR_VARYING if we had a source
+ operand that is VR_VARYING. */
+ if (vr0.type == VR_VARYING)
+ {
+ set_value_range_to_varying (vr);
return;
}
- /* Apply the operation to each end of the range and see what we end
- up with. */
- min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
- max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+ /* Apply the operation to each end of the range and see what we end
+ up with. */
+ if (code == NEGATE_EXPR
+ && !TYPE_UNSIGNED (TREE_TYPE (expr)))
+ {
+ /* NEGATE_EXPR flips the range around. We need to treat
+ TYPE_MIN_VALUE specially. */
+ if (is_positive_overflow_infinity (vr0.max))
+ min = negative_overflow_infinity (TREE_TYPE (expr));
+ else if (is_negative_overflow_infinity (vr0.max))
+ min = positive_overflow_infinity (TREE_TYPE (expr));
+ else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+ else if (needs_overflow_infinity (TREE_TYPE (expr)))
+ {
+ if (supports_overflow_infinity (TREE_TYPE (expr)))
+ min = positive_overflow_infinity (TREE_TYPE (expr));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+ else
+ min = TYPE_MIN_VALUE (TREE_TYPE (expr));
+
+ if (is_positive_overflow_infinity (vr0.min))
+ max = negative_overflow_infinity (TREE_TYPE (expr));
+ else if (is_negative_overflow_infinity (vr0.min))
+ max = positive_overflow_infinity (TREE_TYPE (expr));
+ else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+ else if (needs_overflow_infinity (TREE_TYPE (expr)))
+ {
+ if (supports_overflow_infinity (TREE_TYPE (expr)))
+ max = positive_overflow_infinity (TREE_TYPE (expr));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+ else
+ max = TYPE_MIN_VALUE (TREE_TYPE (expr));
+ }
+ else if (code == NEGATE_EXPR
+ && TYPE_UNSIGNED (TREE_TYPE (expr)))
+ {
+ if (!range_includes_zero_p (&vr0))
+ {
+ max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+ min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+ }
+ else
+ {
+ if (range_is_null (&vr0))
+ set_value_range_to_null (vr, TREE_TYPE (expr));
+ else
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+ else if (code == ABS_EXPR
+ && !TYPE_UNSIGNED (TREE_TYPE (expr)))
+ {
+ /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
+ useful range. */
+ if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
+ && ((vr0.type == VR_RANGE
+ && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ || (vr0.type == VR_ANTI_RANGE
+ && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
+ && !range_includes_zero_p (&vr0))))
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ /* ABS_EXPR may flip the range around, if the original range
+ included negative values. */
+ if (is_overflow_infinity (vr0.min))
+ min = positive_overflow_infinity (TREE_TYPE (expr));
+ else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+ else if (!needs_overflow_infinity (TREE_TYPE (expr)))
+ min = TYPE_MAX_VALUE (TREE_TYPE (expr));
+ else if (supports_overflow_infinity (TREE_TYPE (expr)))
+ min = positive_overflow_infinity (TREE_TYPE (expr));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ if (is_overflow_infinity (vr0.max))
+ max = positive_overflow_infinity (TREE_TYPE (expr));
+ else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+ else if (!needs_overflow_infinity (TREE_TYPE (expr)))
+ max = TYPE_MAX_VALUE (TREE_TYPE (expr));
+ else if (supports_overflow_infinity (TREE_TYPE (expr)))
+ max = positive_overflow_infinity (TREE_TYPE (expr));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+
+ cmp = compare_values (min, max);
+
+ /* If a VR_ANTI_RANGEs contains zero, then we have
+ ~[-INF, min(MIN, MAX)]. */
+ if (vr0.type == VR_ANTI_RANGE)
+ {
+ if (range_includes_zero_p (&vr0))
+ {
+ /* Take the lower of the two values. */
+ if (cmp != 1)
+ max = min;
+
+ /* Create ~[-INF, min (abs(MIN), abs(MAX))]
+ or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
+ flag_wrapv is set and the original anti-range doesn't include
+ TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
+ if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
+ {
+ tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
+
+ min = (vr0.min != type_min_value
+ ? int_const_binop (PLUS_EXPR, type_min_value,
+ integer_one_node, 0)
+ : type_min_value);
+ }
+ else
+ {
+ if (overflow_infinity_range_p (&vr0))
+ min = negative_overflow_infinity (TREE_TYPE (expr));
+ else
+ min = TYPE_MIN_VALUE (TREE_TYPE (expr));
+ }
+ }
+ else
+ {
+ /* All else has failed, so create the range [0, INF], even for
+ flag_wrapv since TYPE_MIN_VALUE is in the original
+ anti-range. */
+ vr0.type = VR_RANGE;
+ min = build_int_cst (TREE_TYPE (expr), 0);
+ if (needs_overflow_infinity (TREE_TYPE (expr)))
+ {
+ if (supports_overflow_infinity (TREE_TYPE (expr)))
+ max = positive_overflow_infinity (TREE_TYPE (expr));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+ else
+ max = TYPE_MAX_VALUE (TREE_TYPE (expr));
+ }
+ }
+
+ /* If the range contains zero then we know that the minimum value in the
+ range will be zero. */
+ else if (range_includes_zero_p (&vr0))
+ {
+ if (cmp == 1)
+ max = min;
+ min = build_int_cst (TREE_TYPE (expr), 0);
+ }
+ else
+ {
+ /* If the range was reversed, swap MIN and MAX. */
+ if (cmp == 1)
+ {
+ tree t = min;
+ min = max;
+ max = t;
+ }
+ }
+ }
+ else
+ {
+ /* Otherwise, operate on each end of the range. */
+ min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+ max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+
+ if (needs_overflow_infinity (TREE_TYPE (expr)))
+ {
+ gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
+ if (is_overflow_infinity (vr0.min))
+ min = vr0.min;
+ else if (TREE_OVERFLOW (min))
+ {
+ if (supports_overflow_infinity (TREE_TYPE (expr)))
+ min = (tree_int_cst_sgn (min) >= 0
+ ? positive_overflow_infinity (TREE_TYPE (min))
+ : negative_overflow_infinity (TREE_TYPE (min)));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+
+ if (is_overflow_infinity (vr0.max))
+ max = vr0.max;
+ else if (TREE_OVERFLOW (max))
+ {
+ if (supports_overflow_infinity (TREE_TYPE (expr)))
+ max = (tree_int_cst_sgn (max) >= 0
+ ? positive_overflow_infinity (TREE_TYPE (max))
+ : negative_overflow_infinity (TREE_TYPE (max)));
+ else
+ {
+ set_value_range_to_varying (vr);
+ return;
+ }
+ }
+ }
+ }
cmp = compare_values (min, max);
if (cmp == -2 || cmp == 1)
/* If the new range has its limits swapped around (MIN > MAX),
then the operation caused one of them to wrap around, mark
the new range VARYING. */
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr);
+ }
+ else
+ set_value_range (vr, vr0.type, min, max, NULL);
+}
+
+
+/* Extract range information from a conditional expression EXPR based on
+ the ranges of each of its operands and the expression code. */
+
+static void
+extract_range_from_cond_expr (value_range_t *vr, tree expr)
+{
+ tree op0, op1;
+ value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+ value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+
+ /* Get value ranges for each operand. For constant operands, create
+ a new value range with the operand to simplify processing. */
+ op0 = COND_EXPR_THEN (expr);
+ if (TREE_CODE (op0) == SSA_NAME)
+ vr0 = *(get_value_range (op0));
+ else if (is_gimple_min_invariant (op0))
+ set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
+ else
+ set_value_range_to_varying (&vr0);
+
+ op1 = COND_EXPR_ELSE (expr);
+ if (TREE_CODE (op1) == SSA_NAME)
+ vr1 = *(get_value_range (op1));
+ else if (is_gimple_min_invariant (op1))
+ set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
+ else
+ set_value_range_to_varying (&vr1);
+
+ /* The resulting value range is the union of the operand ranges */
+ vrp_meet (&vr0, &vr1);
+ copy_value_range (vr, &vr0);
+}
+
+
+/* Extract range information from a comparison expression EXPR based
+ on the range of its operand and the expression code. */
+
+static void
+extract_range_from_comparison (value_range_t *vr, tree expr)
+{
+ bool sop = false;
+ tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
+
+ /* A disadvantage of using a special infinity as an overflow
+ representation is that we lose the ability to record overflow
+ when we don't have an infinity. So we have to ignore a result
+ which relies on overflow. */
+
+ if (val && !is_overflow_infinity (val) && !sop)
+ {
+ /* Since this expression was found on the RHS of an assignment,
+ its type may be different from _Bool. Convert VAL to EXPR's
+ type. */
+ val = fold_convert (TREE_TYPE (expr), val);
+ set_value_range (vr, VR_RANGE, val, val, vr->equiv);
}
else
- set_value_range (vr, vr0.type, min, max);
+ /* The result of a comparison is always true or false. */
+ set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
}
/* Try to compute a useful range out of expression EXPR and store it
- in *VR_P. */
+ in *VR. */
static void
-extract_range_from_expr (value_range *vr, tree expr)
+extract_range_from_expr (value_range_t *vr, tree expr)
{
enum tree_code code = TREE_CODE (expr);
extract_range_from_assert (vr, expr);
else if (code == SSA_NAME)
extract_range_from_ssa_name (vr, expr);
- else if (TREE_CODE_CLASS (code) == tcc_binary)
+ else if (TREE_CODE_CLASS (code) == tcc_binary
+ || code == TRUTH_ANDIF_EXPR
+ || code == TRUTH_ORIF_EXPR
+ || code == TRUTH_AND_EXPR
+ || code == TRUTH_OR_EXPR
+ || code == TRUTH_XOR_EXPR)
extract_range_from_binary_expr (vr, expr);
else if (TREE_CODE_CLASS (code) == tcc_unary)
extract_range_from_unary_expr (vr, expr);
- else if (expr_computes_nonzero (expr))
- set_value_range_to_nonnull (vr, TREE_TYPE (expr));
- else if (TREE_CODE (expr) == INTEGER_CST)
- set_value_range (vr, VR_RANGE, expr, expr);
+ else if (code == COND_EXPR)
+ extract_range_from_cond_expr (vr, expr);
+ else if (TREE_CODE_CLASS (code) == tcc_comparison)
+ extract_range_from_comparison (vr, expr);
+ else if (is_gimple_min_invariant (expr))
+ set_value_range (vr, VR_RANGE, expr, expr, NULL);
else
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
-}
+ set_value_range_to_varying (vr);
+ /* If we got a varying range from the tests above, try a final
+ time to derive a nonnegative or nonzero range. This time
+ relying primarily on generic routines in fold in conjunction
+ with range data. */
+ if (vr->type == VR_VARYING)
+ {
+ bool sop = false;
+
+ if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
+ && vrp_expr_computes_nonnegative (expr, &sop))
+ set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
+ sop || is_overflow_infinity (expr));
+ else if (vrp_expr_computes_nonzero (expr, &sop)
+ && !sop)
+ set_value_range_to_nonnull (vr, TREE_TYPE (expr));
+ }
+}
-/* Given a range VR, a loop L and a variable VAR, determine whether it
+/* Given a range VR, a LOOP and a variable VAR, determine whether it
would be profitable to adjust VR using scalar evolution information
for VAR. If so, update VR with the new limits. */
static void
-adjust_range_with_scev (value_range *vr, struct loop *l, tree var)
+adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
+ tree var)
{
- tree init, step, chrec;
- bool init_is_max;
+ tree init, step, chrec, tmin, tmax, min, max, type;
+ enum ev_direction dir;
/* TODO. Don't adjust anti-ranges. An anti-range may provide
better opportunities than a regular range, but I'm not sure. */
if (vr->type == VR_ANTI_RANGE)
return;
- chrec = analyze_scalar_evolution (l, var);
+ chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
return;
- init = CHREC_LEFT (chrec);
- step = CHREC_RIGHT (chrec);
+ init = initial_condition_in_loop_num (chrec, loop->num);
+ step = evolution_part_in_loop_num (chrec, loop->num);
/* If STEP is symbolic, we can't know whether INIT will be the
- minimum or maximum value in the range. */
- if (!is_gimple_min_invariant (step))
+ minimum or maximum value in the range. Also, unless INIT is
+ a simple expression, compare_values and possibly other functions
+ in tree-vrp won't be able to handle it. */
+ if (step == NULL_TREE
+ || !is_gimple_min_invariant (step)
+ || !valid_value_p (init))
return;
- /* FIXME. When dealing with unsigned types,
- analyze_scalar_evolution sets STEP to very large unsigned values
- when the evolution goes backwards. This confuses this analysis
- because we think that INIT is the smallest value that the range
- can take, instead of the largest. Ignore these chrecs for now. */
- if (INTEGRAL_TYPE_P (TREE_TYPE (step)) && TYPE_UNSIGNED (TREE_TYPE (step)))
+ dir = scev_direction (chrec);
+ if (/* Do not adjust ranges if we do not know whether the iv increases
+ or decreases, ... */
+ dir == EV_DIR_UNKNOWN
+ /* ... or if it may wrap. */
+ || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
+ true))
return;
- /* If STEP is negative, then INIT is the maximum value the range
- will take. Otherwise, INIT is the minimum value. */
- init_is_max = (tree_int_cst_sgn (step) < 0);
+ /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
+ negative_overflow_infinity and positive_overflow_infinity,
+ because we have concluded that the loop probably does not
+ wrap. */
+
+ type = TREE_TYPE (var);
+ if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
+ tmin = lower_bound_in_type (type, type);
+ else
+ tmin = TYPE_MIN_VALUE (type);
+ if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
+ tmax = upper_bound_in_type (type, type);
+ else
+ tmax = TYPE_MAX_VALUE (type);
- if (!POINTER_TYPE_P (TREE_TYPE (init))
- && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
+ if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
{
+ min = tmin;
+ max = tmax;
+
/* For VARYING or UNDEFINED ranges, just about anything we get
from scalar evolutions should be better. */
- if (init_is_max)
- set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)), init);
+
+ if (dir == EV_DIR_DECREASES)
+ max = init;
else
- set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)));
+ min = init;
+
+ /* If we would create an invalid range, then just assume we
+ know absolutely nothing. This may be over-conservative,
+ but it's clearly safe, and should happen only in unreachable
+ parts of code, or for invalid programs. */
+ if (compare_values (min, max) == 1)
+ return;
+
+ set_value_range (vr, VR_RANGE, min, max, vr->equiv);
}
else if (vr->type == VR_RANGE)
{
- if (init_is_max)
+ min = vr->min;
+ max = vr->max;
+
+ if (dir == EV_DIR_DECREASES)
{
- /* INIT is the maximum value. If INIT is lower than
- VR->MAX, set VR->MAX to INIT. */
- if (compare_values (init, vr->max) == -1)
- set_value_range (vr, VR_RANGE, vr->min, init);
+ /* INIT is the maximum value. If INIT is lower than VR->MAX
+ but no smaller than VR->MIN, set VR->MAX to INIT. */
+ if (compare_values (init, max) == -1)
+ {
+ max = init;
+
+ /* If we just created an invalid range with the minimum
+ greater than the maximum, we fail conservatively.
+ This should happen only in unreachable
+ parts of code, or for invalid programs. */
+ if (compare_values (min, max) == 1)
+ return;
+ }
}
else
{
/* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
- if (compare_values (init, vr->min) == 1)
- set_value_range (vr, VR_RANGE, init, vr->max);
+ if (compare_values (init, min) == 1)
+ {
+ min = init;
+
+ /* Again, avoid creating invalid range by failing. */
+ if (compare_values (min, max) == 1)
+ return;
+ }
}
+
+ set_value_range (vr, VR_RANGE, min, max, vr->equiv);
}
}
/* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
- - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for all the
- values in the ranges.
+ - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
+ all the values in the ranges.
- Return BOOLEAN_FALSE_NODE if the comparison always returns false.
- - Return NULL_TREE if it is not always possible to determine the value of
- the comparison. */
+ - Return NULL_TREE if it is not always possible to determine the
+ value of the comparison.
+
+ Also set *STRICT_OVERFLOW_P to indicate whether a range with an
+ overflow infinity was used in the test. */
+
static tree
-compare_ranges (enum tree_code comp, value_range *vr0, value_range *vr1)
+compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
+ bool *strict_overflow_p)
{
/* VARYING or UNDEFINED ranges cannot be compared. */
if (vr0->type == VR_VARYING
if (vr0->type == VR_RANGE)
{
/* To simplify processing, make VR0 the anti-range. */
- value_range *tmp = vr0;
+ value_range_t *tmp = vr0;
vr0 = vr1;
vr1 = tmp;
}
gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
- if (compare_values (vr0->min, vr1->min) == 0
- && compare_values (vr0->max, vr1->max) == 0)
+ if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
+ && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
return NULL_TREE;
}
+ if (!usable_range_p (vr0, strict_overflow_p)
+ || !usable_range_p (vr1, strict_overflow_p))
+ return NULL_TREE;
+
/* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
operands around and change the comparison code. */
if (comp == GT_EXPR || comp == GE_EXPR)
{
- value_range *tmp;
+ value_range_t *tmp;
comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
tmp = vr0;
vr0 = vr1;
{
/* Equality may only be computed if both ranges represent
exactly one value. */
- if (compare_values (vr0->min, vr0->max) == 0
- && compare_values (vr1->min, vr1->max) == 0)
+ if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
+ && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
{
- int cmp_min = compare_values (vr0->min, vr1->min);
- int cmp_max = compare_values (vr0->max, vr1->max);
+ int cmp_min = compare_values_warnv (vr0->min, vr1->min,
+ strict_overflow_p);
+ int cmp_max = compare_values_warnv (vr0->max, vr1->max,
+ strict_overflow_p);
if (cmp_min == 0 && cmp_max == 0)
return boolean_true_node;
else if (cmp_min != -2 && cmp_max != -2)
return boolean_false_node;
}
+ /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
+ else if (compare_values_warnv (vr0->min, vr1->max,
+ strict_overflow_p) == 1
+ || compare_values_warnv (vr1->min, vr0->max,
+ strict_overflow_p) == 1)
+ return boolean_false_node;
return NULL_TREE;
}
make sure that both comparisons yield similar results to
avoid comparing values that cannot be compared at
compile-time. */
- cmp1 = compare_values (vr0->max, vr1->min);
- cmp2 = compare_values (vr0->min, vr1->max);
+ cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
+ cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
return boolean_true_node;
/* If VR0 and VR1 represent a single value and are identical,
return false. */
- else if (compare_values (vr0->min, vr0->max) == 0
- && compare_values (vr1->min, vr1->max) == 0
- && compare_values (vr0->min, vr1->min) == 0
- && compare_values (vr0->max, vr1->max) == 0)
+ else if (compare_values_warnv (vr0->min, vr0->max,
+ strict_overflow_p) == 0
+ && compare_values_warnv (vr1->min, vr1->max,
+ strict_overflow_p) == 0
+ && compare_values_warnv (vr0->min, vr1->min,
+ strict_overflow_p) == 0
+ && compare_values_warnv (vr0->max, vr1->max,
+ strict_overflow_p) == 0)
return boolean_false_node;
/* Otherwise, they may or may not be different. */
int tst;
/* If VR0 is to the left of VR1, return true. */
- tst = compare_values (vr0->max, vr1->min);
+ tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
if ((comp == LT_EXPR && tst == -1)
|| (comp == LE_EXPR && (tst == -1 || tst == 0)))
- return boolean_true_node;
+ {
+ if (overflow_infinity_range_p (vr0)
+ || overflow_infinity_range_p (vr1))
+ *strict_overflow_p = true;
+ return boolean_true_node;
+ }
/* If VR0 is to the right of VR1, return false. */
- tst = compare_values (vr0->min, vr1->max);
+ tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
if ((comp == LT_EXPR && (tst == 0 || tst == 1))
|| (comp == LE_EXPR && tst == 1))
- return boolean_false_node;
+ {
+ if (overflow_infinity_range_p (vr0)
+ || overflow_infinity_range_p (vr1))
+ *strict_overflow_p = true;
+ return boolean_false_node;
+ }
/* Otherwise, we don't know. */
return NULL_TREE;
/* Given a value range VR, a value VAL and a comparison code COMP, return
- BOOLEAN_TRUE_NODE if VR COMP VR1 always returns true for all the
+ BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
values in VR. Return BOOLEAN_FALSE_NODE if the comparison
always returns false. Return NULL_TREE if it is not always
- possible to determine the value of the comparison. */
+ possible to determine the value of the comparison. Also set
+ *STRICT_OVERFLOW_P to indicate whether a range with an overflow
+ infinity was used in the test. */
static tree
-compare_range_with_value (enum tree_code comp, value_range *vr, tree val)
+compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
+ bool *strict_overflow_p)
{
if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
return NULL_TREE;
|| comp == LE_EXPR)
return NULL_TREE;
- /* ~[VAL, VAL] == VAL is always false. */
- if (compare_values (vr->min, val) == 0
- && compare_values (vr->max, val) == 0)
+ /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
+ if (value_inside_range (val, vr) == 1)
return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
return NULL_TREE;
}
+ if (!usable_range_p (vr, strict_overflow_p))
+ return NULL_TREE;
+
if (comp == EQ_EXPR)
{
/* EQ_EXPR may only be computed if VR represents exactly
one value. */
- if (compare_values (vr->min, vr->max) == 0)
+ if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
{
- int cmp = compare_values (vr->min, val);
+ int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
if (cmp == 0)
return boolean_true_node;
else if (cmp == -1 || cmp == 1 || cmp == 2)
return boolean_false_node;
}
+ else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
+ || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
+ return boolean_false_node;
return NULL_TREE;
}
else if (comp == NE_EXPR)
{
/* If VAL is not inside VR, then they are always different. */
- if (compare_values (vr->max, val) == -1
- || compare_values (vr->min, val) == 1)
+ if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
+ || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
return boolean_true_node;
/* If VR represents exactly one value equal to VAL, then return
false. */
- if (compare_values (vr->min, vr->max) == 0
- && compare_values (vr->min, val) == 0)
+ if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
+ && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
return boolean_false_node;
/* Otherwise, they may or may not be different. */
int tst;
/* If VR is to the left of VAL, return true. */
- tst = compare_values (vr->max, val);
+ tst = compare_values_warnv (vr->max, val, strict_overflow_p);
if ((comp == LT_EXPR && tst == -1)
|| (comp == LE_EXPR && (tst == -1 || tst == 0)))
- return boolean_true_node;
+ {
+ if (overflow_infinity_range_p (vr))
+ *strict_overflow_p = true;
+ return boolean_true_node;
+ }
/* If VR is to the right of VAL, return false. */
- tst = compare_values (vr->min, val);
+ tst = compare_values_warnv (vr->min, val, strict_overflow_p);
if ((comp == LT_EXPR && (tst == 0 || tst == 1))
|| (comp == LE_EXPR && tst == 1))
- return boolean_false_node;
+ {
+ if (overflow_infinity_range_p (vr))
+ *strict_overflow_p = true;
+ return boolean_false_node;
+ }
/* Otherwise, we don't know. */
return NULL_TREE;
int tst;
/* If VR is to the right of VAL, return true. */
- tst = compare_values (vr->min, val);
+ tst = compare_values_warnv (vr->min, val, strict_overflow_p);
if ((comp == GT_EXPR && tst == 1)
|| (comp == GE_EXPR && (tst == 0 || tst == 1)))
- return boolean_true_node;
+ {
+ if (overflow_infinity_range_p (vr))
+ *strict_overflow_p = true;
+ return boolean_true_node;
+ }
/* If VR is to the left of VAL, return false. */
- tst = compare_values (vr->max, val);
+ tst = compare_values_warnv (vr->max, val, strict_overflow_p);
if ((comp == GT_EXPR && (tst == -1 || tst == 0))
|| (comp == GE_EXPR && tst == -1))
- return boolean_false_node;
+ {
+ if (overflow_infinity_range_p (vr))
+ *strict_overflow_p = true;
+ return boolean_false_node;
+ }
/* Otherwise, we don't know. */
return NULL_TREE;
/* Debugging dumps. */
+void dump_value_range (FILE *, value_range_t *);
+void debug_value_range (value_range_t *);
+void dump_all_value_ranges (FILE *);
+void debug_all_value_ranges (void);
+void dump_vr_equiv (FILE *, bitmap);
+void debug_vr_equiv (bitmap);
+
+
+/* Dump value range VR to FILE. */
+
void
-dump_value_range (FILE *file, value_range *vr)
+dump_value_range (FILE *file, value_range_t *vr)
{
if (vr == NULL)
fprintf (file, "[]");
fprintf (file, "UNDEFINED");
else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
{
+ tree type = TREE_TYPE (vr->min);
+
fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
- print_generic_expr (file, vr->min, 0);
+
+ if (INTEGRAL_TYPE_P (type)
+ && !TYPE_UNSIGNED (type)
+ && vr->min == TYPE_MIN_VALUE (type))
+ fprintf (file, "-INF");
+ else if (needs_overflow_infinity (type)
+ && is_negative_overflow_infinity (vr->min))
+ fprintf (file, "-INF(OVF)");
+ else
+ print_generic_expr (file, vr->min, 0);
+
fprintf (file, ", ");
- print_generic_expr (file, vr->max, 0);
+
+ if (INTEGRAL_TYPE_P (type)
+ && vr->max == TYPE_MAX_VALUE (type))
+ fprintf (file, "+INF");
+ else if (needs_overflow_infinity (type)
+ && is_positive_overflow_infinity (vr->max))
+ fprintf (file, "+INF(OVF)");
+ else
+ print_generic_expr (file, vr->max, 0);
+
fprintf (file, "]");
+
+ if (vr->equiv)
+ {
+ bitmap_iterator bi;
+ unsigned i, c = 0;
+
+ fprintf (file, " EQUIVALENCES: { ");
+
+ EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
+ {
+ print_generic_expr (file, ssa_name (i), 0);
+ fprintf (file, " ");
+ c++;
+ }
+
+ fprintf (file, "} (%u elements)", c);
+ }
}
else if (vr->type == VR_VARYING)
fprintf (file, "VARYING");
/* Dump value range VR to stderr. */
void
-debug_value_range (value_range *vr)
+debug_value_range (value_range_t *vr)
{
dump_value_range (stderr, vr);
+ fprintf (stderr, "\n");
}
for (i = 0; i < num_ssa_names; i++)
{
- tree var = ssa_name (i);
- if (var && SSA_NAME_VALUE_RANGE (var))
+ if (vr_value[i])
{
- print_generic_expr (file, var, 0);
+ print_generic_expr (file, ssa_name (i), 0);
fprintf (file, ": ");
- dump_value_range (file, SSA_NAME_VALUE_RANGE (var));
+ dump_value_range (file, vr_value[i]);
fprintf (file, "\n");
}
}
}
-/*---------------------------------------------------------------------------
- Value Range Propagation
----------------------------------------------------------------------------*/
-
/* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
create a new SSA name N and return the assertion assignment
'V = ASSERT_EXPR <V, V OP W>'. */
if (COMPARISON_CLASS_P (cond))
{
- /* Build N = ASSERT_EXPR <V, COND>. As a special case, if the
- conditional is an EQ_EXPR (V == Z), just build the assignment
- N = Z. */
- if (TREE_CODE (cond) == EQ_EXPR)
- {
- tree other = get_opposite_operand (cond, v);
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, other);
- }
- else
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n,
- build (ASSERT_EXPR, TREE_TYPE (v), v, cond));
+ tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
+ assertion = build_gimple_modify_stmt (n, a);
}
else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
{
/* Given !V, build the assignment N = false. */
tree op0 = TREE_OPERAND (cond, 0);
gcc_assert (op0 == v);
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
+ assertion = build_gimple_modify_stmt (n, boolean_false_node);
}
else if (TREE_CODE (cond) == SSA_NAME)
{
/* Given V, build the assignment N = true. */
gcc_assert (v == cond);
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
+ assertion = build_gimple_modify_stmt (n, boolean_true_node);
}
else
gcc_unreachable ();
}
-/* Return an expression predicate that represents the range of values
- that can be taken by operand OP after STMT executes. */
+/* If the range of values taken by OP can be inferred after STMT executes,
+ return the comparison code (COMP_CODE_P) and value (VAL_P) that
+ describes the inferred range. Return true if a range could be
+ inferred. */
-static tree
-infer_value_range (tree stmt, tree op)
+static bool
+infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
{
+ *val_p = NULL_TREE;
+ *comp_code_p = ERROR_MARK;
+
/* Do not attempt to infer anything in names that flow through
abnormal edges. */
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
- return NULL_TREE;
+ return false;
- if (POINTER_TYPE_P (TREE_TYPE (op)))
+ /* Similarly, don't infer anything from statements that may throw
+ exceptions. */
+ if (tree_could_throw_p (stmt))
+ return false;
+
+ /* If STMT is the last statement of a basic block with no
+ successors, there is no point inferring anything about any of its
+ operands. We would not be able to find a proper insertion point
+ for the assertion, anyway. */
+ if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
+ return false;
+
+ /* We can only assume that a pointer dereference will yield
+ non-NULL if -fdelete-null-pointer-checks is enabled. */
+ if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
{
bool is_store;
unsigned num_uses, num_derefs;
count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
- if (num_derefs > 0 && flag_delete_null_pointer_checks)
+ if (num_derefs > 0)
{
- /* We can only assume that a pointer dereference will yield
- non-NULL if -fdelete-null-pointer-checks is enabled. */
- tree null = build_int_cst (TREE_TYPE (op), 0);
- tree t = build (NE_EXPR, boolean_type_node, op, null);
- return t;
+ *val_p = build_int_cst (TREE_TYPE (op), 0);
+ *comp_code_p = NE_EXPR;
+ return true;
}
}
- return NULL_TREE;
+ return false;
+}
+
+
+void dump_asserts_for (FILE *, tree);
+void debug_asserts_for (tree);
+void dump_all_asserts (FILE *);
+void debug_all_asserts (void);
+
+/* Dump all the registered assertions for NAME to FILE. */
+
+void
+dump_asserts_for (FILE *file, tree name)
+{
+ assert_locus_t loc;
+
+ fprintf (file, "Assertions to be inserted for ");
+ print_generic_expr (file, name, 0);
+ fprintf (file, "\n");
+
+ loc = asserts_for[SSA_NAME_VERSION (name)];
+ while (loc)
+ {
+ fprintf (file, "\t");
+ print_generic_expr (file, bsi_stmt (loc->si), 0);
+ fprintf (file, "\n\tBB #%d", loc->bb->index);
+ if (loc->e)
+ {
+ fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
+ loc->e->dest->index);
+ dump_edge_info (file, loc->e, 0);
+ }
+ fprintf (file, "\n\tPREDICATE: ");
+ print_generic_expr (file, name, 0);
+ fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
+ print_generic_expr (file, loc->val, 0);
+ fprintf (file, "\n\n");
+ loc = loc->next;
+ }
+
+ fprintf (file, "\n");
+}
+
+
+/* Dump all the registered assertions for NAME to stderr. */
+
+void
+debug_asserts_for (tree name)
+{
+ dump_asserts_for (stderr, name);
+}
+
+
+/* Dump all the registered assertions for all the names to FILE. */
+
+void
+dump_all_asserts (FILE *file)
+{
+ unsigned i;
+ bitmap_iterator bi;
+
+ fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
+ EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
+ dump_asserts_for (file, ssa_name (i));
+ fprintf (file, "\n");
+}
+
+
+/* Dump all the registered assertions for all the names to stderr. */
+
+void
+debug_all_asserts (void)
+{
+ dump_all_asserts (stderr);
+}
+
+
+/* If NAME doesn't have an ASSERT_EXPR registered for asserting
+ 'NAME COMP_CODE VAL' at a location that dominates block BB or
+ E->DEST, then register this location as a possible insertion point
+ for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
+
+ BB, E and SI provide the exact insertion point for the new
+ ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
+ on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
+ BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
+ must not be NULL. */
+
+static void
+register_new_assert_for (tree name,
+ enum tree_code comp_code,
+ tree val,
+ basic_block bb,
+ edge e,
+ block_stmt_iterator si)
+{
+ assert_locus_t n, loc, last_loc;
+ bool found;
+ basic_block dest_bb;
+
+#if defined ENABLE_CHECKING
+ gcc_assert (bb == NULL || e == NULL);
+
+ if (e == NULL)
+ gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
+ && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
+#endif
+
+ /* The new assertion A will be inserted at BB or E. We need to
+ determine if the new location is dominated by a previously
+ registered location for A. If we are doing an edge insertion,
+ assume that A will be inserted at E->DEST. Note that this is not
+ necessarily true.
+
+ If E is a critical edge, it will be split. But even if E is
+ split, the new block will dominate the same set of blocks that
+ E->DEST dominates.
+
+ The reverse, however, is not true, blocks dominated by E->DEST
+ will not be dominated by the new block created to split E. So,
+ if the insertion location is on a critical edge, we will not use
+ the new location to move another assertion previously registered
+ at a block dominated by E->DEST. */
+ dest_bb = (bb) ? bb : e->dest;
+
+ /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
+ VAL at a block dominating DEST_BB, then we don't need to insert a new
+ one. Similarly, if the same assertion already exists at a block
+ dominated by DEST_BB and the new location is not on a critical
+ edge, then update the existing location for the assertion (i.e.,
+ move the assertion up in the dominance tree).
+
+ Note, this is implemented as a simple linked list because there
+ should not be more than a handful of assertions registered per
+ name. If this becomes a performance problem, a table hashed by
+ COMP_CODE and VAL could be implemented. */
+ loc = asserts_for[SSA_NAME_VERSION (name)];
+ last_loc = loc;
+ found = false;
+ while (loc)
+ {
+ if (loc->comp_code == comp_code
+ && (loc->val == val
+ || operand_equal_p (loc->val, val, 0)))
+ {
+ /* If the assertion NAME COMP_CODE VAL has already been
+ registered at a basic block that dominates DEST_BB, then
+ we don't need to insert the same assertion again. Note
+ that we don't check strict dominance here to avoid
+ replicating the same assertion inside the same basic
+ block more than once (e.g., when a pointer is
+ dereferenced several times inside a block).
+
+ An exception to this rule are edge insertions. If the
+ new assertion is to be inserted on edge E, then it will
+ dominate all the other insertions that we may want to
+ insert in DEST_BB. So, if we are doing an edge
+ insertion, don't do this dominance check. */
+ if (e == NULL
+ && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
+ return;
+
+ /* Otherwise, if E is not a critical edge and DEST_BB
+ dominates the existing location for the assertion, move
+ the assertion up in the dominance tree by updating its
+ location information. */
+ if ((e == NULL || !EDGE_CRITICAL_P (e))
+ && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
+ {
+ loc->bb = dest_bb;
+ loc->e = e;
+ loc->si = si;
+ return;
+ }
+ }
+
+ /* Update the last node of the list and move to the next one. */
+ last_loc = loc;
+ loc = loc->next;
+ }
+
+ /* If we didn't find an assertion already registered for
+ NAME COMP_CODE VAL, add a new one at the end of the list of
+ assertions associated with NAME. */
+ n = XNEW (struct assert_locus_d);
+ n->bb = dest_bb;
+ n->e = e;
+ n->si = si;
+ n->comp_code = comp_code;
+ n->val = val;
+ n->next = NULL;
+
+ if (last_loc)
+ last_loc->next = n;
+ else
+ asserts_for[SSA_NAME_VERSION (name)] = n;
+
+ bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
+}
+
+/* COND is a predicate which uses NAME. Extract a suitable test code
+ and value and store them into *CODE_P and *VAL_P so the predicate
+ is normalized to NAME *CODE_P *VAL_P.
+
+ If no extraction was possible, return FALSE, otherwise return TRUE.
+
+ If INVERT is true, then we invert the result stored into *CODE_P. */
+
+static bool
+extract_code_and_val_from_cond (tree name, tree cond, bool invert,
+ enum tree_code *code_p, tree *val_p)
+{
+ enum tree_code comp_code;
+ tree val;
+
+ /* Predicates may be a single SSA name or NAME OP VAL. */
+ if (cond == name)
+ {
+ /* If the predicate is a name, it must be NAME, in which
+ case we create the predicate NAME == true or
+ NAME == false accordingly. */
+ comp_code = EQ_EXPR;
+ val = invert ? boolean_false_node : boolean_true_node;
+ }
+ else
+ {
+ /* Otherwise, we have a comparison of the form NAME COMP VAL
+ or VAL COMP NAME. */
+ if (name == TREE_OPERAND (cond, 1))
+ {
+ /* If the predicate is of the form VAL COMP NAME, flip
+ COMP around because we need to register NAME as the
+ first operand in the predicate. */
+ comp_code = swap_tree_comparison (TREE_CODE (cond));
+ val = TREE_OPERAND (cond, 0);
+ }
+ else
+ {
+ /* The comparison is of the form NAME COMP VAL, so the
+ comparison code remains unchanged. */
+ comp_code = TREE_CODE (cond);
+ val = TREE_OPERAND (cond, 1);
+ }
+
+ /* Invert the comparison code as necessary. */
+ if (invert)
+ comp_code = invert_tree_comparison (comp_code, 0);
+
+ /* VRP does not handle float types. */
+ if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
+ return false;
+
+ /* Do not register always-false predicates.
+ FIXME: this works around a limitation in fold() when dealing with
+ enumerations. Given 'enum { N1, N2 } x;', fold will not
+ fold 'if (x > N2)' to 'if (0)'. */
+ if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
+ && INTEGRAL_TYPE_P (TREE_TYPE (val)))
+ {
+ tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
+ tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
+
+ if (comp_code == GT_EXPR
+ && (!max
+ || compare_values (val, max) == 0))
+ return false;
+
+ if (comp_code == LT_EXPR
+ && (!min
+ || compare_values (val, min) == 0))
+ return false;
+ }
+ }
+ *code_p = comp_code;
+ *val_p = val;
+ return true;
}
+/* OP is an operand of a truth value expression which is known to have
+ a particular value. Register any asserts for OP and for any
+ operands in OP's defining statement.
-/* Return true if OP is the result of an ASSERT_EXPR that tests the
- same condition as COND. */
+ If CODE is EQ_EXPR, then we want to register OP is zero (false),
+ if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
static bool
-has_assert_expr (tree op, tree cond)
+register_edge_assert_for_1 (tree op, enum tree_code code,
+ edge e, block_stmt_iterator bsi)
{
- tree def_stmt = SSA_NAME_DEF_STMT (op);
- tree assert_expr, other_cond, other_op;
+ bool retval = false;
+ tree op_def, rhs, val;
- /* If OP was not generated by an ASSERT_EXPR, return false. */
- if (TREE_CODE (def_stmt) != MODIFY_EXPR
- || TREE_CODE (TREE_OPERAND (def_stmt, 1)) != ASSERT_EXPR)
+ /* We only care about SSA_NAMEs. */
+ if (TREE_CODE (op) != SSA_NAME)
return false;
- assert_expr = TREE_OPERAND (def_stmt, 1);
- other_cond = ASSERT_EXPR_COND (assert_expr);
- other_op = ASSERT_EXPR_VAR (assert_expr);
+ /* We know that OP will have a zero or nonzero value. If OP is used
+ more than once go ahead and register an assert for OP.
- if (TREE_CODE (cond) == TREE_CODE (other_cond))
+ The FOUND_IN_SUBGRAPH support is not helpful in this situation as
+ it will always be set for OP (because OP is used in a COND_EXPR in
+ the subgraph). */
+ if (!has_single_use (op))
{
- tree t1, t2;
+ val = build_int_cst (TREE_TYPE (op), 0);
+ register_new_assert_for (op, code, val, NULL, e, bsi);
+ retval = true;
+ }
- /* If COND is not a comparison predicate, something is wrong. */
- gcc_assert (COMPARISON_CLASS_P (cond));
+ /* Now look at how OP is set. If it's set from a comparison,
+ a truth operation or some bit operations, then we may be able
+ to register information about the operands of that assignment. */
+ op_def = SSA_NAME_DEF_STMT (op);
+ if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
+ return retval;
- /* Note that we only need to compare against one of the operands
- of OTHER_COND.
-
- Suppose that we are about to insert the assertion ASSERT_EXPR
- <x_4, x_4 != 0> and the defining statement for x_4 is x_4 =
- ASSERT_EXPR <x_3, x_3 != 0>.
+ rhs = GIMPLE_STMT_OPERAND (op_def, 1);
- In this case, we don't really want to insert a new
- ASSERT_EXPR for x_4 because that would be redundant. We
- already know that x_4 is not 0. So, when comparing the
- conditionals 'x_3 != 0' and 'x_4 != 0', we don't want to
- compare x_3 and x_4, we just want to compare the predicate's
- code (!=) and the other operand (0). */
- if (TREE_OPERAND (cond, 0) == op)
- t1 = TREE_OPERAND (cond, 1);
- else
- t1 = TREE_OPERAND (cond, 0);
+ if (COMPARISON_CLASS_P (rhs))
+ {
+ bool invert = (code == EQ_EXPR ? true : false);
+ tree op0 = TREE_OPERAND (rhs, 0);
+ tree op1 = TREE_OPERAND (rhs, 1);
+
+ /* Conditionally register an assert for each SSA_NAME in the
+ comparison. */
+ if (TREE_CODE (op0) == SSA_NAME
+ && !has_single_use (op0)
+ && extract_code_and_val_from_cond (op0, rhs,
+ invert, &code, &val))
+ {
+ register_new_assert_for (op0, code, val, NULL, e, bsi);
+ retval = true;
+ }
+
+ /* Similarly for the second operand of the comparison. */
+ if (TREE_CODE (op1) == SSA_NAME
+ && !has_single_use (op1)
+ && extract_code_and_val_from_cond (op1, rhs,
+ invert, &code, &val))
+ {
+ register_new_assert_for (op1, code, val, NULL, e, bsi);
+ retval = true;
+ }
+ }
+ else if ((code == NE_EXPR
+ && (TREE_CODE (rhs) == TRUTH_AND_EXPR
+ || TREE_CODE (rhs) == BIT_AND_EXPR))
+ || (code == EQ_EXPR
+ && (TREE_CODE (rhs) == TRUTH_OR_EXPR
+ || TREE_CODE (rhs) == BIT_IOR_EXPR)))
+ {
+ /* Recurse on each operand. */
+ retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
+ code, e, bsi);
+ retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
+ code, e, bsi);
+ }
+ else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
+ {
+ /* Recurse, flipping CODE. */
+ code = invert_tree_comparison (code, false);
+ retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
+ code, e, bsi);
+ }
+ else if (TREE_CODE (rhs) == SSA_NAME)
+ {
+ /* Recurse through the copy. */
+ retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
+ }
+ else if (TREE_CODE (rhs) == NOP_EXPR
+ || TREE_CODE (rhs) == CONVERT_EXPR
+ || TREE_CODE (rhs) == NON_LVALUE_EXPR)
+ {
+ /* Recurse through the type conversion. */
+ retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
+ code, e, bsi);
+ }
+
+ return retval;
+}
+
+/* Try to register an edge assertion for SSA name NAME on edge E for
+ the condition COND contributing to the conditional jump pointed to by SI.
+ Return true if an assertion for NAME could be registered. */
+
+static bool
+register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
+{
+ tree val;
+ enum tree_code comp_code;
+ bool retval = false;
+ bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
+
+ /* Do not attempt to infer anything in names that flow through
+ abnormal edges. */
+ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
+ return false;
+
+ if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
+ &comp_code, &val))
+ return false;
+
+ /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
+ reachable from E. */
+ if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
+ {
+ register_new_assert_for (name, comp_code, val, NULL, e, si);
+ retval = true;
+ }
+
+ /* If COND is effectively an equality test of an SSA_NAME against
+ the value zero or one, then we may be able to assert values
+ for SSA_NAMEs which flow into COND. */
+
+ /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
+ statement of NAME we can assert both operands of the TRUTH_AND_EXPR
+ have nonzero value. */
+ if (((comp_code == EQ_EXPR && integer_onep (val))
+ || (comp_code == NE_EXPR && integer_zerop (val))))
+ {
+ tree def_stmt = SSA_NAME_DEF_STMT (name);
+
+ if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
+ && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
+ || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
+ {
+ tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
+ tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
+ retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
+ retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
+ }
+ }
+
+ /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
+ statement of NAME we can assert both operands of the TRUTH_OR_EXPR
+ have zero value. */
+ if (((comp_code == EQ_EXPR && integer_zerop (val))
+ || (comp_code == NE_EXPR && integer_onep (val))))
+ {
+ tree def_stmt = SSA_NAME_DEF_STMT (name);
+
+ if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
+ && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
+ || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
+ {
+ tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
+ tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
+ retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
+ retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
+ }
+ }
+
+ return retval;
+}
+
+
+static bool find_assert_locations (basic_block bb);
+
+/* Determine whether the outgoing edges of BB should receive an
+ ASSERT_EXPR for each of the operands of BB's LAST statement.
+ The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
+
+ If any of the sub-graphs rooted at BB have an interesting use of
+ the predicate operands, an assert location node is added to the
+ list of assertions for the corresponding operands. */
+
+static bool
+find_conditional_asserts (basic_block bb, tree last)
+{
+ bool need_assert;
+ block_stmt_iterator bsi;
+ tree op;
+ edge_iterator ei;
+ edge e;
+ ssa_op_iter iter;
- if (TREE_OPERAND (other_cond, 0) == other_op)
- t2 = TREE_OPERAND (other_cond, 1);
- else
- t2 = TREE_OPERAND (other_cond, 0);
+ need_assert = false;
+ bsi = bsi_for_stmt (last);
- return (t1 == t2 || operand_equal_p (t1, t2, 0));
+ /* Look for uses of the operands in each of the sub-graphs
+ rooted at BB. We need to check each of the outgoing edges
+ separately, so that we know what kind of ASSERT_EXPR to
+ insert. */
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if (e->dest == bb)
+ continue;
+
+ /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
+ Otherwise, when we finish traversing each of the sub-graphs, we
+ won't know whether the variables were found in the sub-graphs or
+ if they had been found in a block upstream from BB.
+
+ This is actually a bad idea is some cases, particularly jump
+ threading. Consider a CFG like the following:
+
+ 0
+ /|
+ 1 |
+ \|
+ 2
+ / \
+ 3 4
+
+ Assume that one or more operands in the conditional at the
+ end of block 0 are used in a conditional in block 2, but not
+ anywhere in block 1. In this case we will not insert any
+ assert statements in block 1, which may cause us to miss
+ opportunities to optimize, particularly for jump threading. */
+ FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
+ RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
+
+ /* Traverse the strictly dominated sub-graph rooted at E->DEST
+ to determine if any of the operands in the conditional
+ predicate are used. */
+ if (e->dest != bb)
+ need_assert |= find_assert_locations (e->dest);
+
+ /* Register the necessary assertions for each operand in the
+ conditional predicate. */
+ FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
+ need_assert |= register_edge_assert_for (op, e, bsi,
+ COND_EXPR_COND (last));
}
- return false;
+ /* Finally, indicate that we have found the operands in the
+ conditional. */
+ FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
+ SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
+
+ return need_assert;
}
-/* Traverse all the statements in block BB looking for used variables.
- Variables used in BB are added to bitmap FOUND. The algorithm
- works in three main parts:
+/* Traverse all the statements in block BB looking for statements that
+ may generate useful assertions for the SSA names in their operand.
+ If a statement produces a useful assertion A for name N_i, then the
+ list of assertions already generated for N_i is scanned to
+ determine if A is actually needed.
+
+ If N_i already had the assertion A at a location dominating the
+ current location, then nothing needs to be done. Otherwise, the
+ new location for A is recorded instead.
1- For every statement S in BB, all the variables used by S are
- added to bitmap FOUND.
+ added to bitmap FOUND_IN_SUBGRAPH.
2- If statement S uses an operand N in a way that exposes a known
value range for N, then if N was not already generated by an
- ASSERT_EXPR, create a new ASSERT_EXPR for N. For instance, if N
- is a pointer and the statement dereferences it, we can assume
- that N is not NULL.
+ ASSERT_EXPR, create a new assert location for N. For instance,
+ if N is a pointer and the statement dereferences it, we can
+ assume that N is not NULL.
3- COND_EXPRs are a special case of #2. We can derive range
information from the predicate but need to insert different
conditional block. If the last statement of BB is a conditional
expression of the form 'X op Y', then
- a) Remove X and Y from the set FOUND.
+ a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
- b) If the conditional dominates its THEN_CLAUSE sub-graph,
- recurse into it. On return, if X and/or Y are marked in
- FOUND, then an ASSERT_EXPR is added for the corresponding
- variable.
+ b) If the conditional is the only entry point to the sub-graph
+ corresponding to the THEN_CLAUSE, recurse into it. On
+ return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
+ an ASSERT_EXPR is added for the corresponding variable.
c) Repeat step (b) on the ELSE_CLAUSE.
- d) Mark X and Y in FOUND.
+ d) Mark X and Y in FOUND_IN_SUBGRAPH.
- 4- If BB does not end in a conditional expression, then we recurse
- into BB's dominator children.
-
- At the end of the recursive traversal, ASSERT_EXPRs will have been
- added to the edges of COND_EXPR blocks that have sub-graphs using
- one or both predicate operands. For instance,
+ For instance,
- if (a == 9)
- b = a;
- else
- b = c + 1;
+ if (a == 9)
+ b = a;
+ else
+ b = c + 1;
- In this case, an assertion on the THEN clause is useful to
- determine that 'a' is always 9 on that edge. However, an assertion
- on the ELSE clause would be unnecessary.
+ In this case, an assertion on the THEN clause is useful to
+ determine that 'a' is always 9 on that edge. However, an assertion
+ on the ELSE clause would be unnecessary.
- On exit from this function, all the names created by the newly
- inserted ASSERT_EXPRs need to be added to the SSA web by rewriting
- the SSA names that they replace.
+ 4- If BB does not end in a conditional expression, then we recurse
+ into BB's dominator children.
+ At the end of the recursive traversal, every SSA name will have a
+ list of locations where ASSERT_EXPRs should be added. When a new
+ location for name N is found, it is registered by calling
+ register_new_assert_for. That function keeps track of all the
+ registered assertions to prevent adding unnecessary assertions.
+ For instance, if a pointer P_4 is dereferenced more than once in a
+ dominator tree, only the location dominating all the dereference of
+ P_4 will receive an ASSERT_EXPR.
+
+ If this function returns true, then it means that there are names
+ for which we need to generate ASSERT_EXPRs. Those assertions are
+ inserted by process_assert_insertions.
+
TODO. Handle SWITCH_EXPR. */
static bool
-maybe_add_assert_expr (basic_block bb)
+find_assert_locations (basic_block bb)
{
block_stmt_iterator si;
- tree last;
- bool added;
- use_optype uses;
+ tree last, phi;
+ bool need_assert;
+ basic_block son;
+
+ if (TEST_BIT (blocks_visited, bb->index))
+ return false;
- /* Step 1. Mark all the SSA names used in BB in bitmap FOUND. */
- added = false;
+ SET_BIT (blocks_visited, bb->index);
+
+ need_assert = false;
+
+ /* Traverse all PHI nodes in BB marking used operands. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ use_operand_p arg_p;
+ ssa_op_iter i;
+
+ FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
+ {
+ tree arg = USE_FROM_PTR (arg_p);
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
+ SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
+ }
+ }
+ }
+
+ /* Traverse all the statements in BB marking used names and looking
+ for statements that may infer assertions for their used operands. */
last = NULL_TREE;
for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
{
tree stmt, op;
ssa_op_iter i;
-
+
stmt = bsi_stmt (si);
- /* Mark all the SSA names used by STMT in bitmap FOUND. If STMT
- is inside the sub-graph of a conditional block, when we
- return from this recursive walk, our parent will use the
- FOUND bitset to determine if one of the operands it was
- looking for was present in the sub-graph. */
+ /* See if we can derive an assertion for any of STMT's operands. */
FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
{
- tree cond;
-
- /* If OP is used only once, namely in this STMT, don't
- bother inserting an ASSERT_EXPR for it. Such an
- ASSERT_EXPR would do nothing but increase compile time.
- Experiments show that with this simple check, we can save
- more than 20% of ASSERT_EXPRs. */
- if (has_single_use (op))
- continue;
-
- SET_BIT (found, SSA_NAME_VERSION (op));
-
- cond = infer_value_range (stmt, op);
- if (!cond)
- continue;
-
- /* Step 2. If OP is used in such a way that we can infer a
- value range for it, create a new ASSERT_EXPR for OP
- (unless OP already has an ASSERT_EXPR). */
- gcc_assert (!is_ctrl_stmt (stmt));
+ tree value;
+ enum tree_code comp_code;
+
+ /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
+ the sub-graph of a conditional block, when we return from
+ this recursive walk, our parent will use the
+ FOUND_IN_SUBGRAPH bitset to determine if one of the
+ operands it was looking for was present in the sub-graph. */
+ SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
+
+ /* If OP is used in such a way that we can infer a value
+ range for it, and we don't find a previous assertion for
+ it, create a new assertion location node for OP. */
+ if (infer_value_range (stmt, op, &comp_code, &value))
+ {
+ /* If we are able to infer a nonzero value range for OP,
+ then walk backwards through the use-def chain to see if OP
+ was set via a typecast.
- if (has_assert_expr (op, cond))
- continue;
+ If so, then we can also infer a nonzero value range
+ for the operand of the NOP_EXPR. */
+ if (comp_code == NE_EXPR && integer_zerop (value))
+ {
+ tree t = op;
+ tree def_stmt = SSA_NAME_DEF_STMT (t);
+
+ while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE
+ (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
+ && TREE_CODE
+ (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
+ 0)) == SSA_NAME
+ && POINTER_TYPE_P
+ (TREE_TYPE (TREE_OPERAND
+ (GIMPLE_STMT_OPERAND (def_stmt,
+ 1), 0))))
+ {
+ t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
+ def_stmt = SSA_NAME_DEF_STMT (t);
+
+ /* Note we want to register the assert for the
+ operand of the NOP_EXPR after SI, not after the
+ conversion. */
+ if (! has_single_use (t))
+ {
+ register_new_assert_for (t, comp_code, value,
+ bb, NULL, si);
+ need_assert = true;
+ }
+ }
+ }
- if (!stmt_ends_bb_p (stmt))
- {
- /* If STMT does not end the block, we can insert the new
- assertion right after it. */
- tree t = build_assert_expr_for (cond, op);
- bsi_insert_after (&si, t, BSI_NEW_STMT);
- added = true;
- }
- else
- {
- /* STMT must be the last statement in BB. We can only
- insert new assertions on the non-abnormal edge out of
- BB. Note that since STMT is not control flow, there
- may only be one non-abnormal edge out of BB. */
- edge_iterator ei;
- edge e;
-
- FOR_EACH_EDGE (e, ei, bb->succs)
- if (!(e->flags & EDGE_ABNORMAL))
- {
- tree t = build_assert_expr_for (cond, op);
- bsi_insert_on_edge (e, t);
- added = true;
- break;
- }
+ /* If OP is used only once, namely in this STMT, don't
+ bother creating an ASSERT_EXPR for it. Such an
+ ASSERT_EXPR would do nothing but increase compile time. */
+ if (!has_single_use (op))
+ {
+ register_new_assert_for (op, comp_code, value, bb, NULL, si);
+ need_assert = true;
+ }
}
}
last = stmt;
}
- /* Step 3. If BB's last statement is a conditional expression
+ /* If BB's last statement is a conditional expression
involving integer operands, recurse into each of the sub-graphs
- rooted at BB to determine if we need to add ASSERT_EXPRs.
- Notice that we only care about the first operand of the
- conditional. Adding assertions for both operands may actually
- hinder VRP. FIXME, add example. */
+ rooted at BB to determine if we need to add ASSERT_EXPRs. */
if (last
&& TREE_CODE (last) == COND_EXPR
&& !fp_predicate (COND_EXPR_COND (last))
- && NUM_USES (uses = STMT_USE_OPS (last)) > 0)
+ && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
+ need_assert |= find_conditional_asserts (bb, last);
+
+ /* Recurse into the dominator children of BB. */
+ for (son = first_dom_son (CDI_DOMINATORS, bb);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ need_assert |= find_assert_locations (son);
+
+ return need_assert;
+}
+
+
+/* Create an ASSERT_EXPR for NAME and insert it in the location
+ indicated by LOC. Return true if we made any edge insertions. */
+
+static bool
+process_assert_insertions_for (tree name, assert_locus_t loc)
+{
+ /* Build the comparison expression NAME_i COMP_CODE VAL. */
+ tree stmt, cond, assert_expr;
+ edge_iterator ei;
+ edge e;
+
+ cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
+ assert_expr = build_assert_expr_for (cond, name);
+
+ if (loc->e)
{
- edge e;
- edge_iterator ei;
- tree op, cond;
- basic_block son;
-
- cond = COND_EXPR_COND (last);
+ /* We have been asked to insert the assertion on an edge. This
+ is used only by COND_EXPR and SWITCH_EXPR assertions. */
+#if defined ENABLE_CHECKING
+ gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
+ || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
+#endif
- op = USE_OP (uses, 0);
+ bsi_insert_on_edge (loc->e, assert_expr);
+ return true;
+ }
- /* Do not attempt to infer anything in names that flow through
- abnormal edges. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
- return false;
+ /* Otherwise, we can insert right after LOC->SI iff the
+ statement must not be the last statement in the block. */
+ stmt = bsi_stmt (loc->si);
+ if (!stmt_ends_bb_p (stmt))
+ {
+ bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
+ return false;
+ }
- /* Remove the COND_EXPR operand from the FOUND bitmap.
- Otherwise, when we finish traversing each of the sub-graphs,
- we won't know whether the variables were found in the
- sub-graphs or if they had been found in a block upstream from
- BB. */
- RESET_BIT (found, SSA_NAME_VERSION (op));
-
- /* Look for uses of the operands in each of the sub-graphs
- rooted at BB. We need to check each of the outgoing edges
- separately, so that we know what kind of ASSERT_EXPR to
- insert. */
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- /* If BB strictly dominates the sub-graph at E->DEST,
- recurse into it. */
- if (e->dest != bb
- && dominated_by_p (CDI_DOMINATORS, e->dest, bb))
- added |= maybe_add_assert_expr (e->dest);
-
- /* Once we traversed the sub-graph, check if any block inside
- used either of the predicate's operands. If so, add the
- appropriate ASSERT_EXPR. */
- if (TEST_BIT (found, SSA_NAME_VERSION (op)))
- {
- /* We found a use of OP in the sub-graph rooted at
- E->DEST. Add an ASSERT_EXPR according to whether
- E goes to THEN_CLAUSE or ELSE_CLAUSE. */
- tree c, t;
-
- if (e->flags & EDGE_TRUE_VALUE)
- c = unshare_expr (cond);
- else if (e->flags & EDGE_FALSE_VALUE)
- c = invert_truthvalue (cond);
- else
- gcc_unreachable ();
+ /* If STMT must be the last statement in BB, we can only insert new
+ assertions on the non-abnormal edge out of BB. Note that since
+ STMT is not control flow, there may only be one non-abnormal edge
+ out of BB. */
+ FOR_EACH_EDGE (e, ei, loc->bb->succs)
+ if (!(e->flags & EDGE_ABNORMAL))
+ {
+ bsi_insert_on_edge (e, assert_expr);
+ return true;
+ }
- t = build_assert_expr_for (c, op);
- bsi_insert_on_edge (e, t);
- added = true;
- }
- }
+ gcc_unreachable ();
+}
- /* Finally, mark all the COND_EXPR operands as found. */
- SET_BIT (found, SSA_NAME_VERSION (op));
- /* Recurse into the dominator children of BB that are not BB's
- immediate successors. Note that we have already visited BB's
- other dominator children above. */
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
+/* Process all the insertions registered for every name N_i registered
+ in NEED_ASSERT_FOR. The list of assertions to be inserted are
+ found in ASSERTS_FOR[i]. */
+
+static void
+process_assert_insertions (void)
+{
+ unsigned i;
+ bitmap_iterator bi;
+ bool update_edges_p = false;
+ int num_asserts = 0;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ dump_all_asserts (dump_file);
+
+ EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
+ {
+ assert_locus_t loc = asserts_for[i];
+ gcc_assert (loc);
+
+ while (loc)
{
- if (find_edge (bb, son) == NULL)
- added |= maybe_add_assert_expr (son);
+ assert_locus_t next = loc->next;
+ update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
+ free (loc);
+ loc = next;
+ num_asserts++;
}
}
- else
- {
- /* Step 4. Recurse into the dominator children of BB. */
- basic_block son;
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- added |= maybe_add_assert_expr (son);
- }
+ if (update_edges_p)
+ bsi_commit_edge_inserts ();
- return added;
+ if (dump_file && (dump_flags & TDF_STATS))
+ fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
+ num_asserts);
}
edge_iterator ei;
bool update_ssa_p;
- found = sbitmap_alloc (num_ssa_names);
- sbitmap_zero (found);
+ found_in_subgraph = sbitmap_alloc (num_ssa_names);
+ sbitmap_zero (found_in_subgraph);
+
+ blocks_visited = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (blocks_visited);
+
+ need_assert_for = BITMAP_ALLOC (NULL);
+ asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
calculate_dominance_info (CDI_DOMINATORS);
update_ssa_p = false;
FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
- if (maybe_add_assert_expr (e->dest))
+ if (find_assert_locations (e->dest))
update_ssa_p = true;
if (update_ssa_p)
{
- bsi_commit_edge_inserts ();
+ process_assert_insertions ();
update_ssa (TODO_update_ssa_no_phi);
}
dump_function_to_file (current_function_decl, dump_file, dump_flags);
}
- sbitmap_free (found);
+ sbitmap_free (found_in_subgraph);
+ free (asserts_for);
+ BITMAP_FREE (need_assert_for);
+}
+
+/* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
+ and "struct" hacks. If VRP can determine that the
+ array subscript is a constant, check if it is outside valid
+ range. If the array subscript is a RANGE, warn if it is
+ non-overlapping with valid range.
+ IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
+
+static void
+check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
+{
+ value_range_t* vr = NULL;
+ tree low_sub, up_sub;
+ tree low_bound, up_bound = array_ref_up_bound (ref);
+
+ low_sub = up_sub = TREE_OPERAND (ref, 1);
+
+ if (!up_bound || !locus || TREE_NO_WARNING (ref)
+ || TREE_CODE (up_bound) != INTEGER_CST
+ /* Can not check flexible arrays. */
+ || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
+ && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
+ && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
+ /* Accesses after the end of arrays of size 0 (gcc
+ extension) and 1 are likely intentional ("struct
+ hack"). */
+ || compare_tree_int (up_bound, 1) <= 0)
+ return;
+
+ low_bound = array_ref_low_bound (ref);
+
+ if (TREE_CODE (low_sub) == SSA_NAME)
+ {
+ vr = get_value_range (low_sub);
+ if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
+ {
+ low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
+ up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
+ }
+ }
+
+ if (vr && vr->type == VR_ANTI_RANGE)
+ {
+ if (TREE_CODE (up_sub) == INTEGER_CST
+ && tree_int_cst_lt (up_bound, up_sub)
+ && TREE_CODE (low_sub) == INTEGER_CST
+ && tree_int_cst_lt (low_sub, low_bound))
+ {
+ warning (OPT_Warray_bounds,
+ "%Harray subscript is outside array bounds", locus);
+ TREE_NO_WARNING (ref) = 1;
+ }
+ }
+ else if (TREE_CODE (up_sub) == INTEGER_CST
+ && tree_int_cst_lt (up_bound, up_sub)
+ && !tree_int_cst_equal (up_bound, up_sub)
+ && (!ignore_off_by_one
+ || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
+ up_bound,
+ integer_one_node,
+ 0),
+ up_sub)))
+ {
+ warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
+ locus);
+ TREE_NO_WARNING (ref) = 1;
+ }
+ else if (TREE_CODE (low_sub) == INTEGER_CST
+ && tree_int_cst_lt (low_sub, low_bound))
+ {
+ warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
+ locus);
+ TREE_NO_WARNING (ref) = 1;
+ }
+}
+
+/* walk_tree() callback that checks if *TP is
+ an ARRAY_REF inside an ADDR_EXPR (in which an array
+ subscript one outside the valid range is allowed). Call
+ check_array_ref for each ARRAY_REF found. The location is
+ passed in DATA. */
+
+static tree
+check_array_bounds (tree *tp, int *walk_subtree, void *data)
+{
+ tree t = *tp;
+ tree stmt = (tree)data;
+ location_t *location = EXPR_LOCUS (stmt);
+
+ *walk_subtree = TRUE;
+
+ if (TREE_CODE (t) == ARRAY_REF)
+ check_array_ref (t, location, false /*ignore_off_by_one*/);
+ else if (TREE_CODE (t) == ADDR_EXPR)
+ {
+ use_operand_p op;
+ tree use_stmt;
+ t = TREE_OPERAND (t, 0);
+
+ /* Don't warn on statements like
+
+ ssa_name = 500 + &array[-200]
+
+ or
+
+ ssa_name = &array[-200]
+ other_name = ssa_name + 300;
+
+ which are sometimes
+ produced by other optimizing passes. */
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
+ *walk_subtree = FALSE;
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
+ && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
+ && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
+ && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
+ *walk_subtree = FALSE;
+
+ while (*walk_subtree && handled_component_p (t))
+ {
+ if (TREE_CODE (t) == ARRAY_REF)
+ check_array_ref (t, location, true /*ignore_off_by_one*/);
+ t = TREE_OPERAND (t, 0);
+ }
+ *walk_subtree = FALSE;
+ }
+
+ return NULL_TREE;
+}
+
+/* Walk over all statements of all reachable BBs and call check_array_bounds
+ on them. */
+
+static void
+check_all_array_refs (void)
+{
+ basic_block bb;
+ block_stmt_iterator si;
+
+ FOR_EACH_BB (bb)
+ {
+ /* Skip bb's that are clearly unreachable. */
+ if (single_pred_p (bb))
+ {
+ basic_block pred_bb = EDGE_PRED (bb, 0)->src;
+ tree ls = NULL_TREE;
+
+ if (!bsi_end_p (bsi_last (pred_bb)))
+ ls = bsi_stmt (bsi_last (pred_bb));
+
+ if (ls && TREE_CODE (ls) == COND_EXPR
+ && ((COND_EXPR_COND (ls) == boolean_false_node
+ && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
+ || (COND_EXPR_COND (ls) == boolean_true_node
+ && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
+ continue;
+ }
+ for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ walk_tree (bsi_stmt_ptr (si), check_array_bounds,
+ bsi_stmt (si), NULL);
+ }
}
+/* Convert range assertion expressions into the implied copies and
+ copy propagate away the copies. Doing the trivial copy propagation
+ here avoids the need to run the full copy propagation pass after
+ VRP.
+
+ FIXME, this will eventually lead to copy propagation removing the
+ names that had useful range information attached to them. For
+ instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
+ then N_i will have the range [3, +INF].
+
+ However, by converting the assertion into the implied copy
+ operation N_i = N_j, we will then copy-propagate N_j into the uses
+ of N_i and lose the range information. We may want to hold on to
+ ASSERT_EXPRs a little while longer as the ranges could be used in
+ things like jump threading.
+
+ The problem with keeping ASSERT_EXPRs around is that passes after
+ VRP need to handle them appropriately.
-/* Convert range assertion expressions into copies. FIXME, explain why. */
+ Another approach would be to make the range information a first
+ class property of the SSA_NAME so that it can be queried from
+ any pass. This is made somewhat more complex by the need for
+ multiple ranges to be associated with one SSA_NAME. */
static void
remove_range_assertions (void)
basic_block bb;
block_stmt_iterator si;
+ /* Note that the BSI iterator bump happens at the bottom of the
+ loop and no bump is necessary if we're removing the statement
+ referenced by the current BSI. */
FOR_EACH_BB (bb)
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ for (si = bsi_start (bb); !bsi_end_p (si);)
{
tree stmt = bsi_stmt (si);
+ tree use_stmt;
- if (TREE_CODE (stmt) == MODIFY_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
{
- tree rhs = TREE_OPERAND (stmt, 1);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
tree cond = fold (ASSERT_EXPR_COND (rhs));
+ use_operand_p use_p;
+ imm_use_iterator iter;
+
gcc_assert (cond != boolean_false_node);
- TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
- update_stmt (stmt);
+
+ /* Propagate the RHS into every use of the LHS. */
+ var = ASSERT_EXPR_VAR (rhs);
+ FOR_EACH_IMM_USE_STMT (use_stmt, iter,
+ GIMPLE_STMT_OPERAND (stmt, 0))
+ FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+ {
+ SET_USE (use_p, var);
+ gcc_assert (TREE_CODE (var) == SSA_NAME);
+ }
+
+ /* And finally, remove the copy, it is not needed. */
+ bsi_remove (&si, true);
+ release_defs (stmt);
}
+ else
+ bsi_next (&si);
}
+
+ sbitmap_free (blocks_visited);
}
&& (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
|| POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
return true;
- else if (TREE_CODE (stmt) == MODIFY_EXPR)
+ else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
{
- tree lhs = TREE_OPERAND (stmt, 0);
- stmt_ann_t ann = stmt_ann (stmt);
+ tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ /* In general, assignments with virtual operands are not useful
+ for deriving ranges, with the obvious exception of calls to
+ builtin functions. */
if (TREE_CODE (lhs) == SSA_NAME
&& (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
|| POINTER_TYPE_P (TREE_TYPE (lhs)))
- && NUM_V_MAY_DEFS (V_MAY_DEF_OPS (ann)) == 0
- && NUM_VUSES (VUSE_OPS (ann)) == 0
- && NUM_V_MUST_DEFS (V_MUST_DEF_OPS (ann)) == 0)
+ && ((TREE_CODE (rhs) == CALL_EXPR
+ && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
+ && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
+ && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
+ || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
return true;
}
else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
}
-/* Initialize local data structures for VRP. Return true if VRP
- is worth running (i.e. if we found any statements that could
- benefit from range information). */
+/* Initialize local data structures for VRP. */
-static bool
+static void
vrp_initialize (void)
{
basic_block bb;
- bool do_vrp;
- /* If we don't find any ASSERT_EXPRs in the code, there's no point
- running VRP. */
- do_vrp = false;
+ vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
FOR_EACH_BB (bb)
{
if (!stmt_interesting_for_vrp (phi))
{
tree lhs = PHI_RESULT (phi);
- set_value_range (get_value_range (lhs), VR_VARYING, 0, 0);
+ set_value_range_to_varying (get_value_range (lhs));
DONT_SIMULATE_AGAIN (phi) = true;
}
else
ssa_op_iter i;
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
- set_value_range (get_value_range (def), VR_VARYING, 0, 0);
+ set_value_range_to_varying (get_value_range (def));
DONT_SIMULATE_AGAIN (stmt) = true;
}
else
{
- if (TREE_CODE (stmt) == MODIFY_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
- do_vrp = true;
-
DONT_SIMULATE_AGAIN (stmt) = false;
}
}
}
-
- return do_vrp;
}
tree lhs, rhs, def;
ssa_op_iter iter;
- lhs = TREE_OPERAND (stmt, 0);
- rhs = TREE_OPERAND (stmt, 1);
+ lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ rhs = GIMPLE_STMT_OPERAND (stmt, 1);
/* We only keep track of ranges in integral and pointer types. */
if (TREE_CODE (lhs) == SSA_NAME
- && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+ && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+ /* It is valid to have NULL MIN/MAX values on a type. See
+ build_range_type. */
+ && TYPE_MIN_VALUE (TREE_TYPE (lhs))
+ && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
|| POINTER_TYPE_P (TREE_TYPE (lhs))))
{
- value_range *vr, new_vr;
struct loop *l;
-
- vr = get_value_range (lhs);
+ value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+
extract_range_from_expr (&new_vr, rhs);
/* If STMT is inside a loop, we may be able to know something
else about the range of LHS by examining scalar evolution
information. */
- if (cfg_loops && (l = loop_containing_stmt (stmt)))
- adjust_range_with_scev (&new_vr, l, lhs);
+ if (current_loops && (l = loop_containing_stmt (stmt)))
+ adjust_range_with_scev (&new_vr, l, stmt, lhs);
- if (update_value_range (vr, new_vr.type, new_vr.min, new_vr.max))
+ if (update_value_range (lhs, &new_vr))
{
*output_p = lhs;
if (dump_file && (dump_flags & TDF_DETAILS))
{
- fprintf (dump_file, "Found new range ");
- dump_value_range (dump_file, &new_vr);
- fprintf (dump_file, " for ");
+ fprintf (dump_file, "Found new range for ");
print_generic_expr (dump_file, lhs, 0);
+ fprintf (dump_file, ": ");
+ dump_value_range (dump_file, &new_vr);
fprintf (dump_file, "\n\n");
}
return SSA_PROP_NOT_INTERESTING;
}
- /* Every other statements produces no useful ranges. */
+ /* Every other statement produces no useful ranges. */
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
- set_value_range (get_value_range (def), VR_VARYING, 0, 0);
+ set_value_range_to_varying (get_value_range (def));
return SSA_PROP_VARYING;
}
-/* Given a conditional predicate COND, try to determine if COND yields
- true or false based on the value ranges of its operands. */
-
-static tree
-vrp_evaluate_conditional (tree cond)
+/* Compare all the value ranges for names equivalent to VAR with VAL
+ using comparison code COMP. Return the same value returned by
+ compare_range_with_value, including the setting of
+ *STRICT_OVERFLOW_P. */
+
+static tree
+compare_name_with_value (enum tree_code comp, tree var, tree val,
+ bool *strict_overflow_p)
+{
+ bitmap_iterator bi;
+ unsigned i;
+ bitmap e;
+ tree retval, t;
+ int used_strict_overflow;
+
+ t = retval = NULL_TREE;
+
+ /* Get the set of equivalences for VAR. */
+ e = get_value_range (var)->equiv;
+
+ /* Add VAR to its own set of equivalences so that VAR's value range
+ is processed by this loop (otherwise, we would have to replicate
+ the body of the loop just to check VAR's value range). */
+ bitmap_set_bit (e, SSA_NAME_VERSION (var));
+
+ /* Start at -1. Set it to 0 if we do a comparison without relying
+ on overflow, or 1 if all comparisons rely on overflow. */
+ used_strict_overflow = -1;
+
+ EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
+ {
+ bool sop;
+
+ value_range_t equiv_vr = *(vr_value[i]);
+
+ /* If name N_i does not have a valid range, use N_i as its own
+ range. This allows us to compare against names that may
+ have N_i in their ranges. */
+ if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
+ {
+ equiv_vr.type = VR_RANGE;
+ equiv_vr.min = ssa_name (i);
+ equiv_vr.max = ssa_name (i);
+ }
+
+ sop = false;
+ t = compare_range_with_value (comp, &equiv_vr, val, &sop);
+ if (t)
+ {
+ /* If we get different answers from different members
+ of the equivalence set this check must be in a dead
+ code region. Folding it to a trap representation
+ would be correct here. For now just return don't-know. */
+ if (retval != NULL
+ && t != retval)
+ {
+ retval = NULL_TREE;
+ break;
+ }
+ retval = t;
+
+ if (!sop)
+ used_strict_overflow = 0;
+ else if (used_strict_overflow < 0)
+ used_strict_overflow = 1;
+ }
+ }
+
+ /* Remove VAR from its own equivalence set. */
+ bitmap_clear_bit (e, SSA_NAME_VERSION (var));
+
+ if (retval)
+ {
+ if (used_strict_overflow > 0)
+ *strict_overflow_p = true;
+ return retval;
+ }
+
+ /* We couldn't find a non-NULL value for the predicate. */
+ return NULL_TREE;
+}
+
+
+/* Given a comparison code COMP and names N1 and N2, compare all the
+ ranges equivalent to N1 against all the ranges equivalent to N2
+ to determine the value of N1 COMP N2. Return the same value
+ returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
+ whether we relied on an overflow infinity in the comparison. */
+
+
+static tree
+compare_names (enum tree_code comp, tree n1, tree n2,
+ bool *strict_overflow_p)
+{
+ tree t, retval;
+ bitmap e1, e2;
+ bitmap_iterator bi1, bi2;
+ unsigned i1, i2;
+ int used_strict_overflow;
+
+ /* Compare the ranges of every name equivalent to N1 against the
+ ranges of every name equivalent to N2. */
+ e1 = get_value_range (n1)->equiv;
+ e2 = get_value_range (n2)->equiv;
+
+ /* Add N1 and N2 to their own set of equivalences to avoid
+ duplicating the body of the loop just to check N1 and N2
+ ranges. */
+ bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
+
+ /* If the equivalence sets have a common intersection, then the two
+ names can be compared without checking their ranges. */
+ if (bitmap_intersect_p (e1, e2))
+ {
+ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+
+ return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
+ ? boolean_true_node
+ : boolean_false_node;
+ }
+
+ /* Start at -1. Set it to 0 if we do a comparison without relying
+ on overflow, or 1 if all comparisons rely on overflow. */
+ used_strict_overflow = -1;
+
+ /* Otherwise, compare all the equivalent ranges. First, add N1 and
+ N2 to their own set of equivalences to avoid duplicating the body
+ of the loop just to check N1 and N2 ranges. */
+ EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
+ {
+ value_range_t vr1 = *(vr_value[i1]);
+
+ /* If the range is VARYING or UNDEFINED, use the name itself. */
+ if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
+ {
+ vr1.type = VR_RANGE;
+ vr1.min = ssa_name (i1);
+ vr1.max = ssa_name (i1);
+ }
+
+ t = retval = NULL_TREE;
+ EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
+ {
+ bool sop;
+
+ value_range_t vr2 = *(vr_value[i2]);
+
+ if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
+ {
+ vr2.type = VR_RANGE;
+ vr2.min = ssa_name (i2);
+ vr2.max = ssa_name (i2);
+ }
+
+ t = compare_ranges (comp, &vr1, &vr2, &sop);
+ if (t)
+ {
+ /* If we get different answers from different members
+ of the equivalence set this check must be in a dead
+ code region. Folding it to a trap representation
+ would be correct here. For now just return don't-know. */
+ if (retval != NULL
+ && t != retval)
+ {
+ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+ return NULL_TREE;
+ }
+ retval = t;
+
+ if (!sop)
+ used_strict_overflow = 0;
+ else if (used_strict_overflow < 0)
+ used_strict_overflow = 1;
+ }
+ }
+
+ if (retval)
+ {
+ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+ if (used_strict_overflow > 0)
+ *strict_overflow_p = true;
+ return retval;
+ }
+ }
+
+ /* None of the equivalent ranges are useful in computing this
+ comparison. */
+ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+ return NULL_TREE;
+}
+
+
+/* Given a conditional predicate COND, try to determine if COND yields
+ true or false based on the value ranges of its operands. Return
+ BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
+ BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
+ NULL if the conditional cannot be evaluated at compile time.
+
+ If USE_EQUIV_P is true, the ranges of all the names equivalent with
+ the operands in COND are used when trying to compute its value.
+ This is only used during final substitution. During propagation,
+ we only check the range of each variable and not its equivalents.
+
+ Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
+ infinity to produce the result. */
+
+static tree
+vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
+ bool *strict_overflow_p)
+{
+ gcc_assert (TREE_CODE (cond) == SSA_NAME
+ || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
+
+ if (TREE_CODE (cond) == SSA_NAME)
+ {
+ value_range_t *vr;
+ tree retval;
+
+ if (use_equiv_p)
+ retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
+ strict_overflow_p);
+ else
+ {
+ value_range_t *vr = get_value_range (cond);
+ retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
+ strict_overflow_p);
+ }
+
+ /* If COND has a known boolean range, return it. */
+ if (retval)
+ return retval;
+
+ /* Otherwise, if COND has a symbolic range of exactly one value,
+ return it. */
+ vr = get_value_range (cond);
+ if (vr->type == VR_RANGE && vr->min == vr->max)
+ return vr->min;
+ }
+ else
+ {
+ tree op0 = TREE_OPERAND (cond, 0);
+ tree op1 = TREE_OPERAND (cond, 1);
+
+ /* We only deal with integral and pointer types. */
+ if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
+ && !POINTER_TYPE_P (TREE_TYPE (op0)))
+ return NULL_TREE;
+
+ if (use_equiv_p)
+ {
+ if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
+ return compare_names (TREE_CODE (cond), op0, op1,
+ strict_overflow_p);
+ else if (TREE_CODE (op0) == SSA_NAME)
+ return compare_name_with_value (TREE_CODE (cond), op0, op1,
+ strict_overflow_p);
+ else if (TREE_CODE (op1) == SSA_NAME)
+ return (compare_name_with_value
+ (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
+ strict_overflow_p));
+ }
+ else
+ {
+ value_range_t *vr0, *vr1;
+
+ vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
+ vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
+
+ if (vr0 && vr1)
+ return compare_ranges (TREE_CODE (cond), vr0, vr1,
+ strict_overflow_p);
+ else if (vr0 && vr1 == NULL)
+ return compare_range_with_value (TREE_CODE (cond), vr0, op1,
+ strict_overflow_p);
+ else if (vr0 == NULL && vr1)
+ return (compare_range_with_value
+ (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
+ strict_overflow_p));
+ }
+ }
+
+ /* Anything else cannot be computed statically. */
+ return NULL_TREE;
+}
+
+/* Given COND within STMT, try to simplify it based on value range
+ information. Return NULL if the conditional can not be evaluated.
+ The ranges of all the names equivalent with the operands in COND
+ will be used when trying to compute the value. If the result is
+ based on undefined signed overflow, issue a warning if
+ appropriate. */
+
+tree
+vrp_evaluate_conditional (tree cond, tree stmt)
{
- gcc_assert (TREE_CODE (cond) == SSA_NAME
- || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
+ bool sop;
+ tree ret;
- if (TREE_CODE (cond) == SSA_NAME)
- {
- /* For SSA names, only return a truth value if the range is
- known and contains exactly one value. */
- value_range *vr = SSA_NAME_VALUE_RANGE (cond);
- if (vr && vr->type == VR_RANGE && vr->min == vr->max)
- return vr->min;
- }
- else
+ sop = false;
+ ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
+
+ if (ret && sop)
{
- /* For comparisons, evaluate each operand and compare their
- ranges. */
- tree op0, op1;
- value_range *vr0, *vr1;
+ enum warn_strict_overflow_code wc;
+ const char* warnmsg;
- op0 = TREE_OPERAND (cond, 0);
- vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
+ if (is_gimple_min_invariant (ret))
+ {
+ wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
+ warnmsg = G_("assuming signed overflow does not occur when "
+ "simplifying conditional to constant");
+ }
+ else
+ {
+ wc = WARN_STRICT_OVERFLOW_COMPARISON;
+ warnmsg = G_("assuming signed overflow does not occur when "
+ "simplifying conditional");
+ }
- op1 = TREE_OPERAND (cond, 1);
- vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
+ if (issue_strict_overflow_warning (wc))
+ {
+ location_t locus;
- if (vr0 && vr1)
- return compare_ranges (TREE_CODE (cond), vr0, vr1);
- else if (vr0 && vr1 == NULL)
- return compare_range_with_value (TREE_CODE (cond), vr0, op1);
- else if (vr0 == NULL && vr1)
- return compare_range_with_value (opposite_comparison (TREE_CODE (cond)),
- vr1, op0);
+ if (!EXPR_HAS_LOCATION (stmt))
+ locus = input_location;
+ else
+ locus = EXPR_LOCATION (stmt);
+ warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
+ }
}
- /* Anything else cannot be computed statically. */
- return NULL_TREE;
+ return ret;
}
vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
{
tree cond, val;
+ bool sop;
*taken_edge_p = NULL;
fprintf (dump_file, "\t");
print_generic_expr (dump_file, use, 0);
fprintf (dump_file, ": ");
- dump_value_range (dump_file, SSA_NAME_VALUE_RANGE (use));
+ dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
}
fprintf (dump_file, "\n");
}
/* Compute the value of the predicate COND by checking the known
- ranges of each of its operands. */
- val = vrp_evaluate_conditional (cond);
+ ranges of each of its operands.
+
+ Note that we cannot evaluate all the equivalent ranges here
+ because those ranges may not yet be final and with the current
+ propagation strategy, we cannot determine when the value ranges
+ of the names in the equivalence set have changed.
+
+ For instance, given the following code fragment
+
+ i_5 = PHI <8, i_13>
+ ...
+ i_14 = ASSERT_EXPR <i_5, i_5 != 0>
+ if (i_14 == 1)
+ ...
+
+ Assume that on the first visit to i_14, i_5 has the temporary
+ range [8, 8] because the second argument to the PHI function is
+ not yet executable. We derive the range ~[0, 0] for i_14 and the
+ equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
+ the first time, since i_14 is equivalent to the range [8, 8], we
+ determine that the predicate is always false.
+
+ On the next round of propagation, i_13 is determined to be
+ VARYING, which causes i_5 to drop down to VARYING. So, another
+ visit to i_14 is scheduled. In this second visit, we compute the
+ exact same range and equivalence set for i_14, namely ~[0, 0] and
+ { i_5 }. But we did not have the previous range for i_5
+ registered, so vrp_visit_assignment thinks that the range for
+ i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
+ is not visited again, which stops propagation from visiting
+ statements in the THEN clause of that if().
+
+ To properly fix this we would need to keep the previous range
+ value for the names in the equivalence set. This way we would've
+ discovered that from one visit to the other i_5 changed from
+ range [8, 8] to VR_VARYING.
+
+ However, fixing this apparent limitation may not be worth the
+ additional checking. Testing on several code bases (GCC, DLV,
+ MICO, TRAMP3D and SPEC2000) showed that doing this results in
+ 4 more predicates folded in SPEC. */
+ sop = false;
+ val = vrp_evaluate_conditional_warnv (cond, false, &sop);
if (val)
- *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
+ {
+ if (!sop)
+ *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
+ else
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,
+ "\nIgnoring predicate evaluation because "
+ "it assumes that signed overflow is undefined");
+ val = NULL_TREE;
+ }
+ }
if (dump_file && (dump_flags & TDF_DETAILS))
{
}
ann = stmt_ann (stmt);
- if (TREE_CODE (stmt) == MODIFY_EXPR
- && NUM_V_MAY_DEFS (V_MAY_DEF_OPS (ann)) == 0
- && NUM_VUSES (VUSE_OPS (ann)) == 0
- && NUM_V_MUST_DEFS (V_MUST_DEF_OPS (ann)) == 0)
- return vrp_visit_assignment (stmt, output_p);
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ {
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+
+ /* In general, assignments with virtual operands are not useful
+ for deriving ranges, with the obvious exception of calls to
+ builtin functions. */
+ if ((TREE_CODE (rhs) == CALL_EXPR
+ && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
+ && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
+ && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
+ || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
+ return vrp_visit_assignment (stmt, output_p);
+ }
else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
return vrp_visit_cond_stmt (stmt, taken_edge_p);
/* All other statements produce nothing of interest for VRP, so mark
their outputs varying and prevent further simulation. */
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
- set_value_range (get_value_range (def), VR_VARYING, 0, 0);
+ set_value_range_to_varying (get_value_range (def));
return SSA_PROP_VARYING;
}
/* Meet operation for value ranges. Given two value ranges VR0 and
- VR1, store in VR0 the result of meeting VR0 and VR1.
-
- The meeting rules are as follows:
-
- 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
-
- 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
- union of VR0 and VR1. */
+ VR1, store in VR0 a range that contains both VR0 and VR1. This
+ may not be the smallest possible such range. */
static void
-vrp_meet (value_range *vr0, value_range *vr1)
+vrp_meet (value_range_t *vr0, value_range_t *vr1)
{
if (vr0->type == VR_UNDEFINED)
{
- *vr0 = *vr1;
+ copy_value_range (vr0, vr1);
return;
}
if (vr1->type == VR_VARYING)
{
- *vr0 = *vr1;
- return;
- }
-
- /* If either is a symbolic range, drop to VARYING. */
- if (symbolic_range_p (vr0) || symbolic_range_p (vr1))
- {
- set_value_range (vr0, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr0);
return;
}
if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
{
- /* If VR0 and VR1 have a non-empty intersection, compute the
- union of both ranges. */
- if (value_ranges_intersect_p (vr0, vr1))
- {
- tree min, max;
-
- min = vr0->min;
- max = vr0->max;
+ int cmp;
+ tree min, max;
- /* The lower limit of the new range is the minimum of the
- two ranges. */
- if (compare_values (vr0->min, vr1->min) == 1)
- min = vr1->min;
+ /* Compute the convex hull of the ranges. The lower limit of
+ the new range is the minimum of the two ranges. If they
+ cannot be compared, then give up. */
+ cmp = compare_values (vr0->min, vr1->min);
+ if (cmp == 0 || cmp == 1)
+ min = vr1->min;
+ else if (cmp == -1)
+ min = vr0->min;
+ else
+ goto give_up;
+
+ /* Similarly, the upper limit of the new range is the maximum
+ of the two ranges. If they cannot be compared, then
+ give up. */
+ cmp = compare_values (vr0->max, vr1->max);
+ if (cmp == 0 || cmp == -1)
+ max = vr1->max;
+ else if (cmp == 1)
+ max = vr0->max;
+ else
+ goto give_up;
- /* The upper limit of the new range is the maximum of the
- two ranges. */
- if (compare_values (vr0->max, vr1->max) == -1)
- max = vr1->max;
+ /* The resulting set of equivalences is the intersection of
+ the two sets. */
+ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
+ bitmap_and_into (vr0->equiv, vr1->equiv);
+ else if (vr0->equiv && !vr1->equiv)
+ bitmap_clear (vr0->equiv);
- set_value_range (vr0, vr0->type, min, max);
- }
- else
- {
- /* The two ranges don't intersect, set the result to VR_VARYING. */
- set_value_range (vr0, VR_VARYING, NULL_TREE, NULL_TREE);
- }
+ set_value_range (vr0, vr0->type, min, max, vr0->equiv);
}
else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
{
- /* Two anti-ranges meet only if they are both identical. */
+ /* Two anti-ranges meet only if their complements intersect.
+ Only handle the case of identical ranges. */
if (compare_values (vr0->min, vr1->min) == 0
&& compare_values (vr0->max, vr1->max) == 0
&& compare_values (vr0->min, vr0->max) == 0)
- /* Nothing to do. */ ;
+ {
+ /* The resulting set of equivalences is the intersection of
+ the two sets. */
+ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
+ bitmap_and_into (vr0->equiv, vr1->equiv);
+ else if (vr0->equiv && !vr1->equiv)
+ bitmap_clear (vr0->equiv);
+ }
else
- set_value_range (vr0, VR_VARYING, NULL_TREE, NULL_TREE);
+ goto give_up;
}
else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
{
- /* A range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4] meet
- only if the ranges have an empty intersection. The result of
- the meet operation is the anti-range. */
- if (!value_ranges_intersect_p (vr0, vr1))
+ /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
+ only handle the case where the ranges have an empty intersection.
+ The result of the meet operation is the anti-range. */
+ if (!symbolic_range_p (vr0)
+ && !symbolic_range_p (vr1)
+ && !value_ranges_intersect_p (vr0, vr1))
{
+ /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
+ set. We need to compute the intersection of the two
+ equivalence sets. */
if (vr1->type == VR_ANTI_RANGE)
- *vr0 = *vr1;
+ set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
+
+ /* The resulting set of equivalences is the intersection of
+ the two sets. */
+ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
+ bitmap_and_into (vr0->equiv, vr1->equiv);
+ else if (vr0->equiv && !vr1->equiv)
+ bitmap_clear (vr0->equiv);
}
else
- set_value_range (vr0, VR_VARYING, NULL_TREE, NULL_TREE);
+ goto give_up;
}
else
gcc_unreachable ();
+
+ return;
+
+give_up:
+ /* Failed to find an efficient meet. Before giving up and setting
+ the result to VARYING, see if we can at least derive a useful
+ anti-range. FIXME, all this nonsense about distinguishing
+ anti-ranges from ranges is necessary because of the odd
+ semantics of range_includes_zero_p and friends. */
+ if (!symbolic_range_p (vr0)
+ && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
+ || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
+ && !symbolic_range_p (vr1)
+ && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
+ || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
+ {
+ set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
+
+ /* Since this meet operation did not result from the meeting of
+ two equivalent names, VR0 cannot have any equivalences. */
+ if (vr0->equiv)
+ bitmap_clear (vr0->equiv);
+ }
+ else
+ set_value_range_to_varying (vr0);
}
-
+
/* Visit all arguments for PHI node PHI that flow through executable
edges. If a valid value range can be derived from all the incoming
value ranges, set a new range for the LHS of PHI. */
{
int i;
tree lhs = PHI_RESULT (phi);
- value_range *lhs_vr = get_value_range (lhs);
- value_range vr_result = *lhs_vr;
+ value_range_t *lhs_vr = get_value_range (lhs);
+ value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
+ bool all_const = true;
+
+ copy_value_range (&vr_result, lhs_vr);
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (e->flags & EDGE_EXECUTABLE)
{
tree arg = PHI_ARG_DEF (phi, i);
- value_range vr_arg;
+ value_range_t vr_arg;
if (TREE_CODE (arg) == SSA_NAME)
- vr_arg = *(get_value_range (arg));
+ {
+ vr_arg = *(get_value_range (arg));
+ all_const = false;
+ }
else
{
vr_arg.type = VR_RANGE;
vr_arg.min = arg;
vr_arg.max = arg;
+ vr_arg.equiv = NULL;
}
if (dump_file && (dump_flags & TDF_DETAILS))
}
if (vr_result.type == VR_VARYING)
- {
- set_value_range (lhs_vr, VR_VARYING, 0, 0);
- return SSA_PROP_VARYING;
- }
+ goto varying;
/* To prevent infinite iterations in the algorithm, derive ranges
when the new value is slightly bigger or smaller than the
previous one. */
- if (lhs_vr->type == VR_RANGE)
+ if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
+ && !all_const)
{
if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
{
other case to avoid infinite bouncing between different
minimums. */
if (cmp_min > 0 || cmp_min < 0)
- vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
+ {
+ /* If we will end up with a (-INF, +INF) range, set it
+ to VARYING. */
+ if (is_positive_overflow_infinity (vr_result.max)
+ || (vr_result.max
+ == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max))))
+ goto varying;
+
+ if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
+ vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
+ else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
+ vr_result.min =
+ negative_overflow_infinity (TREE_TYPE (vr_result.min));
+ else
+ goto varying;
+ }
/* Similarly, if the new maximum is smaller or larger than
the previous one, go all the way to +INF. */
if (cmp_max < 0 || cmp_max > 0)
- vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
-
- /* If we ended up with a (-INF, +INF) range, set it to
- VARYING. */
- if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
- && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
{
- set_value_range (lhs_vr, VR_VARYING, 0, 0);
- return SSA_PROP_VARYING;
+ /* If we will end up with a (-INF, +INF) range, set it
+ to VARYING. */
+ if (is_negative_overflow_infinity (vr_result.min)
+ || (vr_result.min
+ == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))))
+ goto varying;
+
+ if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
+ vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
+ else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
+ vr_result.max =
+ positive_overflow_infinity (TREE_TYPE (vr_result.max));
+ else
+ goto varying;
}
}
}
/* If the new range is different than the previous value, keep
iterating. */
- if (update_value_range (lhs_vr, vr_result.type, vr_result.min, vr_result.max))
+ if (update_value_range (lhs, &vr_result))
return SSA_PROP_INTERESTING;
/* Nothing changed, don't add outgoing edges. */
return SSA_PROP_NOT_INTERESTING;
-}
+ /* No match found. Set the LHS to VARYING. */
+varying:
+ set_value_range_to_varying (lhs_vr);
+ return SSA_PROP_VARYING;
+}
-/* Traverse all the blocks folding conditionals with known ranges. */
+/* Simplify a division or modulo operator to a right shift or
+ bitwise and if the first operand is unsigned or is greater
+ than zero and the second operand is an exact power of two. */
static void
-vrp_finalize (void)
+simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
{
- basic_block bb;
- int num_pred_folded = 0;
+ tree val = NULL;
+ tree op = TREE_OPERAND (rhs, 0);
+ value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
- if (dump_file)
+ if (TYPE_UNSIGNED (TREE_TYPE (op)))
{
- fprintf (dump_file, "\nValue ranges after VRP:\n\n");
- dump_all_value_ranges (dump_file);
- fprintf (dump_file, "\n");
+ val = integer_one_node;
+ }
+ else
+ {
+ bool sop = false;
+
+ val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
+
+ if (val
+ && sop
+ && integer_onep (val)
+ && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
+ {
+ location_t locus;
+
+ if (!EXPR_HAS_LOCATION (stmt))
+ locus = input_location;
+ else
+ locus = EXPR_LOCATION (stmt);
+ warning (OPT_Wstrict_overflow,
+ ("%Hassuming signed overflow does not occur when "
+ "simplifying / or %% to >> or &"),
+ &locus);
+ }
}
- FOR_EACH_BB (bb)
+ if (val && integer_onep (val))
+ {
+ tree t;
+ tree op0 = TREE_OPERAND (rhs, 0);
+ tree op1 = TREE_OPERAND (rhs, 1);
+
+ if (rhs_code == TRUNC_DIV_EXPR)
+ {
+ t = build_int_cst (NULL_TREE, tree_log2 (op1));
+ t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
+ }
+ else
+ {
+ t = build_int_cst (TREE_TYPE (op1), 1);
+ t = int_const_binop (MINUS_EXPR, op1, t, 0);
+ t = fold_convert (TREE_TYPE (op0), t);
+ t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
+ }
+
+ GIMPLE_STMT_OPERAND (stmt, 1) = t;
+ update_stmt (stmt);
+ }
+}
+
+/* If the operand to an ABS_EXPR is >= 0, then eliminate the
+ ABS_EXPR. If the operand is <= 0, then simplify the
+ ABS_EXPR into a NEGATE_EXPR. */
+
+static void
+simplify_abs_using_ranges (tree stmt, tree rhs)
+{
+ tree val = NULL;
+ tree op = TREE_OPERAND (rhs, 0);
+ tree type = TREE_TYPE (op);
+ value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
+
+ if (TYPE_UNSIGNED (type))
{
- tree last = last_stmt (bb);
- if (last && TREE_CODE (last) == COND_EXPR)
+ val = integer_zero_node;
+ }
+ else if (vr)
+ {
+ bool sop = false;
+
+ val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
+ if (!val)
{
- tree val = vrp_evaluate_conditional (COND_EXPR_COND (last));
+ sop = false;
+ val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
+ &sop);
+
if (val)
{
+ if (integer_zerop (val))
+ val = integer_one_node;
+ else if (integer_onep (val))
+ val = integer_zero_node;
+ }
+ }
+
+ if (val
+ && (integer_onep (val) || integer_zerop (val)))
+ {
+ tree t;
+
+ if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
+ {
+ location_t locus;
+
+ if (!EXPR_HAS_LOCATION (stmt))
+ locus = input_location;
+ else
+ locus = EXPR_LOCATION (stmt);
+ warning (OPT_Wstrict_overflow,
+ ("%Hassuming signed overflow does not occur when "
+ "simplifying abs (X) to X or -X"),
+ &locus);
+ }
+
+ if (integer_onep (val))
+ t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
+ else
+ t = op;
+
+ GIMPLE_STMT_OPERAND (stmt, 1) = t;
+ update_stmt (stmt);
+ }
+ }
+}
+
+/* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
+ a known value range VR.
+
+ If there is one and only one value which will satisfy the
+ conditional, then return that value. Else return NULL. */
+
+static tree
+test_for_singularity (enum tree_code cond_code, tree op0,
+ tree op1, value_range_t *vr)
+{
+ tree min = NULL;
+ tree max = NULL;
+
+ /* Extract minimum/maximum values which satisfy the
+ the conditional as it was written. */
+ if (cond_code == LE_EXPR || cond_code == LT_EXPR)
+ {
+ /* This should not be negative infinity; there is no overflow
+ here. */
+ min = TYPE_MIN_VALUE (TREE_TYPE (op0));
+
+ max = op1;
+ if (cond_code == LT_EXPR && !is_overflow_infinity (max))
+ {
+ tree one = build_int_cst (TREE_TYPE (op0), 1);
+ max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
+ }
+ }
+ else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
+ {
+ /* This should not be positive infinity; there is no overflow
+ here. */
+ max = TYPE_MAX_VALUE (TREE_TYPE (op0));
+
+ min = op1;
+ if (cond_code == GT_EXPR && !is_overflow_infinity (min))
+ {
+ tree one = build_int_cst (TREE_TYPE (op0), 1);
+ min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
+ }
+ }
+
+ /* Now refine the minimum and maximum values using any
+ value range information we have for op0. */
+ if (min && max)
+ {
+ if (compare_values (vr->min, min) == -1)
+ min = min;
+ else
+ min = vr->min;
+ if (compare_values (vr->max, max) == 1)
+ max = max;
+ else
+ max = vr->max;
+
+ /* If the new min/max values have converged to a single value,
+ then there is only one value which can satisfy the condition,
+ return that value. */
+ if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
+ return min;
+ }
+ return NULL;
+}
+
+/* Simplify a conditional using a relational operator to an equality
+ test if the range information indicates only one value can satisfy
+ the original conditional. */
+
+static void
+simplify_cond_using_ranges (tree stmt)
+{
+ tree cond = COND_EXPR_COND (stmt);
+ tree op0 = TREE_OPERAND (cond, 0);
+ tree op1 = TREE_OPERAND (cond, 1);
+ enum tree_code cond_code = TREE_CODE (cond);
+
+ if (cond_code != NE_EXPR
+ && cond_code != EQ_EXPR
+ && TREE_CODE (op0) == SSA_NAME
+ && INTEGRAL_TYPE_P (TREE_TYPE (op0))
+ && is_gimple_min_invariant (op1))
+ {
+ value_range_t *vr = get_value_range (op0);
+
+ /* If we have range information for OP0, then we might be
+ able to simplify this conditional. */
+ if (vr->type == VR_RANGE)
+ {
+ tree new = test_for_singularity (cond_code, op0, op1, vr);
+
+ if (new)
+ {
+ if (dump_file)
+ {
+ fprintf (dump_file, "Simplified relational ");
+ print_generic_expr (dump_file, cond, 0);
+ fprintf (dump_file, " into ");
+ }
+
+ COND_EXPR_COND (stmt)
+ = build2 (EQ_EXPR, boolean_type_node, op0, new);
+ update_stmt (stmt);
+
+ if (dump_file)
+ {
+ print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
+ fprintf (dump_file, "\n");
+ }
+ return;
+
+ }
+
+ /* Try again after inverting the condition. We only deal
+ with integral types here, so no need to worry about
+ issues with inverting FP comparisons. */
+ cond_code = invert_tree_comparison (cond_code, false);
+ new = test_for_singularity (cond_code, op0, op1, vr);
+
+ if (new)
+ {
if (dump_file)
{
- fprintf (dump_file, "Folding predicate ");
- print_generic_expr (dump_file, COND_EXPR_COND (last), 0);
- fprintf (dump_file, " to ");
- print_generic_expr (dump_file, val, 0);
+ fprintf (dump_file, "Simplified relational ");
+ print_generic_expr (dump_file, cond, 0);
+ fprintf (dump_file, " into ");
+ }
+
+ COND_EXPR_COND (stmt)
+ = build2 (NE_EXPR, boolean_type_node, op0, new);
+ update_stmt (stmt);
+
+ if (dump_file)
+ {
+ print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
fprintf (dump_file, "\n");
}
+ return;
- num_pred_folded++;
- COND_EXPR_COND (last) = val;
- update_stmt (last);
}
}
}
+}
- if (dump_file && (dump_flags & TDF_STATS))
- fprintf (dump_file, "\nNumber of predicates folded: %d\n\n",
- num_pred_folded);
+/* Simplify STMT using ranges if possible. */
+
+void
+simplify_stmt_using_ranges (tree stmt)
+{
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ {
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ enum tree_code rhs_code = TREE_CODE (rhs);
+
+ /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
+ and BIT_AND_EXPR respectively if the first operand is greater
+ than zero and the second operand is an exact power of two. */
+ if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
+ && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
+ && integer_pow2p (TREE_OPERAND (rhs, 1)))
+ simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
+
+ /* Transform ABS (X) into X or -X as appropriate. */
+ if (rhs_code == ABS_EXPR
+ && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
+ && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
+ simplify_abs_using_ranges (stmt, rhs);
+ }
+ else if (TREE_CODE (stmt) == COND_EXPR
+ && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
+ {
+ simplify_cond_using_ranges (stmt);
+ }
+}
+
+/* Stack of dest,src equivalency pairs that need to be restored after
+ each attempt to thread a block's incoming edge to an outgoing edge.
+
+ A NULL entry is used to mark the end of pairs which need to be
+ restored. */
+static VEC(tree,heap) *stack;
+
+/* A trivial wrapper so that we can present the generic jump threading
+ code with a simple API for simplifying statements. STMT is the
+ statement we want to simplify, WITHIN_STMT provides the location
+ for any overflow warnings. */
+
+static tree
+simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
+{
+ /* We only use VRP information to simplify conditionals. This is
+ overly conservative, but it's unclear if doing more would be
+ worth the compile time cost. */
+ if (TREE_CODE (stmt) != COND_EXPR)
+ return NULL;
+
+ return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
+}
+
+/* Blocks which have more than one predecessor and more than
+ one successor present jump threading opportunities. ie,
+ when the block is reached from a specific predecessor, we
+ may be able to determine which of the outgoing edges will
+ be traversed. When this optimization applies, we are able
+ to avoid conditionals at runtime and we may expose secondary
+ optimization opportunities.
+
+ This routine is effectively a driver for the generic jump
+ threading code. It basically just presents the generic code
+ with edges that may be suitable for jump threading.
+
+ Unlike DOM, we do not iterate VRP if jump threading was successful.
+ While iterating may expose new opportunities for VRP, it is expected
+ those opportunities would be very limited and the compile time cost
+ to expose those opportunities would be significant.
+
+ As jump threading opportunities are discovered, they are registered
+ for later realization. */
+
+static void
+identify_jump_threads (void)
+{
+ basic_block bb;
+ tree dummy;
+
+ /* Ugh. When substituting values earlier in this pass we can
+ wipe the dominance information. So rebuild the dominator
+ information as we need it within the jump threading code. */
+ calculate_dominance_info (CDI_DOMINATORS);
+
+ /* We do not allow VRP information to be used for jump threading
+ across a back edge in the CFG. Otherwise it becomes too
+ difficult to avoid eliminating loop exit tests. Of course
+ EDGE_DFS_BACK is not accurate at this time so we have to
+ recompute it. */
+ mark_dfs_back_edges ();
+
+ /* Allocate our unwinder stack to unwind any temporary equivalences
+ that might be recorded. */
+ stack = VEC_alloc (tree, heap, 20);
+
+ /* To avoid lots of silly node creation, we create a single
+ conditional and just modify it in-place when attempting to
+ thread jumps. */
+ dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
+ dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
+
+ /* Walk through all the blocks finding those which present a
+ potential jump threading opportunity. We could set this up
+ as a dominator walker and record data during the walk, but
+ I doubt it's worth the effort for the classes of jump
+ threading opportunities we are trying to identify at this
+ point in compilation. */
+ FOR_EACH_BB (bb)
+ {
+ tree last, cond;
+
+ /* If the generic jump threading code does not find this block
+ interesting, then there is nothing to do. */
+ if (! potentially_threadable_block (bb))
+ continue;
+
+ /* We only care about blocks ending in a COND_EXPR. While there
+ may be some value in handling SWITCH_EXPR here, I doubt it's
+ terribly important. */
+ last = bsi_stmt (bsi_last (bb));
+ if (TREE_CODE (last) != COND_EXPR)
+ continue;
+
+ /* We're basically looking for any kind of conditional with
+ integral type arguments. */
+ cond = COND_EXPR_COND (last);
+ if ((TREE_CODE (cond) == SSA_NAME
+ && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
+ || (COMPARISON_CLASS_P (cond)
+ && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
+ && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
+ && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
+ || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
+ && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
+ {
+ edge_iterator ei;
+ edge e;
+
+ /* We've got a block with multiple predecessors and multiple
+ successors which also ends in a suitable conditional. For
+ each predecessor, see if we can thread it to a specific
+ successor. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ /* Do not thread across back edges or abnormal edges
+ in the CFG. */
+ if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
+ continue;
+
+ thread_across_edge (dummy, e, true,
+ &stack,
+ simplify_stmt_for_jump_threading);
+ }
+ }
+ }
+
+ /* We do not actually update the CFG or SSA graphs at this point as
+ ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
+ handle ASSERT_EXPRs gracefully. */
+}
+
+/* We identified all the jump threading opportunities earlier, but could
+ not transform the CFG at that time. This routine transforms the
+ CFG and arranges for the dominator tree to be rebuilt if necessary.
+
+ Note the SSA graph update will occur during the normal TODO
+ processing by the pass manager. */
+static void
+finalize_jump_threads (void)
+{
+ bool cfg_altered = false;
+ cfg_altered = thread_through_all_blocks ();
+
+ /* If we threaded jumps, then we need to recompute the dominance
+ information. */
+ if (cfg_altered)
+ free_dominance_info (CDI_DOMINATORS);
+ VEC_free (tree, heap, stack);
+}
+
+
+/* Traverse all the blocks folding conditionals with known ranges. */
+
+static void
+vrp_finalize (void)
+{
+ size_t i;
+ prop_value_t *single_val_range;
+ bool do_value_subst_p;
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "\nValue ranges after VRP:\n\n");
+ dump_all_value_ranges (dump_file);
+ fprintf (dump_file, "\n");
+ }
+
+ /* We may have ended with ranges that have exactly one value. Those
+ values can be substituted as any other copy/const propagated
+ value using substitute_and_fold. */
+ single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
+
+ do_value_subst_p = false;
+ for (i = 0; i < num_ssa_names; i++)
+ if (vr_value[i]
+ && vr_value[i]->type == VR_RANGE
+ && vr_value[i]->min == vr_value[i]->max)
+ {
+ single_val_range[i].value = vr_value[i]->min;
+ do_value_subst_p = true;
+ }
+
+ if (!do_value_subst_p)
+ {
+ /* We found no single-valued ranges, don't waste time trying to
+ do single value substitution in substitute_and_fold. */
+ free (single_val_range);
+ single_val_range = NULL;
+ }
+
+ substitute_and_fold (single_val_range, true);
+
+ if (warn_array_bounds)
+ check_all_array_refs ();
+
+ /* We must identify jump threading opportunities before we release
+ the datastructures built by VRP. */
+ identify_jump_threads ();
+
+ /* Free allocated memory. */
+ for (i = 0; i < num_ssa_names; i++)
+ if (vr_value[i])
+ {
+ BITMAP_FREE (vr_value[i]->equiv);
+ free (vr_value[i]);
+ }
+
+ free (single_val_range);
+ free (vr_value);
+
+ /* So that we can distinguish between VRP data being available
+ and not available. */
+ vr_value = NULL;
}
This is essentially an SSA-CCP pass modified to deal with ranges
instead of constants.
+ While propagating ranges, we may find that two or more SSA name
+ have equivalent, though distinct ranges. For instance,
+
+ 1 x_9 = p_3->a;
+ 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
+ 3 if (p_4 == q_2)
+ 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
+ 5 endif
+ 6 if (q_2)
+
+ In the code above, pointer p_5 has range [q_2, q_2], but from the
+ code we can also determine that p_5 cannot be NULL and, if q_2 had
+ a non-varying range, p_5's range should also be compatible with it.
+
+ These equivalences are created by two expressions: ASSERT_EXPR and
+ copy operations. Since p_5 is an assertion on p_4, and p_4 was the
+ result of another assertion, then we can use the fact that p_5 and
+ p_4 are equivalent when evaluating p_5's range.
+
+ Together with value ranges, we also propagate these equivalences
+ between names so that we can take advantage of information from
+ multiple ranges when doing final replacement. Note that this
+ equivalency relation is transitive but not symmetric.
+
+ In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
+ cannot assert that q_2 is equivalent to p_5 because q_2 may be used
+ in contexts where that assertion does not hold (e.g., in line 6).
+
TODO, the main difference between this pass and Patterson's is that
we do not propagate edge probabilities. We only compute whether
edges can be taken or not. That is, instead of having a spectrum
DON'T KNOW. In the future, it may be worthwhile to propagate
probabilities to aid branch prediction. */
-static void
+static unsigned int
execute_vrp (void)
{
insert_range_assertions ();
- cfg_loops = loop_optimizer_init (NULL);
- if (cfg_loops)
- scev_initialize (cfg_loops);
+ loop_optimizer_init (LOOPS_NORMAL);
+ if (current_loops)
+ scev_initialize ();
- if (vrp_initialize ())
- {
- ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
- vrp_finalize ();
- }
+ vrp_initialize ();
+ ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
+ vrp_finalize ();
- if (cfg_loops)
+ if (current_loops)
{
scev_finalize ();
- loop_optimizer_finalize (cfg_loops, NULL);
- current_loops = NULL;
+ loop_optimizer_finalize ();
}
+ /* ASSERT_EXPRs must be removed before finalizing jump threads
+ as finalizing jump threads calls the CFG cleanup code which
+ does not properly handle ASSERT_EXPRs. */
remove_range_assertions ();
+
+ /* If we exposed any new variables, go ahead and put them into
+ SSA form now, before we handle jump threading. This simplifies
+ interactions between rewriting of _DECL nodes into SSA form
+ and rewriting SSA_NAME nodes into SSA form after block
+ duplication and CFG manipulation. */
+ update_ssa (TODO_update_ssa);
+
+ finalize_jump_threads ();
+ return 0;
}
static bool
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