/* Support routines for Value Range Propagation (VRP).
- Copyright (C) 2005 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2006 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-chrec.h"
/* Set of SSA names found during the dominator traversal of a
- sub-graph in maybe_add_assert_expr_on_edges. */
-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);
-/* 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. */
+/* 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;
-static inline tree
-get_opposite_operand (tree cond, tree which)
+ /* 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 true if ARG is marked with the nonnull attribute in the
+ current function signature. */
+
+static bool
+nonnull_arg_p (tree arg)
{
- if (TREE_OPERAND (cond, 0) == which)
- return TREE_OPERAND (cond, 1);
- else
- return TREE_OPERAND (cond, 0);
-}
+ tree t, attrs, fntype;
+ unsigned HOST_WIDE_INT arg_num;
+ gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
-/* 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 ();
+ 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;
cmp = compare_values (min, max);
gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
}
-#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)))
- {
- /* 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;
- return;
- }
+ 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
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);
+ }
}
-/* Similar to set_value_range but return true if any field of VR
- changed from its previous value. */
+/* Copy value range FROM into value range TO. */
-static inline bool
-update_value_range (value_range *vr, enum value_range_type t, tree min,
- tree max)
+static inline void
+copy_value_range (value_range_t *to, value_range_t *from)
{
- bool is_new = vr->type != t || vr->min != min || vr->max != max;
- if (is_new)
- set_value_range (vr, t, min, max);
+ set_value_range (to, from->type, from->min, from->max, from->equiv);
+}
- return is_new;
+/* Set value range VR to a non-negative range of type TYPE. */
+
+static inline void
+set_value_range_to_nonnegative (value_range_t *vr, tree type)
+{
+ tree zero = build_int_cst (type, 0);
+ set_value_range (vr, VR_RANGE, zero, 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);
+}
+
+
+/* Set value range VR to a NULL range of type TYPE. */
+
+static inline void
+set_value_range_to_null (value_range_t *vr, tree type)
+{
+ tree zero = build_int_cst (type, 0);
+ set_value_range (vr, VR_RANGE, zero, zero, vr->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);
}
-/* Return value range information for VAR. Create an empty range if
- none existed. */
+/* Set value range VR to VR_UNDEFINED. */
-value_range *
+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. */
+
+static value_range_t *
get_value_range (tree var)
{
- value_range *vr;
+ value_range_t *vr;
tree sym;
+ unsigned ver = SSA_NAME_VERSION (var);
+
+ /* If we have no recorded ranges, then return NULL. */
+ if (! vr_value)
+ return NULL;
- vr = SSA_NAME_VALUE_RANGE (var);
+ 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 = XNEW (value_range_t);
+ memset (vr, 0, sizeof (*vr));
- /* If VAR is a default definition for a PARM_DECL, then we have to
- assume a VARYING range for it. */
+ /* Allocate an equivalence set. */
+ vr->equiv = BITMAP_ALLOC (NULL);
+
+ /* 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 (var == default_def (sym))
+ {
+ /* 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 value range VR involves at least one symbol. */
+/* 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.
+
+ 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. */
static inline bool
-symbolic_range_p (value_range *vr)
+update_value_range (tree var, value_range_t *new_vr)
{
- return (!is_gimple_min_invariant (vr->min)
- || !is_gimple_min_invariant (vr->max));
-}
+ value_range_t *old_vr;
+ bool is_new;
+
+ /* Update the value range, if necessary. */
+ old_vr = get_value_range (var);
+ is_new = old_vr->type != new_vr->type
+ || old_vr->min != new_vr->min
+ || old_vr->max != new_vr->max
+ || (old_vr->equiv == NULL && new_vr->equiv)
+ || (old_vr->equiv && new_vr->equiv == NULL)
+ || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
+ if (is_new)
+ set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
+ new_vr->equiv);
-/* Return true if EXPR computes a non-zero value. */
+ BITMAP_FREE (new_vr->equiv);
+ new_vr->equiv = NULL;
-bool
-expr_computes_nonzero (tree expr)
-{
- /* Type casts won't change anything, so just strip it. */
- STRIP_NOPS (expr);
+ return is_new;
+}
- /* Calling alloca, guarantees that the value is non-NULL. */
- if (alloca_call_p (expr))
- return true;
- /* 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;
+/* Add VAR and VAR's equivalence set to 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;
+static void
+add_equivalence (bitmap equiv, tree var)
+{
+ unsigned ver = SSA_NAME_VERSION (var);
+ value_range_t *vr = vr_value[ver];
- return false;
+ 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));
}
+/* Like tree_expr_nonnegative_p, but this function uses value ranges
+ obtained so far. */
-/* Set value range VR to a NULL range of type TYPE. */
+static bool
+vrp_expr_computes_nonnegative (tree expr)
+{
+ return tree_expr_nonnegative_p (expr);
+}
-static void
-set_value_range_to_null (value_range *vr, tree type)
+/* Like tree_expr_nonzero_p, but this function uses value ranges
+ obtained so far. */
+
+static bool
+vrp_expr_computes_nonzero (tree expr)
{
- tree zero = build_int_cst (type, 0);
- set_value_range (vr, VR_RANGE, zero, zero);
+ if (tree_expr_nonzero_p (expr))
+ 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;
}
if (val1 == val2)
return 0;
+ /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
+ both integers. */
+ 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)))
{
return -2;
if (!POINTER_TYPE_P (TREE_TYPE (val1)))
- return tree_int_cst_compare (val1, val2);
+ {
+ /* We cannot compare overflowed values. */
+ if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
+ 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 (build2 (LT_EXPR, TREE_TYPE (val1), val1, val2));
+ t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
if (t == boolean_true_node)
return -1;
/* If VAL1 is a higher address than VAL2, return +1. */
- t = fold (build2 (GT_EXPR, TREE_TYPE (val1), val1, val2));
+ t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
if (t == boolean_true_node)
return 1;
/* If VAL1 is different than VAL2, return +2. */
- t = fold (build2 (NE_EXPR, TREE_TYPE (val1), val1, val2));
+ t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
if (t == boolean_true_node)
return 2;
/* 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. */
static inline int
-value_inside_range (tree val, value_range *vr)
+value_inside_range (tree val, value_range_t *vr)
{
int cmp1, cmp2;
intersection. */
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)
{
return (value_inside_range (vr1->min, vr0) == 1
|| value_inside_range (vr1->max, vr0) == 1
}
-/* Extract value range information from an ASSERT_EXPR EXPR and store
- it in *VR_P. */
+/* 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 void
-extract_range_from_assert (value_range *vr_p, tree expr)
+static inline bool
+range_includes_zero_p (value_range_t *vr)
{
- tree var, cond, limit, type;
- value_range *var_vr;
+ tree zero;
- var = ASSERT_EXPR_VAR (expr);
- cond = ASSERT_EXPR_COND (expr);
+ gcc_assert (vr->type != VR_UNDEFINED
+ && vr->type != VR_VARYING
+ && !symbolic_range_p (vr));
- gcc_assert (TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
+ zero = build_int_cst (TREE_TYPE (vr->min), 0);
+ return (value_inside_range (zero, vr) == 1);
+}
- /* Find VAR in the ASSERT_EXPR conditional. */
- limit = get_opposite_operand (cond, var);
- type = TREE_TYPE (limit);
+/* Return true if T, an SSA_NAME, is known to be nonnegative. Return
+ false otherwise or if no value range information is available. */
- gcc_assert (limit != var);
+bool
+ssa_name_nonnegative_p (tree t)
+{
+ value_range_t *vr = get_value_range (t);
- /* 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)
- {
- set_value_range (vr_p, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
- }
+ if (!vr)
+ return false;
- 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)
+ /* 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)
{
- 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)));
- }
- 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)
- {
- 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));
+ int result = compare_values (vr->min, integer_zero_node);
+
+ return (result == 0 || result == 1);
}
- else
- gcc_unreachable ();
+ return false;
+}
- /* 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. */
- 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))
- {
- tree min, max;
+/* Return true if T, an SSA_NAME, is known to be nonzero. Return
+ false otherwise or if no value range information is available. */
- /* 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;
+bool
+ssa_name_nonzero_p (tree t)
+{
+ value_range_t *vr = get_value_range (t);
- /* 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;
+ if (!vr)
+ return false;
- set_value_range (vr_p, vr_p->type, min, max);
- }
+ /* 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;
}
-/* Extract range information from SSA name VAR and store it in VR. If
- VAR has an interesting range, use it. Otherwise, create the
- range [VAR, VAR] and return it. This is useful in situations where
- we may have conditionals testing values of VARYING names. For
- instance,
+/* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
+ initially consider X_i and Y_j equivalent, so the equivalence set
+ of Y_j is added to the equivalence set of X_i. However, it is
+ possible to have a chain of ASSERT_EXPRs whose predicates are
+ actually incompatible. This is usually the result of nesting of
+ contradictory if-then-else statements. For instance, in PR 24670:
- x_3 = y_5;
- if (x_3 > y_5)
- ...
+ count_4 has range [-INF, 63]
- Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
- always false. */
+ if (count_4 != 0)
+ {
+ count_19 = ASSERT_EXPR <count_4, count_4 != 0>
+ if (count_19 > 63)
+ {
+ count_18 = ASSERT_EXPR <count_19, count_19 > 63>
+ if (count_18 <= 63)
+ ...
+ }
+ }
+
+ Notice that 'if (count_19 > 63)' is trivially false and will be
+ folded out at the end. However, during propagation, the flowgraph
+ is not cleaned up and so, VRP will evaluate predicates more
+ predicates than necessary, so it must support these
+ inconsistencies. The problem here is that because of the chaining
+ of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
+ Since count_4 has an incompatible range, we ICE when evaluating the
+ ranges in the equivalency set. So, we need to remove count_4 from
+ it. */
static void
-extract_range_from_ssa_name (value_range *vr, tree var)
+fix_equivalence_set (value_range_t *vr_p)
{
- value_range *var_vr = get_value_range (var);
+ bitmap_iterator bi;
+ unsigned i;
+ bitmap e = vr_p->equiv;
+ bitmap to_remove = BITMAP_ALLOC (NULL);
+
+ /* Only detect inconsistencies on numeric ranges. */
+ if (vr_p->type == VR_VARYING
+ || vr_p->type == VR_UNDEFINED
+ || symbolic_range_p (vr_p))
+ return;
- if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
- *vr = *var_vr;
- else
- set_value_range (vr, VR_RANGE, var, var);
+ EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
+ {
+ value_range_t *equiv_vr = vr_value[i];
+
+ if (equiv_vr->type == VR_VARYING
+ || equiv_vr->type == VR_UNDEFINED
+ || symbolic_range_p (equiv_vr))
+ continue;
+
+ if (equiv_vr->type == VR_RANGE
+ && vr_p->type == VR_RANGE
+ && !value_ranges_intersect_p (vr_p, equiv_vr))
+ bitmap_set_bit (to_remove, i);
+ else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
+ || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
+ {
+ /* A range and an anti-range have an empty intersection if
+ their end points are the same. FIXME,
+ value_ranges_intersect_p should handle this
+ automatically. */
+ if (compare_values (equiv_vr->min, vr_p->min) == 0
+ && compare_values (equiv_vr->max, vr_p->max) == 0)
+ bitmap_set_bit (to_remove, i);
+ }
+ }
+
+ bitmap_and_compl_into (vr_p->equiv, to_remove);
+ BITMAP_FREE (to_remove);
}
-/* Extract range information from a binary expression EXPR based on
- the ranges of each of its operands and the expression code. */
+/* Extract value range information from an ASSERT_EXPR EXPR and store
+ it in *VR_P. */
static void
-extract_range_from_binary_expr (value_range *vr, tree expr)
+extract_range_from_assert (value_range_t *vr_p, tree expr)
{
- enum tree_code code = TREE_CODE (expr);
- tree op0, op1, min, max;
- value_range vr0, vr1;
- int cmp;
+ tree var, cond, limit, min, max, type;
+ value_range_t *var_vr, *limit_vr;
+ enum tree_code cond_code;
- /* Not all binary expressions can be applied to ranges in a
- meaningful way. Handle only arithmetic operations. */
- if (code != PLUS_EXPR
- && code != MINUS_EXPR
- && code != MULT_EXPR
- && code != TRUNC_DIV_EXPR
- && code != FLOOR_DIV_EXPR
- && code != CEIL_DIV_EXPR
- && code != EXACT_DIV_EXPR
- && code != ROUND_DIV_EXPR
- && code != MIN_EXPR
- && code != MAX_EXPR)
- {
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
- }
+ var = ASSERT_EXPR_VAR (expr);
+ cond = ASSERT_EXPR_COND (expr);
- /* Get value ranges for each 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
+ gcc_assert (COMPARISON_CLASS_P (cond));
+
+ /* Find VAR in the ASSERT_EXPR conditional. */
+ if (var == TREE_OPERAND (cond, 0))
{
- 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);
+ /* 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);
}
-
- 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);
- else
- set_value_range (&vr1, VR_VARYING, 0, 0);
+ /* 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));
}
- /* 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;
- }
+ type = TREE_TYPE (limit);
+ gcc_assert (limit != var);
- /* If either range is VARYING, so is the result. */
- if (vr0.type == VR_VARYING || vr1.type == VR_VARYING)
+ /* 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, VR_VARYING, NULL_TREE, NULL_TREE);
+ set_value_range_to_varying (vr_p);
return;
}
- /* If the ranges are of different types, the result is VARYING. */
- if (vr0.type != vr1.type)
+ /* 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;
+
+ /* Special handling for integral types with super-types. Some FEs
+ construct integral types derived from other types and restrict
+ the range of values these new types may take.
+
+ It may happen that LIMIT is actually smaller than TYPE's minimum
+ value. For instance, the Ada FE is generating code like this
+ during bootstrap:
+
+ D.1480_32 = nam_30 - 300000361;
+ if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
+ <L112>:;
+ D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
+
+ All the names are of type types__name_id___XDLU_300000000__399999999
+ which has min == 300000000 and max == 399999999. This means that
+ the ASSERT_EXPR would try to create the range [3000000, 1] which
+ is invalid.
+
+ The fact that the type specifies MIN and MAX values does not
+ automatically mean that every variable of that type will always
+ be within that range, so the predicate may well be true at run
+ time. If we had symbolic -INF and +INF values, we could
+ represent this range, but we currently represent -INF and +INF
+ using the type's min and max values.
+
+ So, the only sensible thing we can do for now is set the
+ resulting range to VR_VARYING. TODO, would having symbolic -INF
+ and +INF values be worth the trouble? */
+ if (TREE_CODE (limit) != SSA_NAME
+ && INTEGRAL_TYPE_P (type)
+ && TREE_TYPE (type))
{
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
+ if (cond_code == LE_EXPR || cond_code == LT_EXPR)
+ {
+ tree type_min = TYPE_MIN_VALUE (type);
+ int cmp = compare_values (limit, type_min);
+
+ /* For < or <= comparisons, if LIMIT is smaller than
+ TYPE_MIN, set the range to VR_VARYING. */
+ if (cmp == -1 || cmp == 0)
+ {
+ set_value_range_to_varying (vr_p);
+ return;
+ }
+ }
+ else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
+ {
+ tree type_max = TYPE_MIN_VALUE (type);
+ int cmp = compare_values (limit, type_max);
+
+ /* For > or >= comparisons, if LIMIT is bigger than
+ TYPE_MAX, set the range to VR_VARYING. */
+ if (cmp == 1 || cmp == 0)
+ {
+ set_value_range_to_varying (vr_p);
+ return;
+ }
+ }
}
- /* TODO. Refuse to do any symbolic range operations for now. */
- if (symbolic_range_p (&vr0) || symbolic_range_p (&vr1))
+ /* 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)
{
- set_value_range (vr, VR_VARYING, NULL_TREE, NULL_TREE);
- return;
- }
+ enum value_range_type range_type;
- /* Now evaluate the expression to determine the new range. */
- if (POINTER_TYPE_P (TREE_TYPE (expr))
- || POINTER_TYPE_P (TREE_TYPE (op0))
+ 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)
+ {
+ /* 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)
+ && max == TYPE_MAX_VALUE (type))
+ 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;
+ }
+
+ /* 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 (cond_code == GE_EXPR || cond_code == GT_EXPR)
+ {
+ 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;
+ }
+
+ /* 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 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);
+
+ /* 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))
+ goto done;
+
+ if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
+ {
+ /* 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 smaller of the two maximums. */
+ if (compare_values (vr_p->max, var_vr->max) == 1)
+ max = var_vr->max;
+ else
+ max = vr_p->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
+ {
+ tree min, max, anti_min, anti_max, real_min, real_max;
+
+ /* We want to compute the logical AND of the two ranges;
+ there are three cases to consider.
+
+
+ 1. The VR_ANTI_RANGE range is competely 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;
+ }
+
+
+ /* 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 reange. */
+ else if ((compare_values (anti_max, real_min) == 1
+ || compare_values (anti_max, real_min) == 0)
+ && compare_values (anti_max, real_max) == -1)
+ {
+ 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 reange. */
+ else if (compare_values (anti_min, real_min) == 1
+ && (compare_values (anti_min, real_max) == -1
+ || compare_values (anti_min, real_max) == 0))
+ {
+ 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);
+ }
+ }
+ }
+
+ /* Remove names from the equivalence set that have ranges
+ incompatible with VR_P. */
+done:
+ fix_equivalence_set (vr_p);
+}
+
+
+/* Extract range information from SSA name VAR and store it in VR. If
+ VAR has an interesting range, use it. Otherwise, create the
+ range [VAR, VAR] and return it. This is useful in situations where
+ we may have conditionals testing values of VARYING names. For
+ instance,
+
+ x_3 = y_5;
+ if (x_3 > y_5)
+ ...
+
+ Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
+ always false. */
+
+static void
+extract_range_from_ssa_name (value_range_t *vr, tree var)
+{
+ value_range_t *var_vr = get_value_range (var);
+
+ if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
+ copy_value_range (vr, var_vr);
+ else
+ 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. */
+
+static inline tree
+vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
+{
+ tree res;
+
+ if (flag_wrapv)
+ return int_const_binop (code, val1, val2, 0);
+
+ /* If we are not using wrapping arithmetic, operate symbolically
+ on -INF and +INF. */
+ res = int_const_binop (code, val1, val2, 0);
+
+ if (TYPE_UNSIGNED (TREE_TYPE (val1)))
+ {
+ int checkz = compare_values (res, val1);
+
+ /* Ensure that res = val1 [+*] val2 >= val1
+ or that res = val1 - val2 <= val1. */
+ if (((code == PLUS_EXPR || code == MULT_EXPR)
+ && !(checkz == 1 || checkz == 0))
+ || (code == MINUS_EXPR
+ && !(checkz == 0 || checkz == -1)))
+ {
+ res = copy_node (res);
+ TREE_OVERFLOW (res) = 1;
+ }
+ }
+ else if (TREE_OVERFLOW (res)
+ && !TREE_OVERFLOW (val1)
+ && !TREE_OVERFLOW (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);
+
+ /* 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. */
+ || (code == PLUS_EXPR && sgn1 > 0)
+ /* For subtraction, the 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. */
+ || (code == MINUS_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 TYPE_MAX_VALUE (TREE_TYPE (res));
+ else
+ return TYPE_MIN_VALUE (TREE_TYPE (res));
+ }
+
+ return res;
+}
+
+
+/* Extract range information from a binary expression EXPR based on
+ the ranges of each of its operands and the expression code. */
+
+static void
+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;
+ 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. */
+ if (code != PLUS_EXPR
+ && code != MINUS_EXPR
+ && code != MULT_EXPR
+ && code != TRUNC_DIV_EXPR
+ && code != FLOOR_DIV_EXPR
+ && code != CEIL_DIV_EXPR
+ && code != EXACT_DIV_EXPR
+ && code != ROUND_DIV_EXPR
+ && code != MIN_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_to_varying (vr);
+ return;
+ }
+
+ /* Get value ranges for each 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
+ 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
+ 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_to_undefined (vr);
+ return;
+ }
+
+ /* 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_to_varying (vr);
+ return;
+ }
+
+ /* Now evaluate the expression to determine the new range. */
+ if (POINTER_TYPE_P (TREE_TYPE (expr))
+ || POINTER_TYPE_P (TREE_TYPE (op0))
|| 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)
+ && !symbolic_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
+ {
+ set_value_range_to_varying (vr);
+ 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)
+ {
+ tree val[4];
+ size_t i;
+
+ /* 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
+ && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
+ {
+ 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. */
+ 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. */
+ val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
+
+ val[1] = (vr1.max != vr1.min)
+ ? vrp_int_const_binop (code, vr0.min, vr1.max)
+ : NULL_TREE;
+
+ val[2] = (vr0.max != vr0.min)
+ ? vrp_int_const_binop (code, vr0.max, vr1.min)
+ : NULL_TREE;
+
+ val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
+ ? vrp_int_const_binop (code, vr0.max, vr1.max)
+ : NULL_TREE;
+
+ /* 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_gimple_min_invariant (max) || TREE_OVERFLOW (max))
+ break;
+
+ if (val[i])
+ {
+ if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (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_expr_nonnegative_p (vr0.max)
+ && TREE_CODE (vr0.max) == INTEGER_CST)
+ {
+ min = build_int_cst (TREE_TYPE (expr), 0);
+ max = vr0.max;
+ }
+ else if (vr1.type == VR_RANGE
+ && vr1.min == vr1.max
+ && tree_expr_nonnegative_p (vr1.max)
+ && TREE_CODE (vr1.max) == INTEGER_CST)
+ {
+ 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. */
+ if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
+ || !is_gimple_min_invariant (max) || TREE_OVERFLOW (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 == FIX_CEIL_EXPR
+ || code == FIX_FLOOR_EXPR
+ || code == FIX_ROUND_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 varying and symbolic ranges. Also, if the
+ operand is neither a pointer nor an integral type, set the
+ resulting range to VARYING. TODO, in some cases we may be able
+ to derive anti-ranges (like nonzero values). */
+ if (vr0.type == VR_VARYING
+ || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
+ && !POINTER_TYPE_P (TREE_TYPE (op0)))
+ || 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))
+ if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
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)
+ {
+ tree new_min, new_max;
+
+ /* Convert VR0's min/max to OUTER_TYPE. */
+ new_min = fold_convert (outer_type, vr0.min);
+ new_max = fold_convert (outer_type, vr0.max);
+
+ /* Verify the new min/max values are gimple values and
+ that they compare equal to VR0's min/max values. */
+ if (is_gimple_val (new_min)
+ && is_gimple_val (new_max)
+ && tree_int_cst_equal (new_min, vr0.min)
+ && tree_int_cst_equal (new_max, vr0.max)
+ && compare_values (new_min, new_max) <= 0
+ && compare_values (new_min, new_max) >= -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);
- return;
+ if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
+ || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
+ {
+ 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);
+ if (code == NEGATE_EXPR
+ && !TYPE_UNSIGNED (TREE_TYPE (expr)))
+ {
+ /* NEGATE_EXPR flips the range around. */
+ min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
+ ? TYPE_MIN_VALUE (TREE_TYPE (expr))
+ : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+
+ max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
+ ? TYPE_MAX_VALUE (TREE_TYPE (expr))
+ : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+
+ }
+ 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 (flag_wrapv
+ && ((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. */
+ min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
+ ? TYPE_MAX_VALUE (TREE_TYPE (expr))
+ : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
+
+ max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
+
+ 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))
+ {
+ tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
+
+ /* 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. */
+ min = (flag_wrapv && vr0.min != type_min_value
+ ? int_const_binop (PLUS_EXPR,
+ type_min_value,
+ integer_one_node, 0)
+ : type_min_value);
+ }
+ 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);
+ 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);
+ }
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 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)
+{
+ tree val = vrp_evaluate_conditional (expr, false);
+ if (val)
+ {
+ /* 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);
+ set_value_range_to_varying (vr);
}
/* 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_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)
+ {
+ if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
+ && vrp_expr_computes_nonnegative (expr))
+ set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
+ else if (vrp_expr_computes_nonzero (expr))
+ 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;
+ bool init_is_max, unknown_max;
/* 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))
+ if (step == NULL_TREE
+ || !is_gimple_min_invariant (step))
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)))
+ /* Do not adjust ranges when chrec may wrap. */
+ if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
+ current_loops->parray[CHREC_VARIABLE (chrec)],
+ &init_is_max, &unknown_max)
+ || unknown_max)
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);
-
if (!POINTER_TYPE_P (TREE_TYPE (init))
&& (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
{
/* For VARYING or UNDEFINED ranges, just about anything we get
from scalar evolutions should be better. */
+ tree min = TYPE_MIN_VALUE (TREE_TYPE (init));
+ tree max = TYPE_MAX_VALUE (TREE_TYPE (init));
+
if (init_is_max)
- set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)), init);
+ 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. */
+ if (compare_values (min, max) == 1)
+ return;
+
+ set_value_range (vr, VR_RANGE, min, max, vr->equiv);
}
else if (vr->type == VR_RANGE)
{
+ tree min = vr->min;
+ tree max = vr->max;
+
if (init_is_max)
{
- /* 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, take the minimum all the
+ way to -INF. */
+ if (compare_values (min, max) == 1)
+ min = TYPE_MIN_VALUE (TREE_TYPE (min));
+ }
}
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;
+
+ /* If we just created an invalid range with the minimum
+ greater than the maximum, take the maximum all the
+ way to +INF. */
+ if (compare_values (min, max) == 1)
+ max = TYPE_MAX_VALUE (TREE_TYPE (max));
+ }
}
+
+ 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. */
+
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)
{
/* 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;
}
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;
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 (vr0->min, vr1->max) == 1
+ || compare_values (vr1->min, vr0->max) == 1)
+ return boolean_false_node;
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. */
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)
{
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;
else if (cmp == -1 || cmp == 1 || cmp == 2)
return boolean_false_node;
}
+ else if (compare_values (val, vr->min) == -1
+ || compare_values (vr->max, val) == -1)
+ return boolean_false_node;
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
+ 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
+ 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);
}
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");
}
}
}
-/* Dump all value ranges to stderr. */
+/* Dump all value ranges to stderr. */
+
+void
+debug_all_value_ranges (void)
+{
+ dump_all_value_ranges (stderr);
+}
+
+
+/* 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>'. */
+
+static tree
+build_assert_expr_for (tree cond, tree v)
+{
+ tree n, assertion;
+
+ gcc_assert (TREE_CODE (v) == SSA_NAME);
+ n = duplicate_ssa_name (v, NULL_TREE);
+
+ if (COMPARISON_CLASS_P (cond))
+ {
+ tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
+ assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), 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 = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
+ }
+ else if (TREE_CODE (cond) == SSA_NAME)
+ {
+ /* Given V, build the assignment N = true. */
+ gcc_assert (v == cond);
+ assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
+ }
+ else
+ gcc_unreachable ();
+
+ SSA_NAME_DEF_STMT (n) = assertion;
+
+ /* The new ASSERT_EXPR, creates a new SSA name that replaces the
+ operand of the ASSERT_EXPR. Register the new name and the old one
+ in the replacement table so that we can fix the SSA web after
+ adding all the ASSERT_EXPRs. */
+ register_new_name_mapping (n, v);
+
+ return assertion;
+}
+
+
+/* Return false if EXPR is a predicate expression involving floating
+ point values. */
+
+static inline bool
+fp_predicate (tree expr)
+{
+ return (COMPARISON_CLASS_P (expr)
+ && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
+}
+
+
+/* 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 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 false;
+
+ /* 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;
+
+ if (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)
+ {
+ /* We can only assume that a pointer dereference will yield
+ non-NULL if -fdelete-null-pointer-checks is enabled. */
+ *val_p = build_int_cst (TREE_TYPE (op), 0);
+ *comp_code_p = NE_EXPR;
+ return true;
+ }
+ }
+
+ 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_value_ranges (void)
+debug_all_asserts (void)
{
- dump_all_value_ranges (stderr);
+ dump_all_asserts (stderr);
}
-/*---------------------------------------------------------------------------
- Value Range Propagation
----------------------------------------------------------------------------*/
+/* 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>.
-/* 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>'. */
+ 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 tree
-build_assert_expr_for (tree cond, tree v)
+static void
+register_new_assert_for (tree name,
+ enum tree_code comp_code,
+ tree val,
+ basic_block bb,
+ edge e,
+ block_stmt_iterator si)
{
- tree n, assertion;
+ assert_locus_t n, loc, last_loc;
+ bool found;
+ basic_block dest_bb;
- gcc_assert (TREE_CODE (v) == SSA_NAME);
- n = duplicate_ssa_name (v, NULL_TREE);
+#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
- if (TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison)
+ /* 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)
{
- /* 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)
+ if (loc->comp_code == comp_code
+ && (loc->val == val
+ || operand_equal_p (loc->val, val, 0)))
{
- tree other = get_opposite_operand (cond, v);
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, other);
+ /* 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;
+ }
}
- else
- assertion = build (MODIFY_EXPR, TREE_TYPE (v), n,
- build (ASSERT_EXPR, TREE_TYPE (v), v, cond));
- }
- 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);
- }
- 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);
- }
- else
- gcc_unreachable ();
- SSA_NAME_DEF_STMT (n) = assertion;
+ /* Update the last node of the list and move to the next one. */
+ last_loc = loc;
+ loc = loc->next;
+ }
- /* The new ASSERT_EXPR, creates a new SSA name that replaces the
- operand of the ASSERT_EXPR. Register the new name and the old one
- in the replacement table so that we can fix the SSA web after
- adding all the ASSERT_EXPRs. */
- register_new_name_mapping (n, v);
+ /* 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;
- return assertion;
+ bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
}
-/* Return false if EXPR is a predicate expression involving floating
- point values. */
+/* Try to register an edge assertion for SSA name NAME on edge E for
+ the conditional jump pointed to by SI. Return true if an assertion
+ for NAME could be registered. */
-static inline bool
-fp_predicate (tree expr)
+static bool
+register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
{
- return TREE_CODE_CLASS (TREE_CODE (expr)) == tcc_comparison
- && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)));
-}
-
+ tree val, stmt;
+ enum tree_code comp_code;
-/* Return an expression predicate that represents the range of values
- that can be taken by operand OP after STMT executes. */
+ stmt = bsi_stmt (si);
-static tree
-infer_value_range (tree stmt, tree op)
-{
/* Do not attempt to infer anything in names that flow through
abnormal edges. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
- return NULL_TREE;
+ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
+ return false;
- if (POINTER_TYPE_P (TREE_TYPE (op)))
- {
- bool is_store;
- unsigned num_uses, num_derefs;
+ /* If NAME was not found in the sub-graph reachable from E, then
+ there's nothing to do. */
+ if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
+ return false;
- count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
- if (num_derefs > 0 && flag_delete_null_pointer_checks)
+ /* We found a use of NAME in the sub-graph rooted at E->DEST.
+ Register an assertion for NAME according to the value that NAME
+ takes on edge E. */
+ if (TREE_CODE (stmt) == COND_EXPR)
+ {
+ /* If BB ends in a COND_EXPR then NAME then we should insert
+ the original predicate on EDGE_TRUE_VALUE and the
+ opposite predicate on EDGE_FALSE_VALUE. */
+ tree cond = COND_EXPR_COND (stmt);
+ bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
+
+ /* Predicates may be a single SSA name or NAME OP VAL. */
+ if (cond == name)
{
- /* 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;
+ /* 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 = (is_else_edge) ? 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);
+ }
- return NULL_TREE;
-}
+ /* If we are inserting the assertion on the ELSE edge, we
+ need to invert the sign comparison. */
+ if (is_else_edge)
+ comp_code = invert_tree_comparison (comp_code, 0);
+
+ /* 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))
+ || SCALAR_FLOAT_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 && compare_values (val, max) == 0)
+ return false;
-/* Return true if OP is the result of an ASSERT_EXPR that tests the
- same condition as COND. */
+ if (comp_code == LT_EXPR && compare_values (val, min) == 0)
+ return false;
+ }
+ }
+ }
+ else
+ {
+ /* FIXME. Handle SWITCH_EXPR. */
+ gcc_unreachable ();
+ }
-static bool
-has_assert_expr (tree op, tree cond)
-{
- tree def_stmt = SSA_NAME_DEF_STMT (op);
- tree assert_expr, other_cond, other_op;
+ register_new_assert_for (name, comp_code, val, NULL, e, si);
+ return true;
+}
- /* 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)
- return false;
- assert_expr = TREE_OPERAND (def_stmt, 1);
- other_cond = ASSERT_EXPR_COND (assert_expr);
- other_op = ASSERT_EXPR_VAR (assert_expr);
+static bool find_assert_locations (basic_block bb);
- if (TREE_CODE (cond) == TREE_CODE (other_cond))
- {
- tree t1, t2;
+/* 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 COND is not a comparison predicate, something is wrong. */
- gcc_assert (TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
+ 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. */
- /* 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>.
-
- 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);
+static bool
+find_conditional_asserts (basic_block bb)
+{
+ bool need_assert;
+ block_stmt_iterator last_si;
+ tree op, last;
+ 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;
+ last_si = bsi_last (bb);
+ last = bsi_stmt (last_si);
- 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, last_si);
}
- 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;
+
+ SET_BIT (blocks_visited, bb->index);
- /* Step 1. Mark all the SSA names used in BB in bitmap FOUND. */
- added = false;
+ 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);
- get_stmt_operands (stmt);
- /* 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;
-
- 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));
-
- if (has_assert_expr (op, cond))
+ 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 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.
+ Experiments show that with this simple check, we can save
+ more than 20% of ASSERT_EXPRs. */
+ if (has_single_use (op))
continue;
- 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
+ /* 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))
{
- /* 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;
- }
+ 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);
+
+ /* 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;
-
- 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);
-
- /* Do not attempt to infer anything in names that flow through
- abnormal edges. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
- 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 ();
-
- t = build_assert_expr_for (c, op);
- bsi_insert_on_edge (e, t);
- added = true;
- }
- }
+ bsi_insert_on_edge (loc->e, assert_expr);
+ return true;
+ }
- /* Finally, mark all the COND_EXPR operands as found. */
- SET_BIT (found, SSA_NAME_VERSION (op));
+ /* 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;
}
- else
+
+ /* 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;
+ }
+
+ gcc_unreachable ();
+}
+
+
+/* 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)
{
- /* Step 4. Recurse into the dominator children of BB. */
- basic_block son;
+ assert_locus_t loc = asserts_for[i];
+ gcc_assert (loc);
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- added |= maybe_add_assert_expr (son);
+ while (loc)
+ {
+ assert_locus_t next = loc->next;
+ update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
+ free (loc);
+ loc = next;
+ num_asserts++;
+ }
}
- return added;
+ if (update_edges_p)
+ bsi_commit_edge_inserts ();
+
+ 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 = XNEWVEC (assert_locus_t, num_ssa_names);
+ memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
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);
}
-/* Convert range assertion expressions into copies. FIXME, explain why. */
+/* 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.
+
+ 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 rhs = TREE_OPERAND (stmt, 1);
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);
+
+ /* The statement is now a copy. Propagate the RHS into
+ every use of the LHS. */
+ FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
+ {
+ SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
+ update_stmt (USE_STMT (use_p));
+ }
+
+ /* And finally, remove the copy, it is not needed. */
+ bsi_remove (&si, true);
}
+ else
+ bsi_next (&si);
}
+
+ sbitmap_free (blocks_visited);
}
else if (TREE_CODE (stmt) == MODIFY_EXPR)
{
tree lhs = TREE_OPERAND (stmt, 0);
- stmt_ann_t ann = stmt_ann (stmt);
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)
+ && 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 = XNEWVEC (value_range_t *, num_ssa_names);
+ memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
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 = TREE_OPERAND (stmt, 0);
+ rhs = TREE_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))
+ /* 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))))
+ {
+ struct loop *l;
+ 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 (current_loops && (l = loop_containing_stmt (stmt)))
+ adjust_range_with_scev (&new_vr, l, stmt, lhs);
+
+ if (update_value_range (lhs, &new_vr))
+ {
+ *output_p = lhs;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ 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");
+ }
+
+ if (new_vr.type == VR_VARYING)
+ return SSA_PROP_VARYING;
+
+ return SSA_PROP_INTERESTING;
+ }
+
+ return SSA_PROP_NOT_INTERESTING;
+ }
+
+ /* Every other statement produces no useful ranges. */
+ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
+ set_value_range_to_varying (get_value_range (def));
+
+ return SSA_PROP_VARYING;
+}
+
+
+/* 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. */
+
+static tree
+compare_name_with_value (enum tree_code comp, tree var, tree val)
+{
+ bitmap_iterator bi;
+ unsigned i;
+ bitmap e;
+ tree retval, t;
+
+ 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));
+
+ EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
+ {
+ 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);
+ }
+
+ t = compare_range_with_value (comp, &equiv_vr, val);
+ if (t)
+ {
+ /* All the ranges should compare the same against VAL. */
+ gcc_assert (retval == NULL || t == retval);
+ retval = t;
+ }
+ }
+
+ /* Remove VAR from its own equivalence set. */
+ bitmap_clear_bit (e, SSA_NAME_VERSION (var));
+
+ if (retval)
+ 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. */
+
+static tree
+compare_names (enum tree_code comp, tree n1, tree n2)
+{
+ tree t, retval;
+ bitmap e1, e2;
+ bitmap_iterator bi1, bi2;
+ unsigned i1, i2;
+
+ /* 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;
+ }
- /* We only keep track of ranges in integral and pointer types. */
- if (TREE_CODE (lhs) == SSA_NAME
- && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
- || POINTER_TYPE_P (TREE_TYPE (lhs))))
+ /* 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 *vr, new_vr;
- struct loop *l;
-
- vr = get_value_range (lhs);
- extract_range_from_expr (&new_vr, rhs);
+ value_range_t vr1 = *(vr_value[i1]);
- /* 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 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);
+ }
- if (update_value_range (vr, new_vr.type, new_vr.min, new_vr.max))
+ t = retval = NULL_TREE;
+ EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
{
- *output_p = lhs;
+ value_range_t vr2 = *(vr_value[i2]);
- if (dump_file && (dump_flags & TDF_DETAILS))
+ if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
{
- fprintf (dump_file, "Found new range ");
- dump_value_range (dump_file, &new_vr);
- fprintf (dump_file, " for ");
- print_generic_expr (dump_file, lhs, 0);
- fprintf (dump_file, "\n\n");
+ vr2.type = VR_RANGE;
+ vr2.min = ssa_name (i2);
+ vr2.max = ssa_name (i2);
}
- if (new_vr.type == VR_VARYING)
- return SSA_PROP_VARYING;
-
- return SSA_PROP_INTERESTING;
+ t = compare_ranges (comp, &vr1, &vr2);
+ if (t)
+ {
+ /* All the ranges in the equivalent sets should compare
+ the same. */
+ gcc_assert (retval == NULL || t == retval);
+ retval = t;
+ }
}
- return SSA_PROP_NOT_INTERESTING;
+ if (retval)
+ {
+ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+ bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+ return retval;
+ }
}
-
- /* Every other statements 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);
- return SSA_PROP_VARYING;
+ /* 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. */
-
-static tree
-vrp_evaluate_conditional (tree cond)
+ 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. */
+
+tree
+vrp_evaluate_conditional (tree cond, bool use_equiv_p)
{
gcc_assert (TREE_CODE (cond) == SSA_NAME
|| TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
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)
+ value_range_t *vr;
+ tree retval;
+
+ if (use_equiv_p)
+ retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
+ else
+ {
+ value_range_t *vr = get_value_range (cond);
+ retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
+ }
+
+ /* 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
{
- /* For comparisons, evaluate each operand and compare their
- ranges. */
- tree op0, op1;
- value_range *vr0, *vr1;
-
- op0 = TREE_OPERAND (cond, 0);
- vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
+ tree op0 = TREE_OPERAND (cond, 0);
+ tree op1 = TREE_OPERAND (cond, 1);
- op1 = TREE_OPERAND (cond, 1);
- vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
+ /* 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 (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 (use_equiv_p)
+ {
+ if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
+ return compare_names (TREE_CODE (cond), op0, op1);
+ else if (TREE_CODE (op0) == SSA_NAME)
+ return compare_name_with_value (TREE_CODE (cond), op0, op1);
+ else if (TREE_CODE (op1) == SSA_NAME)
+ return compare_name_with_value (
+ swap_tree_comparison (TREE_CODE (cond)), op1, op0);
+ }
+ 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);
+ 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 (
+ swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
+ }
}
/* Anything else cannot be computed statically. */
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. */
+ val = vrp_evaluate_conditional (cond, false);
if (val)
*taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
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)
+ && 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;
}
union of VR0 and VR1. */
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;
}
union of both ranges. */
if (value_ranges_intersect_p (vr0, vr1))
{
+ int cmp;
tree min, max;
- min = vr0->min;
- max = vr0->max;
-
/* The lower limit of the new range is the minimum of the
- two ranges. */
- if (compare_values (vr0->min, vr1->min) == 1)
+ two ranges. If they cannot be compared, the result is
+ VARYING. */
+ cmp = compare_values (vr0->min, vr1->min);
+ if (cmp == 0 || cmp == 1)
min = vr1->min;
+ else if (cmp == -1)
+ min = vr0->min;
+ else
+ {
+ set_value_range_to_varying (vr0);
+ return;
+ }
- /* The upper limit of the new range is the maximum of the
- two ranges. */
- if (compare_values (vr0->max, vr1->max) == -1)
+ /* Similarly, the upper limit of the new range is the
+ maximum of the two ranges. If they cannot be compared,
+ the result is VARYING. */
+ cmp = compare_values (vr0->max, vr1->max);
+ if (cmp == 0 || cmp == -1)
max = vr1->max;
+ else if (cmp == 1)
+ max = vr0->max;
+ else
+ {
+ set_value_range_to_varying (vr0);
+ return;
+ }
- set_value_range (vr0, vr0->type, min, 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, vr0->equiv);
}
else
- {
- /* The two ranges don't intersect, set the result to VR_VARYING. */
- set_value_range (vr0, VR_VARYING, NULL_TREE, NULL_TREE);
- }
+ goto no_meet;
}
else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
{
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 no_meet;
}
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))
+ /* A numeric 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 (!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 no_meet;
}
else
gcc_unreachable ();
+
+ return;
+
+no_meet:
+ /* The two range VR0 and VR1 do not 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 };
+
+ 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.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)
{
if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
{
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;
- }
+ 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
+ {
+ val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
}
- 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);
+ }
+
+ TREE_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))
+ {
+ val = integer_zero_node;
+ }
+ else if (vr)
{
- tree last = last_stmt (bb);
- if (last && TREE_CODE (last) == COND_EXPR)
+ val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
+ if (!val)
{
- tree val = vrp_evaluate_conditional (COND_EXPR_COND (last));
+ val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
+
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 (integer_onep (val))
+ t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
+ else
+ t = op;
+
+ TREE_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)
+ {
+ min = TYPE_MIN_VALUE (TREE_TYPE (op0));
+
+ max = op1;
+ if (cond_code == LT_EXPR)
+ {
+ 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)
+ {
+ max = TYPE_MAX_VALUE (TREE_TYPE (op0));
+
+ min = op1;
+ if (cond_code == GT_EXPR)
+ {
+ 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, "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)
{
- 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);
+ 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) == MODIFY_EXPR)
+ {
+ tree rhs = TREE_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. */
+static tree
+simplify_stmt_for_jump_threading (tree 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), true);
+}
+
+/* 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, to safely do that we must clean up the CFG first. */
+ if (cfg_altered)
+ {
+ free_dominance_info (CDI_DOMINATORS);
+ cleanup_tree_cfg ();
+ calculate_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 = XNEWVEC (prop_value_t, num_ssa_names);
+ memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
+
+ 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);
+
+ /* 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
{
insert_range_assertions ();
- cfg_loops = loop_optimizer_init (NULL);
- if (cfg_loops)
- scev_initialize (cfg_loops);
+ current_loops = loop_optimizer_init (LOOPS_NORMAL);
+ if (current_loops)
+ scev_initialize (current_loops);
- 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);
+ loop_optimizer_finalize (current_loops);
current_loops = NULL;
}
+ /* 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 ();
+
}
static bool
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