/* Alias analysis for GNU C
- Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
+ Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
Contributed by John Carr (jfc@mit.edu).
This file is part of GNU CC.
#include "tree.h"
#include "tm_p.h"
#include "function.h"
-#include "insn-flags.h"
#include "expr.h"
#include "regs.h"
#include "hard-reg-set.h"
static int rtx_equal_for_memref_p PARAMS ((rtx, rtx));
static rtx find_symbolic_term PARAMS ((rtx));
-static rtx get_addr PARAMS ((rtx));
+rtx get_addr PARAMS ((rtx));
static int memrefs_conflict_p PARAMS ((int, rtx, int, rtx,
HOST_WIDE_INT));
static void record_set PARAMS ((rtx, rtx, void *));
static rtx find_base_term PARAMS ((rtx));
static int base_alias_check PARAMS ((rtx, rtx, enum machine_mode,
enum machine_mode));
+static int handled_component_p PARAMS ((tree));
+static int can_address_p PARAMS ((tree));
static rtx find_base_value PARAMS ((rtx));
static int mems_in_disjoint_alias_sets_p PARAMS ((rtx, rtx));
static int insert_subset_children PARAMS ((splay_tree_node, void*));
static tree find_base_decl PARAMS ((tree));
static alias_set_entry get_alias_set_entry PARAMS ((HOST_WIDE_INT));
static rtx fixed_scalar_and_varying_struct_p PARAMS ((rtx, rtx, rtx, rtx,
- int (*) (rtx)));
+ int (*) (rtx, int)));
static int aliases_everything_p PARAMS ((rtx));
static int write_dependence_p PARAMS ((rtx, rtx, int));
static int nonlocal_mentioned_p PARAMS ((rtx));
static unsigned int reg_base_value_size; /* size of reg_base_value array */
#define REG_BASE_VALUE(X) \
- (REGNO (X) < reg_base_value_size ? reg_base_value[REGNO (X)] : 0)
+ (REGNO (X) < reg_base_value_size \
+ ? reg_base_value[REGNO (X)] : 0)
/* Vector of known invariant relationships between registers. Set in
loop unrolling. Indexed by register number, if nonzero the value
rtx mem1;
rtx mem2;
{
- alias_set_entry ase;
-
#ifdef ENABLE_CHECKING
/* Perform a basic sanity check. Namely, that there are no alias sets
if we're not using strict aliasing. This helps to catch bugs
abort ();
#endif
- /* If have no alias set information for one of the MEMs, we have to assume
- it can alias anything. */
- if (MEM_ALIAS_SET (mem1) == 0 || MEM_ALIAS_SET (mem2) == 0)
- return 0;
+ return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
+}
- /* If the two alias sets are the same, they may alias. */
- if (MEM_ALIAS_SET (mem1) == MEM_ALIAS_SET (mem2))
- return 0;
+/* Insert the NODE into the splay tree given by DATA. Used by
+ record_alias_subset via splay_tree_foreach. */
+
+static int
+insert_subset_children (node, data)
+ splay_tree_node node;
+ void *data;
+{
+ splay_tree_insert ((splay_tree) data, node->key, node->value);
+
+ return 0;
+}
+
+/* Return 1 if the two specified alias sets may conflict. */
+
+int
+alias_sets_conflict_p (set1, set2)
+ HOST_WIDE_INT set1, set2;
+{
+ alias_set_entry ase;
+
+ /* If have no alias set information for one of the operands, we have
+ to assume it can alias anything. */
+ if (set1 == 0 || set2 == 0
+ /* If the two alias sets are the same, they may alias. */
+ || set1 == set2)
+ return 1;
/* See if the first alias set is a subset of the second. */
- ase = get_alias_set_entry (MEM_ALIAS_SET (mem1));
+ ase = get_alias_set_entry (set1);
if (ase != 0
&& (ase->has_zero_child
|| splay_tree_lookup (ase->children,
- (splay_tree_key) MEM_ALIAS_SET (mem2))))
- return 0;
+ (splay_tree_key) set2)))
+ return 1;
/* Now do the same, but with the alias sets reversed. */
- ase = get_alias_set_entry (MEM_ALIAS_SET (mem2));
+ ase = get_alias_set_entry (set2);
if (ase != 0
&& (ase->has_zero_child
|| splay_tree_lookup (ase->children,
- (splay_tree_key) MEM_ALIAS_SET (mem1))))
- return 0;
+ (splay_tree_key) set1)))
+ return 1;
- /* The two MEMs are in distinct alias sets, and neither one is the
+ /* The two alias sets are distinct and neither one is the
child of the other. Therefore, they cannot alias. */
- return 1;
+ return 0;
}
+\f
+/* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
+ has any readonly fields. If any of the fields have types that
+ contain readonly fields, return true as well. */
-/* Insert the NODE into the splay tree given by DATA. Used by
- record_alias_subset via splay_tree_foreach. */
-
-static int
-insert_subset_children (node, data)
- splay_tree_node node;
- void *data;
+int
+readonly_fields_p (type)
+ tree type;
{
- splay_tree_insert ((splay_tree) data, node->key, node->value);
+ tree field;
+
+ if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
+ && TREE_CODE (type) != QUAL_UNION_TYPE)
+ return 0;
+
+ for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
+ if (TREE_CODE (field) == FIELD_DECL
+ && (TREE_READONLY (field)
+ || readonly_fields_p (TREE_TYPE (field))))
+ return 1;
return 0;
}
\f
+/* Return 1 if any MEM object of type T1 will always conflict (using the
+ dependency routines in this file) with any MEM object of type T2.
+ This is used when allocating temporary storage. If T1 and/or T2 are
+ NULL_TREE, it means we know nothing about the storage. */
+
+int
+objects_must_conflict_p (t1, t2)
+ tree t1, t2;
+{
+ /* If neither has a type specified, we don't know if they'll conflict
+ because we may be using them to store objects of various types, for
+ example the argument and local variables areas of inlined functions. */
+ if (t1 == 0 && t2 == 0)
+ return 0;
+
+ /* If one or the other has readonly fields or is readonly,
+ then they may not conflict. */
+ if ((t1 != 0 && readonly_fields_p (t1))
+ || (t2 != 0 && readonly_fields_p (t2))
+ || (t1 != 0 && TYPE_READONLY (t1))
+ || (t2 != 0 && TYPE_READONLY (t2)))
+ return 0;
+
+ /* If they are the same type, they must conflict. */
+ if (t1 == t2
+ /* Likewise if both are volatile. */
+ || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
+ return 1;
+
+ /* If one is aggregate and the other is scalar then they may not
+ conflict. */
+ if ((t1 != 0 && AGGREGATE_TYPE_P (t1))
+ != (t2 != 0 && AGGREGATE_TYPE_P (t2)))
+ return 0;
+
+ /* Otherwise they conflict only if the alias sets conflict. */
+ return alias_sets_conflict_p (t1 ? get_alias_set (t1) : 0,
+ t2 ? get_alias_set (t2) : 0);
+}
+\f
/* T is an expression with pointer type. Find the DECL on which this
expression is based. (For example, in `a[i]' this would be `a'.)
If there is no such DECL, or a unique decl cannot be determined,
}
}
+/* Return 1 if T is an expression that get_inner_reference handles. */
+
+static int
+handled_component_p (t)
+ tree t;
+{
+ switch (TREE_CODE (t))
+ {
+ case BIT_FIELD_REF:
+ case COMPONENT_REF:
+ case ARRAY_REF:
+ case NON_LVALUE_EXPR:
+ return 1;
+
+ case NOP_EXPR:
+ case CONVERT_EXPR:
+ return (TYPE_MODE (TREE_TYPE (t))
+ == TYPE_MODE (TREE_TYPE (TREE_OPERAND (t, 0))));
+
+ default:
+ return 0;
+ }
+}
+
+/* Return 1 if all the nested component references handled by
+ get_inner_reference in T are such that we can address the object in T. */
+
+static int
+can_address_p (t)
+ tree t;
+{
+ /* If we're at the end, it is vacuously addressable. */
+ if (! handled_component_p (t))
+ return 1;
+
+ /* Bitfields are never addressable. */
+ else if (TREE_CODE (t) == BIT_FIELD_REF)
+ return 0;
+
+ else if (TREE_CODE (t) == COMPONENT_REF
+ && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))
+ && can_address_p (TREE_OPERAND (t, 0)))
+ return 1;
+
+ else if (TREE_CODE (t) == ARRAY_REF
+ && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))
+ && can_address_p (TREE_OPERAND (t, 0)))
+ return 1;
+
+ return 0;
+}
+
/* Return the alias set for T, which may be either a type or an
expression. Call language-specific routine for help, if needed. */
/* Now loop the same way as get_inner_reference and get the alias
set to use. Pick up the outermost object that we could have
a pointer to. */
- while (1)
- {
- /* Unnamed bitfields are not an addressable object. */
- if (TREE_CODE (t) == BIT_FIELD_REF)
- ;
- else if (TREE_CODE (t) == COMPONENT_REF)
- {
- if (! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1)))
- /* Stop at an adressable decl. */
- break;
- }
- else if (TREE_CODE (t) == ARRAY_REF)
- {
- if (! TYPE_NONALIASED_COMPONENT
- (TREE_TYPE (TREE_OPERAND (t, 0))))
- /* Stop at an addresssable array element. */
- break;
- }
- else if (TREE_CODE (t) != NON_LVALUE_EXPR
- && ! ((TREE_CODE (t) == NOP_EXPR
- || TREE_CODE (t) == CONVERT_EXPR)
- && (TYPE_MODE (TREE_TYPE (t))
- == TYPE_MODE (TREE_TYPE (TREE_OPERAND (t, 0))))))
- /* Stop if not one of above and not mode-preserving conversion. */
- break;
+ while (handled_component_p (t) && ! can_address_p (t))
+ t = TREE_OPERAND (t, 0);
- t = TREE_OPERAND (t, 0);
- }
-
if (TREE_CODE (t) == INDIRECT_REF)
{
/* Check for accesses through restrict-qualified pointers. */
/* If this is an aggregate type, we must record any component aliasing
information. */
- if (AGGREGATE_TYPE_P (t))
+ if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
record_component_aliases (t);
return set;
record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
break;
+ case COMPLEX_TYPE:
+ record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
+ break;
+
default:
break;
}
find_base_value (src)
register rtx src;
{
+ unsigned int regno;
switch (GET_CODE (src))
{
case SYMBOL_REF:
return src;
case REG:
+ regno = REGNO (src);
/* At the start of a function, argument registers have known base
values which may be lost later. Returning an ADDRESS
expression here allows optimization based on argument values
even when the argument registers are used for other purposes. */
- if (REGNO (src) < FIRST_PSEUDO_REGISTER && copying_arguments)
- return new_reg_base_value[REGNO (src)];
+ if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
+ return new_reg_base_value[regno];
/* If a pseudo has a known base value, return it. Do not do this
for hard regs since it can result in a circular dependency
The test above is not sufficient because the scheduler may move
a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
- if (REGNO (src) >= FIRST_PSEUDO_REGISTER
- && (unsigned) REGNO (src) < reg_base_value_size
- && reg_base_value[REGNO (src)])
- return reg_base_value[REGNO (src)];
+ if (regno >= FIRST_PSEUDO_REGISTER
+ && regno < reg_base_value_size
+ && reg_base_value[regno])
+ return reg_base_value[regno];
return src;
/* This might not be necessary anymore:
If either operand is a REG that is a known pointer, then it
is the base. */
- else if (GET_CODE (src_0) == REG && REGNO_POINTER_FLAG (REGNO (src_0)))
+ else if (GET_CODE (src_0) == REG && REG_POINTER (src_0))
return find_base_value (src_0);
- else if (GET_CODE (src_1) == REG && REGNO_POINTER_FLAG (REGNO (src_1)))
+ else if (GET_CODE (src_1) == REG && REG_POINTER (src_1))
return find_base_value (src_1);
return 0;
return find_base_value (XEXP (src, 0));
return 0;
+ case TRUNCATE:
+ if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
+ break;
+ /* Fall through. */
case ZERO_EXTEND:
case SIGN_EXTEND: /* used for NT/Alpha pointers */
case HIGH:
switch (GET_CODE (src))
{
case LO_SUM:
- case PLUS:
case MINUS:
if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
new_reg_base_value[regno] = 0;
break;
+ case PLUS:
+ /* If the value we add in the PLUS is also a valid base value,
+ this might be the actual base value, and the original value
+ an index. */
+ {
+ rtx other = NULL_RTX;
+
+ if (XEXP (src, 0) == dest)
+ other = XEXP (src, 1);
+ else if (XEXP (src, 1) == dest)
+ other = XEXP (src, 0);
+
+ if (! other || find_base_value (other))
+ new_reg_base_value[regno] = 0;
+ break;
+ }
case AND:
if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT)
new_reg_base_value[regno] = 0;
return 0;
case ADDRESSOF:
- return (REGNO (XEXP (x, 0)) == REGNO (XEXP (y, 0))
- && XINT (x, 1) == XINT (y, 1));
+ return (XINT (x, 1) == XINT (y, 1)
+ && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)));
default:
break;
/* If either operand is known to be a pointer, then use it
to determine the base term. */
- if (REG_P (tmp1) && REGNO_POINTER_FLAG (REGNO (tmp1)))
+ if (REG_P (tmp1) && REG_POINTER (tmp1))
return find_base_term (tmp1);
- if (REG_P (tmp2) && REGNO_POINTER_FLAG (REGNO (tmp2)))
+ if (REG_P (tmp2) && REG_POINTER (tmp2))
return find_base_term (tmp2);
/* Neither operand was known to be a pointer. Go ahead and find the
it unchanged unless it is a value; in the latter case we call cselib to get
a more useful rtx. */
-static rtx
+rtx
get_addr (x)
rtx x;
{
fixed_scalar_and_varying_struct_p (mem1, mem2, mem1_addr, mem2_addr, varies_p)
rtx mem1, mem2;
rtx mem1_addr, mem2_addr;
- int (*varies_p) PARAMS ((rtx));
+ int (*varies_p) PARAMS ((rtx, int));
{
if (! flag_strict_aliasing)
return NULL_RTX;
if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2)
- && !varies_p (mem1_addr) && varies_p (mem2_addr))
+ && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1))
/* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
varying address. */
return mem1;
if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2)
- && varies_p (mem1_addr) && !varies_p (mem2_addr))
+ && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1))
/* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
varying address. */
return mem2;
rtx mem;
enum machine_mode mem_mode;
rtx x;
- int (*varies) PARAMS ((rtx));
+ int (*varies) PARAMS ((rtx, int));
{
register rtx x_addr, mem_addr;
rtx base;
varies);
}
+/* Canonical true dependence: X is read after store in MEM takes place.
+ Variant of true_dependece which assumes MEM has already been
+ canonicalized (hence we no longer do that here).
+ The mem_addr argument has been added, since true_dependence computed
+ this value prior to canonicalizing. */
+
+int
+canon_true_dependence (mem, mem_mode, mem_addr, x, varies)
+ rtx mem, mem_addr, x;
+ enum machine_mode mem_mode;
+ int (*varies) PARAMS ((rtx, int));
+{
+ register rtx x_addr;
+
+ if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
+ return 1;
+
+ if (DIFFERENT_ALIAS_SETS_P (x, mem))
+ return 0;
+
+ /* If X is an unchanging read, then it can't possibly conflict with any
+ non-unchanging store. It may conflict with an unchanging write though,
+ because there may be a single store to this address to initialize it.
+ Just fall through to the code below to resolve the case where we have
+ both an unchanging read and an unchanging write. This won't handle all
+ cases optimally, but the possible performance loss should be
+ negligible. */
+ if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
+ return 0;
+
+ x_addr = get_addr (XEXP (x, 0));
+
+ if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
+ return 0;
+
+ x_addr = canon_rtx (x_addr);
+ if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
+ SIZE_FOR_MODE (x), x_addr, 0))
+ return 0;
+
+ if (aliases_everything_p (x))
+ return 1;
+
+ /* We cannot use aliases_everyting_p to test MEM, since we must look
+ at MEM_MODE, rather than GET_MODE (MEM). */
+ if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
+ return 1;
+
+ /* In true_dependence we also allow BLKmode to alias anything. Why
+ don't we do this in anti_dependence and output_dependence? */
+ if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
+ return 1;
+
+ return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
+ varies);
+}
+
/* Returns non-zero if a write to X might alias a previous read from
(or, if WRITEP is non-zero, a write to) MEM. */
{
/* Global registers are not local. */
if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
- && global_regs[REGNO (SUBREG_REG (x)) + SUBREG_WORD (x)])
+ && global_regs[subreg_regno (x)])
return 1;
return 0;
}
reg_base_value_size * sizeof (rtx));
memset ((char *)alias_invariant, 0, reg_base_value_size * sizeof (rtx));
}
-
/* The basic idea is that each pass through this loop will use the
"constant" information from the previous pass to propagate alias
if (set != 0
&& GET_CODE (SET_DEST (set)) == REG
- && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
- && REG_NOTES (insn) != 0
- && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
- && REG_N_SETS (REGNO (SET_DEST (set))) == 1)
- || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
- && GET_CODE (XEXP (note, 0)) != EXPR_LIST
- && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
+ && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
{
- int regno = REGNO (SET_DEST (set));
- reg_known_value[regno] = XEXP (note, 0);
- reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
+ unsigned int regno = REGNO (SET_DEST (set));
+ rtx src = SET_SRC (set);
+
+ if (REG_NOTES (insn) != 0
+ && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
+ && REG_N_SETS (regno) == 1)
+ || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
+ && GET_CODE (XEXP (note, 0)) != EXPR_LIST
+ && ! rtx_varies_p (XEXP (note, 0), 1)
+ && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
+ {
+ reg_known_value[regno] = XEXP (note, 0);
+ reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
+ }
+ else if (REG_N_SETS (regno) == 1
+ && GET_CODE (src) == PLUS
+ && GET_CODE (XEXP (src, 0)) == REG
+ && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER
+ && (reg_known_value[REGNO (XEXP (src, 0))])
+ && GET_CODE (XEXP (src, 1)) == CONST_INT)
+ {
+ rtx op0 = XEXP (src, 0);
+ op0 = reg_known_value[REGNO (op0)];
+ reg_known_value[regno]
+ = plus_constant_for_output (op0,
+ INTVAL (XEXP (src, 1)));
+ reg_known_equiv_p[regno] = 0;
+ }
+ else if (REG_N_SETS (regno) == 1
+ && ! rtx_varies_p (src, 1))
+ {
+ reg_known_value[regno] = src;
+ reg_known_equiv_p[regno] = 0;
+ }
}
}
else if (GET_CODE (insn) == NOTE
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