/* Alias analysis for GNU C
- Copyright (C) 1997, 1998, 1999 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 "system.h"
#include "rtl.h"
#include "tree.h"
+#include "tm_p.h"
#include "function.h"
#include "expr.h"
#include "regs.h"
#include "hard-reg-set.h"
+#include "basic-block.h"
#include "flags.h"
#include "output.h"
#include "toplev.h"
+#include "cselib.h"
#include "splay-tree.h"
+#include "ggc.h"
/* The alias sets assigned to MEMs assist the back-end in determining
which MEMs can alias which other MEMs. In general, two MEMs in
- different alias sets to not alias each other. There is one
- exception, however. Consider something like:
+ different alias sets cannot alias each other, with one important
+ exception. Consider something like:
struct S {int i; double d; };
|/_ _\|
int double
- (The arrows are directed and point downwards.) If, when comparing
- two alias sets, we can hold one set fixed, and trace the other set
- downwards, and at some point find the first set, the two MEMs can
- alias one another. In this situation we say the alias set for
- `struct S' is the `superset' and that those for `int' and `double'
- are `subsets'.
+ (The arrows are directed and point downwards.)
+ In this situation we say the alias set for `struct S' is the
+ `superset' and that those for `int' and `double' are `subsets'.
+
+ To see whether two alias sets can point to the same memory, we must
+ see if either alias set is a subset of the other. We need not trace
+ past immediate decendents, however, since we propagate all
+ grandchildren up one level.
Alias set zero is implicitly a superset of all other alias sets.
However, this is no actual entry for alias set zero. It is an
error to attempt to explicitly construct a subset of zero. */
-typedef struct alias_set_entry {
+typedef struct alias_set_entry
+{
/* The alias set number, as stored in MEM_ALIAS_SET. */
- int alias_set;
+ HOST_WIDE_INT alias_set;
/* The children of the alias set. These are not just the immediate
- children, but, in fact, all children. So, if we have:
+ children, but, in fact, all decendents. So, if we have:
struct T { struct S s; float f; }
continuing our example above, the children here will be all of
`int', `double', `float', and `struct S'. */
splay_tree children;
-}* alias_set_entry;
-
-static rtx canon_rtx PROTO((rtx));
-static int rtx_equal_for_memref_p PROTO((rtx, rtx));
-static rtx find_symbolic_term PROTO((rtx));
-static int memrefs_conflict_p PROTO((int, rtx, int, rtx,
- HOST_WIDE_INT));
-static void record_set PROTO((rtx, rtx));
-static rtx find_base_term PROTO((rtx));
-static int base_alias_check PROTO((rtx, rtx, enum machine_mode,
- enum machine_mode));
-static rtx find_base_value PROTO((rtx));
-static int mems_in_disjoint_alias_sets_p PROTO((rtx, rtx));
-static int insert_subset_children PROTO((splay_tree_node,
- void*));
-static alias_set_entry get_alias_set_entry PROTO((int));
-static rtx fixed_scalar_and_varying_struct_p PROTO((rtx, rtx, int (*)(rtx)));
-static int aliases_everything_p PROTO((rtx));
-static int write_dependence_p PROTO((rtx, rtx, int));
+
+ /* Nonzero if would have a child of zero: this effectively makes this
+ alias set the same as alias set zero. */
+ int has_zero_child;
+} *alias_set_entry;
+
+static int rtx_equal_for_memref_p PARAMS ((rtx, rtx));
+static rtx find_symbolic_term 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)));
+static int aliases_everything_p PARAMS ((rtx));
+static int write_dependence_p PARAMS ((rtx, rtx, int));
+static int nonlocal_mentioned_p PARAMS ((rtx));
+
+static int loop_p PARAMS ((void));
/* Set up all info needed to perform alias analysis on memory references. */
+/* Returns the size in bytes of the mode of X. */
#define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
/* Returns nonzero if MEM1 and MEM2 do not alias because they are in
mems_in_disjoint_alias_sets_p (MEM1, MEM2)
/* Cap the number of passes we make over the insns propagating alias
- information through set chains.
-
- 10 is a completely arbitrary choice. */
+ information through set chains. 10 is a completely arbitrary choice. */
#define MAX_ALIAS_LOOP_PASSES 10
/* reg_base_value[N] gives an address to which register N is related.
A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
expressions represent certain special values: function arguments and
- the stack, frame, and argument pointers. The contents of an address
- expression are not used (but they are descriptive for debugging);
- only the address and mode matter. Pointer equality, not rtx_equal_p,
- determines whether two ADDRESS expressions refer to the same base
- address. The mode determines whether it is a function argument or
- other special value. */
-
-rtx *reg_base_value;
-rtx *new_reg_base_value;
-unsigned int reg_base_value_size; /* size of reg_base_value array */
+ the stack, frame, and argument pointers.
+
+ The contents of an ADDRESS is not normally used, the mode of the
+ ADDRESS determines whether the ADDRESS is a function argument or some
+ other special value. Pointer equality, not rtx_equal_p, determines whether
+ two ADDRESS expressions refer to the same base address.
+
+ The only use of the contents of an ADDRESS is for determining if the
+ current function performs nonlocal memory memory references for the
+ purposes of marking the function as a constant function. */
+
+static rtx *reg_base_value;
+static rtx *new_reg_base_value;
+static unsigned int reg_base_value_size; /* size of reg_base_value array */
+
#define REG_BASE_VALUE(X) \
- ((unsigned) 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
after reload. */
static rtx *alias_invariant;
-/* Vector indexed by N giving the initial (unchanging) value known
- for pseudo-register N. */
+/* Vector indexed by N giving the initial (unchanging) value known for
+ pseudo-register N. This array is initialized in
+ init_alias_analysis, and does not change until end_alias_analysis
+ is called. */
rtx *reg_known_value;
/* Indicates number of valid entries in reg_known_value. */
-static int reg_known_value_size;
+static unsigned int reg_known_value_size;
/* Vector recording for each reg_known_value whether it is due to a
REG_EQUIV note. Future passes (viz., reload) may replace the
pseudo with the equivalent expression and so we account for the
- dependences that would be introduced if that happens. */
-/* ??? This is a problem only on the Convex. The REG_EQUIV notes created in
- assign_parms mention the arg pointer, and there are explicit insns in the
- RTL that modify the arg pointer. Thus we must ensure that such insns don't
- get scheduled across each other because that would invalidate the REG_EQUIV
- notes. One could argue that the REG_EQUIV notes are wrong, but solving
- the problem in the scheduler will likely give better code, so we do it
- here. */
+ dependences that would be introduced if that happens.
+
+ The REG_EQUIV notes created in assign_parms may mention the arg
+ pointer, and there are explicit insns in the RTL that modify the
+ arg pointer. Thus we must ensure that such insns don't get
+ scheduled across each other because that would invalidate the
+ REG_EQUIV notes. One could argue that the REG_EQUIV notes are
+ wrong, but solving the problem in the scheduler will likely give
+ better code, so we do it here. */
char *reg_known_equiv_p;
/* True when scanning insns from the start of the rtl to the
NOTE_INSN_FUNCTION_BEG note. */
-
static int copying_arguments;
/* The splay-tree used to store the various alias set entries. */
-
static splay_tree alias_sets;
-
+\f
/* Returns a pointer to the alias set entry for ALIAS_SET, if there is
such an entry, or NULL otherwise. */
static alias_set_entry
get_alias_set_entry (alias_set)
- int alias_set;
+ HOST_WIDE_INT alias_set;
{
- splay_tree_node sn =
- splay_tree_lookup (alias_sets, (splay_tree_key) alias_set);
+ splay_tree_node sn
+ = splay_tree_lookup (alias_sets, (splay_tree_key) alias_set);
- return sn ? ((alias_set_entry) sn->value) : ((alias_set_entry) 0);
+ return sn != 0 ? ((alias_set_entry) sn->value) : 0;
}
-/* Returns nonzero value if the alias sets for MEM1 and MEM2 are such
- that the two MEMs cannot alias each other. */
+/* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
+ the two MEMs cannot alias each other. */
static int
mems_in_disjoint_alias_sets_p (mem1, mem2)
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
gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
use alias sets to indicate that spilled registers cannot alias each
other, we might need to remove this check. */
- if (!flag_strict_aliasing &&
- (MEM_ALIAS_SET (mem1) || MEM_ALIAS_SET (mem2)))
+ if (! flag_strict_aliasing
+ && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0))
abort ();
#endif
- /* The code used in varargs macros are often not conforming ANSI C,
- which can trick the compiler into making incorrect aliasing
- assumptions in these functions. So, we don't use alias sets in
- such a function. FIXME: This should be moved into the front-end;
- it is a language-dependent notion, and there's no reason not to
- still use these checks to handle globals. */
- if (current_function_stdarg || current_function_varargs)
+ return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
+}
+
+/* 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 (set1);
+ if (ase != 0
+ && (ase->has_zero_child
+ || splay_tree_lookup (ase->children,
+ (splay_tree_key) set2)))
+ return 1;
+
+ /* Now do the same, but with the alias sets reversed. */
+ ase = get_alias_set_entry (set2);
+ if (ase != 0
+ && (ase->has_zero_child
+ || splay_tree_lookup (ase->children,
+ (splay_tree_key) set1)))
+ return 1;
+
+ /* The two alias sets are distinct and neither one is the
+ child of the other. Therefore, they cannot alias. */
+ 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. */
+
+int
+readonly_fields_p (type)
+ tree type;
+{
+ tree field;
+
+ if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
+ && TREE_CODE (type) != QUAL_UNION_TYPE)
return 0;
- if (!MEM_ALIAS_SET (mem1) || !MEM_ALIAS_SET (mem2))
- /* We have no alias set information for one of the MEMs, so we
- have to assume it can alias anything. */
+ 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 (MEM_ALIAS_SET (mem1) == MEM_ALIAS_SET (mem2))
- /* The two alias sets are the same, so they may alias. */
+ /* 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;
- /* Iterate through each of the children of the first alias set,
- comparing it with the second alias set. */
- ase = get_alias_set_entry (MEM_ALIAS_SET (mem1));
- if (ase && splay_tree_lookup (ase->children,
- (splay_tree_key) MEM_ALIAS_SET (mem2)))
- 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;
- /* Now do the same, but with the alias sets reversed. */
- ase = get_alias_set_entry (MEM_ALIAS_SET (mem2));
- if (ase && splay_tree_lookup (ase->children,
- (splay_tree_key) MEM_ALIAS_SET (mem1)))
- return 0;
+ /* 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;
- /* The two MEMs are in distinct alias sets, and neither one is the
- child of the other. Therefore, they cannot alias. */
- return 1;
+ /* 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,
+ NULL_TREE is retured. */
+
+static tree
+find_base_decl (t)
+ tree t;
+{
+ tree d0, d1, d2;
-/* Insert the NODE into the splay tree given by DATA. Used by
- record_alias_subset via splay_tree_foreach. */
+ if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t)))
+ return 0;
+
+ /* If this is a declaration, return it. */
+ if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd')
+ return t;
+
+ /* Handle general expressions. It would be nice to deal with
+ COMPONENT_REFs here. If we could tell that `a' and `b' were the
+ same, then `a->f' and `b->f' are also the same. */
+ switch (TREE_CODE_CLASS (TREE_CODE (t)))
+ {
+ case '1':
+ return find_base_decl (TREE_OPERAND (t, 0));
+
+ case '2':
+ /* Return 0 if found in neither or both are the same. */
+ d0 = find_base_decl (TREE_OPERAND (t, 0));
+ d1 = find_base_decl (TREE_OPERAND (t, 1));
+ if (d0 == d1)
+ return d0;
+ else if (d0 == 0)
+ return d1;
+ else if (d1 == 0)
+ return d0;
+ else
+ return 0;
+
+ case '3':
+ d0 = find_base_decl (TREE_OPERAND (t, 0));
+ d1 = find_base_decl (TREE_OPERAND (t, 1));
+ d0 = find_base_decl (TREE_OPERAND (t, 0));
+ d2 = find_base_decl (TREE_OPERAND (t, 2));
+
+ /* Set any nonzero values from the last, then from the first. */
+ if (d1 == 0) d1 = d2;
+ if (d0 == 0) d0 = d1;
+ if (d1 == 0) d1 = d0;
+ if (d2 == 0) d2 = d1;
+
+ /* At this point all are nonzero or all are zero. If all three are the
+ same, return it. Otherwise, return zero. */
+ return (d0 == d1 && d1 == d2) ? d0 : 0;
+
+ default:
+ return 0;
+ }
+}
+
+/* Return 1 if T is an expression that get_inner_reference handles. */
static int
-insert_subset_children (node, data)
- splay_tree_node node;
- void *data;
+handled_component_p (t)
+ tree t;
{
- splay_tree_insert ((splay_tree) data,
- node->key,
- node->value);
+ 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. */
+
+HOST_WIDE_INT
+get_alias_set (t)
+ tree t;
+{
+ tree orig_t;
+ HOST_WIDE_INT set;
+
+ /* If we're not doing any alias analysis, just assume everything
+ aliases everything else. Also return 0 if this or its type is
+ an error. */
+ if (! flag_strict_aliasing || t == error_mark_node
+ || (! TYPE_P (t)
+ && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
+ return 0;
+
+ /* We can be passed either an expression or a type. This and the
+ language-specific routine may make mutually-recursive calls to
+ each other to figure out what to do. At each juncture, we see if
+ this is a tree that the language may need to handle specially.
+ First handle things that aren't types and start by removing nops
+ since we care only about the actual object. */
+ if (! TYPE_P (t))
+ {
+ while (TREE_CODE (t) == NOP_EXPR || TREE_CODE (t) == CONVERT_EXPR
+ || TREE_CODE (t) == NON_LVALUE_EXPR)
+ t = TREE_OPERAND (t, 0);
+
+ /* Now give the language a chance to do something but record what we
+ gave it this time. */
+ orig_t = t;
+ if ((set = lang_get_alias_set (t)) != -1)
+ return set;
+
+ /* 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 (handled_component_p (t) && ! can_address_p (t))
+ t = TREE_OPERAND (t, 0);
+
+ if (TREE_CODE (t) == INDIRECT_REF)
+ {
+ /* Check for accesses through restrict-qualified pointers. */
+ tree decl = find_base_decl (TREE_OPERAND (t, 0));
+
+ if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl))
+ /* We use the alias set indicated in the declaration. */
+ return DECL_POINTER_ALIAS_SET (decl);
+
+ /* If we have an INDIRECT_REF via a void pointer, we don't
+ know anything about what that might alias. */
+ if (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE)
+ return 0;
+ }
+
+ /* Give the language another chance to do something special. */
+ if (orig_t != t
+ && (set = lang_get_alias_set (t)) != -1)
+ return set;
+
+ /* Now all we care about is the type. */
+ t = TREE_TYPE (t);
+ }
+
+ /* Variant qualifiers don't affect the alias set, so get the main
+ variant. If this is a type with a known alias set, return it. */
+ t = TYPE_MAIN_VARIANT (t);
+ if (TYPE_P (t) && TYPE_ALIAS_SET_KNOWN_P (t))
+ return TYPE_ALIAS_SET (t);
+
+ /* See if the language has special handling for this type. */
+ if ((set = lang_get_alias_set (t)) != -1)
+ {
+ /* If the alias set is now known, we are done. */
+ if (TYPE_ALIAS_SET_KNOWN_P (t))
+ return TYPE_ALIAS_SET (t);
+ }
+
+ /* There are no objects of FUNCTION_TYPE, so there's no point in
+ using up an alias set for them. (There are, of course, pointers
+ and references to functions, but that's different.) */
+ else if (TREE_CODE (t) == FUNCTION_TYPE)
+ set = 0;
+ else
+ /* Otherwise make a new alias set for this type. */
+ set = new_alias_set ();
+
+ TYPE_ALIAS_SET (t) = set;
+
+ /* If this is an aggregate type, we must record any component aliasing
+ information. */
+ if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
+ record_component_aliases (t);
+
+ return set;
+}
+
+/* Return a brand-new alias set. */
+
+HOST_WIDE_INT
+new_alias_set ()
+{
+ static HOST_WIDE_INT last_alias_set;
+
+ if (flag_strict_aliasing)
+ return ++last_alias_set;
+ else
+ return 0;
+}
+
/* Indicate that things in SUBSET can alias things in SUPERSET, but
not vice versa. For example, in C, a store to an `int' can alias a
structure containing an `int', but not vice versa. Here, the
structure would be the SUPERSET and `int' the SUBSET. This
- function should be called only once per SUPERSET/SUBSET pair. At
- present any given alias set may only be a subset of one superset.
+ function should be called only once per SUPERSET/SUBSET pair.
It is illegal for SUPERSET to be zero; everything is implicitly a
subset of alias set zero. */
void
record_alias_subset (superset, subset)
- int superset;
- int subset;
+ HOST_WIDE_INT superset;
+ HOST_WIDE_INT subset;
{
alias_set_entry superset_entry;
alias_set_entry subset_entry;
abort ();
superset_entry = get_alias_set_entry (superset);
- if (!superset_entry)
+ if (superset_entry == 0)
{
/* Create an entry for the SUPERSET, so that we have a place to
attach the SUBSET. */
- superset_entry =
- (alias_set_entry) xmalloc (sizeof (struct alias_set_entry));
+ superset_entry
+ = (alias_set_entry) xmalloc (sizeof (struct alias_set_entry));
superset_entry->alias_set = superset;
superset_entry->children
= splay_tree_new (splay_tree_compare_ints, 0, 0);
- splay_tree_insert (alias_sets,
- (splay_tree_key) superset,
+ superset_entry->has_zero_child = 0;
+ splay_tree_insert (alias_sets, (splay_tree_key) superset,
(splay_tree_value) superset_entry);
+ }
+
+ if (subset == 0)
+ superset_entry->has_zero_child = 1;
+ else
+ {
+ subset_entry = get_alias_set_entry (subset);
+ /* If there is an entry for the subset, enter all of its children
+ (if they are not already present) as children of the SUPERSET. */
+ if (subset_entry)
+ {
+ if (subset_entry->has_zero_child)
+ superset_entry->has_zero_child = 1;
+ splay_tree_foreach (subset_entry->children, insert_subset_children,
+ superset_entry->children);
+ }
+
+ /* Enter the SUBSET itself as a child of the SUPERSET. */
+ splay_tree_insert (superset_entry->children,
+ (splay_tree_key) subset, 0);
}
+}
+
+/* Record that component types of TYPE, if any, are part of that type for
+ aliasing purposes. For record types, we only record component types
+ for fields that are marked addressable. For array types, we always
+ record the component types, so the front end should not call this
+ function if the individual component aren't addressable. */
- subset_entry = get_alias_set_entry (subset);
- if (subset_entry)
- /* There is an entry for the subset. Enter all of its children
- (if they are not already present) as children of the SUPERSET. */
- splay_tree_foreach (subset_entry->children,
- insert_subset_children,
- superset_entry->children);
-
- /* Enter the SUBSET itself as a child of the SUPERSET. */
- splay_tree_insert (superset_entry->children,
- (splay_tree_key) subset,
- /*value=*/0);
+void
+record_component_aliases (type)
+ tree type;
+{
+ HOST_WIDE_INT superset = get_alias_set (type);
+ tree field;
+
+ if (superset == 0)
+ return;
+
+ switch (TREE_CODE (type))
+ {
+ case ARRAY_TYPE:
+ if (! TYPE_NONALIASED_COMPONENT (type))
+ record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
+ break;
+
+ case RECORD_TYPE:
+ case UNION_TYPE:
+ case QUAL_UNION_TYPE:
+ for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
+ if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
+ 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;
+ }
+}
+
+/* Allocate an alias set for use in storing and reading from the varargs
+ spill area. */
+
+HOST_WIDE_INT
+get_varargs_alias_set ()
+{
+ static HOST_WIDE_INT set = -1;
+
+ if (set == -1)
+ set = new_alias_set ();
+
+ return set;
+}
+
+/* Likewise, but used for the fixed portions of the frame, e.g., register
+ save areas. */
+
+HOST_WIDE_INT
+get_frame_alias_set ()
+{
+ static HOST_WIDE_INT set = -1;
+
+ if (set == -1)
+ set = new_alias_set ();
+
+ return set;
}
/* Inside SRC, the source of a SET, find a base address. */
find_base_value (src)
register rtx src;
{
+ unsigned int regno;
switch (GET_CODE (src))
{
case SYMBOL_REF:
return src;
case REG:
- /* At the start of a function argument registers have known base
+ 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;
src = XEXP (src, 0);
if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
break;
- /* fall through */
+
+ /* ... fall through ... */
case PLUS:
case MINUS:
if (GET_CODE (src_0) == REG)
{
temp = find_base_value (src_0);
- if (temp)
+ if (temp != 0)
src_0 = temp;
}
if (GET_CODE (src_1) == REG)
{
temp = find_base_value (src_1);
- if (temp)
+ if (temp!= 0)
src_1 = temp;
}
- /* Guess which operand is the base address.
-
+ /* Guess which operand is the base address:
If either operand is a symbol, then it is the base. If
either operand is a CONST_INT, then the other is the base. */
-
- if (GET_CODE (src_1) == CONST_INT
- || GET_CODE (src_0) == SYMBOL_REF
- || GET_CODE (src_0) == LABEL_REF
- || GET_CODE (src_0) == CONST)
+ if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0))
return find_base_value (src_0);
-
- if (GET_CODE (src_0) == CONST_INT
- || GET_CODE (src_1) == SYMBOL_REF
- || GET_CODE (src_1) == LABEL_REF
- || GET_CODE (src_1) == CONST)
+ else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1))
return find_base_value (src_1);
- /* This might not be necessary anymore.
-
+ /* This might not be necessary anymore:
If either operand is a REG that is a known pointer, then it
is the base. */
- 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);
-
- 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:
/* Called from init_alias_analysis indirectly through note_stores. */
-/* while scanning insns to find base values, reg_seen[N] is nonzero if
+/* While scanning insns to find base values, reg_seen[N] is nonzero if
register N has been set in this function. */
static char *reg_seen;
static int unique_id;
static void
-record_set (dest, set)
+record_set (dest, set, data)
rtx dest, set;
+ void *data ATTRIBUTE_UNUSED;
{
- register int regno;
+ register unsigned regno;
rtx src;
if (GET_CODE (dest) != REG)
regno = REGNO (dest);
+ if (regno >= reg_base_value_size)
+ abort ();
+
if (set)
{
/* A CLOBBER wipes out any old value but does not prevent a previously
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;
reg_seen[regno] = 1;
}
-/* Called from loop optimization when a new pseudo-register is created. */
+/* Called from loop optimization when a new pseudo-register is
+ created. It indicates that REGNO is being set to VAL. f INVARIANT
+ is true then this value also describes an invariant relationship
+ which can be used to deduce that two registers with unknown values
+ are different. */
+
void
record_base_value (regno, val, invariant)
- int regno;
+ unsigned int regno;
rtx val;
int invariant;
{
- if ((unsigned) regno >= reg_base_value_size)
+ if (regno >= reg_base_value_size)
return;
- /* If INVARIANT is true then this value also describes an invariant
- relationship which can be used to deduce that two registers with
- unknown values are different. */
if (invariant && alias_invariant)
alias_invariant[regno] = val;
if (GET_CODE (val) == REG)
{
- if ((unsigned) REGNO (val) < reg_base_value_size)
- {
- reg_base_value[regno] = reg_base_value[REGNO (val)];
- }
+ if (REGNO (val) < reg_base_value_size)
+ reg_base_value[regno] = reg_base_value[REGNO (val)];
+
return;
}
+
reg_base_value[regno] = find_base_value (val);
}
-static rtx
+/* Returns a canonical version of X, from the point of view alias
+ analysis. (For example, if X is a MEM whose address is a register,
+ and the register has a known value (say a SYMBOL_REF), then a MEM
+ whose address is the SYMBOL_REF is returned.) */
+
+rtx
canon_rtx (x)
rtx x;
{
return gen_rtx_PLUS (GET_MODE (x), x0, x1);
}
}
+
/* This gives us much better alias analysis when called from
the loop optimizer. Note we want to leave the original
MEM alone, but need to return the canonicalized MEM with
else if (GET_CODE (x) == MEM)
{
rtx addr = canon_rtx (XEXP (x, 0));
+
if (addr != XEXP (x, 0))
{
rtx new = gen_rtx_MEM (GET_MODE (x), addr);
- RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x);
+
MEM_COPY_ATTRIBUTES (new, x);
- MEM_ALIAS_SET (new) = MEM_ALIAS_SET (x);
x = new;
}
}
return 1;
if (x == 0 || y == 0)
return 0;
+
x = canon_rtx (x);
y = canon_rtx (y);
if (GET_MODE (x) != GET_MODE (y))
return 0;
- /* REG, LABEL_REF, and SYMBOL_REF can be compared nonrecursively. */
+ /* Some RTL can be compared without a recursive examination. */
+ switch (code)
+ {
+ case REG:
+ return REGNO (x) == REGNO (y);
+
+ case LABEL_REF:
+ return XEXP (x, 0) == XEXP (y, 0);
+
+ case SYMBOL_REF:
+ return XSTR (x, 0) == XSTR (y, 0);
+
+ case CONST_INT:
+ case CONST_DOUBLE:
+ /* There's no need to compare the contents of CONST_DOUBLEs or
+ CONST_INTs because pointer equality is a good enough
+ comparison for these nodes. */
+ return 0;
+
+ case ADDRESSOF:
+ return (XINT (x, 1) == XINT (y, 1)
+ && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)));
- if (code == REG)
- return REGNO (x) == REGNO (y);
- if (code == LABEL_REF)
- return XEXP (x, 0) == XEXP (y, 0);
- if (code == SYMBOL_REF)
- return XSTR (x, 0) == XSTR (y, 0);
- if (code == CONST_INT)
- return INTVAL (x) == INTVAL (y);
- if (code == ADDRESSOF)
- return REGNO (XEXP (x, 0)) == REGNO (XEXP (y, 0)) && XINT (x, 1) == XINT (y, 1);
+ default:
+ break;
+ }
/* For commutative operations, the RTX match if the operand match in any
order. Also handle the simple binary and unary cases without a loop. */
/* And the corresponding elements must match. */
for (j = 0; j < XVECLEN (x, i); j++)
- if (rtx_equal_for_memref_p (XVECEXP (x, i, j), XVECEXP (y, i, j)) == 0)
+ if (rtx_equal_for_memref_p (XVECEXP (x, i, j),
+ XVECEXP (y, i, j)) == 0)
return 0;
break;
find_base_term (x)
register rtx x;
{
+ cselib_val *val;
+ struct elt_loc_list *l;
+
+#if defined (FIND_BASE_TERM)
+ /* Try machine-dependent ways to find the base term. */
+ x = FIND_BASE_TERM (x);
+#endif
+
switch (GET_CODE (x))
{
case REG:
case POST_DEC:
return find_base_term (XEXP (x, 0));
+ case VALUE:
+ val = CSELIB_VAL_PTR (x);
+ for (l = val->locs; l; l = l->next)
+ if ((x = find_base_term (l->loc)) != 0)
+ return x;
+ return 0;
+
case CONST:
x = XEXP (x, 0);
if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
is a shift or multiply, then it must be the index register and the
other operand is the base register. */
+ if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
+ return find_base_term (tmp2);
+
/* 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
/* If either base term is named object or a special address
(like an argument or stack reference), then use it for the
base term. */
- if (tmp1
+ if (tmp1 != 0
&& (GET_CODE (tmp1) == SYMBOL_REF
|| GET_CODE (tmp1) == LABEL_REF
|| (GET_CODE (tmp1) == ADDRESS
&& GET_MODE (tmp1) != VOIDmode)))
return tmp1;
- if (tmp2
+ if (tmp2 != 0
&& (GET_CODE (tmp2) == SYMBOL_REF
|| GET_CODE (tmp2) == LABEL_REF
|| (GET_CODE (tmp2) == ADDRESS
case LABEL_REF:
return x;
+ case ADDRESSOF:
+ return REG_BASE_VALUE (frame_pointer_rtx);
+
default:
return 0;
}
if (x_base == 0)
{
rtx x_c;
+
if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
return 1;
+
x_base = find_base_term (x_c);
if (x_base == 0)
return 1;
rtx y_c;
if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
return 1;
+
y_base = find_base_term (y_c);
if (y_base == 0)
return 1;
return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode);
}
+/* Convert the address X into something we can use. This is done by returning
+ it unchanged unless it is a value; in the latter case we call cselib to get
+ a more useful rtx. */
+
+rtx
+get_addr (x)
+ rtx x;
+{
+ cselib_val *v;
+ struct elt_loc_list *l;
+
+ if (GET_CODE (x) != VALUE)
+ return x;
+ v = CSELIB_VAL_PTR (x);
+ for (l = v->locs; l; l = l->next)
+ if (CONSTANT_P (l->loc))
+ return l->loc;
+ for (l = v->locs; l; l = l->next)
+ if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
+ return l->loc;
+ if (v->locs)
+ return v->locs->loc;
+ return x;
+}
+
/* Return the address of the (N_REFS + 1)th memory reference to ADDR
where SIZE is the size in bytes of the memory reference. If ADDR
is not modified by the memory reference then ADDR is returned. */
Nice to notice that varying addresses cannot conflict with fp if no
local variables had their addresses taken, but that's too hard now. */
-
static int
memrefs_conflict_p (xsize, x, ysize, y, c)
register rtx x, y;
int xsize, ysize;
HOST_WIDE_INT c;
{
+ if (GET_CODE (x) == VALUE)
+ x = get_addr (x);
+ if (GET_CODE (y) == VALUE)
+ y = get_addr (y);
if (GET_CODE (x) == HIGH)
x = XEXP (x, 0);
else if (GET_CODE (x) == LO_SUM)
return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c);
}
+ if (GET_CODE (x) == ADDRESSOF)
+ {
+ if (y == frame_pointer_rtx
+ || GET_CODE (y) == ADDRESSOF)
+ return xsize <= 0 || ysize <= 0;
+ }
+ if (GET_CODE (y) == ADDRESSOF)
+ {
+ if (x == frame_pointer_rtx)
+ return xsize <= 0 || ysize <= 0;
+ }
+
if (CONSTANT_P (x))
{
if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
canon_rtx (XEXP (y, 0)), c);
if (CONSTANT_P (y))
- return (xsize < 0 || ysize < 0
+ return (xsize <= 0 || ysize <= 0
|| (rtx_equal_for_memref_p (x, y)
- && (xsize == 0 || ysize == 0
- || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
+ && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
return 1;
}
changed. A volatile and non-volatile reference can be interchanged
though.
- A MEM_IN_STRUCT reference at a non-QImode non-AND varying address can never
- conflict with a non-MEM_IN_STRUCT reference at a fixed address. We must
- allow QImode aliasing because the ANSI C standard allows character
- pointers to alias anything. We are assuming that characters are
- always QImode here. We also must allow AND addresses, because they may
- generate accesses outside the object being referenced. This is used to
- generate aligned addresses from unaligned addresses, for instance, the
- alpha storeqi_unaligned pattern. */
+ A MEM_IN_STRUCT reference at a non-AND varying address can never
+ conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
+ also must allow AND addresses, because they may generate accesses
+ outside the object being referenced. This is used to generate
+ aligned addresses from unaligned addresses, for instance, the alpha
+ storeqi_unaligned pattern. */
/* Read dependence: X is read after read in MEM takes place. There can
only be a dependence here if both reads are volatile. */
MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
value is returned MEM1 and MEM2 can never alias. VARIES_P is used
to decide whether or not an address may vary; it should return
- nozero whenever variation is possible. */
-
-static rtx
-fixed_scalar_and_varying_struct_p (mem1, mem2, varies_p)
- rtx mem1;
- rtx mem2;
- int (*varies_p) PROTO((rtx));
-{
- rtx mem1_addr = XEXP (mem1, 0);
- rtx mem2_addr = XEXP (mem2, 0);
+ nonzero whenever variation is possible.
+ MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
+static rtx
+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));
+{
+ 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;
aliases_everything_p (mem)
rtx mem;
{
- if (GET_MODE (mem) == QImode)
- /* ANSI C says that a `char*' can point to anything. */
- return 1;
-
if (GET_CODE (XEXP (mem, 0)) == AND)
/* If the address is an AND, its very hard to know at what it is
actually pointing. */
rtx mem;
enum machine_mode mem_mode;
rtx x;
- int (*varies) PROTO((rtx));
+ int (*varies) PARAMS ((rtx, int));
{
register rtx x_addr, mem_addr;
+ rtx base;
+
+ if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
+ return 1;
+
+ if (DIFFERENT_ALIAS_SETS_P (x, mem))
+ return 0;
+
+ /* Unchanging memory can't conflict with non-unchanging memory.
+ A non-unchanging read can conflict with a non-unchanging write.
+ An unchanging read can conflict with an unchanging write since
+ there may be a single store to this address to initialize it.
+ Note that an unchanging store can conflict with a non-unchanging read
+ since we have to make conservative assumptions when we have a
+ record with readonly fields and we are copying the whole thing.
+ Just fall through to the code below to resolve potential conflicts.
+ 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;
+
+ if (mem_mode == VOIDmode)
+ mem_mode = GET_MODE (mem);
+
+ x_addr = get_addr (XEXP (x, 0));
+ mem_addr = get_addr (XEXP (mem, 0));
+
+ base = find_base_term (x_addr);
+ if (base && (GET_CODE (base) == LABEL_REF
+ || (GET_CODE (base) == SYMBOL_REF
+ && CONSTANT_POOL_ADDRESS_P (base))))
+ return 0;
+
+ if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
+ return 0;
+
+ x_addr = canon_rtx (x_addr);
+ mem_addr = canon_rtx (mem_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);
+}
+
+/* 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 (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
return 0;
- if (mem_mode == VOIDmode)
- mem_mode = GET_MODE (mem);
+ x_addr = get_addr (XEXP (x, 0));
- if (! base_alias_check (XEXP (x, 0), XEXP (mem, 0), GET_MODE (x), mem_mode))
+ if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
return 0;
- x_addr = canon_rtx (XEXP (x, 0));
- mem_addr = canon_rtx (XEXP (mem, 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 (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
return 1;
- return !fixed_scalar_and_varying_struct_p (mem, x, varies);
+ 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
{
rtx x_addr, mem_addr;
rtx fixed_scalar;
+ rtx base;
if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
return 1;
+ if (DIFFERENT_ALIAS_SETS_P (x, mem))
+ return 0;
+
+ /* Unchanging memory can't conflict with non-unchanging memory. */
+ if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem))
+ return 0;
+
/* If MEM is an unchanging read, then it can't possibly conflict with
the store to X, because there is at most one store to MEM, and it must
have occurred somewhere before MEM. */
- if (!writep && RTX_UNCHANGING_P (mem))
+ if (! writep && RTX_UNCHANGING_P (mem))
return 0;
- if (! base_alias_check (XEXP (x, 0), XEXP (mem, 0), GET_MODE (x),
- GET_MODE (mem)))
- return 0;
+ x_addr = get_addr (XEXP (x, 0));
+ mem_addr = get_addr (XEXP (mem, 0));
- x = canon_rtx (x);
- mem = canon_rtx (mem);
+ if (! writep)
+ {
+ base = find_base_term (mem_addr);
+ if (base && (GET_CODE (base) == LABEL_REF
+ || (GET_CODE (base) == SYMBOL_REF
+ && CONSTANT_POOL_ADDRESS_P (base))))
+ return 0;
+ }
- if (DIFFERENT_ALIAS_SETS_P (x, mem))
+ if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
+ GET_MODE (mem)))
return 0;
- x_addr = XEXP (x, 0);
- mem_addr = XEXP (mem, 0);
+ x_addr = canon_rtx (x_addr);
+ mem_addr = canon_rtx (mem_addr);
if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
SIZE_FOR_MODE (x), x_addr, 0))
return 0;
fixed_scalar
- = fixed_scalar_and_varying_struct_p (mem, x, rtx_addr_varies_p);
-
+ = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
+ rtx_addr_varies_p);
+
return (!(fixed_scalar == mem && !aliases_everything_p (x))
&& !(fixed_scalar == x && !aliases_everything_p (mem)));
}
return write_dependence_p (mem, x, /*writep=*/1);
}
-/* Returns non-zero if X might refer to something which is not
+/* Returns non-zero if X mentions something which is not
local to the function and is not constant. */
static int
-nonlocal_reference_p (x)
+nonlocal_mentioned_p (x)
rtx x;
{
rtx base;
if (GET_RTX_CLASS (code) == 'i')
{
- /* Constant functions are constant. */
+ /* Constant functions can be constant if they don't use
+ scratch memory used to mark function w/o side effects. */
if (code == CALL_INSN && CONST_CALL_P (x))
- return 0;
- x = PATTERN (x);
+ {
+ x = CALL_INSN_FUNCTION_USAGE (x);
+ if (x == 0)
+ return 0;
+ }
+ else
+ x = PATTERN (x);
code = GET_CODE (x);
}
{
/* 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;
}
return 1;
case CALL:
- /* Recursion introduces no additional considerations. */
- if (GET_CODE (XEXP (x, 0)) == MEM
- && GET_CODE (XEXP (XEXP (x, 0), 0)) == SYMBOL_REF
- && strcmp(XSTR (XEXP (XEXP (x, 0), 0), 0),
- IDENTIFIER_POINTER (
- DECL_ASSEMBLER_NAME (current_function_decl))) == 0)
- return 0;
+ /* Non-constant calls and recursion are not local. */
return 1;
case MEM:
base = find_base_term (XEXP (x, 0));
if (base)
{
- /* Stack references are local. */
- if (GET_CODE (base) == ADDRESS && GET_MODE (base) == Pmode)
+ /* A Pmode ADDRESS could be a reference via the structure value
+ address or static chain. Such memory references are nonlocal.
+
+ Thus, we have to examine the contents of the ADDRESS to find
+ out if this is a local reference or not. */
+ if (GET_CODE (base) == ADDRESS
+ && GET_MODE (base) == Pmode
+ && (XEXP (base, 0) == stack_pointer_rtx
+ || XEXP (base, 0) == arg_pointer_rtx
+#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
+ || XEXP (base, 0) == hard_frame_pointer_rtx
+#endif
+ || XEXP (base, 0) == frame_pointer_rtx))
return 0;
/* Constants in the function's constant pool are constant. */
if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))
}
return 1;
+ case UNSPEC_VOLATILE:
case ASM_INPUT:
- case ASM_OPERANDS:
return 1;
+ case ASM_OPERANDS:
+ if (MEM_VOLATILE_P (x))
+ return 1;
+
+ /* FALLTHROUGH */
+
default:
break;
}
/* Recursively scan the operands of this expression. */
{
- register char *fmt = GET_RTX_FORMAT (code);
+ register const char *fmt = GET_RTX_FORMAT (code);
register int i;
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
- if (fmt[i] == 'e')
+ if (fmt[i] == 'e' && XEXP (x, i))
{
- if (nonlocal_reference_p (XEXP (x, i)))
+ if (nonlocal_mentioned_p (XEXP (x, i)))
return 1;
}
- if (fmt[i] == 'E')
+ else if (fmt[i] == 'E')
{
register int j;
for (j = 0; j < XVECLEN (x, i); j++)
- if (nonlocal_reference_p (XVECEXP (x, i, j)))
+ if (nonlocal_mentioned_p (XVECEXP (x, i, j)))
return 1;
}
}
return 0;
}
+/* Return non-zero if a loop (natural or otherwise) is present.
+ Inspired by Depth_First_Search_PP described in:
+
+ Advanced Compiler Design and Implementation
+ Steven Muchnick
+ Morgan Kaufmann, 1997
+
+ and heavily borrowed from flow_depth_first_order_compute. */
+
+static int
+loop_p ()
+{
+ edge *stack;
+ int *pre;
+ int *post;
+ int sp;
+ int prenum = 1;
+ int postnum = 1;
+ sbitmap visited;
+
+ /* Allocate the preorder and postorder number arrays. */
+ pre = (int *) xcalloc (n_basic_blocks, sizeof (int));
+ post = (int *) xcalloc (n_basic_blocks, sizeof (int));
+
+ /* Allocate stack for back-tracking up CFG. */
+ stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
+ sp = 0;
+
+ /* Allocate bitmap to track nodes that have been visited. */
+ visited = sbitmap_alloc (n_basic_blocks);
+
+ /* None of the nodes in the CFG have been visited yet. */
+ sbitmap_zero (visited);
+
+ /* Push the first edge on to the stack. */
+ stack[sp++] = ENTRY_BLOCK_PTR->succ;
+
+ while (sp)
+ {
+ edge e;
+ basic_block src;
+ basic_block dest;
+
+ /* Look at the edge on the top of the stack. */
+ e = stack[sp - 1];
+ src = e->src;
+ dest = e->dest;
+
+ /* Check if the edge destination has been visited yet. */
+ if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
+ {
+ /* Mark that we have visited the destination. */
+ SET_BIT (visited, dest->index);
+
+ pre[dest->index] = prenum++;
+
+ if (dest->succ)
+ {
+ /* Since the DEST node has been visited for the first
+ time, check its successors. */
+ stack[sp++] = dest->succ;
+ }
+ else
+ post[dest->index] = postnum++;
+ }
+ else
+ {
+ if (dest != EXIT_BLOCK_PTR
+ && pre[src->index] >= pre[dest->index]
+ && post[dest->index] == 0)
+ break;
+
+ if (! e->succ_next && src != ENTRY_BLOCK_PTR)
+ post[src->index] = postnum++;
+
+ if (e->succ_next)
+ stack[sp - 1] = e->succ_next;
+ else
+ sp--;
+ }
+ }
+
+ free (pre);
+ free (post);
+ free (stack);
+ sbitmap_free (visited);
+
+ return sp;
+}
+
/* Mark the function if it is constant. */
void
mark_constant_function ()
{
rtx insn;
+ int nonlocal_mentioned;
if (TREE_PUBLIC (current_function_decl)
|| TREE_READONLY (current_function_decl)
+ || DECL_IS_PURE (current_function_decl)
|| TREE_THIS_VOLATILE (current_function_decl)
|| TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode)
return;
+ /* A loop might not return which counts as a side effect. */
+ if (loop_p ())
+ return;
+
+ nonlocal_mentioned = 0;
+
+ init_alias_analysis ();
+
/* Determine if this is a constant function. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
- if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
- && nonlocal_reference_p (insn))
- return;
+ if (INSN_P (insn) && nonlocal_mentioned_p (insn))
+ {
+ nonlocal_mentioned = 1;
+ break;
+ }
+
+ end_alias_analysis ();
/* Mark the function. */
- TREE_READONLY (current_function_decl) = 1;
+ if (! nonlocal_mentioned)
+ TREE_READONLY (current_function_decl) = 1;
}
alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0);
}
+/* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
+ array. */
+
void
init_alias_analysis ()
{
reg_known_value_size = maxreg;
- reg_known_value
- = (rtx *) oballoc ((maxreg - FIRST_PSEUDO_REGISTER) * sizeof (rtx))
+ reg_known_value
+ = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx))
+ - FIRST_PSEUDO_REGISTER;
+ reg_known_equiv_p
+ = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char))
- FIRST_PSEUDO_REGISTER;
- reg_known_equiv_p =
- oballoc (maxreg - FIRST_PSEUDO_REGISTER) - FIRST_PSEUDO_REGISTER;
- bzero ((char *) (reg_known_value + FIRST_PSEUDO_REGISTER),
- (maxreg-FIRST_PSEUDO_REGISTER) * sizeof (rtx));
- bzero (reg_known_equiv_p + FIRST_PSEUDO_REGISTER,
- (maxreg - FIRST_PSEUDO_REGISTER) * sizeof (char));
/* Overallocate reg_base_value to allow some growth during loop
optimization. Loop unrolling can create a large number of
registers. */
reg_base_value_size = maxreg * 2;
- reg_base_value = (rtx *)oballoc (reg_base_value_size * sizeof (rtx));
- new_reg_base_value = (rtx *)alloca (reg_base_value_size * sizeof (rtx));
- reg_seen = (char *)alloca (reg_base_value_size);
- bzero ((char *) reg_base_value, reg_base_value_size * sizeof (rtx));
+ reg_base_value = (rtx *) xcalloc (reg_base_value_size, sizeof (rtx));
+ ggc_add_rtx_root (reg_base_value, reg_base_value_size);
+
+ new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx));
+ reg_seen = (char *) xmalloc (reg_base_value_size);
if (! reload_completed && flag_unroll_loops)
{
+ /* ??? Why are we realloc'ing if we're just going to zero it? */
alias_invariant = (rtx *)xrealloc (alias_invariant,
reg_base_value_size * sizeof (rtx));
- bzero ((char *)alias_invariant, 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
copying_arguments = 1;
/* Wipe the potential alias information clean for this pass. */
- bzero ((char *) new_reg_base_value, reg_base_value_size * sizeof (rtx));
+ memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx));
/* Wipe the reg_seen array clean. */
- bzero ((char *) reg_seen, reg_base_value_size);
+ memset ((char *) reg_seen, 0, reg_base_value_size);
/* Mark all hard registers which may contain an address.
The stack, frame and argument pointers may contain an address.
new_reg_base_value[HARD_FRAME_POINTER_REGNUM]
= gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
#endif
- if (struct_value_incoming_rtx
- && GET_CODE (struct_value_incoming_rtx) == REG)
- new_reg_base_value[REGNO (struct_value_incoming_rtx)]
- = gen_rtx_ADDRESS (Pmode, struct_value_incoming_rtx);
-
- if (static_chain_rtx
- && GET_CODE (static_chain_rtx) == REG)
- new_reg_base_value[REGNO (static_chain_rtx)]
- = gen_rtx_ADDRESS (Pmode, static_chain_rtx);
/* Walk the insns adding values to the new_reg_base_value array. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
-#if defined (HAVE_prologue) || defined (HAVE_epilogue)
- if (prologue_epilogue_contains (insn))
- continue;
-#endif
- if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
+ if (INSN_P (insn))
{
rtx note, set;
+
+#if defined (HAVE_prologue) || defined (HAVE_epilogue)
+ /* The prologue/epilouge insns are not threaded onto the
+ insn chain until after reload has completed. Thus,
+ there is no sense wasting time checking if INSN is in
+ the prologue/epilogue until after reload has completed. */
+ if (reload_completed
+ && prologue_epilogue_contains (insn))
+ continue;
+#endif
+
/* If this insn has a noalias note, process it, Otherwise,
scan for sets. A simple set will have no side effects
which could change the base value of any other register. */
if (GET_CODE (PATTERN (insn)) == SET
- && (find_reg_note (insn, REG_NOALIAS, NULL_RTX)))
- record_set (SET_DEST (PATTERN (insn)), NULL_RTX);
+ && REG_NOTES (insn) != 0
+ && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
+ record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
else
- note_stores (PATTERN (insn), record_set);
+ note_stores (PATTERN (insn), record_set, NULL);
set = single_set (insn);
if (set != 0
&& GET_CODE (SET_DEST (set)) == REG
- && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
- && (((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
}
while (changed && pass < MAX_ALIAS_LOOP_PASSES);
+ /* Clean up. */
+ free (new_reg_base_value);
new_reg_base_value = 0;
+ free (reg_seen);
reg_seen = 0;
}
void
end_alias_analysis ()
{
+ free (reg_known_value + FIRST_PSEUDO_REGISTER);
reg_known_value = 0;
- reg_base_value = 0;
+ reg_known_value_size = 0;
+ free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
+ reg_known_equiv_p = 0;
+ if (reg_base_value)
+ {
+ ggc_del_root (reg_base_value);
+ free (reg_base_value);
+ reg_base_value = 0;
+ }
reg_base_value_size = 0;
if (alias_invariant)
{
- free ((char *)alias_invariant);
+ free (alias_invariant);
alias_invariant = 0;
}
}
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