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re PR target/35258 (two memcpy calls merged incorrectly with -O1) 

2008-02-25  Andreas Krebbel  <krebbel1@de.ibm.com>

	PR target/35258
	* cse.c (cse_insn): Avoid creation of overlapping MEMs.
	* alias.c (nonoverlapping_memrefs_p): Export for use in other modules.
	* alias.h (nonoverlapping_memrefs_p): Likewise.

2008-02-25  Andreas Krebbel  <krebbel1@de.ibm.com>

	PR target/35258
	* gcc.dg/pr35258.c: New testcase.

From-SVN: r132628
This commit is contained in:
Andreas Krebbel 2008-02-25 15:07:17 +00:00 committed by Andreas Krebbel
parent 891984af0f
commit 2e4e39f615
6 changed files with 59 additions and 2 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2008-02-25 Andreas Krebbel <krebbel1@de.ibm.com>
PR target/35258
* cse.c (cse_insn): Avoid creation of overlapping MEMs.
* alias.c (nonoverlapping_memrefs_p): Export for use in other modules.
* alias.h (nonoverlapping_memrefs_p): Likewise.
2008-02-25 Jan Beulich <jbeulich@novell.com>
* Makefile.in: Also prefix uses of crt0.o and mcrt0.o with

3
gcc/alias.c
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@ -164,7 +164,6 @@ static int aliases_everything_p (const_rtx);
static bool nonoverlapping_component_refs_p (const_tree, const_tree);
static tree decl_for_component_ref (tree);
static rtx adjust_offset_for_component_ref (tree, rtx);
static int nonoverlapping_memrefs_p (const_rtx, const_rtx);
static int write_dependence_p (const_rtx, const_rtx, int);
static void memory_modified_1 (rtx, const_rtx, void *);
@ -1976,7 +1975,7 @@ adjust_offset_for_component_ref (tree x, rtx offset)
/* Return nonzero if we can determine the exprs corresponding to memrefs
X and Y and they do not overlap. */
static int
int
nonoverlapping_memrefs_p (const_rtx x, const_rtx y)
{
tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);

1
gcc/alias.h
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@ -28,6 +28,7 @@ extern alias_set_type get_varargs_alias_set (void);
extern alias_set_type get_frame_alias_set (void);
extern bool component_uses_parent_alias_set (const_tree);
extern bool alias_set_subset_of (alias_set_type, alias_set_type);
extern int nonoverlapping_memrefs_p (const_rtx, const_rtx);
/* This alias set can be used to force a memory to conflict with all
other memories, creating a barrier across which no memory reference

17
gcc/cse.c
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@ -4753,6 +4753,23 @@ cse_insn (rtx insn, rtx libcall_insn)
src_elt_cost = MAX_COST;
}
/* Avoid creation of overlapping memory moves. */
if (MEM_P (trial) && MEM_P (SET_DEST (sets[i].rtl)))
{
rtx src, dest;
/* BLKmode moves are not handled by cse anyway. */
if (GET_MODE (trial) == BLKmode)
break;
src = canon_rtx (trial);
dest = canon_rtx (SET_DEST (sets[i].rtl));
if (!MEM_P (src) || !MEM_P (dest)
|| !nonoverlapping_memrefs_p (src, dest))
break;
}
/* We don't normally have an insn matching (set (pc) (pc)), so
check for this separately here. We will delete such an
insn below.

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2008-02-25 Andreas Krebbel <krebbel1@de.ibm.com>
PR target/35258
* gcc.dg/pr35258.c: New testcase.
2008-02-25 Jan Beulich <jbeulich@novell.com>
* gcc.dg/20020426-2.c: Remove bogus workaround.

28
gcc/testsuite/gcc.dg/pr35258.c Normal file
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@ -0,0 +1,28 @@
/* { dg-do run } */
/* { dg-options "-O1" } */
extern void *memcpy (void *, const void *, __SIZE_TYPE__);
extern int memcmp (const void *, const void *, __SIZE_TYPE__);
extern void abort(void);
char str[9] = "1234";
void
bar (void)
{
unsigned int temp;
char *p = &str[2];
memcpy (&temp, &str[1], 4);
memcpy (p, &temp, 4);
str[1] = '.';
}
int main()
{
bar();
if (memcmp (str, "1.234", 5) != 0)
abort ();
return 0;
}