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re PR tree-optimization/38051 (Miscompilation of glibc's memcmp)

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2008-11-15  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/38051
	* tree-ssa-alias.c (update_alias_info_1): Manually find
	written variables.

	* gcc.c-torture/execute/pr38051.c: New testcase.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r141887
This commit is contained in:
Richard Guenther 2008-11-15 15:37:57 +00:00 committed by Richard Biener
parent ee9a72e50c
commit 6389463779
4 changed files with 237 additions and 15 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2008-11-15 Richard Guenther <rguenther@suse.de>
PR tree-optimization/38051
* tree-ssa-alias.c (update_alias_info_1): Manually find
written variables.
2008-11-15 Joshua Kinard <kumba@gentoo.org>
* doc/invoke.texi (-mfix-r10000): Document.

6
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,9 @@
2008-11-15 Richard Guenther <rguenther@suse.de>
Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/38051
* gcc.c-torture/execute/pr38051.c: New testcase.
2008-11-15 Joshua Kinard <kumba@gentoo.org>
Richard Sandiford <rdsandiford@goolemail.com>

205
gcc/testsuite/gcc.c-torture/execute/pr38051.c Normal file
View File

@ -0,0 +1,205 @@
typedef __SIZE_TYPE__ size_t;
static int mymemcmp1 (unsigned long int, unsigned long int)
__attribute__ ((__nothrow__));
__inline static int
mymemcmp1 (unsigned long int a, unsigned long int b)
{
long int srcp1 = (long int) &a;
long int srcp2 = (long int) &b;
unsigned long int a0, b0;
do
{
a0 = ((unsigned char *) srcp1)[0];
b0 = ((unsigned char *) srcp2)[0];
srcp1 += 1;
srcp2 += 1;
}
while (a0 == b0);
return a0 - b0;
}
static int mymemcmp2 (long, long, size_t) __attribute__ ((__nothrow__));
static int
mymemcmp2 (long int srcp1, long int srcp2, size_t len)
{
unsigned long int a0, a1;
unsigned long int b0, b1;
switch (len % 4)
{
default:
case 2:
a0 = ((unsigned long int *) srcp1)[0];
b0 = ((unsigned long int *) srcp2)[0];
srcp1 -= 2 * (sizeof (unsigned long int));
srcp2 -= 2 * (sizeof (unsigned long int));
len += 2;
goto do1;
case 3:
a1 = ((unsigned long int *) srcp1)[0];
b1 = ((unsigned long int *) srcp2)[0];
srcp1 -= (sizeof (unsigned long int));
srcp2 -= (sizeof (unsigned long int));
len += 1;
goto do2;
case 0:
if (16 <= 3 * (sizeof (unsigned long int)) && len == 0)
return 0;
a0 = ((unsigned long int *) srcp1)[0];
b0 = ((unsigned long int *) srcp2)[0];
goto do3;
case 1:
a1 = ((unsigned long int *) srcp1)[0];
b1 = ((unsigned long int *) srcp2)[0];
srcp1 += (sizeof (unsigned long int));
srcp2 += (sizeof (unsigned long int));
len -= 1;
if (16 <= 3 * (sizeof (unsigned long int)) && len == 0)
goto do0;
}
do
{
a0 = ((unsigned long int *) srcp1)[0];
b0 = ((unsigned long int *) srcp2)[0];
if (a1 != b1)
return mymemcmp1 ((a1), (b1));
do3:
a1 = ((unsigned long int *) srcp1)[1];
b1 = ((unsigned long int *) srcp2)[1];
if (a0 != b0)
return mymemcmp1 ((a0), (b0));
do2:
a0 = ((unsigned long int *) srcp1)[2];
b0 = ((unsigned long int *) srcp2)[2];
if (a1 != b1)
return mymemcmp1 ((a1), (b1));
do1:
a1 = ((unsigned long int *) srcp1)[3];
b1 = ((unsigned long int *) srcp2)[3];
if (a0 != b0)
return mymemcmp1 ((a0), (b0));
srcp1 += 4 * (sizeof (unsigned long int));
srcp2 += 4 * (sizeof (unsigned long int));
len -= 4;
}
while (len != 0);
do0:
if (a1 != b1)
return mymemcmp1 ((a1), (b1));
return 0;
}
static int mymemcmp3 (long, long, size_t) __attribute__ ((__nothrow__));
static int
mymemcmp3 (long int srcp1, long int srcp2, size_t len)
{
unsigned long int a0, a1, a2, a3;
unsigned long int b0, b1, b2, b3;
unsigned long int x;
int shl, shr;
shl = 8 * (srcp1 % (sizeof (unsigned long int)));
shr = 8 * (sizeof (unsigned long int)) - shl;
srcp1 &= -(sizeof (unsigned long int));
switch (len % 4)
{
default:
case 2:
a1 = ((unsigned long int *) srcp1)[0];
a2 = ((unsigned long int *) srcp1)[1];
b2 = ((unsigned long int *) srcp2)[0];
srcp1 -= 1 * (sizeof (unsigned long int));
srcp2 -= 2 * (sizeof (unsigned long int));
len += 2;
goto do1;
case 3:
a0 = ((unsigned long int *) srcp1)[0];
a1 = ((unsigned long int *) srcp1)[1];
b1 = ((unsigned long int *) srcp2)[0];
srcp2 -= 1 * (sizeof (unsigned long int));
len += 1;
goto do2;
case 0:
if (16 <= 3 * (sizeof (unsigned long int)) && len == 0)
return 0;
a3 = ((unsigned long int *) srcp1)[0];
a0 = ((unsigned long int *) srcp1)[1];
b0 = ((unsigned long int *) srcp2)[0];
srcp1 += 1 * (sizeof (unsigned long int));
goto do3;
case 1:
a2 = ((unsigned long int *) srcp1)[0];
a3 = ((unsigned long int *) srcp1)[1];
b3 = ((unsigned long int *) srcp2)[0];
srcp1 += 2 * (sizeof (unsigned long int));
srcp2 += 1 * (sizeof (unsigned long int));
len -= 1;
if (16 <= 3 * (sizeof (unsigned long int)) && len == 0)
goto do0;
}
do
{
a0 = ((unsigned long int *) srcp1)[0];
b0 = ((unsigned long int *) srcp2)[0];
x = (((a2) >> (shl)) | ((a3) << (shr)));
if (x != b3)
return mymemcmp1 ((x), (b3));
do3:
a1 = ((unsigned long int *) srcp1)[1];
b1 = ((unsigned long int *) srcp2)[1];
x = (((a3) >> (shl)) | ((a0) << (shr)));
if (x != b0)
return mymemcmp1 ((x), (b0));
do2:
a2 = ((unsigned long int *) srcp1)[2];
b2 = ((unsigned long int *) srcp2)[2];
x = (((a0) >> (shl)) | ((a1) << (shr)));
if (x != b1)
return mymemcmp1 ((x), (b1));
do1:
a3 = ((unsigned long int *) srcp1)[3];
b3 = ((unsigned long int *) srcp2)[3];
x = (((a1) >> (shl)) | ((a2) << (shr)));
if (x != b2)
return mymemcmp1 ((x), (b2));
srcp1 += 4 * (sizeof (unsigned long int));
srcp2 += 4 * (sizeof (unsigned long int));
len -= 4;
}
while (len != 0);
do0:
x = (((a2) >> (shl)) | ((a3) << (shr)));
if (x != b3)
return mymemcmp1 ((x), (b3));
return 0;
}
__attribute__ ((noinline))
int mymemcmp (const void *s1, const void *s2, size_t len)
{
unsigned long int a0;
unsigned long int b0;
long int srcp1 = (long int) s1;
long int srcp2 = (long int) s2;
if (srcp1 % (sizeof (unsigned long int)) == 0)
return mymemcmp2 (srcp1, srcp2, len / (sizeof (unsigned long int)));
else
return mymemcmp3 (srcp1, srcp2, len / (sizeof (unsigned long int)));
}
char buf[256] __attribute__((aligned (16)));
char buf2[256] __attribute__((aligned (16)));
int
main (void)
{
__builtin_memcpy (buf + 9,
"\x1\x37\x82\xa7\x55\x49\x9d\xbf\xf8\x44\xb6\x55\x17\x8e\xf9", 15);
__builtin_memcpy (buf2 + 24,
"\x1\x37\x82\xa7\x55\x49\xd0\xf3\xb7\x2a\x6d\x23\x71\x49\x6a", 15);
if (mymemcmp (buf + 9, buf2 + 24, 33) != -51)
__builtin_abort ();
return 0;
}

35
gcc/tree-ssa-alias.c
View File

@ -2667,6 +2667,17 @@ update_alias_info_1 (gimple stmt, struct alias_info *ai)
mem_ref_stats->num_mem_stmts++;
/* Add all decls written to to the list of written variables. */
if (gimple_has_lhs (stmt)
&& TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME)
{
tree lhs = gimple_get_lhs (stmt);
while (handled_component_p (lhs))
lhs = TREE_OPERAND (lhs, 0);
if (DECL_P (lhs))
pointer_set_insert (ai->written_vars, lhs);
}
/* Notice that we only update memory reference stats for symbols
loaded and stored by the statement if the statement does not
contain pointer dereferences and it is not a call/asm site.
@ -2689,25 +2700,19 @@ update_alias_info_1 (gimple stmt, struct alias_info *ai)
dereferences (e.g., MEMORY_VAR = *PTR) or if a call site has
memory symbols in its argument list, but these cases do not
occur so frequently as to constitute a serious problem. */
if (gimple_stored_syms (stmt))
EXECUTE_IF_SET_IN_BITMAP (gimple_stored_syms (stmt), 0, i, bi)
{
tree sym = referenced_var (i);
pointer_set_insert (ai->written_vars, sym);
if (!stmt_dereferences_ptr_p
&& stmt_escape_type != ESCAPE_TO_CALL
&& stmt_escape_type != ESCAPE_TO_PURE_CONST
&& stmt_escape_type != ESCAPE_TO_ASM)
update_mem_sym_stats_from_stmt (sym, stmt, 0, 1);
}
if (!stmt_dereferences_ptr_p
&& gimple_loaded_syms (stmt)
&& stmt_escape_type != ESCAPE_TO_CALL
&& stmt_escape_type != ESCAPE_TO_PURE_CONST
&& stmt_escape_type != ESCAPE_TO_ASM)
EXECUTE_IF_SET_IN_BITMAP (gimple_loaded_syms (stmt), 0, i, bi)
update_mem_sym_stats_from_stmt (referenced_var (i), stmt, 1, 0);
{
if (gimple_stored_syms (stmt))
EXECUTE_IF_SET_IN_BITMAP (gimple_stored_syms (stmt), 0, i, bi)
update_mem_sym_stats_from_stmt (referenced_var (i), stmt, 0, 1);
if (gimple_loaded_syms (stmt))
EXECUTE_IF_SET_IN_BITMAP (gimple_loaded_syms (stmt), 0, i, bi)
update_mem_sym_stats_from_stmt (referenced_var (i), stmt, 1, 0);
}
}
}