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tree-optimization/103961: Never compute offset for -1 size 

Never try to compute size for offset when the object size is -1, which
is either unknown maximum or uninitialized minimum irrespective of the
osi->pass number.

gcc/ChangeLog:

	PR tree-optimization/103961
	* tree-object-size.c (plus_stmt_object_size): Always avoid
	computing offset for -1 size.

gcc/testsuite/ChangeLog:

	PR tree-optimization/103961
	* gcc.dg/pr103961.c: New test case.

Co-authored-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
This commit is contained in:
Siddhesh Poyarekar 2022-01-11 16:07:29 +05:30
parent 71b7213201
commit 026d44cbbd
2 changed files with 34 additions and 7 deletions
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30
gcc/testsuite/gcc.dg/pr103961.c Normal file
View File

@ -0,0 +1,30 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
extern void abort ();
extern inline __attribute__ ((__gnu_inline__)) int
sprintf (char *restrict s, const char *restrict fmt, ...)
{
return __builtin___sprintf_chk (s, 1, __builtin_object_size (s, 1),
fmt, __builtin_va_arg_pack ());
}
void
cap_to_text (int c)
{
char buf[1572];
char *p;
int n, t;
p = 20 + buf;
for (t = 8; t--; )
{
for (n = 0; n < c; n++)
p += sprintf (p, "a,");
p--;
if (__builtin_object_size (p, 1) == 0)
abort ();
}
}
/* { dg-final { scan-assembler-not "abort" } } */

11
gcc/tree-object-size.c
View File

@ -990,13 +990,10 @@ plus_stmt_object_size (struct object_size_info *osi, tree var, gimple *stmt)
addr_object_size (osi, op0, object_size_type, &bytes, &wholesize);
}
/* In the first pass, do not compute size for offset if either the
maximum size is unknown or the minimum size is not initialized yet;
the latter indicates a dependency loop and will be resolved in
subsequent passes. We attempt to compute offset for 0 minimum size
too because a negative offset could be within bounds of WHOLESIZE,
giving a non-zero result for VAR. */
if (osi->pass != 0 || !size_unknown_p (bytes, 0))
/* size_for_offset doesn't make sense for -1 size, but it does for size 0
since the wholesize could be non-zero and a negative offset could give
a non-zero size. */
if (!size_unknown_p (bytes, 0))
bytes = size_for_offset (bytes, op1, wholesize);
}
else