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Fix string/tst-xbzero-opt if build with gcc head.

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On s390x, the test string/tst-xbzero-opt is failing if build with gcc head:
FAIL: no clear/prepare: expected 32 got 0
FAIL: no clear/test: expected some got 0
FAIL: ordinary clear/prepare: expected 32 got 0
INFO: ordinary clear/test: found 0 patterns (memset not eliminated)
PASS: explicit clear/prepare: expected 32 got 32
PASS: explicit clear/test: expected 0 got 0

In setup_no_clear / setup_ordinary_clear, GCC is omitting the memcpy loop
in prepare_test_buffer. Thus count_test_patterns does not find any of the
test_pattern.

This patch calls use_test_buffer in order to force the compiler to really copy
the pattern to buf.

ChangeLog:

	* string/tst-xbzero-opt.c (use_test_buffer): New function.
	(prepare_test_buffer): Call use_test_buffer as compiler barrier.
This commit is contained in:
Stefan Liebler 2018-07-26 17:09:44 +02:00
parent cfba5dbb10
commit c9dc4d5117
2 changed files with 20 additions and 0 deletions
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5
ChangeLog
View file

@ -1,3 +1,8 @@
2018-07-26 Stefan Liebler <stli@linux.ibm.com>
* string/tst-xbzero-opt.c (use_test_buffer): New function.
(prepare_test_buffer): Call use_test_buffer as compiler barrier.
2018-07-26 Florian Weimer <fweimer@redhat.com>
* htl/lockfile.c (flockfile, funlockfile, ftrylockfile): Use weak

15
string/tst-xbzero-opt.c
View file

@ -97,6 +97,17 @@ static const unsigned char test_pattern[16] =
static ucontext_t uc_main, uc_co;
static __attribute__ ((noinline, noclone)) int
use_test_buffer (unsigned char *buf)
{
unsigned int sum = 0;
for (unsigned int i = 0; i < PATTERN_REPS; i++)
sum += buf[i * PATTERN_SIZE];
return (sum == 2 * PATTERN_REPS) ? 0 : 1;
}
/* Always check the test buffer immediately after filling it; this
makes externally visible side effects depend on the buffer existing
and having been filled in. */
@ -116,6 +127,10 @@ prepare_test_buffer (unsigned char *buf)
if (swapcontext (&uc_co, &uc_main))
abort ();
/* Force the compiler to really copy the pattern to buf. */
if (use_test_buffer (buf))
abort ();
}
static void