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[msan] Fix performance issue in fast_memset.

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Fast path was never triggered when called from __msan_poison.

llvm-svn: 212715
This commit is contained in:
Evgeniy Stepanov 2014-07-10 12:45:56 +00:00
parent 0b666e0648
commit 8fc7e1fb13
1 changed files with 6 additions and 5 deletions
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11
compiler-rt/lib/msan/msan_interceptors.cc
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@ -1264,13 +1264,14 @@ void *fast_memset(void *ptr, int c, SIZE_T n) {
// hack until we have a really fast internal_memset
if (sizeof(uptr) == 8 &&
(n % 8) == 0 &&
((uptr)ptr % 8) == 0 &&
(c == 0 || c == -1)) {
// Printf("memset %p %zd %x\n", ptr, n, c);
uptr to_store = c ? -1L : 0L;
((uptr)ptr % 8) == 0) {
uptr c8 = (unsigned)c & 0xFF;
c8 = (c8 << 8) | c8;
c8 = (c8 << 16) | c8;
c8 = (c8 << 32) | c8;
uptr *p = (uptr*)ptr;
for (SIZE_T i = 0; i < n / 8; i++)
p[i] = to_store;
p[i] = c8;
return ptr;
}
return internal_memset(ptr, c, n);