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BUG/MEDIUM: tools: fix direction of my_ffsl()

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Commit 27346b01a ("OPTIM: tools: optimize my_ffsl() for x86_64") optimized
my_ffsl() for intensive use cases in the scheduler, but as half of the times
I got it wrong so it counted bits the reverse way. It doesn't matter for the
scheduler nor fd cache but it broke cpu-map with threads which heavily relies
on proper ordering.

We should probably consider dropping support for gcc < 3.4 and switching
to builtins for these ones, though often they are as ambiguous.

No backport is needed.
This commit is contained in:
Willy Tarreau 2018-10-29 16:09:57 +01:00
parent bddf292cbd
commit ce487aab46
1 changed files with 1 additions and 1 deletions
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2
include/common/standard.h
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@ -815,7 +815,7 @@ static inline unsigned int my_ffsl(unsigned long a)
unsigned long cnt; unsigned long cnt;
#if defined(__x86_64__) #if defined(__x86_64__)
__asm__("bsr %1,%0\n" : "=r" (cnt) : "rm" (a)); __asm__("bsf %1,%0\n" : "=r" (cnt) : "rm" (a));
cnt++; cnt++;
#else #else