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Subject: [Bug target/47000] Major performance regression in parallel SSE2 impl of SHA256 hash algorithm
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47000

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> 2010-12-18 15:36:30 UTC ---
(In reply to comment #3)
> Compiled like so:
> $ gcc-4.4.2 -S -O2 sha256_4way.i -o sha256_4way-44.s
> $ gcc-4.5.0 -S -O2 sha256_4way.i -o sha256_4way-45.s
> 
> $ grep -c call *.s
> sha256_4way-44.s:0
> sha256_4way-45.s:484
> $ grep call *.s|head
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> sha256_4way-45.s:    call    ROTR
> $ 
> 
> ROTR should have been inlined:
> 
> static inline __m128i ROTR(__m128i x, const int n) {
>     return _mm_srli_epi32(x, n) | _mm_slli_epi32(x, 32 - n);
> }
> 
> This probably explains the slowdown.

This is caused by revision 151511:

http://gcc.gnu.org/ml/gcc-cvs/2009-09/msg00257.html