--- Comment #1 from hjl dot tools at gmail dot com 2008-11-30 15:00 ---
Can you try -fno-ira to see if it fixes the problem?
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hjl dot tools at gmail dot com changed:
What|Removed |Added
--- Comment #2 from sgunderson at bigfoot dot com 2008-11-30 15:06 ---
OK, I looked at the source. The issue here seems to be that 4.4 likes to
compile this:
z3 = ((z3) * (- ((INT32) 16069)));
into this:
10 0.0403 : 805cc87: lea(%ecx,%ecx,4),%ebx
:
--- Comment #3 from rguenth at gcc dot gnu dot org 2008-11-30 16:23 ---
Which tuning are you using? Try enabling -mtune=generic (possibly by default).
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
--- Comment #4 from sgunderson at bigfoot dot com 2008-11-30 20:32 ---
Subject: Re: Massive performance regression
for jpeg_idct_islow
On Sun, Nov 30, 2008 at 04:23:31PM -, rguenth at gcc dot gnu dot org wrote:
Which tuning are you using? Try enabling -mtune=generic
--- Comment #5 from rguenth at gcc dot gnu dot org 2008-11-30 20:37 ---
What is the gcc output if you append -v?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
--- Comment #6 from sgunderson at bigfoot dot com 2008-11-30 20:40 ---
Subject: Re: Massive performance regression
for jpeg_idct_islow
On Sun, Nov 30, 2008 at 08:37:31PM -, rguenth at gcc dot gnu dot org wrote:
--- Comment #5 from rguenth at gcc dot gnu dot org
--- Comment #7 from rguenth at gcc dot gnu dot org 2008-11-30 21:04 ---
Append -v to the command-line you use for compiling ;) Seriously, if using
-mtune=generic works then this is a Debian packaging issue of their
gcc-snapshot compiler.
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--- Comment #8 from sgunderson at bigfoot dot com 2008-11-30 21:19 ---
Subject: Re: Massive performance regression
for jpeg_idct_islow
On Sun, Nov 30, 2008 at 09:04:07PM -, rguenth at gcc dot gnu dot org wrote:
Append -v to the command-line you use for compiling ;)
--- Comment #9 from sgunderson at bigfoot dot com 2008-11-30 21:22 ---
Subject: Re: Massive performance regression
for jpeg_idct_islow
On Sun, Nov 30, 2008 at 09:19:08PM -, sgunderson at bigfoot dot com wrote:
-mtune=generic still produces these long series of leas.
--- Comment #10 from rguenth at gcc dot gnu dot org 2008-11-30 21:29
---
/usr/lib/gcc-snapshot/libexec/gcc/i486-linux-gnu/4.4.0/cc1 -quiet -v -I.
-D_REENTRANT -DPIC ./jidctint.c -quiet -dumpbase jidctint.c -mtune=i486
-auxbase-strip .libs/jidctint.o -g -g -O2 -Wall -version -fPIC -o
--- Comment #11 from sgunderson at bigfoot dot com 2008-11-30 22:48 ---
Subject: Re: Massive performance regression
for jpeg_idct_islow
On Sun, Nov 30, 2008 at 09:29:29PM -, rguenth at gcc dot gnu dot org wrote:
so it uses -mtune=i486 - this optimizes the multiplication
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