[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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? -- hjl dot tools at gmail dot com changed: What|Removed |Added CC||hjl dot tools at gmail dot ||com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 : 805cc8a: lea(%ebx,%ebx,4),%ebx 20 0.0805 : 805cc8d: lea(%ebx,%ebx,4),%ebx 7 0.0282 : 805cc90: lea(%ecx,%ebx,2),%ebx 3 0.0121 : 805cc93: shl$0x4,%ebx 38 0.1530 : 805cc96: add%ecx,%ebx 8 0.0322 : 805cc98: lea(%ecx,%ebx,4),%esi 4.3 uses imul here, which is a lot faster. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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). -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 (possibly by default). The compile flags are -g -O2 -D_REENTRANT, IIRC. No weird compile options. /* Steinar */ -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 2008-11-30 20:37 --- What is the gcc output if you append -v? fugl:~ /usr/lib/gcc-snapshot/bin/gcc -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 20081117-1' --with-bugurl=file:///usr/share/doc/gcc-snapshot/README.Bugs --enable-languages=c,c++,java,fortran,objc,obj-c++,ada --prefix=/usr/lib/gcc-snapshot --enable-shared --with-system-zlib --disable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-awt=gtk --enable-gtk-cairo --disable-plugin --with-java-home=/usr/lib/gcc-snapshot/java-1.5.0-gcj-4.4-1.5.0.0/jre --enable-java-home --with-jvm-root-dir=/usr/lib/gcc-snapshot/jvm --with-jvm-jar-dir=/usr/lib/gcc-snapshot/jvm-exports --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-mpfr --enable-targets=all --enable-cld --disable-werror --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.4.0 20081117 (experimental) [trunk revision 141948] (Debian 20081117-1) /* Steinar */ -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 ;) Seriously, if using -mtune=generic works then this is a Debian packaging issue of their gcc-snapshot compiler. fugl:~/nmu/libjpeg6b-6b /usr/lib/gcc-snapshot/bin/gcc -D_REENTRANT -g -Wall -O2 -g -I. -c ./jidctint.c -fPIC -DPIC -o .libs/jidctint.o -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 20081117-1' --with-bugurl=file:///usr/share/doc/gcc-snapshot/README.Bugs --enable-languages=c,c++,java,fortran,objc,obj-c++,ada --prefix=/usr/lib/gcc-snapshot --enable-shared --with-system-zlib --disable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-awt=gtk --enable-gtk-cairo --disable-plugin --with-java-home=/usr/lib/gcc-snapshot/java-1.5.0-gcj-4.4-1.5.0.0/jre --enable-java-home --with-jvm-root-dir=/usr/lib/gcc-snapshot/jvm --with-jvm-jar-dir=/usr/lib/gcc-snapshot/jvm-exports --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-mpfr --enable-targets=all --enable-cld --disable-werror --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.4.0 20081117 (experimental) [trunk revision 141948] (Debian 20081117-1) COLLECT_GCC_OPTIONS='-D_REENTRANT' '-g' '-Wall' '-O2' '-g' '-I.' '-c' '-fPIC' '-DPIC' '-o' '.libs/jidctint.o' '-v' '-mtune=i486' /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 /tmp/cc5hqg0m.s ignoring nonexistent directory /usr/local/include/i486-linux-gnu ignoring nonexistent directory /usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/../../../../i486-linux-gnu/include ignoring nonexistent directory /usr/include/i486-linux-gnu #include ... search starts here: #include ... search starts here: . /usr/local/include /usr/lib/gcc-snapshot/include /usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/include /usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/include-fixed /usr/include End of search list. GNU C (Debian 20081117-1) version 4.4.0 20081117 (experimental) [trunk revision 141948] (i486-linux-gnu) compiled by GNU C version 4.4.0 20081117 (experimental) [trunk revision 141948], GMP version 4.2.2, MPFR version 2.3.2. GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096 Compiler executable checksum: 445209552aa2d93e7e967b7473e83cd6 COLLECT_GCC_OPTIONS='-D_REENTRANT' '-g' '-Wall' '-O2' '-g' '-I.' '-c' '-fPIC' '-DPIC' '-o' '.libs/jidctint.o' '-v' '-mtune=i486' as -V -Qy -o .libs/jidctint.o /tmp/cc5hqg0m.s GNU assembler version 2.18.0 (i486-linux-gnu) using BFD version (GNU Binutils for Debian) 2.18.0.20080103 COMPILER_PATH=/usr/lib/gcc-snapshot/libexec/gcc/i486-linux-gnu/4.4.0/:/usr/lib/gcc-snapshot/libexec/gcc/i486-linux-gnu/4.4.0/:/usr/lib/gcc-snapshot/libexec/gcc/i486-linux-gnu/:/usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/:/usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/:/usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc-snapshot/lib/gcc/i486-linux-gnu/4.4.0/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-D_REENTRANT' '-g' '-Wall' '-O2' '-g' '-I.' '-c' '-fPIC' '-DPIC' '-o' '.libs/jidctint.o' '-v' '-mtune=i486' -mtune=generic still produces these long series of leas. /* Steinar */ -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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. Sorry, I objdumped the wrong file. -mtune=generic appears to fix it (although I haven't checked the performance). /* Steinar */ -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 /tmp/cc5hqg0m.s so it uses -mtune=i486 - this optimizes the multiplication for i486 where imul is slow. The difference to 4.3 is a packaging issue in Debian. -- rguenth at gcc dot gnu dot org changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution||INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
[Bug tree-optimization/38328] Massive performance regression for jpeg_idct_islow
--- 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 for i486 where imul is slow. The difference to 4.3 is a packaging issue in Debian. Thanks! I'll file a bug against the package. /* Steinar */ -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38328
