http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61068
Bug ID: 61068 Summary: -O3 generates bad code (when tree-vectorize or inline-functions is on) Product: gcc Version: 4.8.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: wence at gmx dot li Created attachment 32738 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32738&action=edit preprocessed source The attached program segfaults at runtime when compiled with -O3. If I compile with either -fno-tree-vectorize or -fno-inline then the output is correct (verified externally, this is a cut down example). Note that if I split the increments into A[j][k] and A[(j+3)][(k+3)] into separate loops, then the segfault also goes away. I am currently building 4.9 to see if the problem still exists there. Compilation command: gcc-4.8 -v -std=c99 -O3 foo.c -save-temps -v output: Using built-in specs. COLLECT_GCC=gcc-4.8 COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/lto-wrapper Target: x86_64-apple-darwin13.0.0 Configured with: ../configure --build=x86_64-apple-darwin13.0.0 --prefix=/usr/local/Cellar/gcc48/4.8.2 --enable-languages=c,c++,objc,obj-c++ --program-suffix=-4.8 --with-gmp=/usr/local/opt/gmp4 --with-mpfr=/usr/local/opt/mpfr2 --with-mpc=/usr/local/opt/libmpc08 --with-cloog=/usr/local/opt/cloog018 --with-isl=/usr/local/opt/isl011 --with-system-zlib --enable-version-specific-runtime-libs --enable-libstdcxx-time=yes --enable-stage1-checking --enable-checking=release --enable-lto --disable-werror --enable-plugin --disable-nls --disable-multilib Thread model: posix gcc version 4.8.2 (GCC) COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.9.1' '-v' '-std=c99' '-O3' '-save-temps' '-mtune=core2' /usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/cc1 -E -quiet -v -D__DYNAMIC__ foo.c -fPIC -mmacosx-version-min=10.9.1 -mtune=core2 -std=c99 -O3 -fpch-preprocess -o foo.i ignoring nonexistent directory "/usr/local/Cellar/gcc48/4.8.2/include" ignoring nonexistent directory "/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/../../../../x86_64-apple-darwin13.0.0/include" #include "..." search starts here: #include <...> search starts here: /usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/include /usr/local/include /usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/include-fixed /usr/include /System/Library/Frameworks /Library/Frameworks End of search list. COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.9.1' '-v' '-std=c99' '-O3' '-save-temps' '-mtune=core2' /usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/cc1 -fpreprocessed foo.i -fPIC -quiet -dumpbase foo.c -mmacosx-version-min=10.9.1 -mtune=core2 -auxbase foo -O3 -std=c99 -version -o foo.s GNU C (GCC) version 4.8.2 (x86_64-apple-darwin13.0.0) compiled by GNU C version 4.8.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C (GCC) version 4.8.2 (x86_64-apple-darwin13.0.0) compiled by GNU C version 4.8.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 077b529d6cfe035508c45a2f30143407 COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.9.1' '-v' '-std=c99' '-O3' '-save-temps' '-mtune=core2' as -arch x86_64 -force_cpusubtype_ALL -o foo.o foo.s COMPILER_PATH=/usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/:/usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/:/usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/:/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/:/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/ LIBRARY_PATH=/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/:/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/../../../:/usr/lib/ COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.9.1' '-v' '-std=c99' '-O3' '-save-temps' '-mtune=core2' /usr/local/Cellar/gcc48/4.8.2/libexec/gcc/x86_64-apple-darwin13.0.0/4.8.2/collect2 -dynamic -arch x86_64 -macosx_version_min 10.9.1 -weak_reference_mismatches non-weak -o a.out -L/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2 -L/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/../../.. foo.o -no_compact_unwind -lSystem -lgcc_ext.10.5 -lgcc -lSystem -v collect2 version 4.8.2 /usr/bin/ld -dynamic -arch x86_64 -macosx_version_min 10.9.1 -weak_reference_mismatches non-weak -o a.out -L/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2 -L/usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/../../.. foo.o -no_compact_unwind -lSystem -lgcc_ext.10.5 -lgcc -lSystem -v @(#)PROGRAM:ld PROJECT:ld64-236.4 configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 armv6m armv7m armv7em Library search paths: /usr/local/Cellar/gcc48/4.8.2/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2 /usr/local/Cellar/gcc48/4.8.2/lib /usr/lib /usr/local/lib Framework search paths: /Library/Frameworks/ /System/Library/Frameworks/