http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57866
Bug ID: 57866 Summary: Erroneous constant folding of SSE intrinsics Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: other Assignee: unassigned at gcc dot gnu.org Reporter: artem.alimarin at gmail dot com Created attachment 30484 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30484&action=edit Tiny C++ bug reproducer The expected output of the resulting program: ok = 1 The real output with -O3: ok = 0 When compiled with -O0 the output is as expected. With -O3 the ADDSD instruction is not generated. As the result the MXCSR flags are not set correctly. Apparently the optimizer performs incorrect constant folding with SSE built-ins. Compilation: [artem@desktop ~]$ g++ -v -O3 -o sse sse.cpp Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) COLLECT_GCC_OPTIONS='-v' '-O3' '-o' 'sse' '-shared-libgcc' '-mtune=generic' /usr/libexec/gcc/x86_64-redhat-linux/4.4.7/cc1plus -quiet -v -D_GNU_SOURCE sse.cpp -quiet -dumpbase sse.cpp -mtune=generic -auxbase sse -O3 -version -o /tmp/cchr9Wzi.s ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.4.7/include-fixed" ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../x86_64-redhat-linux/include" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7 /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/x86_64-redhat-linux /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/backward /usr/local/include /usr/lib/gcc/x86_64-redhat-linux/4.4.7/include /usr/include End of search list. GNU C++ (GCC) version 4.4.7 20120313 (Red Hat 4.4.7-3) (x86_64-redhat-linux) compiled by GNU C version 4.4.7 20120313 (Red Hat 4.4.7-3), GMP version 4.3.1, MPFR version 2.4.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 223f8a064e7bf286655580f46ccd9b7c COLLECT_GCC_OPTIONS='-v' '-O3' '-o' 'sse' '-shared-libgcc' '-mtune=generic' as -V -Qy -o /tmp/ccZ96kdM.o /tmp/cchr9Wzi.s GNU assembler version 2.20.51.0.2 (x86_64-redhat-linux) using BFD version version 2.20.51.0.2-5.36.el6 20100205 COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/ LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-v' '-O3' '-o' 'sse' '-shared-libgcc' '-mtune=generic' /usr/libexec/gcc/x86_64-redhat-linux/4.4.7/collect2 --eh-frame-hdr --build-id -m elf_x86_64 --hash-style=gnu -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o sse /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crti.o /usr/lib/gcc/x86_64-redhat-linux/4.4.7/crtbegin.o -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../.. /tmp/ccZ96kdM.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-redhat-linux/4.4.7/crtend.o /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crtn.o