When compiling the attached testcase, current trunk gcc uses all available memory on my system (4GB) and then swaps until I interrupt the process. This only happens with -O3; using -O2 works as expected. gcc 4.5 comiles the file as expected with -O3.
/scratch/tmp/devel2/build.linux_gcc/libcfitsio>gcc -c -O3 -v checksum.i Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/afs/mpa/data/martin/ugcc/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: /scratch/martin/gcc/configure --disable-bootstrap --enable-gold --enable-plugins --prefix=/afs/mpa/data/martin/ugcc --with-ppl=/afs/mpa/data/martin/numlibs64 --with-cloog=/afs/mpa/data/martin/numlibs64 --with-libelf=/afs/mpa/data/martin/numlibs64 --enable-languages=c++,fortran --enable-target=all --enable-checking=release Thread model: posix gcc version 4.6.0 20100609 (experimental) [trunk revision 160476] (GCC) COLLECT_GCC_OPTIONS='-c' '-O3' '-v' '-mtune=generic' '-march=x86-64' /afs/mpa/data/martin/ugcc/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/cc1 -fpreprocessed checksum.i -quiet -dumpbase checksum.i -mtune=generic -march=x86-64 -auxbase checksum -O3 -version -o /tmp/ccibJbLw.s GNU C (GCC) version 4.6.0 20100609 (experimental) [trunk revision 160476] (x86_64-unknown-linux-gnu) compiled by GNU C version 4.4.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1 warning: GMP header version 4.3.2 differs from library version 4.3.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C (GCC) version 4.6.0 20100609 (experimental) [trunk revision 160476] (x86_64-unknown-linux-gnu) compiled by GNU C version 4.4.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1 warning: GMP header version 4.3.2 differs from library version 4.3.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: f4e23293da4cc17049a858a32373cf07 ^C /scratch/tmp/devel2/build.linux_gcc/libcfitsio> -- Summary: [4.6 regression] gcc consumes all available memory when optimizing Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: martin at mpa-garching dot mpg dot de GCC build triplet: x86_64-unknown-linux-gnu GCC host triplet: x86_64-unknown-linux-gnu GCC target triplet: x86_64-unknown-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44483