https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69036
Bug ID: 69036 Summary: g++ hangs compiling tree-ssa-loop-ivopts.c at -O3 Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: gary at intrepid dot com Target Milestone: --- While trying to build and bootstrap GCC at -O3 (using --with-build-config=bootstrap-O3) on an x86-64, the compiler hangs in the final stage while trying to build tree-ssa-loop-ivopts.o. As shown below, the failure can be triggered by doing a regular bootstrap build and then forcing the compilation of tree-ssa-loop-ivopts.c at -O3. Interestingly, it does not replicate _unless_ the compiler is fully bootstrap, which may indicate there is an issue with GCC (prev-gcc) compiling itself. Also, when the compiler hangs, it appears that its memory requirement steadily climbs over time. The first failing version appears to be this one: r231674 | rguenth | 2015-12-16 01:21:04 -0800 (Wed, 16 Dec 2015) | 8 lines 2015-12-16 Richard Biener <rguent...@suse.de> PR tree-optimization/68892 * tree-vect-slp.c (vect_analyze_slp_cost_1): Properly compute cost for permuted loads. * gcc.dg/vect/bb-slp-pr68892.c: New testcase. Steps to reproduce. 1. Standard configure and make. (cd ./src; svn up -q -r231674) src=`cd src; pwd` rm -rf bld mkdir bld cd bld $src/configure nj=`getconf _NPROCESSORS_ONLN` make -j$nj >& make.log 2. cd into gcc build directory and attempt to remake tree-ssa-loop-ivopts.o at -O3. cd gcc rm tree-ssa-loop-ivopts.o make CXXFLAGS='-O3 -g' tree-ssa-loop-ivopts.o [compiler hangs]