https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83668
Bug ID: 83668 Summary: [8 Regression] wrong code with -O -fno-tree-dominator-opts -fgraphite-identity Product: gcc Version: 8.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: zsojka at seznam dot cz Target Milestone: --- Host: x86_64-pc-linux-gnu Target: x86_64-pc-linux-gnu Created attachment 43015 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43015&action=edit reduced testcase I have encountered several miscompilations with graphite, the minimum set of flags seems to be the one reported in this PR. -fno-tree-dominator-opts seems to be always present in the flags. Output: $ x86_64-pc-linux-gnu-gcc -O -fno-tree-dominator-opts -fgraphite-identity testcase.c $ ./a.out Aborted Here, a == 0. $ x86_64-pc-linux-gnu-gcc -v Using built-in specs. COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-256069-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/8.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++ --enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra --disable-bootstrap --with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld --with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch --prefix=/repo/gcc-trunk//binary-trunk-256069-checking-yes-rtl-df-extra-nobootstrap-amd64 Thread model: posix gcc version 8.0.0 20180102 (experimental) (GCC)