https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68520
Bug ID: 68520 Summary: ICE on valid code at -O3 on x86_64-linux-gnu in quick_push, at vec.h:845 Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu Target Milestone: --- The following code causes an ICE when compiled with the current gcc trunk at -O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes. It is a regression from 5.2.x. $ gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk --enable-languages=c,c++ --disable-werror --enable-multilib Thread model: posix gcc version 6.0.0 20151122 (experimental) [trunk revision 230719] (GCC) $ $ gcc-trunk -O2 -c small.c $ gcc-5.2 -O3 -c small.c $ $ gcc-trunk -O3 -c small.c small.c: In function ‘fn2’: small.c:10:1: internal compiler error: in quick_push, at vec.h:845 } ^ 0xac60d2 vec<basic_block_def*, va_heap, vl_embed>::quick_push(basic_block_def* const&) ../../gcc-trunk/gcc/vec.h:845 0xac60d2 vec<basic_block_def*, va_heap, vl_ptr>::quick_push(basic_block_def* const&) ../../gcc-trunk/gcc/vec.h:1503 0xac60d2 try_shrink_wrapping(edge_def**, bitmap_head*, rtx_insn*) ../../gcc-trunk/gcc/shrink-wrap.c:714 0x870058 thread_prologue_and_epilogue_insns() ../../gcc-trunk/gcc/function.c:6021 0x870a92 rest_of_handle_thread_prologue_and_epilogue ../../gcc-trunk/gcc/function.c:6543 0x870a92 execute ../../gcc-trunk/gcc/function.c:6585 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <http://gcc.gnu.org/bugs.html> for instructions. $ ------------------------------ int a, b, c, d; void fn2 () { if (c) for (; d; d = a+b) for (c = 0; c < 2; c++) fn2 (); }