[Bug tree-optimization/77544] New: [Regression 6/7] segfault at -O0 - infinite loop in simplification

[babokin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77544

            Bug ID: 77544
           Summary: [Regression 6/7] segfault at -O0 - infinite loop in
                    simplification
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: babokin at gmail dot com
  Target Milestone: ---

Created attachment 39594
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39594&action=edit
reproducer

> g++ -O0 -c func.cpp
g++: internal compiler error: Segmentation fault (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Here's top of the stack when it fails (stack is huge):
#0  0x0000000000a37c59 in operand_equal_p (...) at
./svn/trunk/gcc/fold-const.c:2744
#1  0x0000000000a37e50 in operand_equal_p (...) at
./svn/trunk/gcc/fold-const.c:2750
#2  0x000000000115c676 in generic_simplify_MINUS_EXPR (...) at
generic-match.c:11785
#3  0x0000000001174bbe in generic_simplify (...) at generic-match.c:31249
#4  0x0000000000a47af3 in fold_binary_loc (...) at
./svn/trunk/gcc/fold-const.c:9161
#5  0x0000000000a52a0b in fold_build2_stat_loc (...) at
./svn/trunk/gcc/fold-const.c:12291
#6  0x0000000001138dc0 in generic_simplify_181 (...) at generic-match.c:6690
#7  0x000000000114c81b in generic_simplify_PLUS_EXPR (...) at
generic-match.c:11152
#8  0x0000000001174bde in generic_simplify (...) at generic-match.c:31245
#9  0x0000000000a47af3 in fold_binary_loc (...) at
./svn/trunk/gcc/fold-const.c:9161
#10 0x0000000000a52a0b in fold_build2_stat_loc (...) at
./svn/trunk/gcc/fold-const.c:12291
#11 0x0000000000a4a142 in fold_binary_loc (...) at
./svn/trunk/gcc/fold-const.c:9695
#12 0x0000000000a52a0b in fold_build2_stat_loc (...) at
./svn/trunk/gcc/fold-const.c:12291
#13 0x000000000115c762 in generic_simplify_MINUS_EXPR (...) at
generic-match.c:12390

It's reproducible with gcc6 and trunk. gcc5 works.

GCC build details:
> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/users/ddd/gcc_20160909/bin/../libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /users/ddd/stability/svn/trunk/configure --with-arch=corei7
--with-cpu=corei7 --enable-clocale=gnu --enable-libmpx=yes --with-system-zlib
--enable-shared --with-demangler-in-ld --enable-cloog-backend=isl
--with-fpmath=sse --with-pkgversion=Revision=240038/svn-rev:240038/
--prefix=/users/ddd/stability/work/trunk/64/install
--enable-languages=c,c++,fortran,java,lto
Thread model: posix
gcc version 7.0.0 20160908 (experimental) (Revision=240038/svn-rev:240038/)