[Bug rtl-optimization/77401] New: [7 Regression] ICE: in simplify_binary_operation_1, at simplify-rtx.c:3731 with out-of-bounds vector access

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77401

            Bug ID: 77401
           Summary: [7 Regression] ICE: in simplify_binary_operation_1, at
                    simplify-rtx.c:3731 with out-of-bounds vector access
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: rtl-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
             Build: x86_64-pc-linux-gnu

Compiler output:
$ x86_64-pc-linux-gnu-gcc testcase.c -O testcase.c 
testcase.c: In function 'foo':
testcase.c:6:1: internal compiler error: in simplify_binary_operation_1, at
simplify-rtx.c:3731
 }
 ^
0xba48b8 simplify_binary_operation_1
        /repo/gcc-trunk/gcc/simplify-rtx.c:3730
0xba516d simplify_binary_operation(rtx_code, machine_mode, rtx_def*, rtx_def*)
        /repo/gcc-trunk/gcc/simplify-rtx.c:2063
0x14584b4 combine_simplify_rtx
        /repo/gcc-trunk/gcc/combine.c:5529
0x145f033 subst
        /repo/gcc-trunk/gcc/combine.c:5461
0x145eeda subst
        /repo/gcc-trunk/gcc/combine.c:5399
0x14613a2 try_combine
        /repo/gcc-trunk/gcc/combine.c:3271
0x146d39c combine_instructions
        /repo/gcc-trunk/gcc/combine.c:1267
0x146d39c rest_of_handle_combine
        /repo/gcc-trunk/gcc/combine.c:14389
0x146d39c execute
        /repo/gcc-trunk/gcc/combine.c:14432
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.
testcase.c: In function 'foo':
testcase.c:6:1: internal compiler error: in simplify_binary_operation_1, at
simplify-rtx.c:3731
 }
 ^
0xba48b8 simplify_binary_operation_1
        /repo/gcc-trunk/gcc/simplify-rtx.c:3730
0xba516d simplify_binary_operation(rtx_code, machine_mode, rtx_def*, rtx_def*)
        /repo/gcc-trunk/gcc/simplify-rtx.c:2063
0x14584b4 combine_simplify_rtx
        /repo/gcc-trunk/gcc/combine.c:5529
0x145f033 subst
        /repo/gcc-trunk/gcc/combine.c:5461
0x145eeda subst
        /repo/gcc-trunk/gcc/combine.c:5399
0x14613a2 try_combine
        /repo/gcc-trunk/gcc/combine.c:3271
0x146d39c combine_instructions
        /repo/gcc-trunk/gcc/combine.c:1267
0x146d39c rest_of_handle_combine
        /repo/gcc-trunk/gcc/combine.c:14389
0x146d39c execute
        /repo/gcc-trunk/gcc/combine.c:14432
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.


$ 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-239769-checking-yes-rtl-df-extra-nographite-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/7.0.0/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
--without-cloog --without-ppl --without-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-239769-checking-yes-rtl-df-extra-nographite-amd64
Thread model: posix
gcc version 7.0.0 20160826 (experimental) (GCC) 


I don't know why is the backtrace printed twice.
I got this code while auto-reducing for another ICE.
The resulting code has undefined behaviour due to the out-of-bounds access.

Tested revisions:
r239769 - ICE
6-branch r239319 - OK