[Bug target/68497] New: ICE: in output_387_binary_op, at config/i386/i386.c:17689 with -fno-checking

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68497

            Bug ID: 68497
           Summary: ICE: in output_387_binary_op, at
                    config/i386/i386.c:17689 with -fno-checking
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---

Created attachment 36806
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36806&action=edit
reduced testcase

Compiler output:
$ gcc -fno-checking testcase.c 
testcase.c: In function 'foo':
testcase.c:5:1: internal compiler error: in output_387_binary_op, at
config/i386/i386.c:17689
 }
 ^

0xecd4d6 output_387_binary_op(rtx_def*, rtx_def**)
        /repo/gcc-trunk/gcc/config/i386/i386.c:17689
0x85693b final_scan_insn(rtx_insn*, _IO_FILE*, int, int, int*)
        /repo/gcc-trunk/gcc/final.c:2947
0x8584c2 final(rtx_insn*, _IO_FILE*, int)
        /repo/gcc-trunk/gcc/final.c:2044
0x858e69 rest_of_handle_final
        /repo/gcc-trunk/gcc/final.c:4435
0x858e69 execute
        /repo/gcc-trunk/gcc/final.c:4510
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.

$ gcc -v                       
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest/bin/gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-230738-checking-yes-rtl-df-nographite/bin/../libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-checking=yes,rtl,df --without-cloog --without-ppl --without-isl
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-230738-checking-yes-rtl-df-nographite
Thread model: posix
gcc version 6.0.0 20151123 (experimental) (GCC) 

The failing assertion is:
17686:      && (STACK_TOP_P (operands[1]) || STACK_TOP_P (operands[2])))
17687:    ; /* ok */
17688:  else
17689:    gcc_checking_assert (is_sse);
17690:
17691:  switch (GET_CODE (operands[3]))
17692:    {


The above if(flag_checking ... ) is false for -fno-checking, but
gcc_checking_assert() doesn't care about -fno-checking.


Tested revisions:
r230738 - ICE