[Bug middle-end/89690] New: ICE on a MEM_REF in trivial gimple

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89690

            Bug ID: 89690
           Summary: ICE on a MEM_REF in trivial gimple
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

The following test case is one of a few I tried that triggers an ICE.  I'm not
sure if it's valid or not but I put it together in response to the suggestion
here: https://gcc.gnu.org/ml/gcc-patches/2019-03/msg00543.html

$ cat z.c && gcc -O2 -S -Wall -fdump-tree-gimple=/dev/stdout -fgimple z.c
void __GIMPLE () h (void)
{
  unsigned char a[4];

  __MEM <void *>((char*)&a + 16) = 0;   // ditto with MEM <void*> ((char*)&a) =
0;
}
h ()
{
  unsigned char a[4];

  MEM[(char *)&a + 16B] = 0;
  return;
}


z.c: In function ‘h’:
z.c:1:18: error: non-trivial conversion at assignment
    1 | void __GIMPLE () h (void)
      |                  ^
void *
int
MEM[(char *)&a + 16B] = 0;
during GIMPLE pass: *warn_unused_result
z.c:1:18: internal compiler error: verify_gimple failed
0x11d4f03 verify_gimple_in_seq(gimple*)
        /src/gcc/git-svn/gcc/tree-cfg.c:5094
0xfd9b5d execute_function_todo
        /src/gcc/git-svn/gcc/passes.c:1979
0xfd8a82 do_per_function
        /src/gcc/git-svn/gcc/passes.c:1638
0xfd9d57 execute_todo
        /src/gcc/git-svn/gcc/passes.c:2031
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