[Bug c/105163] New: ICE: SSA corruption

["gscfq@t-online.de" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105163

            Bug ID: 105163
           Summary: ICE: SSA corruption
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

Affects versions down to at least r5, at -O1+ :
(follow-up of pr79411.c)


$ cat z1.c
typedef struct __jmp_buf_tag { char buf[1024]; } jmp_buf[1];
extern int setjmp (jmp_buf);
extern int bar (unsigned int *);
extern jmp_buf *baz (void);
struct C { int c1; };
void foo (struct C *x, int *z, int e)
{
  unsigned int d = 0;
  long f;
  setjmp (*baz());
  f = 1 + ~d;
  d = 8;
  if ((!0) && !e && bar(z)) *z = 1 + f;
}


$ gcc-12-20220403 -c z1.c -O2

Unable to coalesce ssa_names 5 and 17 which are marked as MUST COALESCE.
d_5(ab) and  d_17(ab)
during RTL pass: expand
z1.c: In function 'foo':
z1.c:6:6: internal compiler error: SSA corruption
    6 | void foo (struct C *x, int *z, int e)
      |      ^~~
0xd18bc8 fail_abnormal_edge_coalesce
        ../../gcc/tree-ssa-coalesce.cc:1003
0xd18bc8 coalesce_partitions
        ../../gcc/tree-ssa-coalesce.cc:1425
0xd18bc8 coalesce_ssa_name(_var_map*)
        ../../gcc/tree-ssa-coalesce.cc:1755
0xcc26a0 remove_ssa_form
        ../../gcc/tree-outof-ssa.cc:1065
0xcc26a0 rewrite_out_of_ssa(ssaexpand*)
        ../../gcc/tree-outof-ssa.cc:1323
0x7cfa73 execute
        ../../gcc/cfgexpand.cc:6585