[Bug tree-optimization/83491] New: [8 Regression] ICE in execute_cse_reciprocals_1 at gcc/tree-ssa-math-opts.c:585

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83491

            Bug ID: 83491
           Summary: [8 Regression] ICE in execute_cse_reciprocals_1 at
                    gcc/tree-ssa-math-opts.c:585
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: wilco at gcc dot gnu.org, woodruff.jackson at gmail dot com
  Target Milestone: ---

Starting from r255141 we ICE on:

$ cat ice.c
float a;
float b;
void bar ()
{
  a = __builtin_nanf ("");
  b = __builtin_powf (a, 2.5F);
}

$ gcc ice.c -funsafe-math-optimizations -O1 -c -fdump-tree-gimple=/dev/stdout
bar ()
{
  a =  Nan;
  a.0_1 = a;
  _2 = __builtin_powf (a.0_1, 2.5e+0);
  b = _2;
}


during GIMPLE pass: recip
ice.c: In function ‘bar’:
ice.c:3:6: internal compiler error: tree check: expected ssa_name, have
real_cst in first_readonly_imm_use, at ssa-iterators.h:351
 void bar ()
      ^~~
0x5bf740 tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        ../../gcc/tree.c:9129
0x5b52a9 tree_check(tree_node*, char const*, int, char const*, tree_code)
        ../../gcc/tree.h:3119
0x5b52a9 first_readonly_imm_use
        ../../gcc/ssa-iterators.h:351
0xd5645b first_readonly_imm_use
        ../../gcc/tree.h:3233
0xd5645b execute_cse_reciprocals_1
        ../../gcc/tree-ssa-math-opts.c:585
0xd5a155 execute
        ../../gcc/tree-ssa-math-opts.c:760