[Bug tree-optimization/69244] New: [6 Regression] ICE in plus_constant, at explow.c:87 on i686-linux-gnu

["doko at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69244

            Bug ID: 69244
           Summary: [6 Regression] ICE in plus_constant, at explow.c:87 on
                    i686-linux-gnu
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at gcc dot gnu.org
  Target Milestone: ---

r232188, i686-linux-gnu, works with -O0

reduced test case:

typedef union {
  float f;
  int i;
} ls_pcast32;
float a, b;
void fn1();
void fn2() {
  int c;
  float d, e = a;
  fn1();
  d = e;
  ls_pcast32 p;
  p.f = d += 2;
  c = p.i - 4;
  b = c;
}

$ gcc -c -g -O1 plugin.i
plugin.i: In function 'fn2':
plugin.i:16:1: internal compiler error: in plus_constant, at explow.c:87
 }
 ^

0x835faff plus_constant(machine_mode, rtx_def*, long long, bool)
        ../../src/gcc/explow.c:87
0x835fb39 plus_constant(machine_mode, rtx_def*, long long, bool)
        ../../src/gcc/explow.c:143
0x84a4c51 form_sum
        ../../src/gcc/lra-eliminations.c:213
0x84a5a42 lra_eliminate_regs_1(rtx_insn*, rtx_def*, machine_mode, bool, bool,
long long, bool)
        ../../src/gcc/lra-eliminations.c:436
0x84a611e eliminate_regs_in_insn(rtx_insn*, bool, bool, long long)
        ../../src/gcc/lra-eliminations.c:1116
0x84a687e process_insn_for_elimination
        ../../src/gcc/lra-eliminations.c:1408
0x84a687e lra_eliminate(bool, bool)
        ../../src/gcc/lra-eliminations.c:1472
0x8492724 lra(_IO_FILE*)
        ../../src/gcc/lra.c:2370
0x8453477 do_reload
        ../../src/gcc/ira.c:5385
0x8453477 execute
        ../../src/gcc/ira.c:5556
Please submit a full bug report,
with preprocessed source if appropriate.