[Bug target/80125] New: [7 Regression] r246297 causes segfault in reg_used_between_p()

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80125

            Bug ID: 80125
           Summary: [7 Regression] r246297 causes segfault in
                    reg_used_between_p()
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
                CC: segher at gcc dot gnu.org
  Target Milestone: ---
              Host: ppc64le
            Target: ppc64le
             Build: ppc64le

Since r246297 I see:

trippels@gcc2-power8 ffmpeg % cat postprocess.i
int a[1];
void dering_altivec() {
  __attribute__((altivec(vector__))) int b, e, f, g, h, j, n;
  __attribute__((altivec(vector__))) unsigned c, d;
  f = __builtin_vec_sums(h, b);
  __attribute__((altivec(vector__))) int i = __builtin_vec_mergel(f, g);
  __attribute__((altivec(vector__))) int k = __builtin_vec_mergel(i, j);
  __attribute__((altivec(vector__))) int l = __builtin_vec_sl(k, c);
  __attribute__((altivec(vector__))) int m = __builtin_vec_sl(l, d);
  __attribute__((altivec(vector__))) char o;
  __attribute__((altivec(vector__))) int p = __builtin_vec_perm(m, n, o);
  e = __builtin_vec_sra(p, c);
  __builtin_vec_st(e, 0, a);
}

trippels@gcc2-power8 ffmpeg % gcc -c -O2 postprocess.i
postprocess.i: In function ‘dering_altivec’:
postprocess.i:14:1: internal compiler error: Segmentation fault
 }
 ^
0x108d4d73 crash_signal
        ../../gcc/gcc/toplev.c:337
0x1084f7d8 reg_used_between_p(rtx_def const*, rtx_insn const*, rtx_insn const*)
        ../../gcc/gcc/rtlanal.c:1093
0x110a4677 can_combine_p
        ../../gcc/gcc/combine.c:1958
0x110ae71f try_combine
        ../../gcc/gcc/combine.c:2985
0x110b5497 combine_instructions
        ../../gcc/gcc/combine.c:1294
0x110b5497 rest_of_handle_combine
        ../../gcc/gcc/combine.c:14645
0x110b5497 execute
        ../../gcc/gcc/combine.c:14690
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.