[Bug debug/66688] New: [6 Regression] compare debug failure building Linux kernel on ppc64le

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66688

            Bug ID: 66688
           Summary: [6 Regression] compare debug failure building Linux
                    kernel on ppc64le
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---
            Target: powerpc64le-unknown-linux-gnu

trippels@gcc2-power8 linux-3.18.16 % cat fdt_sw.i
struct fdt_header {
  unsigned magic;
} *a;
int d;
int __fswab32(int p1) { return __builtin_bswap32(p1); }
void fdt_set_magic(int p1) {
  struct fdt_header *b = a;
  b->magic = __builtin_constant_p(p1) ?: __fswab32(p1);
}
int _fdt_sw_check_header() {
  int c = ((struct fdt_header *)1)->magic;
  if (c)
    return 1;
  return 0;
}
int fdt_finish() {
  if (_fdt_sw_check_header())
    if (d)
      return 0;
  fdt_set_magic(0);
  return 0;
}

trippels@gcc2-power8 linux-3.18.16 % gcc -save-temps -fcompare-debug -O2
-fno-reorder-blocks -c fdt_sw.i
gcc: error: fdt_sw.i: -fcompare-debug failure (length)

trippels@gcc2-power8 linux-3.18.16 % diff -u fdt_sw.gkd fdt_sw.gk.gkd
--- fdt_sw.gkd  2015-06-27 06:32:59.842703885 +0000
+++ fdt_sw.gk.gkd       2015-06-27 06:32:59.862704267 +0000
@@ -181,7 +181,7 @@
         (expr_list:REG_DEAD (reg/f:DI 9 9 [orig:162 a ] [162])
             (nil))))
 (jump_insn # 0 0 (set (pc)
-        (label_ref #))# {jump}
+        (label_ref #)) fdt_sw.i:21# {jump}
      (nil)
  -> 8)
 (barrier # 0 0)