[Bug tree-optimization/71379] New: [7 regression] Bootstrap fail on S/390 32 bit starting with r236831

[krebbel at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71379

            Bug ID: 71379
           Summary: [7 regression] Bootstrap fail on S/390 32 bit starting
                    with r236831
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krebbel at gcc dot gnu.org
  Target Milestone: ---

S/390 32 bit bootstrap appears to fail in stage 2 starting with r236831:

In file included from /home/andreas/clean/../gcc/gcc/config/s390/s390.c:41:0:
/home/andreas/clean/../gcc/gcc/recog.h: In function 'rtx_def*
s390_expand_builtin(tree, rtx, rtx, machine_mode, int)':
/home/andreas/clean/../gcc/gcc/recog.h:306:136: error: 'op[5]' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
   rtx_insn * operator () (rtx a0, rtx a1, rtx a2, rtx a3, rtx a4, rtx a5, rtx
a6) const { return ((f7)func) (a0, a1, a2, a3, a4, a5, a6); }

                                                        ^
/home/andreas/clean/../gcc/gcc/config/s390/s390.c:799:7: note: 'op[5]' was
declared here
   rtx op[MAX_ARGS], pat;
       ^~

Probably related or even duplicates of PR71335 or PR71316.

Unfortunately there was another commit causing a bootstrap fail in that
timeframe which needs to be reverted first: r236826. That commit got reverted
with r236850 anyway.