[PATCH] combine: Use correct mode in new comparison (PR86902)

[Segher Boessenkool]

This code in try_combine uses the wrong mode.  This fails (with RTL
checking) in trunk, but not in any released branches.

Committing to trunk.


Segher


2018-09-19  Segher Boessenkool  <seg...@kernel.crashing.org>

        * combine.c (try_combine): When changing the CC mode used, don't change
        an unrelated mode in other_insn to that new CC mode.

---
 gcc/combine.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/combine.c b/gcc/combine.c
index d3f7143..256b5a4 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3338,7 +3338,7 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, 
rtx_insn *i0,
                {
                  /* Replace cc_use_loc with entire new RTX.  */
                  SUBST (*cc_use_loc,
-                        gen_rtx_fmt_ee (compare_code, compare_mode,
+                        gen_rtx_fmt_ee (compare_code, GET_MODE (*cc_use_loc),
                                         newpat_dest, const0_rtx));
                  undobuf.other_insn = cc_use_insn;
                }
@@ -3347,7 +3347,7 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, 
rtx_insn *i0,
                  /* Just replace the CC reg with a new mode.  */
                  SUBST (XEXP (*cc_use_loc, 0), newpat_dest);
                  undobuf.other_insn = cc_use_insn;
-               }             
+               }
            }
 
          /* Now we modify the current newpat:
-- 
1.8.3.1