[committed] x86: Emit "#" instead of calling gcc_unreachable for invalid insns.

[Uros Bizjak]

Implement standard approach by emitting "#" for insns that have to be split.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

2020-02-06  Uroš Bizjak  <ubiz...@gmail.com>

    * config/i386/i386.md (*pushtf): Emit "#" instead of
    calling gcc_unreachable in insn output.
    (*pushxf): Ditto.
    (*pushdf): Ditto.
    (*pushsf_rex64): Ditto for alternatives other than 1.
    (*pushsf): Ditto for alternatives other than 1.

Committed to mainline.

Uros.

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 496a8666643..34649c010b8 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -3032,7 +3032,7 @@
   "TARGET_64BIT || TARGET_SSE"
 {
   /* This insn should be already split before reg-stack.  */
-  gcc_unreachable ();
+  return ("#");
 }
   [(set_attr "isa" "*,x64")
    (set_attr "type" "multi")
@@ -3087,7 +3087,7 @@
   ""
 {
   /* This insn should be already split before reg-stack.  */
-  gcc_unreachable ();
+  return ("#");
 }
   [(set_attr "isa" "*,*,*,nox64,x64")
    (set_attr "type" "multi")
@@ -3123,7 +3123,7 @@
   ""
 {
   /* This insn should be already split before reg-stack.  */
-  gcc_unreachable ();
+  return ("#");
 }
   [(set_attr "isa" "*,nox64,nox64,nox64,x64,sse2")
    (set_attr "type" "multi")
@@ -3156,7 +3156,8 @@
   "TARGET_64BIT"
 {
   /* Anything else should be already split before reg-stack.  */
-  gcc_assert (which_alternative == 1);
+  if (which_alternative != 1)
+    return ("#");
   return "push{q}\t%q1";
 }
   [(set_attr "type" "multi,push,multi")
@@ -3169,7 +3170,8 @@
   "!TARGET_64BIT"
 {
   /* Anything else should be already split before reg-stack.  */
-  gcc_assert (which_alternative == 1);
+  if (which_alternative != 1)
+    return ("#");
   return "push{l}\t%1";
 }
   [(set_attr "type" "multi,push,multi")