[PATCH][AArch64] Simplify ashl3 expander for SHORT modes

[Kyrill Tkachov]

Hi all,

The ashl<mode>3 expander for QI and HI modes is needlessly obfuscated.
The 2nd operand predicate accepts nonmemory_operand but the expand code
FAILs if it's not a CONST_INT. We can just demand a const_int_operand in
the predicate and remove the extra CONST_INT check.

Looking at git blame, it seems it was written that way as a result of some
other refactoring a few years back for an unrelated change.

Bootstrapped and tested on aarch64-none-linux-gnu.
Ok for trunk?

Thanks,
Kyrill

2016-04-27  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    * config/aarch64/aarch64.md (ashl<mode>3, SHORT modes):
    Use const_int_operand for operand 2 predicate.  Simplify expand code
    as a result.

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index d7a669e40f9d4ae863c3e48b73f0eebdecea340d..c08e89bc4eb7b51dbb1e5f893238824caeb5f317 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -3770,22 +3770,16 @@ (define_expand "<optab><mode>3"
 (define_expand "ashl<mode>3"
   [(set (match_operand:SHORT 0 "register_operand")
 	(ashift:SHORT (match_operand:SHORT 1 "register_operand")
-		      (match_operand:QI 2 "nonmemory_operand")))]
+		      (match_operand:QI 2 "const_int_operand")))]
   ""
   {
-    if (CONST_INT_P (operands[2]))
-      {
-        operands[2] = GEN_INT (INTVAL (operands[2])
-                               & (GET_MODE_BITSIZE (<MODE>mode) - 1));
+    operands[2] = GEN_INT (INTVAL (operands[2]) & GET_MODE_MASK (<MODE>mode));
 
-        if (operands[2] == const0_rtx)
-          {
-	    emit_insn (gen_mov<mode> (operands[0], operands[1]));
-	    DONE;
-          }
+    if (operands[2] == const0_rtx)
+      {
+	emit_insn (gen_mov<mode> (operands[0], operands[1]));
+	DONE;
       }
-    else
-      FAIL;
   }
 )