[PATCH v2 5/9] aarch64: Provide expander for sub3_compare1

[Richard Henderson via Gcc-patches]

In a couple of places we open-code a special case of this
pattern into the more specific sub<GPI>3_compare1_imm.
Centralize that special case into an expander.

        * config/aarch64/aarch64.md (*sub<GPI>3_compare1): Rename
        from sub<GPI>3_compare1.
        (sub<GPI>3_compare1): New expander.
---
 gcc/config/aarch64/aarch64.md | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 076158b0071..47eeba7311c 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -3120,7 +3120,7 @@
   [(set_attr "type" "alus_imm")]
 )
 
-(define_insn "sub<mode>3_compare1"
+(define_insn "*sub<mode>3_compare1"
   [(set (reg:CC CC_REGNUM)
        (compare:CC
          (match_operand:GPI 1 "aarch64_reg_or_zero" "rkZ")
@@ -3132,6 +3132,26 @@
   [(set_attr "type" "alus_sreg")]
 )
 
+(define_expand "sub<mode>3_compare1"
+  [(parallel
+    [(set (reg:CC CC_REGNUM)
+         (compare:CC
+           (match_operand:GPI 1 "aarch64_reg_or_zero")
+           (match_operand:GPI 2 "aarch64_reg_or_imm")))
+     (set (match_operand:GPI 0 "register_operand")
+         (minus:GPI (match_dup 1) (match_dup 2)))])]
+  ""
+{
+  if (aarch64_plus_immediate (operands[2], <MODE>mode))
+    {
+      emit_insn (gen_sub<mode>3_compare1_imm
+                (operands[0], operands[1], operands[2],
+                 GEN_INT (-INTVAL (operands[2]))));
+      DONE;
+    }
+  operands[2] = force_reg (<MODE>mode, operands[2]);
+})
+
 (define_peephole2
   [(set (match_operand:GPI 0 "aarch64_general_reg")
        (minus:GPI (match_operand:GPI 1 "aarch64_reg_or_zero")
-- 
2.20.1