From e49d8b68a2330971c75ba7ff625c770e6f2ce2b9 Mon Sep 17 00:00:00 2001
From: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date: Mon, 5 Jun 2017 08:46:28 +0000
Subject: [PATCH] [AArch64] Peephole for SUBS

	* config/aarch64/aarch64.c (define_peephole2 above
	*sub_<shift>_<mode>): New peephole.

	* gcc.target/aarch64/subs_compare_1.c: New test.

From-SVN: r248869
---
 gcc/ChangeLog                                  |  5 +++++
 gcc/config/aarch64/aarch64.md                  | 18 ++++++++++++++++++
 gcc/testsuite/ChangeLog                        |  4 ++++
 .../gcc.target/aarch64/subs_compare_1.c        | 15 +++++++++++++++
 4 files changed, 42 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/subs_compare_1.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 037168e20c6..eb7e9ca9774 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-05  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* config/aarch64/aarch64.c (define_peephole2 above
+	*sub_<shift>_<mode>): New peephole.
+
 2017-05-23  Jan Hubicka  <hubicka@ucw.cz>
 
 	* config/i386/i386.c (make_resolver_func): Update.
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 93972d134b1..475c6d7e85d 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -2234,6 +2234,24 @@
   [(set_attr "type" "alus_sreg")]
 )
 
+(define_peephole2
+  [(set (match_operand:GPI 0 "register_operand")
+	(minus:GPI (match_operand:GPI 1 "aarch64_reg_or_zero")
+		    (match_operand:GPI 2 "aarch64_reg_or_zero")))
+   (set (reg:CC CC_REGNUM)
+	(compare:CC
+	  (match_dup 1)
+	  (match_dup 2)))]
+  "!reg_overlap_mentioned_p (operands[0], operands[1])
+   && !reg_overlap_mentioned_p (operands[0], operands[2])"
+  [(const_int 0)]
+  {
+    emit_insn (gen_sub<mode>3_compare1 (operands[0], operands[1],
+					 operands[2]));
+    DONE;
+  }
+)
+
 (define_insn "*sub_<shift>_<mode>"
   [(set (match_operand:GPI 0 "register_operand" "=r")
 	(minus:GPI (match_operand:GPI 3 "register_operand" "r")
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ef8d6389aba..027a802d04d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2017-06-05  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* gcc.target/aarch64/subs_compare_1.c: New test.
+
 2017-06-05  Chenghua Xu  <paul.hua.gm@gmail.com>
 
 	* gcc.target/mips/div-9.c: Delete duplicate test.
diff --git a/gcc/testsuite/gcc.target/aarch64/subs_compare_1.c b/gcc/testsuite/gcc.target/aarch64/subs_compare_1.c
new file mode 100644
index 00000000000..95c8f696fee
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/subs_compare_1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int
+foo (int a, int b)
+{
+  int x = a - b;
+  if (a <= b)
+    return x;
+  else
+    return 0;
+}
+
+/* { dg-final { scan-assembler-times "subs\\tw\[0-9\]+, w\[0-9\]+, w\[0-9\]+" 1 } } */
+/* { dg-final { scan-assembler-not "cmp\\tw\[0-9\]+, w\[0-9\]+" } } */
-- 
2.30.2