From: James Greenhalgh <james.greenhalgh@arm.com>
Date: Thu, 21 Jul 2016 15:41:59 +0000 (+0000)
Subject: [Patch 3/2 ifcvt costs] Don't expand a conditional move between identical sources
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=f5a459a4392cacb1750c09bd2ecee8455d12af12;p=gcc.git

[Patch 3/2 ifcvt costs] Don't expand a conditional move between identical sources

gcc/

	* optabs.c (emit_condiitonal_move): Short circuit for identical
	sources.

From-SVN: r238595
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 602c7b8eeaa..0757c89bf84 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2016-07-21  James Greenhalgh  <james.greenhalgh@arm.com>
+
+	* optabs.c (emit_condiitonal_move): Short circuit for identical
+	sources.
+
 2016-07-21  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	* ifcvt.c (noce_if_info): New fields: speed_p, original_cost,
diff --git a/gcc/optabs.c b/gcc/optabs.c
index 51e10e21769..87b4f978420 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -4214,6 +4214,17 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1,
   enum insn_code icode;
   enum rtx_code reversed;
 
+  /* If the two source operands are identical, that's just a move.  */
+
+  if (rtx_equal_p (op2, op3))
+    {
+      if (!target)
+	target = gen_reg_rtx (mode);
+
+      emit_move_insn (target, op3);
+      return target;
+    }
+
   /* If one operand is constant, make it the second one.  Only do this
      if the other operand is not constant as well.  */