From: ktkachov <ktkachov@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 20 Jul 2015 12:51:45 +0000 (+0000)
Subject: [simplify-rtx][2/2] Simplify - (y ? -x : x) -> (!y ? -x : x)
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5ced42f848b676f2528f544c99283bb49d76c5a6;p=thirdparty%2Fgcc.git

[simplify-rtx][2/2] Simplify - (y ? -x : x) -> (!y ? -x : x)

	* simplify-rtx.c (simplify_unary_operation_1, NEG case):
	(neg (x ? (neg y) : y)) -> !x ? (neg y) : y.

	* gcc.target/aarch64/neg_abs_1.c: New test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@225997 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5972a0035712..addf8ad6a32d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-20  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* simplify-rtx.c (simplify_unary_operation_1, NEG case):
+	(neg (x ? (neg y) : y)) -> !x ? (neg y) : y.
+
 2015-07-20  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* combine.c (combine_simplify_rtx): Move simplification step
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index fde99445e54d..4332a42ced4a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -957,6 +957,32 @@ simplify_unary_operation_1 (enum rtx_code code, machine_mode mode, rtx op)
       if (GET_CODE (op) == NEG)
 	return XEXP (op, 0);
 
+      /* (neg (x ? (neg y) : y)) == !x ? (neg y) : y.
+	 If comparison is not reversible use
+	 x ? y : (neg y).  */
+      if (GET_CODE (op) == IF_THEN_ELSE)
+	{
+	  rtx cond = XEXP (op, 0);
+	  rtx true_rtx = XEXP (op, 1);
+	  rtx false_rtx = XEXP (op, 2);
+
+	  if ((GET_CODE (true_rtx) == NEG
+	       && rtx_equal_p (XEXP (true_rtx, 0), false_rtx))
+	       || (GET_CODE (false_rtx) == NEG
+		   && rtx_equal_p (XEXP (false_rtx, 0), true_rtx)))
+	    {
+	      if (reversed_comparison_code (cond, NULL_RTX) != UNKNOWN)
+		temp = reversed_comparison (cond, mode);
+	      else
+		{
+		  temp = cond;
+		  std::swap (true_rtx, false_rtx);
+		}
+	      return simplify_gen_ternary (IF_THEN_ELSE, mode,
+					    mode, temp, true_rtx, false_rtx);
+	    }
+	}
+
       /* (neg (plus X 1)) can become (not X).  */
       if (GET_CODE (op) == PLUS
 	  && XEXP (op, 1) == const1_rtx)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 214ad673d89a..9df1d41c151c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-07-20  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* gcc.target/aarch64/neg_abs_1.c: New test.
+
 2015-07-18  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/66922
diff --git a/gcc/testsuite/gcc.target/aarch64/neg_abs_1.c b/gcc/testsuite/gcc.target/aarch64/neg_abs_1.c
new file mode 100644
index 000000000000..cb2a387088cc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/neg_abs_1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-save-temps -O2" } */
+
+int
+f1 (int x)
+{
+  return x < 0 ? x : -x;
+}
+
+long long
+f2 (long long x)
+{
+  return x < 0 ? x : -x;
+}
+
+/* { dg-final { scan-assembler-not "\tneg\tw\[0-9\]*.*" } } */
+/* { dg-final { scan-assembler-not "\tneg\tx\[0-9\]*.*" } } */