From: rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Tue, 10 Nov 2015 09:43:54 +0000 (+0000)
Subject: 2015-11-10  Richard Biener  <rguenther@suse.de>
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b873d7f7eba25120074b3d74add21224e860df43;p=thirdparty%2Fgcc.git

2015-11-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56118
	* tree-vect-slp.c (vect_bb_vectorization_profitable_p): Make equal
	cost favor vectorized version.

	* gcc.target/i386/pr56118.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230091 138bc75d-0d04-0410-961f-82ee72b054a4
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5a7e44cf2920..68163747ca15 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-11-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/56118
+	* tree-vect-slp.c (vect_bb_vectorization_profitable_p): Make equal
+	cost favor vectorized version.
+
 2015-11-10  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* config/aarch64/aarch64.md (<neg_not_op><mode>cc): New define_expand.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5c258f4404ef..bbaf9a347c8e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-11-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/56118
+	* gcc.target/i386/pr56118.c: New testcase.
+
 2015-11-10  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* gcc.target/aarch64/cond_op_imm_1.c: New test.
diff --git a/gcc/testsuite/gcc.target/i386/pr56118.c b/gcc/testsuite/gcc.target/i386/pr56118.c
new file mode 100644
index 000000000000..11a543cafe83
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr56118.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -msse2" } */
+
+#include <emmintrin.h>
+
+__m128d f()
+{
+  __m128d r={3,4};
+  r[0]=1;
+  r[1]=2;
+  return r;
+}
+
+/* We want to "vectorize" this to a aligned vector load from the
+   constant pool.  */
+
+/* { dg-final { scan-assembler "movapd" } } */
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 954b85ef8bce..6dda2ec9eae1 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -2317,9 +2317,12 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo)
       dump_printf (MSG_NOTE, "  Scalar cost of basic block: %d\n", scalar_cost);
     }
 
-  /* Vectorization is profitable if its cost is less than the cost of scalar
-     version.  */
-  if (vec_outside_cost + vec_inside_cost >= scalar_cost)
+  /* Vectorization is profitable if its cost is more than the cost of scalar
+     version.  Note that we err on the vector side for equal cost because
+     the cost estimate is otherwise quite pessimistic (constant uses are
+     free on the scalar side but cost a load on the vector side for
+     example).  */
+  if (vec_outside_cost + vec_inside_cost > scalar_cost)
     return false;
 
   return true;