From patchwork Sat Oct 13 09:25:37 2012
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Subject: PR54915 (ssa-forwprop, vec_perm_expr)
From: Marc Glisse <marc.glisse@inria.fr>
X-Patchwork-Id: 191288
Message-Id: <alpine.DEB.2.02.1210131123460.16300@stedding.saclay.inria.fr>
To: gcc-patches@gcc.gnu.org
Date: Sat, 13 Oct 2012 11:25:37 +0200 (CEST)

On Fri, 12 Oct 2012, Marc Glisse wrote:

> Hello,
>
> apparently, in the optimization that recognizes that {v[1],v[0]} is a 
> VEC_PERM_EXPR, I forgot to check that v is a 2-element vector... (not that 
> there aren't things that could be done if v has a different size, just not 
> directly a VEC_PERM_EXPR, and not right now, priority is to fix the bug)
>
> Checking that v has the same type as the result seemed like the easiest way, 
> but there are many variations that could be slightly better or worse.
>
> bootstrap+testsuite ok.
>
> 2012-10-02  Marc Glisse  <marc.glisse@inria.fr>
>
> 	PR tree-optimization/54915
>
> gcc/
> 	* tree-ssa-forwprop.c (simplify_vector_constructor): Check
> 	argument's type.
>
> gcc/testsuite/
> 	* gcc.dg/tree-ssa/pr54915.c: New testcase.

This new version, with a slightly relaxed test, seems preferable and also 
passes testing.


Index: testsuite/gcc.dg/tree-ssa/pr54915.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/pr54915.c	(revision 0)
+++ testsuite/gcc.dg/tree-ssa/pr54915.c	(revision 0)
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef double v2df __attribute__ ((__vector_size__ (16)));
+typedef double v4df __attribute__ ((__vector_size__ (32)));
+
+void f (v2df *ret, v4df* xp)
+{
+  v4df x = *xp;
+  v2df xx = { x[2], x[3] };
+  *ret = xx;
+}

Property changes on: testsuite/gcc.dg/tree-ssa/pr54915.c
___________________________________________________________________
Added: svn:eol-style
   + native
Added: svn:keywords
   + Author Date Id Revision URL

Index: tree-ssa-forwprop.c
===================================================================
--- tree-ssa-forwprop.c	(revision 192420)
+++ tree-ssa-forwprop.c	(working copy)
@@ -2833,20 +2833,22 @@ simplify_vector_constructor (gimple_stmt
       ref = TREE_OPERAND (op1, 0);
       if (orig)
 	{
 	  if (ref != orig)
 	    return false;
 	}
       else
 	{
 	  if (TREE_CODE (ref) != SSA_NAME)
 	    return false;
+	  if (!useless_type_conversion_p (type, TREE_TYPE (ref)))
+	    return false;
 	  orig = ref;
 	}
       if (TREE_INT_CST_LOW (TREE_OPERAND (op1, 1)) != elem_size)
 	return false;
       sel[i] = TREE_INT_CST_LOW (TREE_OPERAND (op1, 2)) / elem_size;
       if (sel[i] != i) maybe_ident = false;
     }
   if (i < nelts)
     return false;