Re: PR54915 (ssa-forwprop, vec_perm_expr)

[Marc Glisse]

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.gli...@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.

--
Marc GlisseIndex: 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;