re PR tree-optimization/52631 (VN does not use simplified expression for lookup)

        PR tree-optimization/52631
        * tree-ssa-sccvn (visit_use): Before looking up the original
        statement, try looking up the simplified expression.

        PR tree-optimization/52631
        * tree-ssa/pr52631.c: New test.
        * tree-ssa/ssa-fre-9: Update expected output.

From-SVN: r195318

gcc/ChangeLog

+2013-01-19  Andrew Pinski  <apinski@cavium.com>
+
+	PR tree-optimization/52631
+	* tree-ssa-sccvn (visit_use): Before looking up the original
+	statement, try looking up the simplified expression.
+
 2013-01-19  Anthony Green  <green@moxielogic.com>
 
 	* config/moxie/moxie.c (moxie_expand_prologue): Set

gcc/testsuite/ChangeLog

+2013-01-19  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/52631
+	* tree-ssa/pr52631.c: New test.
+	* tree-ssa/ssa-fre-9: Update expected output.
+
 2013-01-19  Anthony Green  <green@moxielogic.com>
 
 	* gcc.dg/tree-ssa/asm-2.c (REGISTER): Pick an appropriate register

gcc/testsuite/gcc.dg/tree-ssa/pr52631.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-fre1-details" } */
+
+unsigned f(unsigned a)
+{
+  unsigned b = a >> 31;
+  return b&1;
+}
+
+/* We want to verify that we replace the b & 1 with b.  */
+/* { dg-final { scan-tree-dump-times "Replaced b_\[0-9\]+ & 1 with b_\[0-9\]+ in" 1 "fre1"} } */
+ 
+/* { dg-final { cleanup-tree-dump "fre1" } } */
+

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-9.c

@@ -23,6 +23,6 @@ void __frame_state_for1 (volatile char *state_in)
     }
 }
 
-/* { dg-final { scan-tree-dump-times "Eliminated: 1" 2 "fre1" } } */
+/* { dg-final { scan-tree-dump-times "Eliminated: 2" 2 "fre1" } } */
 /* { dg-final { scan-tree-dump-times "Insertions: 1" 2 "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/tree-ssa-sccvn.c

@@ -3422,6 +3422,28 @@ visit_use (tree use)
 		}
 	      else
 		{
+		  /* First try to lookup the simplified expression.  */
+		  if (simplified)
+		    {
+		      enum gimple_rhs_class rhs_class;
+
+
+		      rhs_class = get_gimple_rhs_class (TREE_CODE (simplified));
+		      if ((rhs_class == GIMPLE_UNARY_RHS
+			   || rhs_class == GIMPLE_BINARY_RHS
+			   || rhs_class == GIMPLE_TERNARY_RHS)
+			  && valid_gimple_rhs_p (simplified))
+			{
+			  tree result = vn_nary_op_lookup (simplified, NULL);
+			  if (result)
+			    {
+			      changed = set_ssa_val_to (lhs, result);
+			      goto done;
+			    }
+			}
+		    }
+
+		  /* Otherwise visit the original statement.  */
 		  switch (vn_get_stmt_kind (stmt))
 		    {
 		    case VN_NARY: