Relax VIEW_CONVERT_EXPR - CONVERT_EXPR combination

2017-05-25  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* match.pd (view_convert (convert@0 @1)): Handle zero-extension.

gcc/testsuite/
	* gcc.dg/tree-ssa/vce-1.c: New file.

From-SVN: r248449

gcc/ChangeLog

 2017-05-25  Marc Glisse  <marc.glisse@inria.fr>
 
+	* match.pd (view_convert (convert@0 @1)): Handle zero-extension.
+
+2017-05-25  Marc Glisse  <marc.glisse@inria.fr>
+
 	* match.pd ((A +- CST1) +- CST2): Allow some conversions.
 	* tree.c (drop_tree_overflow): Handle COMPLEX_CST and VECTOR_CST.
 

gcc/match.pd

@@ -1856,13 +1856,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (@0)))
    (convert @0)))
 
-/* Strip inner integral conversions that do not change precision or size.  */
+/* Strip inner integral conversions that do not change precision or size, or
+   zero-extend while keeping the same size (for bool-to-char).  */
 (simplify
   (view_convert (convert@0 @1))
   (if ((INTEGRAL_TYPE_P (TREE_TYPE (@0)) || POINTER_TYPE_P (TREE_TYPE (@0)))
        && (INTEGRAL_TYPE_P (TREE_TYPE (@1)) || POINTER_TYPE_P (TREE_TYPE (@1)))
-       && (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE (@1)))
-       && (TYPE_SIZE (TREE_TYPE (@0)) == TYPE_SIZE (TREE_TYPE (@1))))
+       && TYPE_SIZE (TREE_TYPE (@0)) == TYPE_SIZE (TREE_TYPE (@1))
+       && (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE (@1))
+	   || (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (TREE_TYPE (@1))
+	       && TYPE_UNSIGNED (TREE_TYPE (@1)))))
    (view_convert @1)))
 
 /* Re-association barriers around constants and other re-association

gcc/testsuite/ChangeLog

 2017-05-25  Marc Glisse  <marc.glisse@inria.fr>
 
+	* gcc.dg/tree-ssa/vce-1.c: New file.
+
+2017-05-25  Marc Glisse  <marc.glisse@inria.fr>
+
 	* gcc.dg/tree-ssa/addadd.c: New file.
 
 2017-05-24  Nathan Sidwell  <nathan@acm.org>

gcc/testsuite/gcc.dg/tree-ssa/vce-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+typedef struct { _Bool b; } A;
+_Bool f(double u){
+  A a;
+  if(u==0)
+    a.b=1;
+  else
+    a.b=0;
+  return a.b;
+}
+
+/* { dg-final { scan-tree-dump-not "VIEW_CONVERT_EXPR" "optimized" } } */