[backport gcc-4.9/trunk r197843, needed by PR57051 fix <mikpe@it.uu.se>]

List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
Date: Thu, 11 Apr 2013 18:24:02 +0200 (CEST)
From: Marc Glisse <marc dot glisse at inria dot fr>
Subject: Fold {2, 3, 4, 5} >> 31

Hello,

here is a patch to handle constant folding of mixed vector-integer 
operations. I could have shared the loop with the vector-vector case, but 
that would have meant re-testing if arg2 was a vector at every iteration 
(I can go back to that version if you prefer).

bootstrap+testsuite on x86_64-linux-gnu

gcc/

2013-04-12  Marc Glisse  <marc.glisse@inria.fr>

	* fold-const.c (const_binop): Handle vector shifts by a scalar.
	(fold_binary_loc): Call const_binop also for mixed vector-scalar
	operations.

gcc/testsuite/

2013-04-12  Marc Glisse  <marc.glisse@inria.fr>

	* gcc.dg/fold-cstvecshift.c: New testcase.

--- gcc-4.8.0/gcc/fold-const.c.~1~	2013-02-26 11:00:31.000000000 +0100
+++ gcc-4.8.0/gcc/fold-const.c	2013-04-30 12:35:55.920486334 +0200
@@ -1342,21 +1342,44 @@ const_binop (enum tree_code code, tree a
   if (TREE_CODE (arg1) == VECTOR_CST
       && TREE_CODE (arg2) == VECTOR_CST)
     {
-      tree type = TREE_TYPE(arg1);
+      tree type = TREE_TYPE (arg1);
       int count = TYPE_VECTOR_SUBPARTS (type), i;
-      tree *elts =  XALLOCAVEC (tree, count);
+      tree *elts = XALLOCAVEC (tree, count);
 
       for (i = 0; i < count; i++)
 	{
-          tree elem1 = VECTOR_CST_ELT (arg1, i);
+	  tree elem1 = VECTOR_CST_ELT (arg1, i);
 	  tree elem2 = VECTOR_CST_ELT (arg2, i);
 
-          elts[i] = const_binop (code, elem1, elem2);
+	  elts[i] = const_binop (code, elem1, elem2);
 
-          /* It is possible that const_binop cannot handle the given
-            code and return NULL_TREE */
-          if(elts[i] == NULL_TREE)
-            return NULL_TREE;
+	  /* It is possible that const_binop cannot handle the given
+	     code and return NULL_TREE */
+	  if (elts[i] == NULL_TREE)
+	    return NULL_TREE;
+	}
+
+      return build_vector (type, elts);
+    }
+
+  /* Shifts allow a scalar offset for a vector.  */
+  if (TREE_CODE (arg1) == VECTOR_CST
+      && TREE_CODE (arg2) == INTEGER_CST)
+    {
+      tree type = TREE_TYPE (arg1);
+      int count = TYPE_VECTOR_SUBPARTS (type), i;
+      tree *elts = XALLOCAVEC (tree, count);
+
+      for (i = 0; i < count; i++)
+	{
+	  tree elem1 = VECTOR_CST_ELT (arg1, i);
+
+	  elts[i] = const_binop (code, elem1, arg2);
+
+	  /* It is possible that const_binop cannot handle the given
+	     code and return NULL_TREE */
+	  if (elts[i] == NULL_TREE)
+	    return NULL_TREE;
 	}
 
       return build_vector (type, elts);
@@ -9855,7 +9878,8 @@ fold_binary_loc (location_t loc,
       || (TREE_CODE (arg0) == FIXED_CST && TREE_CODE (arg1) == FIXED_CST)
       || (TREE_CODE (arg0) == FIXED_CST && TREE_CODE (arg1) == INTEGER_CST)
       || (TREE_CODE (arg0) == COMPLEX_CST && TREE_CODE (arg1) == COMPLEX_CST)
-      || (TREE_CODE (arg0) == VECTOR_CST && TREE_CODE (arg1) == VECTOR_CST))
+      || (TREE_CODE (arg0) == VECTOR_CST && TREE_CODE (arg1) == VECTOR_CST)
+      || (TREE_CODE (arg0) == VECTOR_CST && TREE_CODE (arg1) == INTEGER_CST))
     {
       if (kind == tcc_binary)
 	{
--- gcc-4.8.0/gcc/testsuite/gcc.dg/fold-cstvecshift.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.8.0/gcc/testsuite/gcc.dg/fold-cstvecshift.c	2013-04-30 12:35:55.920486334 +0200
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+typedef int vec __attribute__ ((vector_size (4 * sizeof (int))));
+
+void f (vec *r)
+{
+  vec a = { 2, 3, 4, 5 };
+  *r = (a << 2) >> 1;
+}
+
+/* { dg-final { scan-tree-dump "{ 4, 6, 8, 10 }" "ccp1"} } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */