[backport proposed gcc-4.9/trunk bug fix in C++ FE for vector/scalar ops <mikpe@it.uu.se>]

List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
Date: Fri, 26 Apr 2013 14:23:32 +0200 (CEST)
From: Marc Glisse <marc dot glisse at inria dot fr>
Subject: Re: Logic operators ! && || for vectors

Ping http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00783.html

Even if we decide not to implement logic operators in the front-end, we 
still need the fix for the wrong code (the 2 save_expr in 
cp_build_binary_op, is that part of the patch ok with the 
vector-scalar-2.c testcase? and for 4.8?) and to avoid ICEing on __m128i 
f(__m128d a,__m128d b){return a<b&&b<a;} as we currently do in 
warn_logical_operator.

On Fri, 12 Apr 2013, Marc Glisse wrote:

> Hello,
>
> this adds support for vector !, && and ||. In the long run, I think it would 
> be good to be able to use TRUTH_*_EXPR with vectors, but that's probably a 
> lot of work.
>
> It currently restricts && and || to vector-vector operations. I'd like to 
> also support mixed scalar-vector later, but it is a bit more complicated. 
> With vectors, && evaluates both sides. For scal && vec, we have the choice of 
> making it short-circuit: cond_expr((bool)scal, vec!=0, {0}) or do a vector 
> and. For vec && scal, it seems clear we have to evaluate both operands, but 
> then we can also make it a cond_expr instead of a BIT_AND_EXPR (technically, 
> I think I can achieve that with save_expr and a compound_expr, I don't know 
> if there is a better way to add statements).
>
> The missing save_expr before build_vector_from_val are a bug I introduced 
> when I adapted the code from the C front-end. This bit (and the 
> vector-scalar-2.c testcase that goes with it) should probably be backported 
> to 4.8.
>
> The code we generate for these examples is not very good, but that's a 
> different issue.
>
> Bootstrap+testsuite on x86_64-linux-gnu.
>
> 2013-04-12  Marc Glisse  <marc.glisse@inria.fr>
>
> gcc/cp/
> 	* typeck.c (cp_build_binary_op): Call save_expr before
> 	build_vector_from_val.
>
> gcc/testsuite/
> 	* c-c++-common/vector-scalar-2.c: New testcase.

--- gcc-4.8.0/gcc/cp/typeck.c.~1~	2013-03-11 17:22:16.000000000 +0100
+++ gcc-4.8.0/gcc/cp/typeck.c	2013-04-30 12:46:45.908332128 +0200
@@ -3939,7 +3939,7 @@ cp_build_binary_op (location_t location,
             return error_mark_node;
           case stv_firstarg:
             {
-              op0 = convert (TREE_TYPE (type1), op0);
+              op0 = save_expr (convert (TREE_TYPE (type1), op0));
               op0 = build_vector_from_val (type1, op0);
               type0 = TREE_TYPE (op0);
               code0 = TREE_CODE (type0);
@@ -3948,7 +3948,7 @@ cp_build_binary_op (location_t location,
             }
           case stv_secondarg:
             {
-              op1 = convert (TREE_TYPE (type0), op1);
+              op1 = save_expr (convert (TREE_TYPE (type0), op1));
               op1 = build_vector_from_val (type0, op1);
               type1 = TREE_TYPE (op1);
               code1 = TREE_CODE (type1);
--- gcc-4.8.0/gcc/testsuite/c-c++-common/vector-scalar-2.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.8.0/gcc/testsuite/c-c++-common/vector-scalar-2.c	2013-04-30 12:46:45.908332128 +0200
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-gimple" } */
+
+typedef int veci __attribute__ ((vector_size (4 * sizeof (int))));
+
+int c;
+
+void f (veci *a)
+{
+  *a = *a + ++c;
+}
+
+/* { dg-final { scan-tree-dump-times " \\\+ 1" 1 "gimple" } } */
+/* { dg-final { cleanup-tree-dump "gimple" } } */