[C++] PR58950: warn for unused __builtin_shuffle result

[Marc Glisse]

Hello,

this is the piece of patch you commented on in the PR.

Bootstrap+testsuite on x86_64-unknown-linux-gnu.

2014-01-03  Marc Glisse  <marc.gli...@inria.fr>

        PR c++/58950
gcc/cp/
        * cvt.c (convert_to_void): Handle VEC_PERM_EXPR and VEC_COND_EXPR.
gcc/testsuite/
        * g++.dg/pr58950.C: New file.

--
Marc Glisse
Index: gcc/cp/cvt.c
===================================================================
--- gcc/cp/cvt.c        (revision 206313)
+++ gcc/cp/cvt.c        (working copy)
@@ -1396,21 +1396,23 @@ convert_to_void (tree expr, impl_conv_vo
              code = TREE_CODE (e);
              tclass = TREE_CODE_CLASS (code);
              if ((tclass == tcc_comparison
                   || tclass == tcc_unary
                   || (tclass == tcc_binary
                       && !(code == MODIFY_EXPR
                            || code == INIT_EXPR
                            || code == PREDECREMENT_EXPR
                            || code == PREINCREMENT_EXPR
                            || code == POSTDECREMENT_EXPR
-                           || code == POSTINCREMENT_EXPR)))
+                           || code == POSTINCREMENT_EXPR))
+                  || code == VEC_PERM_EXPR
+                  || code == VEC_COND_EXPR)
                   && (complain & tf_warning))
                warning_at (loc, OPT_Wunused_value, "value computed is not 
used");
            }
        }
       expr = build1 (CONVERT_EXPR, void_type_node, expr);
     }
   if (! TREE_SIDE_EFFECTS (expr))
     expr = void_zero_node;
   return expr;
 }
Index: gcc/testsuite/g++.dg/pr58950.C
===================================================================
--- gcc/testsuite/g++.dg/pr58950.C      (revision 0)
+++ gcc/testsuite/g++.dg/pr58950.C      (working copy)
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+void f(){
+  int i __attribute__((vector_size(2*sizeof(int)))) = { 2, 3 };
+  __builtin_shuffle (i, i); /* { dg-warning "value computed is not used" } */
+  ++i?1:0; /* { dg-warning "value computed is not used" } */
+}

Property changes on: gcc/testsuite/g++.dg/pr58950.C
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