[PATCH, powerpc] Fix PR47197

[William J. Schmidt]

This fixes an error wherein a nontrivial expression oassed to an Altivec
built-in results in an ICE, following Joseph Myers's suggested approach
in the bugzilla.

Bootstrapped and tested with no new regressions on
powerpc64-unknown-linux-gnu.  Ok for trunk?

Thanks,
Bill


gcc:

2012-04-24  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR target/47197
	* config/rs6000/rs6000-c.c (fully_fold_convert): New function.
	(altivec_build_resolved_builtin): Call fully_fold_convert.

gcc/testsuite:

2012-04-24  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR target/47197
	* gcc.target/powerpc/pr47197.c: New test.


Index: gcc/testsuite/gcc.target/powerpc/pr47197.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/pr47197.c	(revision 0)
+++ gcc/testsuite/gcc.target/powerpc/pr47197.c	(revision 0)
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-maltivec" } */
+
+/* Compile-only test to ensure that expressions can be passed to
+   Altivec builtins without error.  */
+
+#include <altivec.h>
+
+void func(unsigned char *buf, unsigned len)
+{
+        vec_dst(buf, (len >= 256 ? 0 : len) | 512, 2);
+}
Index: gcc/config/rs6000/rs6000-c.c
===================================================================
--- gcc/config/rs6000/rs6000-c.c	(revision 186761)
+++ gcc/config/rs6000/rs6000-c.c	(working copy)
@@ -3421,6 +3421,22 @@ rs6000_builtin_type_compatible (tree t, int id)
 }
 
 
+/* In addition to calling fold_convert for EXPR of type TYPE, also
+   call c_fully_fold to remove any C_MAYBE_CONST_EXPRs that could be
+   hiding there (PR47197).  */
+
+static tree
+fully_fold_convert (tree type, tree expr)
+{
+  tree result = fold_convert (type, expr);
+  bool maybe_const = true;
+
+  if (!c_dialect_cxx ())
+    result = c_fully_fold (result, false, &maybe_const);
+
+  return result;
+}
+
 /* Build a tree for a function call to an Altivec non-overloaded builtin.
    The overloaded builtin that matched the types and args is described
    by DESC.  The N arguments are given in ARGS, respectively.  
@@ -3470,18 +3486,18 @@ altivec_build_resolved_builtin (tree *args, int n,
       break;
     case 1:
       call = build_call_expr (impl_fndecl, 1,
-			      fold_convert (arg_type[0], args[0]));
+			      fully_fold_convert (arg_type[0], args[0]));
       break;
     case 2:
       call = build_call_expr (impl_fndecl, 2,
-			      fold_convert (arg_type[0], args[0]),
-			      fold_convert (arg_type[1], args[1]));
+			      fully_fold_convert (arg_type[0], args[0]),
+			      fully_fold_convert (arg_type[1], args[1]));
       break;
     case 3:
       call = build_call_expr (impl_fndecl, 3,
-			      fold_convert (arg_type[0], args[0]),
-			      fold_convert (arg_type[1], args[1]),
-			      fold_convert (arg_type[2], args[2]));
+			      fully_fold_convert (arg_type[0], args[0]),
+			      fully_fold_convert (arg_type[1], args[1]),
+			      fully_fold_convert (arg_type[2], args[2]));
       break;
     default:
       gcc_unreachable ();