[c++-delayed-folding] Introduce convert_to_pointer_nofold

[Marek Polacek <polacek at redhat dot com>]

This patch introduces convert_to_pointer_nofold; a variant that only folds
CONSTANT_CLASS_P expressions.  In the C++ FE, convert_to_pointer was only used
in cp_convert_to_pointer which is only used in cp_convert.  Instead of
introducing many _nofold variants, I just made cp_convert_to_pointer use the
convert_to_pointer_nofold.

Bootstrapped/regtested on x86_64-linux, ok for branch?

diff --git gcc/convert.c gcc/convert.c
index 1ce8099..79b4138 100644
--- gcc/convert.c
+++ gcc/convert.c
@@ -39,10 +39,11 @@ along with GCC; see the file COPYING3.  If not see
 
 /* Convert EXPR to some pointer or reference type TYPE.
    EXPR must be pointer, reference, integer, enumeral, or literal zero;
-   in other cases error is called.  */
+   in other cases error is called.  If FOLD_P is true, try to fold the
+   expression.  */
 
-tree
-convert_to_pointer (tree type, tree expr)
+static tree
+convert_to_pointer_1 (tree type, tree expr, bool fold_p)
 {
   location_t loc = EXPR_LOCATION (expr);
   if (TREE_TYPE (expr) == type)
@@ -58,10 +59,21 @@ convert_to_pointer (tree type, tree expr)
 	addr_space_t to_as = TYPE_ADDR_SPACE (TREE_TYPE (type));
 	addr_space_t from_as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (expr)));
 
-	if (to_as == from_as)
-	  return fold_build1_loc (loc, NOP_EXPR, type, expr);
+	if (fold_p)
+	  {
+	    if (to_as == from_as)
+	      return fold_build1_loc (loc, NOP_EXPR, type, expr);
+	    else
+	      return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type,
+				      expr);
+	  }
 	else
-	  return fold_build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
+	  {
+	    if (to_as == from_as)
+	      return build1_loc (loc, NOP_EXPR, type, expr);
+	    else
+	      return build1_loc (loc, ADDR_SPACE_CONVERT_EXPR, type, expr);
+	  }
       }
 
     case INTEGER_TYPE:
@@ -75,20 +87,43 @@ convert_to_pointer (tree type, tree expr)
 	unsigned int pprec = TYPE_PRECISION (type);
 	unsigned int eprec = TYPE_PRECISION (TREE_TYPE (expr));
 
- 	if (eprec != pprec)
-	  expr = fold_build1_loc (loc, NOP_EXPR,
-			      lang_hooks.types.type_for_size (pprec, 0),
-			      expr);
+	if (eprec != pprec)
+	  {
+	    tree totype = lang_hooks.types.type_for_size (pprec, 0);
+	    if (fold_p)
+	      expr = fold_build1_loc (loc, NOP_EXPR, totype, expr);
+	    else
+	      expr = build1_loc (loc, NOP_EXPR, totype, expr);
+	  }
       }
 
-      return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
+      if (fold_p)
+	return fold_build1_loc (loc, CONVERT_EXPR, type, expr);
+      return build1_loc (loc, CONVERT_EXPR, type, expr);
 
     default:
       error ("cannot convert to a pointer type");
-      return convert_to_pointer (type, integer_zero_node);
+      return convert_to_pointer_1 (type, integer_zero_node, fold_p);
     }
 }
 
+/* A wrapper around convert_to_pointer_1 that always folds the
+   expression.  */
+
+tree
+convert_to_pointer (tree type, tree expr)
+{
+  return convert_to_pointer_1 (type, expr, true);
+}
+
+/* A wrapper around convert_to_pointer_1 that only folds the
+   expression if it is CONSTANT_CLASS_P.  */
+
+tree
+convert_to_pointer_nofold (tree type, tree expr)
+{
+  return convert_to_pointer_1 (type, expr, CONSTANT_CLASS_P (expr));
+}
 
 /* Convert EXPR to some floating-point type TYPE.
 
diff --git gcc/convert.h gcc/convert.h
index ac78f95..24fa6bf 100644
--- gcc/convert.h
+++ gcc/convert.h
@@ -23,6 +23,7 @@ along with GCC; see the file COPYING3.  If not see
 extern tree convert_to_integer (tree, tree);
 extern tree convert_to_integer_nofold (tree, tree);
 extern tree convert_to_pointer (tree, tree);
+extern tree convert_to_pointer_nofold (tree, tree);
 extern tree convert_to_real (tree, tree);
 extern tree convert_to_fixed (tree, tree);
 extern tree convert_to_complex (tree, tree);
diff --git gcc/cp/cvt.c gcc/cp/cvt.c
index 0a30270..cb73bb7 100644
--- gcc/cp/cvt.c
+++ gcc/cp/cvt.c
@@ -241,7 +241,7 @@ cp_convert_to_pointer (tree type, tree expr, tsubst_flags_t complain)
       gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
 		  == GET_MODE_SIZE (TYPE_MODE (type)));
 
-      return convert_to_pointer (type, expr);
+      return convert_to_pointer_nofold (type, expr);
     }
 
   if (type_unknown_p (expr))

	Marek