[Patch]: Fix ICE on VMS when using SImode pointers

[Tristan Gingold <gingold@adacore.com>]

Hi,

this patch fixes a build time failure on VMS (while compiling Ada RTS file i-cstrin.adb) due to the use of short pointers:

i-cstrin.adb: In function 'Interfaces.C.Strings.To_Chars_Ptr':
i-cstrin.adb:236:8: error: unrecognizable insn:
(insn 80 79 81 13 (set (reg:SI 384)
        (const_int 4294967288 [0xfffffff8])) i-cstrin.adb:234 -1
     (nil))
+===========================GNAT BUG DETECTED==============================+
| Pro 7.1.0w (20120403-47) (ia64-hp-openvms) GCC error:                    |
| in extract_insn, at recog.c:2123                                         |
| Error detected around i-cstrin.adb:236:8                                 |


Expansion of POINTER_PLUS_EXPR doesn't handle the case of PRECISION(sizetype) > PRECISION(type), leading to RTL expressions with different modes.

This patch fixes the build issue, tested on ia64-hp-openvms.
Also tested with our internal testsuite.
I haven't run the GCC testsuite on a regular platform, as the condition will never trigger.

Ok for trunk ?

Tristan.

2012-04-04  Tristan Gingold  <gingold@adacore.com>

	* expr.c (expand_expr_real_2): Handle larger sizetype in
	POINTER_PLUS_EXPR.

--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -7957,6 +7957,9 @@ expand_expr_real_2 (sepops ops, rtx target, enum machine_m
        treeop1 = fold_convert_loc (loc, type,
                                    fold_convert_loc (loc, ssizetype,
                                                      treeop1));
+      else if (TYPE_PRECISION (sizetype) > TYPE_PRECISION (type))
+       treeop1 = fold_convert_loc (loc, type, treeop1);
+
     case PLUS_EXPR:
       /* If we are adding a constant, a VAR_DECL that is sp, fp, or ap, and
         something else, make sure we add the register to the constant and
u