[4.6] Fix type of SRAed enum accesses

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Sep 27, 2011 at 03:26:03PM +0100, Richard Sandiford wrote:
> This patch fixes a miscompilation of stage1 c-parser.o in an ARM bootstrap.
> When an access to an enum field was SRAed, a component ref used the type
> of the integer temporary variable instead of the type of the enum.
> It therefore didn't alias other accesses to the same structure,
> and was scheduled after a copy-load.
> 
> Tested on x86_64-linux-gnu, and by verifying that c-parser.o is correctly
> compiled for ARM after the patch.  Martin says he's going to test on ia64
> too (thanks) -- I'll add 50326 to the changelog if that goes OK.
> 
> OK to install if there are no regressions on ia64?

As mentioned in bugzilla, the patch that caused this regression has been
committed to 4.6 branch as well.

Here is a backport of that patch to 4.6 branch, bootstrapped/regtested on
x86_64-linux and i686-linux and Matthias AFAIK bootstrapped it on ia64-linux
(where it previously failed to bootstrap because of this), regtest pending.

Ok for 4.6?

2011-10-18  Jakub Jelinek  <jakub@redhat.com>

	PR target/50350
	Backport from mainline
	2011-09-27  Richard Sandiford  <rdsandiford@googlemail.com>

	PR middle-end/50386
	PR middle-end/50326
	* tree-sra.c (build_ref_for_model): Use the type of the field as
	the type of the COMPONENT_REF.

--- gcc/tree-sra.c.jj	2011-09-30 17:19:10.000000000 +0200
+++ gcc/tree-sra.c	2011-10-18 08:01:28.682647833 +0200
@@ -1448,12 +1448,12 @@ build_ref_for_model (location_t loc, tre
 {
   if (TREE_CODE (model->expr) == COMPONENT_REF)
     {
-      tree t, exp_type;
-      offset -= int_bit_position (TREE_OPERAND (model->expr, 1));
+      tree t, exp_type, fld = TREE_OPERAND (model->expr, 1);
+      offset -= int_bit_position (fld);
       exp_type = TREE_TYPE (TREE_OPERAND (model->expr, 0));
       t = build_ref_for_offset (loc, base, offset, exp_type, gsi, insert_after);
-      return fold_build3_loc (loc, COMPONENT_REF, model->type, t,
-			      TREE_OPERAND (model->expr, 1), NULL_TREE);
+      return fold_build3_loc (loc, COMPONENT_REF, TREE_TYPE (fld), t, fld,
+			      NULL_TREE);
     }
   else
     return build_ref_for_offset (loc, base, offset, model->type,

	Jakub