[Bug middle-end/48124] [4.4/4.5/4.6/4.7 Regression] likely wrong code bug
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Feb 1 12:49:00 GMT 2012
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48124
--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-01 12:48:56 UTC ---
(In reply to comment #9)
> Simpler patch I am going to test. Let's hope the wreckage adjust_address
> does to the to_rtx MEM (apart from setting its mode) is harmless.
>
> Index: expr.c
> ===================================================================
> --- expr.c (revision 183791)
> +++ expr.c (working copy)
> @@ -4705,6 +4705,21 @@ expand_assignment (tree to, tree from, b
> to_rtx = adjust_address (to_rtx, mode1, 0);
> else if (GET_MODE (to_rtx) == VOIDmode)
> to_rtx = adjust_address (to_rtx, BLKmode, 0);
> + /* If the alignment of tem is larger than its size and we
> + are performing a bitfield access limit the mode we use
> + for the access to make sure we do not access the decl
> + beyond its end. See PR48124. */
> + else if (GET_MODE (to_rtx) == BLKmode
> + && mode1 == VOIDmode
> + && DECL_P (tem)
> + && TREE_CODE (DECL_SIZE (tem)) == INTEGER_CST
> + && TREE_INT_CST_LOW (DECL_SIZE (tem)) % DECL_ALIGN (tem))
> + {
> + mode1 = mode_for_size (TREE_INT_CST_LOW (DECL_SIZE (tem))
> + % DECL_ALIGN (tem),
> + MODE_INT, 0);
> + to_rtx = adjust_address (to_rtx, mode1, 0);
> + }
> }
>
> if (offset != 0)
Or rather
Index: gcc/expr.c
===================================================================
--- gcc/expr.c (revision 183791)
+++ gcc/expr.c (working copy)
@@ -4705,6 +4705,22 @@ expand_assignment (tree to, tree from, b
to_rtx = adjust_address (to_rtx, mode1, 0);
else if (GET_MODE (to_rtx) == VOIDmode)
to_rtx = adjust_address (to_rtx, BLKmode, 0);
+ /* If the alignment of tem is larger than its size and we
+ are performing a bitfield access limit the mode we use
+ for the access to make sure we do not access the decl
+ beyond its end. See PR48124. */
+ else if (GET_MODE (to_rtx) == BLKmode
+ && mode1 == VOIDmode
+ && DECL_P (tem)
+ && TREE_CODE (DECL_SIZE (tem)) == INTEGER_CST
+ && (TREE_INT_CST_LOW (DECL_SIZE (tem))
+ & (DECL_ALIGN (tem) - 1)) != 0)
+ {
+ unsigned HOST_WIDE_INT mis;
+ mis = TREE_INT_CST_LOW (DECL_SIZE (tem)) & (DECL_ALIGN (tem) -
1);
+ mode1 = mode_for_size (mis & -mis, MODE_INT, 0);
+ to_rtx = adjust_address (to_rtx, mode1, 0);
+ }
}
if (offset != 0)
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