Re: [PATCH] Don't handle CAST_RESTRICT (PR tree-optimization/49279)

[Tom de Vries <Tom_deVries at mentor dot com>]

[ quote-pasted from 
https://gcc.gnu.org/ml/gcc-patches/2011-10/msg00464.html ]

> CAST_RESTRICT based disambiguation unfortunately isn't reliable,
> e.g. to store a non-restrict pointer into a restricted field,
> we add a non-useless cast to restricted pointer in the gimplifier,
> and while we don't consider that field to have a special restrict tag
> because it is unsafe to do so, we unfortunately create it for the
> CAST_RESTRICT before that and end up with different restrict tags
> for the same thing.  See the PR for more details.
>
> This patch turns off CAST_RESTRICT handling for now, in the future
> we might try to replace it by explicit CAST_RESTRICT stmts in some form,
> but need to solve problems with multiple inlined copies of the same function
> with restrict arguments or restrict variables in it and intermixed code from
> them (or similarly code from different non-overlapping source blocks).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 4.6 too?
>
> 2011-10-06  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR tree-optimization/49279
> 	* tree-ssa-structalias.c (find_func_aliases): Don't handle
> 	CAST_RESTRICT.
> 	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Allow
> 	restrict propagation.
> 	* tree-ssa.c (useless_type_conversion_p): Don't return false
> 	if TYPE_RESTRICT differs.
>
> 	* gcc.dg/tree-ssa/restrict-4.c: XFAIL.
> 	* gcc.c-torture/execute/pr49279.c: New test.

Hi,

In the patch adding support for CAST_RESTRICT ( 
https://gcc.gnu.org/ml/gcc-patches/2011-10/msg00176.html ) there was 
also a bit:
...
	* fold-const.c (fold_unary_loc): Don't optimize
	POINTER_PLUS_EXPR casted to TYPE_RESTRICT pointer by
	casting the inner pointer if it isn't TYPE_RESTRICT.
...
which is still around. I suppose we can remove this bit as well.

OK for trunk if bootstrap and reg-test succeeds?

Thanks,
- Tom


Allow CAST_RESTRICT folding

2015-10-29  Tom de Vries  <tom@codesourcery.com>

	* fold-const.c (fold_unary_loc): Remove folding inhibition for restrict
	types.
---
 gcc/fold-const.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index c4be017..1cd911a 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7728,7 +7728,6 @@ fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
 	 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
       if (POINTER_TYPE_P (type)
 	  && TREE_CODE (arg0) == POINTER_PLUS_EXPR
-	  && (!TYPE_RESTRICT (type) || TYPE_RESTRICT (TREE_TYPE (arg0)))
 	  && (TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
 	      || TREE_CODE (TREE_OPERAND (arg0, 0)) == NOP_EXPR
 	      || TREE_CODE (TREE_OPERAND (arg0, 1)) == NOP_EXPR))
-- 
1.9.1