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Re: [PATCH] Fix rotate discovery in fold-const.c (PR tree-optimization/65014)
- From: Richard Biener <rguenther at suse dot de>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 12 Feb 2015 10:07:21 +0100 (CET)
- Subject: Re: [PATCH] Fix rotate discovery in fold-const.c (PR tree-optimization/65014)
- Authentication-results: sourceware.org; auth=none
- References: <20150212074040 dot GU1746 at tucnak dot redhat dot com>
On Thu, 12 Feb 2015, Jakub Jelinek wrote:
> Hi!
>
> We pass the values after STRIP_NOPS to *ROTATE_EXPR build, which is
> undesirable, as the testcase shows, the operand could very well end up being
> a pointer rather than integer.
Ugh, indeed tree_nop_conversion_p allows conversion to/from pointer
types... (I wonder if tree_nop_conversion_p should simply map to
useless_type_conversion_p ... for example tree_nop_conversion_p
happily drops conversion between pointers to different address-spaces).
Of course useless_type_conversion_p preserves sign-changes as well.
> This patch fixes it by passing the original trees instead.
> Alternatively we could fold_convert the STRIP_NOPS result to the original
> type, but I'd be afraid that in the common case that would just create more
> GC garbage.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2015-02-12 Jakub Jelinek <jakub@redhat.com>
>
> PR tree-optimization/65014
> * fold-const.c (fold_binary_loc): When creating {L,R}ROTATE_EXPR,
> use original second operand of arg0 or arg1 instead of
> that adjusted by STRIP_NOPS.
>
> * gcc.c-torture/compile/pr65014.c: New test.
>
> --- gcc/fold-const.c.jj 2015-01-22 19:30:59.000000000 +0100
> +++ gcc/fold-const.c 2015-02-11 15:06:52.628078961 +0100
> @@ -10261,7 +10261,9 @@ fold_binary_loc (location_t loc,
> tem = build2_loc (loc, LROTATE_EXPR,
> TREE_TYPE (TREE_OPERAND (arg0, 0)),
> TREE_OPERAND (arg0, 0),
> - code0 == LSHIFT_EXPR ? tree01 : tree11);
> + code0 == LSHIFT_EXPR
> + ? TREE_OPERAND (arg0, 1)
> + : TREE_OPERAND (arg1, 1));
> return fold_convert_loc (loc, type, tem);
> }
> else if (code11 == MINUS_EXPR)
> @@ -10283,7 +10285,8 @@ fold_binary_loc (location_t loc,
> ? LROTATE_EXPR
> : RROTATE_EXPR),
> TREE_TYPE (TREE_OPERAND (arg0, 0)),
> - TREE_OPERAND (arg0, 0), tree01));
> + TREE_OPERAND (arg0, 0),
> + TREE_OPERAND (arg0, 1)));
> }
> else if (code01 == MINUS_EXPR)
> {
> @@ -10304,7 +10307,7 @@ fold_binary_loc (location_t loc,
> ? LROTATE_EXPR
> : RROTATE_EXPR),
> TREE_TYPE (TREE_OPERAND (arg0, 0)),
> - TREE_OPERAND (arg0, 0), tree11));
> + TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1, 1)));
> }
> }
> }
> --- gcc/testsuite/gcc.c-torture/compile/pr65014.c.jj 2015-02-11 15:21:19.175681614 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr65014.c 2015-02-11 15:22:18.040703653 +0100
> @@ -0,0 +1,10 @@
> +/* PR tree-optimization/65014 */
> +/* { dg-do compile { target int32plus } } */
> +
> +extern int x;
> +
> +unsigned
> +foo (unsigned int y)
> +{
> + return (y << ((__INTPTR_TYPE__) &x)) | (y >> (32 - ((__INTPTR_TYPE__) &x)));
> +}
>
> Jakub
>
>
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Jennifer Guild,
Dilip Upmanyu, Graham Norton HRB 21284 (AG Nuernberg)