On 21/07/15 11:11, Richard Biener wrote:
On Tue, 21 Jul 2015, Kyrill Tkachov wrote:
On 21/07/15 08:24, Richard Biener wrote:
On Mon, 20 Jul 2015, Kyrill Tkachov wrote:
Hi all,
This patch fixes the PR in question which is a miscompilation of
gcc.dg/fixed-point/unary.c on arm.
It just restricts the A - B -> A + (-B) transformation when the type is
fixed-point.
This fixes the testcase for me.
Is this the right approach?
Bootstrap and test on arm and x86 running.
Ok if testing is clean?
Ok, but I think the fold-const.c code has the same issue, no:
/* A - B -> A + (-B) if B is easily negatable. */
if (negate_expr_p (arg1)
&& !TYPE_OVERFLOW_SANITIZED (type)
&& ((FLOAT_TYPE_P (type)
/* Avoid this transformation if B is a positive REAL_CST.
*/
&& (TREE_CODE (arg1) != REAL_CST
|| REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1))))
|| INTEGRAL_TYPE_P (type)))
return fold_build2_loc (loc, PLUS_EXPR, type,
fold_convert_loc (loc, type, arg0),
fold_convert_loc (loc, type,
negate_expr (arg1)));
ah, no. The above only applies to float-type and integral-types.
Thus yes, your patch is ok. Can you double-check the other pattern,
/* -(A + B) -> (-B) - A. */
(simplify
(negate (plus:c @0 negate_expr_p@1))
(if (!HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type))
&& !HONOR_SIGNED_ZEROS (element_mode (type)))
(minus (negate @1) @0)))
?
Thanks, committed with r226028.
I can add (FLOAT_TYPE_P (type) || INTEGRAL_TYPE_P (type)) to the condition.
That would more closely mirror the original logic, right?
That passes x86_64 bootstrap and aarch64 testing looks ok.
Yeah, that works for me, too.
How about this patch then?
Bootstrapped and tested on x86_64 and aarch64.
Thanks,
Kyrill
2015-07-23 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
* match.pd (-(A + B) -> (-B) - A): Restrict to floating point
and integral types.
Thanks,
Richard.
commit d514c81a7965fd24b9d8c294b12179b2369c8aa4
Author: Kyrylo Tkachov <kyrylo.tkac...@arm.com>
Date: Tue Jul 21 10:18:31 2015 +0100
[match.pd] Restrict -(A + B) -> (-B) - A to integral or float types
diff --git a/gcc/match.pd b/gcc/match.pd
index 3d7b32e..29367f2 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -515,7 +515,8 @@ along with GCC; see the file COPYING3. If not see
/* -(A + B) -> (-B) - A. */
(simplify
(negate (plus:c @0 negate_expr_p@1))
- (if (!HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type))
+ (if ((FLOAT_TYPE_P (type) || INTEGRAL_TYPE_P (type))
+ && !HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type))
&& !HONOR_SIGNED_ZEROS (element_mode (type)))
(minus (negate @1) @0)))
