From: Alan Modra <amodra@gmail.com>
To: gcc-patches@gcc.gnu.org
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Combine simplify_set WORD_REGISTER_OPERATIONS
Date: Sun, 31 Jan 2016 22:16:00 -0000 [thread overview]
Message-ID: <20160131221641.GV17028@bubble.grove.modra.org> (raw)
The comment says this test is supposed to prevent "a narrower
operation than requested", but it actually only allows a larger
subreg, not one the same size. Fix that.
Bootstrapped and regression tested powerpc64-linux. OK for stage1?
Note that this bug was found when investigating why gcc-6 does not
suffer from pr69548, ie. this bug was masking a powerpc backend bug.
* combine.c (simplify_set): Correct WORD_REGISTER_OPERATIONS test.
diff --git a/gcc/combine.c b/gcc/combine.c
index 858552d..9f284a7 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6736,7 +6736,7 @@ simplify_set (rtx x)
+ (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))
&& (WORD_REGISTER_OPERATIONS
|| (GET_MODE_SIZE (GET_MODE (src))
- < GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))))
+ <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (src)))))
#ifdef CANNOT_CHANGE_MODE_CLASS
&& ! (REG_P (dest) && REGNO (dest) < FIRST_PSEUDO_REGISTER
&& REG_CANNOT_CHANGE_MODE_P (REGNO (dest),
--
Alan Modra
Australia Development Lab, IBM
next reply other threads:[~2016-01-31 22:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-31 22:16 Alan Modra [this message]
2016-02-01 0:02 ` Segher Boessenkool
2016-02-01 1:13 ` Alan Modra
2016-02-08 16:27 ` Jeff Law
2016-02-09 11:18 ` Alan Modra
2016-02-09 17:37 ` Segher Boessenkool
2016-04-26 21:02 ` Jeff Law
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