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From: "gcc-bugzilla at mkarcher dot dialup.fu-berlin.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/63783] [4.9/5 Regression] [SH] Miscompilation of boolean negation on SH4 using -O2
Date: Sat, 22 Nov 2014 10:14:00 -0000	[thread overview]
Message-ID: <bug-63783-4-ww3GIXDjW6@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-63783-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63783

--- Comment #18 from Michael Karcher <gcc-bugzilla at mkarcher dot dialup.fu-berlin.de> ---
As I said, I did not try your patch, but just read the source. The assembly you
quoted convinces me that there is no problem in the code actually produced by
your patch, which is great. This is caused by the pattern
or-then-SImode-compare, as you explained.

The or-then-SImode-compare optimization has an adverse effect on the test
coverage, it seems. In both cases, GET_MODE(src_reg) and GET_MODE(dst_reg) are
SImode, so the DImode output branch is not tested by any of your two example
source files. Furthermore, it looks like make_not_reg_insn will actually
produce bad code if it were ever called with GET_MODE(src_reg) == DImode. So I
would strongly suggest to narrow it to only accept SImode input operands, so it
fails to apply instead of generate bad code if something manages to call it
with DImode input.


  parent reply	other threads:[~2014-11-22 10:14 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-08 20:52 [Bug c/63783] New: gcc-4.9: " glaubitz at physik dot fu-berlin.de
2014-11-09  1:12 ` [Bug target/63783] [4.9/5 Regression] [SH] " kkojima at gcc dot gnu.org
2014-11-09  7:14 ` olegendo at gcc dot gnu.org
2014-11-12 23:25 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16  2:36 ` olegendo at gcc dot gnu.org
2014-11-16  7:37 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16  8:24 ` olegendo at gcc dot gnu.org
2014-11-16 10:02 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16 10:41 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16 11:01 ` olegendo at gcc dot gnu.org
2014-11-16 12:24 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16 18:54 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-16 23:44 ` olegendo at gcc dot gnu.org
2014-11-19 13:27 ` rguenth at gcc dot gnu.org
2014-11-21  3:41 ` olegendo at gcc dot gnu.org
2014-11-21 18:53 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-22  3:28 ` olegendo at gcc dot gnu.org
2014-11-22  3:33 ` olegendo at gcc dot gnu.org
2014-11-22 10:14 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de [this message]
2014-11-22 10:39 ` olegendo at gcc dot gnu.org
2014-11-22 11:07 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-22 15:34 ` olegendo at gcc dot gnu.org
2014-11-22 15:37 ` gcc-bugzilla at mkarcher dot dialup.fu-berlin.de
2014-11-22 15:50 ` olegendo at gcc dot gnu.org
2014-11-22 16:08 ` olegendo at gcc dot gnu.org
2014-11-24 16:57 ` rguenth at gcc dot gnu.org

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