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From: "tg at swox dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/12654] [3.3/3.4 regression] Incorrect comparison code generated for Alpha Date: Fri, 17 Oct 2003 15:25:00 -0000 [thread overview] Message-ID: <20031017152225.16464.qmail@sources.redhat.com> (raw) In-Reply-To: <20031017020801.12654.tg@swox.com> PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12654 ------- Additional Comments From tg at swox dot com 2003-10-17 15:22 ------- Subject: Re: [3.3/3.4 regression] Incorrect comparison code generated for Alpha "falk at debian dot org" <gcc-bugzilla@gcc.gnu.org> writes: (the posted test case is technically invalid). The test case is perfectly valid. The test is the function foo. In order to drive that portably, a somewhat odd expression is needed. Are you saying the ~0L is "technically invalid", since it contains an overflow of signed data? Is that relevant for the test case's validity? Please take a look at gcc's testsuite for one million of examples where driver programs for constants that ate "technically invalid". I wrote the test in the c-torture style, intended for its execute category, since I really don't want this sort of bugs to come back. We had problems like this back in the gcc 1.x days, and I am disapppointed we now again have somebody with poor two's complement understanding checking in code in gcc. gcc 2.95 got it right, 3.2 not. Probably target dependent, but I don't have anything else to test currently. Poking around the gcc sources (alpha.c alpha_emit_conditional_branch) showns that the bogus code has been there for a while. The bogus variant is actually slightly better WRT register pressure, so we might want to retain it for int arguments. Huh? Not sure what you are suggesting. Adding and then comarping to 0 is *wrong* also for int arguments when since the add risks to overflow.
next prev parent reply other threads:[~2003-10-17 15:22 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-10-17 2:08 [Bug c/12654] New: " tg at swox dot com 2003-10-17 9:52 ` [Bug c/12654] [3.3/3.4 regression] " falk at debian dot org 2003-10-17 15:25 ` tg at swox dot com [this message] 2003-10-17 15:58 ` falk dot hueffner at student dot uni-tuebingen dot de 2003-10-17 21:01 ` falk at debian dot org 2003-10-17 22:01 ` [Bug target/12654] " pinskia at gcc dot gnu dot org 2003-10-17 23:29 ` tg at swox dot com 2003-10-18 14:23 ` falk dot hueffner at student dot uni-tuebingen dot de 2003-10-18 14:31 ` tg at swox dot com 2003-10-18 15:20 ` falk dot hueffner at student dot uni-tuebingen dot de 2003-10-19 7:08 ` tg at swox dot com 2003-10-20 8:05 ` cvs-commit at gcc dot gnu dot org 2003-10-20 8:35 ` falk at debian dot org 2003-10-23 0:23 ` wilson at specifixinc dot com 2003-10-27 20:56 ` cvs-commit at gcc dot gnu dot org 2003-10-27 22:04 ` tg at swox dot com 2003-10-27 23:12 ` falk dot hueffner at student dot uni-tuebingen dot de
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