From: Ian Lance Taylor <iant@google.com>
To: "Deng Shi" <Deng.Shi@synopsys.com>
Cc: <gcc-help@gcc.gnu.org>
Subject: Re: Inconsistent floating point result when using G++ 3.3.6 with option -O0 or -O1 separately
Date: Fri, 14 Jul 2006 05:52:00 -0000 [thread overview]
Message-ID: <m3sll4pwbs.fsf@localhost.localdomain> (raw)
In-Reply-To: <63E93BF3055BAC45A75523C731737ECBDFA187@JP01WEMBX1.internal.synopsys.com>
"Deng Shi" <Deng.Shi@synopsys.com> writes:
> I found our application tool gave the inconsistent floating point result when using different optimization level -O0 or -O1.
http://gcc.gnu.org/PR323
> Even if I used -O1 plus all the disabling options which includes in
> -O1, like -O1 -fno-merge-all-constants -fno-zero-initialized-in-bss
> -fno-function-cse -fno-keep-static-consts -fno-omit-frame-pointer
> -fno-merge-constants -fno-loop-optimize -fno-cprop-registers
> -fno-if-conversion -fno-if-conversion2 -fno-delayed-branch
> -fno-guess-branch-probability -fno-defer-pop -fno-crossjumping
> -fno-thread-jumps " which command line setting should be equal to
> -O0, but I still didn't get the consistent result.
> I wonder whether there is any additional optimization enabled by -O1
> for C++ language which is not documented in GCC manual?
-O1 turns on optimization in general, affecting code generation in a
-number of ways. -O1 is more than the sum of the -f options.
Ian
next prev parent reply other threads:[~2006-07-14 5:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-14 5:13 Deng Shi
2006-07-14 5:52 ` Ian Lance Taylor [this message]
2006-07-14 12:28 ` Tim Prince
2006-07-14 6:17 Deng Shi
2006-07-14 6:21 ` Ian Lance Taylor
2006-07-17 0:45 Deng Shi
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