Date: Tue, 13 Mar 2007 10:13:12 -0300 From: Ricardo Nabinger Sanchez <rnsanchez@wait4.org> To: Andrey Chernov <ache@freebsd.org> Cc: freebsd-bugs@FreeBSD.ORG, freebsd-current@FreeBSD.ORG Subject: Re: Bad gcc -O optimization cause core dump. What to do? Message-ID: <20070313101312.71d35c32.rnsanchez@wait4.org> In-Reply-To: <20070313121106.GA96293@nagual.pp.ru> References: <20070313121106.GA96293@nagual.pp.ru>
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On Tue, 13 Mar 2007 15:11:07 +0300
Andrey Chernov <ache@freebsd.org> wrote:
> cc -O -S a.c
> .file "a.c"
> .text
> .p2align 2,,3
> .globl main
> .type main, @function
> main:
> pushl %ebp
> movl %esp, %ebp
> subl $8, %esp
> andl $-16, %esp
> subl $28, %esp
> pushl $0
> call puts
> leave
> ret
> .size main, .-main
> .ident "GCC: (GNU) 3.4.6 [FreeBSD] 20060825"
Confirmed on FreeBSD-6.1 RELEASE:
.file "bla.c"
.text
.p2align 2,,3
.globl main
.type main, @function
main:
pushl %ebp
movl %esp, %ebp
subl $8, %esp
andl $-16, %esp
subl $28, %esp
pushl $0
call puts
leave
ret
.size main, .-main
.ident "GCC: (GNU) 3.4.4 [FreeBSD] 20050518"
> It calls "puts(NULL)" with core dump.
> It means "printf("%s\n", NULL)" is overoptimized.
> BTW, things like "printf("1%s\n", NULL)" are not overoptimized.
> Any ideas? Is it right or needs to be fixed?
Given that this is not what the user asked (replacing printf with puts), I
consider this a bug. GCC made its assumption, and it was incorrect--it's not
user's fault.
--
Ricardo Nabinger Sanchez <rnsanchez@{gmail.com,wait4.org}>
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