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Re: PATCH: Initialize tmp_obstack
- From: Daniel Jacobowitz <drow at false dot org>
- To: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- Cc: gdb-patches at sourceware dot org
- Date: Tue, 5 Dec 2006 16:56:39 -0500
- Subject: Re: PATCH: Initialize tmp_obstack
- References: <20061202182712.GA623@lucon.org> <20061205204003.GB25572@nevyn.them.org> <12601.163.1.150.229.1165354805.squirrel@webmail.xs4all.nl> <20061205214306.GA29801@nevyn.them.org> <20637.163.1.150.229.1165355320.squirrel@webmail.xs4all.nl>
On Tue, Dec 05, 2006 at 10:48:40PM +0100, Mark Kettenis wrote:
> Sorry, yes, this was meant to go to the list. My proposal is not to "fix"
> this at all. It's a GCC bug, that's presumably fixed, and we'll ship
> with -Werror turned off by default anyway.
Well, there seem to be enough systems with affected GCC that HJ, Jim,
and I all hit it - Ubuntu Edgy is one such.
We could discuss this till we're blue in the face without getting
anywhere; the uninitialized warnings are not reliable in face of this
sort of pattern (isn't it a classical example of why uninitialized
warnings are hard?).
I think we're being overly optimistic if we expect GCC to get it right
all the time. In fact, I asked a bunch of GCC developers about it on
IRC and the best response I got was "then you are screwed". Or Diego's
explanation:
> We don't explicitly try to handle it. it's mostly side-effect of
> various optimizations. some times it's jump-threading, others it's
> PRE, others it's CCP, others it's VRP.
> that irritates the hell out of me. we depend on optimizations for
> this warning.
I know that's a widely held position.
--
Daniel Jacobowitz
CodeSourcery