Re: C++ exception breaks inside Apple code
Re: C++ exception breaks inside Apple code
- Subject: Re: C++ exception breaks inside Apple code
- From: Marshall Clow <email@hidden>
- Date: Sat, 10 Oct 2009 12:22:13 -0700
On Oct 10, 2009, at 11:44 AM, Jens Alfke wrote:
On Oct 10, 2009, at 11:12 AM, Michael A. Crawford wrote:
Yeah, when I recompiled some CoreAudio code that worked flawlessly
in Leopard using Snow-Leopard my initial thought was that something
in CoreAudio got broke. Scared the he11 out of me until I realized
what was happening.
I used to file bug reports on this kind of thing, back when I was
still at Apple. Besides just the annoyance to C++ developers using
the framework, it's also bad for performance — the "zero overhead"
exception model assumes exceptions aren't thrown in normal usage, so
it's only 'try' that has zero overhead; when the 'throw' occurs the
runtime has to start loading in symbol tables and parsing its way up
the stack looking for 'catch' blocks, and that's very expensive.
Especially if you are using GCC.
Metrowerks' exception handling was _much_ cheaper in both CPU and
memory usage.
I'm hoping that clang/LLVM can do a good job here.
-- Marshall _______________________________________________
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