Date: Sat, 15 Jul 2006 13:44:56 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: joerg@britannica.bec.de Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: kern/99979: Get Ready for Kernel Module in C++ Message-ID: <20060715.134456.63053925.imp@bsdimp.com> In-Reply-To: <20060714074419.GC14113@britannica.bec.de> References: <20060712132059.GA3906@britannica.bec.de> <ac7deb50607122246k7df45813hf9cb34e1f8269c77@mail.gmail.com> <20060714074419.GC14113@britannica.bec.de>
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In message: <20060714074419.GC14113@britannica.bec.de>
Joerg Sonnenberger <joerg@britannica.bec.de> writes:
: On Thu, Jul 13, 2006 at 11:16:18AM +0530, Kamal R. Prasad wrote:
: > Im sorry I didn't understand you. setjmp() stores a few register contents
: > [notably ip] in a jmpbuf -which are restored after a longjmp(). How is the
: > try/catch mechanism more efficient than a setjmp()/longjmp() in terms of
: > space/time complexity?
:
: Because you have to run setjmp for *every* try{}, independent of whether
: it is ever actually needed.
It is worse than even that.
You have to run setjmp for every frame, because there could be an
exception thrown from a lower frame to an upper frame and you have to
cleanup your frame when that happens. Variables go out of scope, and
must be destructed, etc.
Warner
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