Messages in this thread | | | Date | Tue, 1 Jun 2004 07:25:11 +0200 | From | Jörn Engel <> | Subject | Re: 4k stacks in 2.6 |
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On Thu, 27 May 2004 17:34:26 +0200, Arjan van de Ven wrote: > > you can write "add 100,%esp" as "sub -100, %esp" :) > compilers seem to do that at times, probably some cpu model inside the > compiler decides the later is better code in some cases :)
That and even worse things. sys_sendfile has a "sub $0x10,%esp" followed by an "add $0x20,%esp". Can you explain that one as well? 0x20 is the size of all automatic variables on i386.
I have no idea what kind of trick gcc is playing there, but it appears to work which makes me only more curious.
Jörn
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