Messages in this thread | | | From | yodaiken@chelm ... | Subject | Re: The Kommunity vs. Dick Johnson | Date | Tue, 17 Nov 1998 12:31:18 -0700 (MST) |
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> > Date: Mon, 16 Nov 1998 08:17:25 -0500 (EST) > From: Isaac Connor <iconnor@penultima.ml.org> > > I am aware of many instances where gcc was able to produce better code > than some asm-advocates I know. It also seems to me, that you have to > look at register use, and how that affects code before and after the asm > function. > > This of course proves nothing. The real acid test is whether or not GCC > can produce better code than the what the *best* asm-advocates can > produce. For example, I've yet to see a version of gcc which can do a > good job of compiling the MD5 crypto checksum. The problem is that you > have to be really clever to keep all of the MD5 accumulators in > registers, and every gcc I've played with fails to do this, and ends up > placing at least one or more of the MD5 state variables on the stack. > Hence, in general gcc doesn't seem to handle algorithms which puts > pressure on the i386's absurdly small register file.
Does that have a measurable cost on a PII? The likelhood that the register will be in a shadow register, a write buffer, or in cache seems close to 100% if it is used soon again. I'm curious about whether the hardware is making register allocation less critical.
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