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Re: [Qemu-devel] [patch] gcc4 host support

From: Paul Brook
Subject: Re: [Qemu-devel] [patch] gcc4 host support
Date: Wed, 18 May 2005 21:48:50 +0100
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On Wednesday 18 May 2005 20:29, John Hogerhuis wrote:
> This all feels wrong in general. The changes should either be adding
> some facility to gcc which permits QEMU to use it in this way (gcc is
> an open source project after all, so it's at least a possibility), 

Are you willing to write and maintain the gcc patches necessary to do this?

qemu is pretty much the only think that has this particular set of 
requirelents (the return instruction must be the last instruction in the 
function). The fact is qemu is abusing the output of gcc in ways that were 
never guaranteed to work.

> or we should generate the dynamic code generator once with whatever
> version of GCC and make that part of the build, perhaps even letting
> it diverge (i.e. add enhancements/optimizations directly to the
> generated assembly).

IMHO That's not really an option. The whole point of dyngen is to avoid having 
to write and maintain big chunks of assembly for every single target.

It's been said before that the long-term solution is to [incrementally] remove 
dyngen altogether, and replace it with a had-written code generator.
I've discussed this in a bit more detail with Fabrice, and have an 
almost-working prototype implementation. When I get something that actually 
works I'll post it to the list for comments.


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