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Re: [Qemu-devel] [patch] make qemu work with GCC 4
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [patch] make qemu work with GCC 4 |
Date: |
Wed, 29 Aug 2007 16:06:10 +0100 |
User-agent: |
KMail/1.9.7 |
> I solved that by placing one of the T[012] operands into memory
> for HOST_I386, thereby freeing one reg. Here's some justification
> of why that doesn't really cost performance: with three free regs
> GCC is already spilling like mad in the snippets, we just trade one
> of those memory accesses (to stack) with one other mem access to
> the cpu_state structure, which will be in cache.
Do you have any evidence to support this claim? Last time I did this it caused
a significant performance hit. I'd guess that most common ops are simple
enough that we don't need more than 3 registers.
> --- qemu-0.9.0.cvs.orig/softmmu_header.h
> - : "%eax", "%ecx", "%edx", "memory", "cc");
> + : "%eax", "%edx", "memory", "cc");
This change is wrong. The inline asm calls C code which clobbers %ecx.
Paul
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, (continued)
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Blue Swirl, 2007/08/29
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Carlo Marcelo Arenas Belon, 2007/08/30
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Johannes Schindelin, 2007/08/29
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Ronald, 2007/08/29
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Johannes Schindelin, 2007/08/29
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Andreas Färber, 2007/08/29
- Re: [Qemu-devel] [patch] make qemu work with GCC 4, Andreas Färber, 2007/08/29
Re: [Qemu-devel] [patch] make qemu work with GCC 4, Johannes Schindelin, 2007/08/29
Re: [Qemu-devel] [patch] make qemu work with GCC 4,
Paul Brook <=
Re: [Qemu-devel] [patch] make qemu work with GCC 4, Anthony Liguori, 2007/08/29
Re: [Qemu-devel] [patch] make qemu work with GCC 4, Thiemo Seufer, 2007/08/30