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Re: [Qemu-devel] [PULL 5/8] tcg: Put opcodes in a linked list
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PULL 5/8] tcg: Put opcodes in a linked list |
Date: |
Mon, 17 Aug 2015 08:44:08 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 08/17/2015 04:35 AM, Artyom Tarasenko wrote:
> Hi Richard,
>
> this patch seems to break a build when USE_LIVENESS_ANALYSIS is undefined.
I suppose that's possible. If so, it must be a trivial error somewhere.
Why in the world would you want !USE_LIVENESS_ANALYSIS?
Are you simply trying to see what sort of performance impact it has? I can
tell you it's fairly important for generating x86 code. The two operand nature
of the ISA means that if we don't know that the source operand is dead, we
often have to introduce an extra move to preserve it.
r~