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Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion |
Date: |
Thu, 29 Mar 2012 12:28:42 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120316 Thunderbird/11.0 |
On 03/29/2012 11:42 AM, Laurent Desnogues wrote:
> That will indeed probably make the real problem, which is that
> this patch increases the size of generated code, less obvious
> on small benchmarks that don't put pressure on instruction
> cache. But the fact is that generated code is larger and will
> have to execute more instructions, so no matter what you do,
> this will have an impact on speed.
While this is true, the benefit of using a more standard calling
convention on reliability and debug-ability is enormous.
Consider the i686 host, where we currently obscond with EBP.
While I'm not aware of any current problems with -O0 or spill
failures under optimization, it's not inconceivable.
Consider sparc-linux host, where we have *no* call-saved global
register at all, and (currently) try very hard to use a call-
clobbered global register, with occasionally disastrous results.
See the patch set I posted recently where I give up on this entirely
and make sparc use a TLS variable instead of a hard register at all.
This regresses the Sparc host on speed for a progression in reliability.
The conversion to explicit env arguments fixes essentially all of
the speed regression since we then receive ENV in %o0 instead of
having to read from TLS.
r~
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, (continued)
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Lluís Vilanova, 2012/03/26
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Paul Brook, 2012/03/26
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Blue Swirl, 2012/03/26
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Lluís Vilanova, 2012/03/26
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Laurent Desnogues, 2012/03/27
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Blue Swirl, 2012/03/27
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Laurent Desnogues, 2012/03/27
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Artyom Tarasenko, 2012/03/27
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion, Laurent Desnogues, 2012/03/29
- Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion,
Richard Henderson <=