[llvm-commits] [PATCH] Add GR8_H register class to X86 backend

[Jakob Stoklund Olesen]

On 27/04/2009, at 02.37, Dan Gohman wrote:

> Thanks for pointing this out.  This looks right to me.  I'll apply the
> patch
> soon. Do you happen to have a testcase which shows the extra copies?

The coalescer is actually quite effective at eliminating the bad  
vregs, so I have not been able to find a difference when running  
normally. You can see the difference by disabling the coalescer:

	llc -join-liveintervals=0 < test/CodeGen/X86/h-registers-2.ll

Before applying this patch, an extra "movb %ah, %al" is inserted by  
LowerSubregs.

My other submitted patch, coalesce-phys-virt.patch, causes a bunch of  
test failures without this one.

Thanks,

/jakob
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