[LLVMdev] request for help writing a register allocator
clattner at apple.com
Tue Oct 20 14:49:55 CDT 2009
On Oct 20, 2009, at 12:46 PM, Susan Horwitz wrote:
> On Tue, 20 Oct 2009, Chris Lattner wrote:
>> Each virtual register has an assigned register class. However,
>> register classes relate to each other, and the machine IR also has
>> subreg references. For example, this is how X86 handles AL/AX/EAX/
>> RAX all aliasing each other. In the Sparc backend, the only aliases
>> are in the FPU, and it doesn't use subregs to model them at this
> So if AL is a sub-register of EAX (assume this is true even if not),
> then will getAliasSet(AL) include EAX, and will getAliasSet(EAX)
> include AL? If yes, then I think I'm OK.
Yes, I believe so.
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