[llvm-commits] Fixing Bug 13662: paired register for inline asm with 64-bit data on ARM

[Weiming Zhao]

Interesting. I tried GPRPair before, but get troubles with legalization of
64 bit data type. 
I didn't know there is "untyped" type, let me try that.

Thanks for the info.

Weiming


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-----Original Message-----
From: Jakob Stoklund Olesen [mailto:stoklund at 2pi.dk] 
Sent: Tuesday, October 02, 2012 9:34 AM
To: Jim Grosbach
Cc: Weiming Zhao; llvm-commits at cs.uiuc.edu LLVM
Subject: Re: [llvm-commits] Fixing Bug 13662: paired register for inline asm
with 64-bit data on ARM


On Oct 1, 2012, at 8:40 AM, Jim Grosbach <grosbach at apple.com> wrote:

> Hello,
> 
> I'm a bit confused by the following FIXME from the patch:
> +      // FIXME: When LLVM supports paired register class for 64-bit data
in
> +      // future, we should just return that register class here and let
register
> +      // allocator to assign physical registers.
> 
> Why not just add such a register class and use it? It seems that would
make all of the AssignedPhysRegs handling unnecessary.

I agree, we need a GPRPair register class similar to the DPair class.

The problems caused by SelectionDAG's type system can be worked around by
making the register class untyped, like the DTriple class. I agree that i64
should not be a legal type on ARM.

/jakob