[LLVMdev] Register class conversions

Evan Cheng evan.cheng at apple.com
Thu Oct 23 11:14:03 PDT 2008

On Oct 22, 2008, at 1:28 PM, Villmow, Micah wrote:

> Is there a simple way to specify the relationship between two  
> different register classes of various sizes and alignments as being  
> legal to convert between them?

I don't get it. What does it mean to "convert" between two register  
classes? You can move between different register classes.

> I have my backend written up using a single register class for i32,  
> i64, f32 and f64 types, however, because the type

You mean several types all map to the same register class? Why not  
specify several classes instead?


> information is not propagated down to the machine instruction  
> register level, it is not known to me how to determine which data  
> type my current register is. In working on moving to using 4  
> separate register classes I ran into the problem where some of my  
> setup code needs the larger type and not the smaller type.
>  So is it possible to have the register class I have setup for i32  
> type be automatically converted to the generic register type instead  
> of aborting?
> Micah Villmow
> Systems Engineer
> Advanced Technology & Performance
> Advanced Micro Devices Inc.
> 4555 Great America Pkwy,
> Santa Clara, CA. 95054
> P: 408-572-6219
> F: 408-572-6596
> _______________________________________________
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> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

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