[LLVMdev] Comments on the bundle proposal

Andrew Trick atrick at apple.com
Wed Dec 7 10:23:55 PST 2011

On Dec 6, 2011, at 11:24 PM, Pekka Jääskeläinen wrote:

> Hi,
> On 12/07/2011 01:10 AM, Krzysztof Parzyszek wrote:
>> Another approach would be to have a pseudo-instruction (say, "macro"),
>> which would be associated with a sequence of instructions, which have
>> been outlined, and which have been replaced by the "macro" instruction.
>> The "macro" instruction would have the information about registers used
>> and defined, and it would have a link to the actual instructions that
>> define it.
> BTW did anyone seriously consider the Carlos' proposal? The inheritance idea
> has its merits as it can hide several behaviors/semantics behind the "mother" 
> MachineInstrBundle class, as far as I've understood.
> http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043798.html

I know Evan seriously considered this, which is why he mentioned it in the proposal. But I don't think MachineInstr can be subclassed while residing in the same MI list with non-bundled instructions. I think Evan's proposal still captures the important concepts of hiding bundled MIs within their bundle.


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