[LLVMdev] Regular Expressions

Chris Lattner clattner at apple.com
Mon Jun 15 12:35:14 PDT 2009

On Jun 15, 2009, at 11:33 AM, David Greene wrote:
> To reduce redundancy, developers must be able to write generic  
> patterns
> like this:
> [(set DSTREGCLASS:$dst,  // rr, rrr
>       (xor (INTSRCTYPE (bitconvert (SRCTYPE SRCREGCLASS:$src1))),
>       (INTSRCTYPE (bitconvert (SRCTYPE SRCREGCLASS:$src2)))))],
> The substitution then fills in the appropriate types, etc. based
> on which variant (32-bit, 64-bit, AVX, etc.) is being produced.
> I suppose you could argue that additional parameters specifying
> the source and dest types could be passed, but why bother when
> it is already encoded in the mnemonic?  That would just be
> adding error-prone redundancy.

Why not synthesize the opcode string from the information passed down?


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