[LLVMdev] Early-clobber constraint in TableGen

Nate Begeman natebegeman at me.com
Wed Dec 16 11:28:54 PST 2009

On Dec 16, 2009, at 11:15 AM, David Greene wrote:

>> I'm not hugely tied to the name. I chose it because it matches the
>> usage in GCC documentation for inline assembly with the same concepts
>> and how the concept is expressed elsewhere in the compiler. If I'm not
>> mistaken, due to the GCC nomenclature, the linux kernel also refers to
>> this sort of thing as an early-clobber.
> This is my own bias speaking, but gcc has some fantastically stupid names
> for things.  I don't necessarily see it as meritorious to follow its
> example.

I agree with this, "earlyclobber" doesn't mean obviously mean anything to me, unless I were to already have read the GCC manual, which probably shouldn't be a prerequisite for understanding .td files.  For instance, LLVM replaced "three-address" with an actual meaningful constraint pattern at some point in the recent past, which was nice.

>> I think you're right that it's best to go ahead with this for now and
>> then if a better solution is arrived at later, we can update things to
>> use that.

Sure, getting something working now is probably more valuable than waiting around for the perfect solution to present itself.


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