[llvm-dev] Global non-use of ISD::BR_CC and ISD::CONDCODE

Liad Mordekoviz via llvm-dev llvm-dev at lists.llvm.org
Sun Dec 10 07:40:03 PST 2017


Hello,
I came across a consistent behavior in most (if not all) backends,
when handling conditional branches, specifically those with ISD::BR_CC,
everyone
use TargetLowering::LowerOperation hook to replace the ISD::CONDCODE chain
node with constant, and then find it with a pattern using the tablegen.

I tried using the built in types of llvm to use tablegen and recognize
ISD:BR_CC, unfortunately found no way to extract the specific condition of
the ISD::CONDCODE, I suppose this is the reason why nobody uses it, but it
just means this part of llvm is completely dead code..

I was wondering if anyone came across this thing, or has any insights on it.

Thanks,
Liad.
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