[PATCH] D84679: [VPlan] Disconnect VPValue and VPUser.

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

I was trying very recently to get VPlan to perform some vector combines. Things like recognizing vmulh patterns.

The code I had was still in a very rough state but I ended up going in completely the opposite direction. I had VPRecipeBase inherit from VPUser, which in turn inherited from VPValue. Like I said it was all very rough and I'm not sure yet if it was necessary, but I felt like it simplified things. It was useful to know you could inspect operands and uses of any recipe, and properly walk up and down the def-uses chain. Perform things like replaceAllUsesWith and recursively delete dead recipes after replacing them with others.

Perhaps I need to look at that again, as I certainly hadn't tried to tackle multiple producing values. My gut instinct would be to use something like the SDValue from ISel, but I hadn't looked at all into what that would really look like. This way might well be better in the long run, I'm not sure. I had gotten distracted into cost modelling instead..


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https://reviews.llvm.org/D84679