[PATCH] D90558: [VPlan] Add VPDef class.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
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This patch introduces a new VPDef class, which can be used to
manage VPValues defined by recipes/VPInstructions.

The idea here is to mirror VPUser for values defined by a recipe. A
VPDef can produce either zero (e.g. a store recipe), one (most recipes)
or multiple (VPInterleaveRecipe) result VPValues.

To traverse the def-use chain from a VPDef to its users, one has to
traverse the users of all values defined by a VPDef.

VPValues now contain a pointer to their corresponding VPDef, if one
exists. To traverse the def-use chain upwards from a VPValue, we first
need to check if the VPValue is defined by a VPDef. If it does not have
a VPDef, this means we have a VPValue that is not directly defined
iniside the plan and we are done.

If we have a VPDef, we have to traverse all operands of the VPDef.

Note that we need to add an additional field to to VPVAlue to link them
to their defs. The space increase is going to be offset by being able to
remove the SubclassID field in future patches.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90558

Files:
  llvm/lib/Transforms/Vectorize/VPlan.cpp
  llvm/lib/Transforms/Vectorize/VPlanValue.h
  llvm/unittests/Transforms/Vectorize/VPlanTest.cpp

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