[PATCH] D101100: [ConstFold] Simplify a load's GEP operand through local aliases

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
aeubanks added reviewers: rnk, pcc, nikic.
Herald added subscribers: dexonsmith, hiraditya, Prazek.
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MSVC-style RTTI produces loads through a GEP of a local alias which
itself is a GEP. Currently we aren't able to devirtualize any virtual
calls when MSVC RTTI is enabled.

This patch attempts to simplify a load's GEP operand by calling
SymbolicallyEvaluateGEP() with an option to look through local aliases.
This calls for a new pointer stripping method which can look through
local aliases, but cannot look through zero-indices GEPs since we need
to preserve GEP indices to pass to
ConstantFoldLoadThroughGEPConstantExpr().


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101100

Files:
  llvm/include/llvm/IR/Value.h
  llvm/lib/Analysis/ConstantFolding.cpp
  llvm/lib/IR/Value.cpp
  llvm/test/Transforms/InstSimplify/ConstProp/gep-alias-gep-load.ll

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