[PATCH] D99904: [WebAssembly] Fix for PIC external symbol ISEL

[Wouter van Oortmerssen via Phabricator via llvm-commits]

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wasm64 was missing DAG ISEL patterns for external symbol based global.get, but simply adding these analogous to the existing 32-bit versions doesn't work.
This is because we are conflating the 32-bit global index with the pointer represented by the external symbol, which for wasm32 happened to work.
The simplest fix is to pretend we have a 64-bit global index. This sounds incorrect, but is immaterial since once this index is stored as a MachineOperand it becomes 64-bit anyway (and has been all along). As such, the EmitInstrWithCustomInserter based implementation I experimented with become a no-op and no further changes in the C++ code are required.


https://reviews.llvm.org/D99904

Files:
  llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
  llvm/test/CodeGen/WebAssembly/load-store-pic.ll

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