[PATCH] D116941: [GlobalISel] Fix incorrect sign extension when combining G_INTTOPTR and G_ADD

[Lucas Prates via Phabricator via llvm-commits]

pratlucas created this revision.
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The GlobalISel combiner currently uses sign extension when manipulating
the LHS constant when combining a sequence of the following sequence of
machine instructions into a single constant:

  %0:_(s32) = G_CONSTANT i32 <CONSTANT>
  %1:_(p0) = G_INTTOPTR %0:_(s32)
  %2:_(s64) = G_CONSTANT i64 <CONSTANT>
  %3:_(p0) = G_PTR_ADD %1:_, %2:_(s64)

This causes an issue when the bit width of the first contant and the
target pointer size are different, as G_INTTOPTR has no sign extension
semantics.

This patch fixes this by capture an arbitrary precision in when matching
the constant, allowing the matching function to correctly zero extend
it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116941

Files:
  llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h
  llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/combine-inttoptr-add.mir
  llvm/test/CodeGen/AArch64/GlobalISel/inttoptr_add.ll

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