[PATCH] D119432: [FastISel] Reuse register for bitcast that does not change MVT

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added reviewers: craig.topper, RKSimon, spatel.
Herald added subscribers: pengfei, hiraditya.
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The current FastISel code reuses the register for a bitcast that doesn't change the IR type, but uses a reg-to-reg copy if it changes the MVT. However, we can simply reuse the register in that case as well.

In particular, this avoids unnecessary reg-to-reg copies for pointer bitcasts. This was found while inspecting `O0` codegen differences between typed and opaque pointers.


https://reviews.llvm.org/D119432

Files:
  llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
  llvm/test/CodeGen/AArch64/swifterror.ll
  llvm/test/CodeGen/ARM/swifterror.ll
  llvm/test/CodeGen/X86/atomic64.ll
  llvm/test/CodeGen/X86/swifterror.ll

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