[PATCH] D59535: [SelectionDAG] Compute known bits of CopyFromReg

[Piotr Sobczak via Phabricator via llvm-commits]

piotr created this revision.
Herald added subscribers: llvm-commits, jdoerfert, jsji, javed.absar, nhaehnle, jvesely, nemanjai.
Herald added a project: LLVM.

Teach SelectionDAG how to compute known bits of ISD::CopyFromReg if
the virtual reg used has one def only.

This can be particularly useful when calling isBaseWithConstantOffset()
with the ISD::CopyFromReg argument, as more optimizations may get enabled
in the result.

Also add a missing truncation on X86, found by testing of this patch.

Change-Id: Id1c9fceec862d118c54a5b53adf72ada5d6daefa


Repository:
  rL LLVM

https://reviews.llvm.org/D59535

Files:
  lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/AMDGPU/llvm.amdgcn.s.buffer.load.ll
  test/CodeGen/ARM/atomic-op.ll
  test/CodeGen/PowerPC/pr35688.ll
  test/CodeGen/SystemZ/subregliveness-04.ll
  test/CodeGen/X86/fold-tied-op.ll
  test/CodeGen/X86/pr28444.ll

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