[PATCH] D73573: [AArch64][GlobalISel] Fold G_AND into G_BRCOND

[Jessica Paquette via Phabricator via llvm-commits]

paquette created this revision.
paquette added a reviewer: aemerson.
Herald added subscribers: Petar.Avramovic, hiraditya, kristof.beyls, rovka.
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When a G_BRCOND is fed by an eq or ne G_ICMP, it may be possible to fold a G_AND into the branch by producing a tbnz/tbz instead.

This happens when

1. We have a ne/eq G_ICMP feeding into the G_BRCOND
2. The G_ICMP is a comparison against 0
3. One of the operands of the G_AND is a power of 2 constant

This is very similar to the code in AArch64TargetLowering::LowerBR_CC.

Add opt-and-tbnz-tbz to test this.

(I think that we can probably factor out all the CB(N)Z into a function like this, but I want to finish implementing the other parts of AArch64TargetLowering::LowerBR_CC first.)


https://reviews.llvm.org/D73573

Files:
  llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/opt-and-tbnz-tbz.mir

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