[PATCH] D144099: [WIP][AMDGPU] Fold more AGPR copies/PHIs in SIFoldOperands

[Pierre van Houtryve via Phabricator via llvm-commits]

Pierre-vh added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/SIFoldOperands.cpp:1631
 
-// Try to hoist an AGPR to VGPR copy out of the loop across a LCSSA PHI.
+static Register tryFindExistingCopy(MachineRegisterInfo &MRI,
+                                    MachineInstr &Begin, Register FromReg,
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arsenm wrote:
> If SIFoldOperands worked like PeepholeOpt, you would have a map of these already. I'd rather avoid a linear scan backwards for every copy
Do you mean that it's fine to store these in a map, or that we can't do that here?
I'd also like to avoid the backwards scan if possible


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  https://reviews.llvm.org/D144099/new/

https://reviews.llvm.org/D144099