[PATCH] D86294: AMDGPU/GlobalISel: Add tablegen operator that looks through copies

[Petar Avramovic via Phabricator via llvm-commits]

Petar.Avramovic added a comment.

You can take over. I am not so sure this will be useful as is. Just looking through copies will break constant bus limit. Then there are constants and their register banks.  
I didn't like g_maybe_cross_reg_bank_copy it would be better to have some field in PatFrag recognized by the global-isel emitter (it would generate GIM_CheckOpcodeIgnoreCopies instead of GIM_CheckOpcode for all opcode checks in pattern). 
But that can break constant bus limit. There is a mechanism to collect operands with
PredicateCodeUsesOperands = 1
Maybe you could add another field in PatFrag that will be a signal to generate jump-table entries that will go through collected operands and check constant bus limit for collected operands.
Just to clarify by `have some field in PatFrag recognized by the global-isel emitter` I meant something like HasNoUse but sdag emitter will ignore it.


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  https://reviews.llvm.org/D86294/new/

https://reviews.llvm.org/D86294