Sanjay Patel f4b53972ce [SDAG] fold bitwise logic with shifted operands ...

This extends acb96ffd14 to 'and' and 'xor' opcodes.

Copying from that message:

LOGIC (LOGIC (SH X0, Y), Z), (SH X1, Y) --> LOGIC (SH (LOGIC X0, X1), Y), Z

https://alive2.llvm.org/ce/z/QmR9rR

This is a reassociation + factoring fold. The common shift operation is moved
after a bitwise logic op on 2 input operands.
We get simpler cases of these patterns in IR, but I suspect we would miss all
of these exact tests in IR too. We also handle the simpler form of this plus
several other folds in DAGCombiner::hoistLogicOpWithSameOpcodeHands().

2022-03-05 11:14:45 -05:00

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