[PATCH] D132322: [AArch64][SelectionDAG] Optimize multiplication by constant

[Aditya Kumar via Phabricator via llvm-commits]

hiraditya added a subscriber: eli.friedman.
hiraditya added a comment.

I agree with @eli.friedman that decomposing multiply into two separate instructions may not be profitable.
Even when latency of multiply is high, having two instructions in the pipeline adds complexity (dependencies, re-ordering, retiring etc).

Another thing to  consider would be the number of ALUs and MACs(Multiply Accumulate units).
In case the ALU pressure is high MAC operations may be more efficient as there wont be stalls.


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  https://reviews.llvm.org/D132322/new/

https://reviews.llvm.org/D132322