forked from OSchip/llvm-project
ad3d6f993d
Clang emits (and (ctpop X), 1) for __builtin_parity. If ctpop isn't natively supported by the target, this leads to poor codegen due to the expansion of ctpop being more complex than what is needed for parity. This adds a DAG combine to convert the pattern to ISD::PARITY before operation legalization. Type legalization is updated to handled Expanding and Promoting this operation. If after type legalization, CTPOP is supported for this type, LegalizeDAG will turn it back into CTPOP+AND. Otherwise LegalizeDAG will emit a series of shifts and xors followed by an AND with 1. I've avoided vectors in this patch to avoid more legalization complexity for this patch. X86 previously had a custom DAG combiner for this. This is now moved to Custom lowering for the new opcode. There is a minor regression in vector-reduce-xor-bool.ll, but a follow up patch can easily fix that. Fixes PR47433 Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D87209 |
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