Yingwei Zheng 650026897c [RISCV][SDAG] Prefer ShortForwardBranch to lower sdiv by pow2 (#67364) ...

This patch lowers `sdiv x, +/-2**k` to `add + select + shift` when the
short forward branch optimization is enabled. The latter inst seq
performs faster than the seq generated by target-independent
DAGCombiner. This algorithm is described in ***Hacker's Delight***.

This patch also removes duplicate logic in the X86 and AArch64 backend.
But we cannot do this for the PowerPC backend since it generates a
special instruction `addze`.

2023-11-10 21:38:47 +08:00

435 KiB

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