[all-commits] [llvm/llvm-project] 650026: [RISCV][SDAG] Prefer ShortForwardBranch to lower s...
Yingwei Zheng via All-commits
all-commits at lists.llvm.org
Fri Nov 10 05:39:00 PST 2023
Branch: refs/heads/main
Home: https://github.com/llvm/llvm-project
Commit: 650026897c38ffebabd8c8377596141c37b65699
https://github.com/llvm/llvm-project/commit/650026897c38ffebabd8c8377596141c37b65699
Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: 2023-11-10 (Fri, 10 Nov 2023)
Changed paths:
M llvm/include/llvm/CodeGen/TargetLowering.h
M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
M llvm/lib/Target/RISCV/RISCVISelLowering.h
M llvm/lib/Target/X86/X86ISelLowering.cpp
A llvm/test/CodeGen/RISCV/sdiv-pow2-cmov.ll
Log Message:
-----------
[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`.
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