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| author | Alex Bradbury <asb@lowrisc.org> | 2018-11-30 09:56:54 +0000 |
|---|---|---|
| committer | Alex Bradbury <asb@lowrisc.org> | 2018-11-30 09:56:54 +0000 |
| commit | e0e62e97dfddb01a6f2e32d2f951c317a7478f9a (patch) | |
| tree | 258079ea1dc9509b8bfb1fc63de9a416143bbb04 /llvm/lib/Target/RISCV/RISCVISelLowering.h | |
| parent | deaa3e2068cf14834e4063729887bb19eb4a9c2d (diff) | |
| download | bcm5719-llvm-e0e62e97dfddb01a6f2e32d2f951c317a7478f9a.tar.gz bcm5719-llvm-e0e62e97dfddb01a6f2e32d2f951c317a7478f9a.zip | |
[TargetLowering][RISCV] Introduce isSExtCheaperThanZExt hook and implement for RISC-V
DAGTypeLegalizer::PromoteSetCCOperands currently prefers to zero-extend
operands when it is able to do so. For some targets this is more expensive
than a sign-extension, which is also a valid choice. Introduce the
isSExtCheaperThanZExt hook and use it in the new SExtOrZExtPromotedInteger
helper. On RISC-V, we prefer sign-extension for FromTy == MVT::i32 and ToTy ==
MVT::i64, as it can be performed using a single instruction.
Differential Revision: https://reviews.llvm.org/D52978
llvm-svn: 347977
Diffstat (limited to 'llvm/lib/Target/RISCV/RISCVISelLowering.h')
| -rw-r--r-- | llvm/lib/Target/RISCV/RISCVISelLowering.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.h b/llvm/lib/Target/RISCV/RISCVISelLowering.h index a99e2c2f53b..6970900bb06 100644 --- a/llvm/lib/Target/RISCV/RISCVISelLowering.h +++ b/llvm/lib/Target/RISCV/RISCVISelLowering.h @@ -54,6 +54,7 @@ public: bool isTruncateFree(Type *SrcTy, Type *DstTy) const override; bool isTruncateFree(EVT SrcVT, EVT DstVT) const override; bool isZExtFree(SDValue Val, EVT VT2) const override; + bool isSExtCheaperThanZExt(EVT SrcVT, EVT DstVT) const override; // Provide custom lowering hooks for some operations. SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override; |
