In addition, this commit does the following combine
vfmv.v.f + fmv.[dhw].x -> vmv.v.x
vfmv.s.f + fmv.[dhw].x -> vmv.s.x
vfmerge.vfm + fmv.[dhw].x -> vmerge.vxm
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| Differential D142953
[RISCV] Don't use constantpool for floating-point value if the value can be easily constructed by integer sequence and a floating-point move. ClosedPublic Authored by HanKuanChen on Jan 30 2023, 10:55 PM.
Details Summary In addition, this commit does the following combine vfmv.v.f + fmv.[dhw].x -> vmv.v.x
Diff Detail
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Comment Actions Was the motivation for adding the combines mentioned in the patch description to prevent a regression due to this change? In the absence of that, we'd typically try to keep each patch as minimal as possible. I'm curious if anyone has concerns about cases where converting an int to float might be more expensive that isn't captured in the current cost modelling - from a quick look it does seem likely to be a win unless the int/fp conversion cost is particularly high. Are there other targets that make this same choice? From a quick look at Arm it appears to use an int->float move when doing execute-only codegen but otherwise. Of course it has a wider set of options available in that ISA for efficiently materialising FP constants. Comment Actions
Without the vector isel changes, we'd do scalar integer lui -> scalar int to scalar fp move -> scalar fp to vector. The vector isel changes move the integer directly to vector. Comment Actions I generally support this change once normal review completes. I don't *think* this is likely to be too painful on any CPUs I'm currently aware of, but if it is, having it under a cpu tuning flag at a minimum makes sense. I'd been thinking about this myself a bit in the background, and this patch looks basically identical to what I'd settled on heuristic wise. This does kick in more than I'd expected. Apparently, I'd misjudged how many floats this would actually pickup.
Comment Actions LGTM, but please wait a day or two before landing in case @craig.topper has comments. I still don't consider myself to fully understand the ISEL interactions. I *think* this is good to go, but probably good to have him double check.
This revision is now accepted and ready to land.Feb 3 2023, 7:41 AM Closed by commit rGd02b9869b242: [RISCV] Don't use constantpool for floating-point value if the value can be… (authored by HanKuanChen). · Explain WhyFeb 3 2023, 10:42 PM This revision was automatically updated to reflect the committed changes. Comment Actions FYI, I found RV32 vector crash after this patch. Fixed in 712e143883d694d3b5817dae714da2315eae8c89
Revision Contents
Diff 493812 llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
llvm/lib/Target/RISCV/RISCVISelLowering.cpp
llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td
llvm/test/CodeGen/RISCV/calling-conv-half.ll
llvm/test/CodeGen/RISCV/calling-conv-ilp32f-ilp32d-common.ll
llvm/test/CodeGen/RISCV/codemodel-lowering.ll
llvm/test/CodeGen/RISCV/float-convert.ll
llvm/test/CodeGen/RISCV/float-imm.ll
llvm/test/CodeGen/RISCV/float-intrinsics.ll
llvm/test/CodeGen/RISCV/float-round-conv-sat.ll
llvm/test/CodeGen/RISCV/float-round-conv.ll
llvm/test/CodeGen/RISCV/float-select-verify.ll
llvm/test/CodeGen/RISCV/fp-imm.ll
llvm/test/CodeGen/RISCV/half-convert.ll
llvm/test/CodeGen/RISCV/half-imm.ll
llvm/test/CodeGen/RISCV/half-intrinsics.ll
llvm/test/CodeGen/RISCV/half-round-conv-sat.ll
llvm/test/CodeGen/RISCV/half-round-conv.ll
llvm/test/CodeGen/RISCV/rvv/ceil-vp.ll
llvm/test/CodeGen/RISCV/rvv/extractelt-fp.ll
llvm/test/CodeGen/RISCV/rvv/fceil-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/ffloor-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-ceil-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-extract.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-floor-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fround.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-froundeven.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-nearbyint-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-fp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-rint-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-round-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-roundeven-vp.ll
llvm/test/CodeGen/RISCV/rvv/fixed-vectors-roundtozero-vp.ll
llvm/test/CodeGen/RISCV/rvv/float-round-conv.ll
llvm/test/CodeGen/RISCV/rvv/floor-vp.ll
llvm/test/CodeGen/RISCV/rvv/fround-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/froundeven-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/ftrunc-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/nearbyint-vp.ll
llvm/test/CodeGen/RISCV/rvv/rint-vp.ll
llvm/test/CodeGen/RISCV/rvv/round-vp.ll
llvm/test/CodeGen/RISCV/rvv/roundeven-vp.ll
llvm/test/CodeGen/RISCV/rvv/roundtozero-vp.ll
llvm/test/CodeGen/RISCV/rvv/vreductions-fp-sdnode.ll
llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll
llvm/test/CodeGen/RISCV/select-const.ll
llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
llvm/test/CodeGen/RISCV/zfh-imm.ll
llvm/test/CodeGen/RISCV/zfhmin-imm.ll
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Drop Scalar from this. It's never a vector. Nor is it an Elt