[PATCH] D117468: [RISCV] Add intrinsic for Zbt extension

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:4246
+  case Intrinsic::riscv_fsl:
+    return DAG.getNode(RISCVISD::FSL, DL, XLenVT, Op.getOperand(1),
+                       Op.getOperand(2), Op.getOperand(3));
----------------
craig.topper wrote:
> The operand order for RISCVISD::FSL/FSR match llvm.fshl and llvm.fshr rather than rs1, rs2, rs3 order. I think the operand order you want for riscv.fsl and riscv.fsr should be rs1, rs2, rs3.
> 
> And the assembly printing for fsl/fsr prints $rd, $rs1, $rs3, $rs2 makes this even more confusing.
> 
> I'll put up a patch to change RISCVISD::FSL/FSR and RISCVISD::FSLW/FSRW order to be in rs1, rs2, rs3 order.
i just noticed the proposed intrinsic order here https://github.com/riscv/riscv-bitmanip/blob/main-history/cproofs/rvintrin.h  uses rs1, rs3, rs2/shamt ordering. Which is different than the order used in the spec pseudo code. But rs1, rs3, rs2/shamt matches how the instructions are printed.

So I guess we should use rs1, rs3, rs2/shamt order. I'll update the RISCVISD opcodes accordingly.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D117468/new/

https://reviews.llvm.org/D117468