[PATCH] D120302: [RISCV] DAG Combine vcpop and vfirst with VL=0 to li imm

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8508
+        VL = N->getOperand(3);
+      auto *C = dyn_cast<ConstantSDNode>(VL);
+      if (!C || !C->isZero())
----------------
You can use isNullConstant(VL)


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8513
+      SDLoc DL(N);
+      EVT VT = VL.getValueType();
+      SDValue Zero = DAG.getConstant(0, DL, VT);
----------------
Use N->getValueType(0), not the type of the VL.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8519
+        Imm = DAG.getConstant(-1, DL, VT);
+      return DAG.getNode(ISD::ADD, DL, VT, Zero, Imm);
+    }
----------------
There's no reason to make an ISD::ADD. You can just return DAG.getConstant


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120302/new/

https://reviews.llvm.org/D120302