[RISCV] Correct the cost model for the i1 reduce.add and reduce.or.

[topperc]

reduce.add uses the same sequence as reduce.xor. reduce.or should use vmor not vmxor.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

Changes

reduce.add uses the same sequence as reduce.xor. reduce.or should use vmor not vmxor.

---

Full diff: https://github.com/llvm/llvm-project/pull/122349.diff

1 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+4-3)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 850d6244affa50..66be30c4b42bae 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -1548,7 +1548,7 @@ RISCVTTIImpl::getArithmeticReductionCost(unsigned Opcode, VectorType *Ty,
              getRISCVInstructionCost(RISCV::VCPOP_M, LT.second, CostKind) +
              getCmpSelInstrCost(Instruction::ICmp, ElementTy, ElementTy,
                                 CmpInst::ICMP_EQ, CostKind);
-    } else if (ISD == ISD::XOR) {
+    } else if (ISD == ISD::XOR || ISD == ISD::ADD) {
       // Example sequences:
       //   vsetvli a0, zero, e8, mf8, ta, ma
       //   vmxor.mm v8, v0, v8 ; needed every time type is split
@@ -1558,13 +1558,14 @@ RISCVTTIImpl::getArithmeticReductionCost(unsigned Opcode, VectorType *Ty,
                  getRISCVInstructionCost(RISCV::VMXOR_MM, LT.second, CostKind) +
              getRISCVInstructionCost(RISCV::VCPOP_M, LT.second, CostKind) + 1;
     } else {
+      assert(ISD == ISD::OR);
       // Example sequences:
       //   vsetvli a0, zero, e8, mf8, ta, ma
-      //   vmxor.mm v8, v9, v8 ; needed every time type is split
+      //   vmor.mm v8, v9, v8 ; needed every time type is split
       //   vcpop.m a0, v0
       //   snez a0, a0
       return (LT.first - 1) *
-                 getRISCVInstructionCost(RISCV::VMXOR_MM, LT.second, CostKind) +
+                 getRISCVInstructionCost(RISCV::VMOR_MM, LT.second, CostKind) +
              getRISCVInstructionCost(RISCV::VCPOP_M, LT.second, CostKind) +
              getCmpSelInstrCost(Instruction::ICmp, ElementTy, ElementTy,
                                 CmpInst::ICMP_NE, CostKind);

[preames]

LGTM

[sunshaoce]

LGTM. I think this can land before #119160.