[llvm] [RISCV][CostModel][NFC] Add getRISCVInstructionCost() to TTI for Cost… (PR #73651)

[Luke Lau via llvm-commits]

================
@@ -34,6 +34,53 @@ static cl::opt<unsigned> SLPMaxVF(
         "exclusively by SLP vectorizer."),
     cl::Hidden);
 
+InstructionCost
+RISCVTTIImpl::getRISCVInstructionCost(RISCVInstruction Inst, MVT VT,
+                                      unsigned NumInstr,
+                                      TTI::TargetCostKind CostKind) {
+  if (CostKind == TTI::TCK_CodeSize)
+    return NumInstr;
+
+  InstructionCost LMUL = TLI->getLMULCost(VT);
+  InstructionCost Cost = LMUL * NumInstr;
+
+  if ((CostKind == TTI::TCK_RecipThroughput) ||
+      (CostKind == TTI::TCK_Latency)) {
+    switch (Inst) {
+    case RISCVInstruction::VRGATHER_VI:
+      return NumInstr * TLI->getVRGatherVICost(VT);
+    case RISCVInstruction::VRGATHER_VV:
+      return NumInstr * TLI->getVRGatherVVCost(VT);
+    case RISCVInstruction::VSLIDE:
+      return NumInstr * TLI->getVSlideCost(VT);
+    case RISCVInstruction::VSIMPLE_INT_RED:
+    case RISCVInstruction::VMINMAX_INTFP_RED:
+    case RISCVInstruction::VUNORD_FP_RED: {
+      unsigned VL = VT.getVectorMinNumElements();
+      if (!VT.isFixedLengthVector()) {
+        VL *= *getVScaleForTuning();
+      }
+      return Log2_32_Ceil(VL);
+    }
+    case RISCVInstruction::VORD_FP_RED: {
+      unsigned VL = VT.getVectorMinNumElements();
+      if (!VT.isFixedLengthVector()) {
+        VL *= *getVScaleForTuning();
+      }
+      return VL;
+    }
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lukel97 wrote:

Is the plan to use these in a later patch?

https://github.com/llvm/llvm-project/pull/73651