| //===- CostModel.cpp ------ Cost Model Analysis ---------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the cost model analysis. It provides a very basic cost |
| // estimation for LLVM-IR. This analysis uses the services of the codegen |
| // to approximate the cost of any IR instruction when lowered to machine |
| // instructions. The cost results are unit-less and the cost number represents |
| // the throughput of the machine assuming that all loads hit the cache, all |
| // branches are predicted, etc. The cost numbers can be added in order to |
| // compare two or more transformation alternatives. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/CostModel.h" |
| #include "llvm/Analysis/Passes.h" |
| #include "llvm/Analysis/TargetTransformInfo.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/InitializePasses.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| using namespace llvm; |
| |
| static cl::opt<TargetTransformInfo::TargetCostKind> CostKind( |
| "cost-kind", cl::desc("Target cost kind"), |
| cl::init(TargetTransformInfo::TCK_RecipThroughput), |
| cl::values(clEnumValN(TargetTransformInfo::TCK_RecipThroughput, |
| "throughput", "Reciprocal throughput"), |
| clEnumValN(TargetTransformInfo::TCK_Latency, |
| "latency", "Instruction latency"), |
| clEnumValN(TargetTransformInfo::TCK_CodeSize, |
| "code-size", "Code size"), |
| clEnumValN(TargetTransformInfo::TCK_SizeAndLatency, |
| "size-latency", "Code size and latency"))); |
| |
| static cl::opt<bool> TypeBasedIntrinsicCost("type-based-intrinsic-cost", |
| cl::desc("Calculate intrinsics cost based only on argument types"), |
| cl::init(false)); |
| |
| #define CM_NAME "cost-model" |
| #define DEBUG_TYPE CM_NAME |
| |
| PreservedAnalyses CostModelPrinterPass::run(Function &F, |
| FunctionAnalysisManager &AM) { |
| auto &TTI = AM.getResult<TargetIRAnalysis>(F); |
| OS << "Printing analysis 'Cost Model Analysis' for function '" << F.getName() << "':\n"; |
| for (BasicBlock &B : F) { |
| for (Instruction &Inst : B) { |
| // TODO: Use a pass parameter instead of cl::opt CostKind to determine |
| // which cost kind to print. |
| InstructionCost Cost; |
| auto *II = dyn_cast<IntrinsicInst>(&Inst); |
| if (II && TypeBasedIntrinsicCost) { |
| IntrinsicCostAttributes ICA(II->getIntrinsicID(), *II, |
| InstructionCost::getInvalid(), true); |
| Cost = TTI.getIntrinsicInstrCost(ICA, CostKind); |
| } |
| else { |
| Cost = TTI.getInstructionCost(&Inst, CostKind); |
| } |
| |
| if (auto CostVal = Cost.getValue()) |
| OS << "Cost Model: Found an estimated cost of " << *CostVal; |
| else |
| OS << "Cost Model: Invalid cost"; |
| |
| OS << " for instruction: " << Inst << "\n"; |
| } |
| } |
| return PreservedAnalyses::all(); |
| } |