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