llvm/llvm/lib/Target/X86/X86InsertPrefetch.cpp

//===------- X86InsertPrefetch.cpp - Insert cache prefetch hints ----------===//
//
// 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 pass applies cache prefetch instructions based on a profile. The pass
// assumes DiscriminateMemOps ran immediately before, to ensure debug info
// matches the one used at profile generation time. The profile is encoded in
// afdo format (text or binary). It contains prefetch hints recommendations.
// Each recommendation is made in terms of debug info locations, a type (i.e.
// nta, t{0|1|2}) and a delta. The debug info identifies an instruction with a
// memory operand (see X86DiscriminateMemOps). The prefetch will be made for
// a location at that memory operand + the delta specified in the
// recommendation.
//
//===----------------------------------------------------------------------===//

#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86InstrInfo.h"
#include "X86MachineFunctionInfo.h"
#include "X86Subtarget.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Module.h"
#include "llvm/ProfileData/SampleProf.h"
#include "llvm/ProfileData/SampleProfReader.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Transforms/IPO/SampleProfile.h"
usingnamespacellvm;
usingnamespacesampleprof;

static cl::opt<std::string>
    PrefetchHintsFile("prefetch-hints-file",
                      cl::desc("Path to the prefetch hints profile. See also "
                               "-x86-discriminate-memops"),
                      cl::Hidden);
namespace {

class X86InsertPrefetch : public MachineFunctionPass { … };

PrefetchHints;

// Return any prefetching hints for the specified MachineInstruction. The hints
// are returned as pairs (name, delta).
ErrorOr<const PrefetchHints &>
getPrefetchHints(const FunctionSamples *TopSamples, const MachineInstr &MI) { … }

// The prefetch instruction can't take memory operands involving vector
// registers.
bool IsMemOpCompatibleWithPrefetch(const MachineInstr &MI, int Op) { … }

} // end anonymous namespace

//===----------------------------------------------------------------------===//
//            Implementation
//===----------------------------------------------------------------------===//

char X86InsertPrefetch::ID = …;

X86InsertPrefetch::X86InsertPrefetch(const std::string &PrefetchHintsFilename)
    : … { … }

/// Return true if the provided MachineInstruction has cache prefetch hints. In
/// that case, the prefetch hints are stored, in order, in the Prefetches
/// vector.
bool X86InsertPrefetch::findPrefetchInfo(const FunctionSamples *TopSamples,
                                         const MachineInstr &MI,
                                         Prefetches &Prefetches) const { … }

bool X86InsertPrefetch::doInitialization(Module &M) { … }

void X86InsertPrefetch::getAnalysisUsage(AnalysisUsage &AU) const { … }

bool X86InsertPrefetch::runOnMachineFunction(MachineFunction &MF) { … }

FunctionPass *llvm::createX86InsertPrefetchPass() { … }