forked from OSchip/llvm-project
472 lines
18 KiB
C++
472 lines
18 KiB
C++
//===- InlineAdvisor.cpp - analysis pass implementation -------------------===//
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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 implements InlineAdvisorAnalysis and DefaultInlineAdvisor, and
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// related types.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/InlineAdvisor.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/Analysis/OptimizationRemarkEmitter.h"
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/IR/DebugInfoMetadata.h"
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#include "llvm/IR/Instructions.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 <sstream>
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using namespace llvm;
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#define DEBUG_TYPE "inline"
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// This weirdly named statistic tracks the number of times that, when attempting
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// to inline a function A into B, we analyze the callers of B in order to see
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// if those would be more profitable and blocked inline steps.
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STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed");
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/// Flag to add inline messages as callsite attributes 'inline-remark'.
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static cl::opt<bool>
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InlineRemarkAttribute("inline-remark-attribute", cl::init(false),
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cl::Hidden,
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cl::desc("Enable adding inline-remark attribute to"
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" callsites processed by inliner but decided"
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" to be not inlined"));
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// An integer used to limit the cost of inline deferral. The default negative
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// number tells shouldBeDeferred to only take the secondary cost into account.
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static cl::opt<int>
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InlineDeferralScale("inline-deferral-scale",
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cl::desc("Scale to limit the cost of inline deferral"),
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cl::init(2), cl::Hidden);
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void DefaultInlineAdvice::recordUnsuccessfulInliningImpl(
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const InlineResult &Result) {
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using namespace ore;
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llvm::setInlineRemark(*OriginalCB, std::string(Result.getFailureReason()) +
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"; " + inlineCostStr(*OIC));
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ORE.emit([&]() {
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return OptimizationRemarkMissed(DEBUG_TYPE, "NotInlined", DLoc, Block)
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<< NV("Callee", Callee) << " will not be inlined into "
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<< NV("Caller", Caller) << ": "
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<< NV("Reason", Result.getFailureReason());
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});
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}
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void DefaultInlineAdvice::recordInliningWithCalleeDeletedImpl() {
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if (EmitRemarks)
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emitInlinedInto(ORE, DLoc, Block, *Callee, *Caller, *OIC);
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}
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void DefaultInlineAdvice::recordInliningImpl() {
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if (EmitRemarks)
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emitInlinedInto(ORE, DLoc, Block, *Callee, *Caller, *OIC);
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}
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llvm::Optional<llvm::InlineCost> static getDefaultInlineAdvice(
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CallBase &CB, FunctionAnalysisManager &FAM, const InlineParams &Params) {
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Function &Caller = *CB.getCaller();
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ProfileSummaryInfo *PSI =
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FAM.getResult<ModuleAnalysisManagerFunctionProxy>(Caller)
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.getCachedResult<ProfileSummaryAnalysis>(
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*CB.getParent()->getParent()->getParent());
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auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(Caller);
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auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
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return FAM.getResult<AssumptionAnalysis>(F);
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};
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auto GetBFI = [&](Function &F) -> BlockFrequencyInfo & {
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return FAM.getResult<BlockFrequencyAnalysis>(F);
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};
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auto GetTLI = [&](Function &F) -> const TargetLibraryInfo & {
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return FAM.getResult<TargetLibraryAnalysis>(F);
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};
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auto GetInlineCost = [&](CallBase &CB) {
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Function &Callee = *CB.getCalledFunction();
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auto &CalleeTTI = FAM.getResult<TargetIRAnalysis>(Callee);
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bool RemarksEnabled =
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Callee.getContext().getDiagHandlerPtr()->isMissedOptRemarkEnabled(
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DEBUG_TYPE);
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return getInlineCost(CB, Params, CalleeTTI, GetAssumptionCache, GetTLI,
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GetBFI, PSI, RemarksEnabled ? &ORE : nullptr);
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};
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return llvm::shouldInline(CB, GetInlineCost, ORE,
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Params.EnableDeferral.getValueOr(false));
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}
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std::unique_ptr<InlineAdvice>
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DefaultInlineAdvisor::getAdviceImpl(CallBase &CB) {
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auto OIC = getDefaultInlineAdvice(CB, FAM, Params);
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return std::make_unique<DefaultInlineAdvice>(
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this, CB, OIC,
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FAM.getResult<OptimizationRemarkEmitterAnalysis>(*CB.getCaller()));
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}
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InlineAdvice::InlineAdvice(InlineAdvisor *Advisor, CallBase &CB,
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OptimizationRemarkEmitter &ORE,
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bool IsInliningRecommended)
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: Advisor(Advisor), Caller(CB.getCaller()), Callee(CB.getCalledFunction()),
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DLoc(CB.getDebugLoc()), Block(CB.getParent()), ORE(ORE),
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IsInliningRecommended(IsInliningRecommended) {}
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void InlineAdvisor::markFunctionAsDeleted(Function *F) {
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assert((!DeletedFunctions.count(F)) &&
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"Cannot put cause a function to become dead twice!");
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DeletedFunctions.insert(F);
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}
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void InlineAdvisor::freeDeletedFunctions() {
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for (auto *F : DeletedFunctions)
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delete F;
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DeletedFunctions.clear();
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}
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void InlineAdvice::recordInliningWithCalleeDeleted() {
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markRecorded();
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Advisor->markFunctionAsDeleted(Callee);
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recordInliningWithCalleeDeletedImpl();
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}
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AnalysisKey InlineAdvisorAnalysis::Key;
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bool InlineAdvisorAnalysis::Result::tryCreate(InlineParams Params,
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InliningAdvisorMode Mode) {
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auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
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switch (Mode) {
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case InliningAdvisorMode::Default:
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Advisor.reset(new DefaultInlineAdvisor(FAM, Params));
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break;
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case InliningAdvisorMode::Development:
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#ifdef LLVM_HAVE_TF_API
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Advisor =
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llvm::getDevelopmentModeAdvisor(M, MAM, [&FAM, Params](CallBase &CB) {
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auto OIC = getDefaultInlineAdvice(CB, FAM, Params);
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return OIC.hasValue();
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});
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#endif
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break;
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case InliningAdvisorMode::Release:
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#ifdef LLVM_HAVE_TF_AOT
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Advisor = llvm::getReleaseModeAdvisor(M, MAM);
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#endif
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break;
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}
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return !!Advisor;
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}
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/// Return true if inlining of CB can block the caller from being
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/// inlined which is proved to be more beneficial. \p IC is the
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/// estimated inline cost associated with callsite \p CB.
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/// \p TotalSecondaryCost will be set to the estimated cost of inlining the
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/// caller if \p CB is suppressed for inlining.
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static bool
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shouldBeDeferred(Function *Caller, InlineCost IC, int &TotalSecondaryCost,
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function_ref<InlineCost(CallBase &CB)> GetInlineCost) {
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// For now we only handle local or inline functions.
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if (!Caller->hasLocalLinkage() && !Caller->hasLinkOnceODRLinkage())
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return false;
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// If the cost of inlining CB is non-positive, it is not going to prevent the
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// caller from being inlined into its callers and hence we don't need to
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// defer.
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if (IC.getCost() <= 0)
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return false;
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// Try to detect the case where the current inlining candidate caller (call
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// it B) is a static or linkonce-ODR function and is an inlining candidate
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// elsewhere, and the current candidate callee (call it C) is large enough
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// that inlining it into B would make B too big to inline later. In these
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// circumstances it may be best not to inline C into B, but to inline B into
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// its callers.
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//
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// This only applies to static and linkonce-ODR functions because those are
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// expected to be available for inlining in the translation units where they
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// are used. Thus we will always have the opportunity to make local inlining
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// decisions. Importantly the linkonce-ODR linkage covers inline functions
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// and templates in C++.
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//
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// FIXME: All of this logic should be sunk into getInlineCost. It relies on
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// the internal implementation of the inline cost metrics rather than
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// treating them as truly abstract units etc.
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TotalSecondaryCost = 0;
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// The candidate cost to be imposed upon the current function.
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int CandidateCost = IC.getCost() - 1;
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// If the caller has local linkage and can be inlined to all its callers, we
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// can apply a huge negative bonus to TotalSecondaryCost.
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bool ApplyLastCallBonus = Caller->hasLocalLinkage() && !Caller->hasOneUse();
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// This bool tracks what happens if we DO inline C into B.
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bool InliningPreventsSomeOuterInline = false;
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unsigned NumCallerUsers = 0;
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for (User *U : Caller->users()) {
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CallBase *CS2 = dyn_cast<CallBase>(U);
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// If this isn't a call to Caller (it could be some other sort
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// of reference) skip it. Such references will prevent the caller
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// from being removed.
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if (!CS2 || CS2->getCalledFunction() != Caller) {
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ApplyLastCallBonus = false;
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continue;
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}
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InlineCost IC2 = GetInlineCost(*CS2);
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++NumCallerCallersAnalyzed;
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if (!IC2) {
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ApplyLastCallBonus = false;
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continue;
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}
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if (IC2.isAlways())
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continue;
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// See if inlining of the original callsite would erase the cost delta of
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// this callsite. We subtract off the penalty for the call instruction,
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// which we would be deleting.
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if (IC2.getCostDelta() <= CandidateCost) {
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InliningPreventsSomeOuterInline = true;
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TotalSecondaryCost += IC2.getCost();
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NumCallerUsers++;
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}
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}
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if (!InliningPreventsSomeOuterInline)
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return false;
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// If all outer calls to Caller would get inlined, the cost for the last
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// one is set very low by getInlineCost, in anticipation that Caller will
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// be removed entirely. We did not account for this above unless there
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// is only one caller of Caller.
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if (ApplyLastCallBonus)
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TotalSecondaryCost -= InlineConstants::LastCallToStaticBonus;
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// If InlineDeferralScale is negative, then ignore the cost of primary
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// inlining -- IC.getCost() multiplied by the number of callers to Caller.
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if (InlineDeferralScale < 0)
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return TotalSecondaryCost < IC.getCost();
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int TotalCost = TotalSecondaryCost + IC.getCost() * NumCallerUsers;
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int Allowance = IC.getCost() * InlineDeferralScale;
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return TotalCost < Allowance;
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}
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namespace llvm {
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static std::basic_ostream<char> &operator<<(std::basic_ostream<char> &R,
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const ore::NV &Arg) {
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return R << Arg.Val;
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}
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template <class RemarkT>
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RemarkT &operator<<(RemarkT &&R, const InlineCost &IC) {
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using namespace ore;
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if (IC.isAlways()) {
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R << "(cost=always)";
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} else if (IC.isNever()) {
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R << "(cost=never)";
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} else {
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R << "(cost=" << ore::NV("Cost", IC.getCost())
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<< ", threshold=" << ore::NV("Threshold", IC.getThreshold()) << ")";
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}
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if (const char *Reason = IC.getReason())
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R << ": " << ore::NV("Reason", Reason);
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return R;
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}
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} // namespace llvm
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std::string llvm::inlineCostStr(const InlineCost &IC) {
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std::stringstream Remark;
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Remark << IC;
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return Remark.str();
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}
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void llvm::setInlineRemark(CallBase &CB, StringRef Message) {
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if (!InlineRemarkAttribute)
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return;
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Attribute Attr = Attribute::get(CB.getContext(), "inline-remark", Message);
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CB.addAttribute(AttributeList::FunctionIndex, Attr);
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}
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/// Return the cost only if the inliner should attempt to inline at the given
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/// CallSite. If we return the cost, we will emit an optimisation remark later
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/// using that cost, so we won't do so from this function. Return None if
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/// inlining should not be attempted.
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Optional<InlineCost>
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llvm::shouldInline(CallBase &CB,
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function_ref<InlineCost(CallBase &CB)> GetInlineCost,
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OptimizationRemarkEmitter &ORE, bool EnableDeferral) {
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using namespace ore;
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InlineCost IC = GetInlineCost(CB);
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Instruction *Call = &CB;
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Function *Callee = CB.getCalledFunction();
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Function *Caller = CB.getCaller();
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if (IC.isAlways()) {
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LLVM_DEBUG(dbgs() << " Inlining " << inlineCostStr(IC)
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<< ", Call: " << CB << "\n");
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return IC;
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}
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if (!IC) {
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LLVM_DEBUG(dbgs() << " NOT Inlining " << inlineCostStr(IC)
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<< ", Call: " << CB << "\n");
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if (IC.isNever()) {
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ORE.emit([&]() {
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return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline", Call)
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<< NV("Callee", Callee) << " not inlined into "
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<< NV("Caller", Caller) << " because it should never be inlined "
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<< IC;
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});
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} else {
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ORE.emit([&]() {
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return OptimizationRemarkMissed(DEBUG_TYPE, "TooCostly", Call)
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<< NV("Callee", Callee) << " not inlined into "
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<< NV("Caller", Caller) << " because too costly to inline "
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<< IC;
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});
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}
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setInlineRemark(CB, inlineCostStr(IC));
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return None;
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}
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int TotalSecondaryCost = 0;
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if (EnableDeferral &&
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shouldBeDeferred(Caller, IC, TotalSecondaryCost, GetInlineCost)) {
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LLVM_DEBUG(dbgs() << " NOT Inlining: " << CB
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<< " Cost = " << IC.getCost()
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<< ", outer Cost = " << TotalSecondaryCost << '\n');
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ORE.emit([&]() {
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return OptimizationRemarkMissed(DEBUG_TYPE, "IncreaseCostInOtherContexts",
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Call)
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<< "Not inlining. Cost of inlining " << NV("Callee", Callee)
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<< " increases the cost of inlining " << NV("Caller", Caller)
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<< " in other contexts";
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});
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setInlineRemark(CB, "deferred");
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// IC does not bool() to false, so get an InlineCost that will.
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// This will not be inspected to make an error message.
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return None;
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}
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LLVM_DEBUG(dbgs() << " Inlining " << inlineCostStr(IC) << ", Call: " << CB
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<< '\n');
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return IC;
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}
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std::string llvm::getCallSiteLocation(DebugLoc DLoc) {
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std::ostringstream CallSiteLoc;
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bool First = true;
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for (DILocation *DIL = DLoc.get(); DIL; DIL = DIL->getInlinedAt()) {
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if (!First)
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CallSiteLoc << " @ ";
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// Note that negative line offset is actually possible, but we use
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// unsigned int to match line offset representation in remarks so
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// it's directly consumable by relay advisor.
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uint32_t Offset =
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DIL->getLine() - DIL->getScope()->getSubprogram()->getLine();
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uint32_t Discriminator = DIL->getBaseDiscriminator();
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StringRef Name = DIL->getScope()->getSubprogram()->getLinkageName();
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if (Name.empty())
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Name = DIL->getScope()->getSubprogram()->getName();
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CallSiteLoc << Name.str() << ":" << llvm::utostr(Offset) << ":"
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<< llvm::utostr(DIL->getColumn());
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if (Discriminator)
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CallSiteLoc << "." << llvm::utostr(Discriminator);
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First = false;
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}
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return CallSiteLoc.str();
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}
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void llvm::addLocationToRemarks(OptimizationRemark &Remark, DebugLoc DLoc) {
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if (!DLoc.get()) {
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return;
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}
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bool First = true;
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Remark << " at callsite ";
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for (DILocation *DIL = DLoc.get(); DIL; DIL = DIL->getInlinedAt()) {
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if (!First)
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Remark << " @ ";
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unsigned int Offset = DIL->getLine();
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Offset -= DIL->getScope()->getSubprogram()->getLine();
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unsigned int Discriminator = DIL->getBaseDiscriminator();
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StringRef Name = DIL->getScope()->getSubprogram()->getLinkageName();
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if (Name.empty())
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Name = DIL->getScope()->getSubprogram()->getName();
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Remark << Name << ":" << ore::NV("Line", Offset) << ":"
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<< ore::NV("Column", DIL->getColumn());
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if (Discriminator)
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Remark << "." << ore::NV("Disc", Discriminator);
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First = false;
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}
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Remark << ";";
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}
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void llvm::emitInlinedInto(OptimizationRemarkEmitter &ORE, DebugLoc DLoc,
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const BasicBlock *Block, const Function &Callee,
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const Function &Caller, const InlineCost &IC,
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bool ForProfileContext, const char *PassName) {
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ORE.emit([&]() {
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bool AlwaysInline = IC.isAlways();
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StringRef RemarkName = AlwaysInline ? "AlwaysInline" : "Inlined";
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OptimizationRemark Remark(PassName ? PassName : DEBUG_TYPE, RemarkName,
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DLoc, Block);
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Remark << ore::NV("Callee", &Callee) << " inlined into ";
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Remark << ore::NV("Caller", &Caller);
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if (ForProfileContext)
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Remark << " to match profiling context";
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Remark << " with " << IC;
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addLocationToRemarks(Remark, DLoc);
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return Remark;
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});
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}
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std::unique_ptr<InlineAdvice> InlineAdvisor::getMandatoryAdvice(CallBase &CB,
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bool Advice) {
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return std::make_unique<InlineAdvice>(this, CB, getCallerORE(CB), Advice);
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}
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InlineAdvisor::MandatoryInliningKind
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InlineAdvisor::getMandatoryKind(CallBase &CB, FunctionAnalysisManager &FAM,
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OptimizationRemarkEmitter &ORE) {
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auto &Callee = *CB.getCalledFunction();
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auto GetTLI = [&](Function &F) -> const TargetLibraryInfo & {
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return FAM.getResult<TargetLibraryAnalysis>(F);
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};
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auto &TIR = FAM.getResult<TargetIRAnalysis>(Callee);
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auto TrivialDecision =
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llvm::getAttributeBasedInliningDecision(CB, &Callee, TIR, GetTLI);
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if (TrivialDecision.hasValue()) {
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if (TrivialDecision->isSuccess())
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return MandatoryInliningKind::Always;
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else
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return MandatoryInliningKind::Never;
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}
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return MandatoryInliningKind::NotMandatory;
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}
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std::unique_ptr<InlineAdvice> InlineAdvisor::getAdvice(CallBase &CB,
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bool MandatoryOnly) {
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if (!MandatoryOnly)
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return getAdviceImpl(CB);
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bool Advice = CB.getCaller() != CB.getCalledFunction() &&
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MandatoryInliningKind::Always ==
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getMandatoryKind(CB, FAM, getCallerORE(CB));
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return getMandatoryAdvice(CB, Advice);
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}
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OptimizationRemarkEmitter &InlineAdvisor::getCallerORE(CallBase &CB) {
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return FAM.getResult<OptimizationRemarkEmitterAnalysis>(*CB.getCaller());
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}
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