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llvm-mirror/lib/Transforms/IPO/PartialInlining.cpp
Sander de Smalen 6da35d08b6 NFC: Migrate PartialInlining to work on InstructionCost 
This patch migrates cost values and arithmetic to work on InstructionCost.
When the interfaces to TargetTransformInfo are changed, any InstructionCost
state will propagate naturally.

See this patch for the introduction of the type: https://reviews.llvm.org/D91174
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2020-November/146408.html

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D97382
2021-03-30 11:59:45 +01:00

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//===- PartialInlining.cpp - Inline parts of functions --------------------===//
//
// 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 performs partial inlining, typically by inlining an if statement
// that surrounds the body of the function.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/PartialInlining.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/User.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/BlockFrequency.h"
#include "llvm/Support/BranchProbability.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/CodeExtractor.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <functional>
#include <iterator>
#include <memory>
#include <tuple>
#include <vector>
using namespace llvm;
#define DEBUG_TYPE "partial-inlining"
STATISTIC(NumPartialInlined,
"Number of callsites functions partially inlined into.");
STATISTIC(NumColdOutlinePartialInlined, "Number of times functions with "
"cold outlined regions were partially "
"inlined into its caller(s).");
STATISTIC(NumColdRegionsFound,
"Number of cold single entry/exit regions found.");
STATISTIC(NumColdRegionsOutlined,
"Number of cold single entry/exit regions outlined.");
// Command line option to disable partial-inlining. The default is false:
static cl::opt<bool>
DisablePartialInlining("disable-partial-inlining", cl::init(false),
cl::Hidden, cl::desc("Disable partial inlining"));
// Command line option to disable multi-region partial-inlining. The default is
// false:
static cl::opt<bool> DisableMultiRegionPartialInline(
"disable-mr-partial-inlining", cl::init(false), cl::Hidden,
cl::desc("Disable multi-region partial inlining"));
// Command line option to force outlining in regions with live exit variables.
// The default is false:
static cl::opt<bool>
ForceLiveExit("pi-force-live-exit-outline", cl::init(false), cl::Hidden,
cl::desc("Force outline regions with live exits"));
// Command line option to enable marking outline functions with Cold Calling
// Convention. The default is false:
static cl::opt<bool>
MarkOutlinedColdCC("pi-mark-coldcc", cl::init(false), cl::Hidden,
cl::desc("Mark outline function calls with ColdCC"));
// This is an option used by testing:
static cl::opt<bool> SkipCostAnalysis("skip-partial-inlining-cost-analysis",
cl::init(false), cl::ZeroOrMore,
cl::ReallyHidden,
cl::desc("Skip Cost Analysis"));
// Used to determine if a cold region is worth outlining based on
// its inlining cost compared to the original function. Default is set at 10%.
// ie. if the cold region reduces the inlining cost of the original function by
// at least 10%.
static cl::opt<float> MinRegionSizeRatio(
"min-region-size-ratio", cl::init(0.1), cl::Hidden,
cl::desc("Minimum ratio comparing relative sizes of each "
"outline candidate and original function"));
// Used to tune the minimum number of execution counts needed in the predecessor
// block to the cold edge. ie. confidence interval.
static cl::opt<unsigned>
MinBlockCounterExecution("min-block-execution", cl::init(100), cl::Hidden,
cl::desc("Minimum block executions to consider "
"its BranchProbabilityInfo valid"));
// Used to determine when an edge is considered cold. Default is set to 10%. ie.
// if the branch probability is 10% or less, then it is deemed as 'cold'.
static cl::opt<float> ColdBranchRatio(
"cold-branch-ratio", cl::init(0.1), cl::Hidden,
cl::desc("Minimum BranchProbability to consider a region cold."));
static cl::opt<unsigned> MaxNumInlineBlocks(
"max-num-inline-blocks", cl::init(5), cl::Hidden,
cl::desc("Max number of blocks to be partially inlined"));
// Command line option to set the maximum number of partial inlining allowed
// for the module. The default value of -1 means no limit.
static cl::opt<int> MaxNumPartialInlining(
"max-partial-inlining", cl::init(-1), cl::Hidden, cl::ZeroOrMore,
cl::desc("Max number of partial inlining. The default is unlimited"));
// Used only when PGO or user annotated branch data is absent. It is
// the least value that is used to weigh the outline region. If BFI
// produces larger value, the BFI value will be used.
static cl::opt<int>
OutlineRegionFreqPercent("outline-region-freq-percent", cl::init(75),
cl::Hidden, cl::ZeroOrMore,
cl::desc("Relative frequency of outline region to "
"the entry block"));
static cl::opt<unsigned> ExtraOutliningPenalty(
"partial-inlining-extra-penalty", cl::init(0), cl::Hidden,
cl::desc("A debug option to add additional penalty to the computed one."));
namespace {
struct FunctionOutliningInfo {
FunctionOutliningInfo() = default;
// Returns the number of blocks to be inlined including all blocks
// in Entries and one return block.
unsigned getNumInlinedBlocks() const { return Entries.size() + 1; }
// A set of blocks including the function entry that guard
// the region to be outlined.
SmallVector<BasicBlock *, 4> Entries;
// The return block that is not included in the outlined region.
BasicBlock *ReturnBlock = nullptr;
// The dominating block of the region to be outlined.
BasicBlock *NonReturnBlock = nullptr;
// The set of blocks in Entries that that are predecessors to ReturnBlock
SmallVector<BasicBlock *, 4> ReturnBlockPreds;
};
struct FunctionOutliningMultiRegionInfo {
FunctionOutliningMultiRegionInfo()
: ORI() {}
// Container for outline regions
struct OutlineRegionInfo {
OutlineRegionInfo(ArrayRef<BasicBlock *> Region,
BasicBlock *EntryBlock, BasicBlock *ExitBlock,
BasicBlock *ReturnBlock)
: Region(Region.begin(), Region.end()), EntryBlock(EntryBlock),
ExitBlock(ExitBlock), ReturnBlock(ReturnBlock) {}
SmallVector<BasicBlock *, 8> Region;
BasicBlock *EntryBlock;
BasicBlock *ExitBlock;
BasicBlock *ReturnBlock;
};
SmallVector<OutlineRegionInfo, 4> ORI;
};
struct PartialInlinerImpl {
PartialInlinerImpl(
function_ref<AssumptionCache &(Function &)> GetAC,
function_ref<AssumptionCache *(Function &)> LookupAC,
function_ref<TargetTransformInfo &(Function &)> GTTI,
function_ref<const TargetLibraryInfo &(Function &)> GTLI,
ProfileSummaryInfo &ProfSI,
function_ref<BlockFrequencyInfo &(Function &)> GBFI = nullptr)
: GetAssumptionCache(GetAC), LookupAssumptionCache(LookupAC),
GetTTI(GTTI), GetBFI(GBFI), GetTLI(GTLI), PSI(ProfSI) {}
bool run(Module &M);
// Main part of the transformation that calls helper functions to find
// outlining candidates, clone & outline the function, and attempt to
// partially inline the resulting function. Returns true if
// inlining was successful, false otherwise. Also returns the outline
// function (only if we partially inlined early returns) as there is a
// possibility to further "peel" early return statements that were left in the
// outline function due to code size.
std::pair<bool, Function *> unswitchFunction(Function &F);
// This class speculatively clones the function to be partial inlined.
// At the end of partial inlining, the remaining callsites to the cloned
// function that are not partially inlined will be fixed up to reference
// the original function, and the cloned function will be erased.
struct FunctionCloner {
// Two constructors, one for single region outlining, the other for
// multi-region outlining.
FunctionCloner(Function *F, FunctionOutliningInfo *OI,
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC,
function_ref<TargetTransformInfo &(Function &)> GetTTI);
FunctionCloner(Function *F, FunctionOutliningMultiRegionInfo *OMRI,
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC,
function_ref<TargetTransformInfo &(Function &)> GetTTI);
~FunctionCloner();
// Prepare for function outlining: making sure there is only
// one incoming edge from the extracted/outlined region to
// the return block.
void normalizeReturnBlock() const;
// Do function outlining for cold regions.
bool doMultiRegionFunctionOutlining();
// Do function outlining for region after early return block(s).
// NOTE: For vararg functions that do the vararg handling in the outlined
// function, we temporarily generate IR that does not properly
// forward varargs to the outlined function. Calling InlineFunction
// will update calls to the outlined functions to properly forward
// the varargs.
Function *doSingleRegionFunctionOutlining();
Function *OrigFunc = nullptr;
Function *ClonedFunc = nullptr;
typedef std::pair<Function *, BasicBlock *> FuncBodyCallerPair;
// Keep track of Outlined Functions and the basic block they're called from.
SmallVector<FuncBodyCallerPair, 4> OutlinedFunctions;
// ClonedFunc is inlined in one of its callers after function
// outlining.
bool IsFunctionInlined = false;
// The cost of the region to be outlined.
InstructionCost OutlinedRegionCost = 0;
// ClonedOI is specific to outlining non-early return blocks.
std::unique_ptr<FunctionOutliningInfo> ClonedOI = nullptr;
// ClonedOMRI is specific to outlining cold regions.
std::unique_ptr<FunctionOutliningMultiRegionInfo> ClonedOMRI = nullptr;
std::unique_ptr<BlockFrequencyInfo> ClonedFuncBFI = nullptr;
OptimizationRemarkEmitter &ORE;
function_ref<AssumptionCache *(Function &)> LookupAC;
function_ref<TargetTransformInfo &(Function &)> GetTTI;
};
private:
int NumPartialInlining = 0;
function_ref<AssumptionCache &(Function &)> GetAssumptionCache;
function_ref<AssumptionCache *(Function &)> LookupAssumptionCache;
function_ref<TargetTransformInfo &(Function &)> GetTTI;
function_ref<BlockFrequencyInfo &(Function &)> GetBFI;
function_ref<const TargetLibraryInfo &(Function &)> GetTLI;
ProfileSummaryInfo &PSI;
// Return the frequency of the OutlininingBB relative to F's entry point.
// The result is no larger than 1 and is represented using BP.
// (Note that the outlined region's 'head' block can only have incoming
// edges from the guarding entry blocks).
BranchProbability
getOutliningCallBBRelativeFreq(FunctionCloner &Cloner) const;
// Return true if the callee of CB should be partially inlined with
// profit.
bool shouldPartialInline(CallBase &CB, FunctionCloner &Cloner,
BlockFrequency WeightedOutliningRcost,
OptimizationRemarkEmitter &ORE) const;
// Try to inline DuplicateFunction (cloned from F with call to
// the OutlinedFunction into its callers. Return true
// if there is any successful inlining.
bool tryPartialInline(FunctionCloner &Cloner);
// Compute the mapping from use site of DuplicationFunction to the enclosing
// BB's profile count.
void
computeCallsiteToProfCountMap(Function *DuplicateFunction,
DenseMap<User *, uint64_t> &SiteCountMap) const;
bool isLimitReached() const {
return (MaxNumPartialInlining != -1 &&
NumPartialInlining >= MaxNumPartialInlining);
}
static CallBase *getSupportedCallBase(User *U) {
if (isa<CallInst>(U) || isa<InvokeInst>(U))
return cast<CallBase>(U);
llvm_unreachable("All uses must be calls");
return nullptr;
}
static CallBase *getOneCallSiteTo(Function &F) {
User *User = *F.user_begin();
return getSupportedCallBase(User);
}
std::tuple<DebugLoc, BasicBlock *> getOneDebugLoc(Function &F) const {
CallBase *CB = getOneCallSiteTo(F);
DebugLoc DLoc = CB->getDebugLoc();
BasicBlock *Block = CB->getParent();
return std::make_tuple(DLoc, Block);
}
// Returns the costs associated with function outlining:
// - The first value is the non-weighted runtime cost for making the call
// to the outlined function, including the addtional setup cost in the
// outlined function itself;
// - The second value is the estimated size of the new call sequence in
// basic block Cloner.OutliningCallBB;
std::tuple<InstructionCost, InstructionCost>
computeOutliningCosts(FunctionCloner &Cloner) const;
// Compute the 'InlineCost' of block BB. InlineCost is a proxy used to
// approximate both the size and runtime cost (Note that in the current
// inline cost analysis, there is no clear distinction there either).
static InstructionCost computeBBInlineCost(BasicBlock *BB,
TargetTransformInfo *TTI);
std::unique_ptr<FunctionOutliningInfo>
computeOutliningInfo(Function &F) const;
std::unique_ptr<FunctionOutliningMultiRegionInfo>
computeOutliningColdRegionsInfo(Function &F,
OptimizationRemarkEmitter &ORE) const;
};
struct PartialInlinerLegacyPass : public ModulePass {
static char ID; // Pass identification, replacement for typeid
PartialInlinerLegacyPass() : ModulePass(ID) {
initializePartialInlinerLegacyPassPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<ProfileSummaryInfoWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
bool runOnModule(Module &M) override {
if (skipModule(M))
return false;
AssumptionCacheTracker *ACT = &getAnalysis<AssumptionCacheTracker>();
TargetTransformInfoWrapperPass *TTIWP =
&getAnalysis<TargetTransformInfoWrapperPass>();
ProfileSummaryInfo &PSI =
getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
auto GetAssumptionCache = [&ACT](Function &F) -> AssumptionCache & {
return ACT->getAssumptionCache(F);
};
auto LookupAssumptionCache = [ACT](Function &F) -> AssumptionCache * {
return ACT->lookupAssumptionCache(F);
};
auto GetTTI = [&TTIWP](Function &F) -> TargetTransformInfo & {
return TTIWP->getTTI(F);
};
auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
};
return PartialInlinerImpl(GetAssumptionCache, LookupAssumptionCache, GetTTI,
GetTLI, PSI)
.run(M);
}
};
} // end anonymous namespace
std::unique_ptr<FunctionOutliningMultiRegionInfo>
PartialInlinerImpl::computeOutliningColdRegionsInfo(
Function &F, OptimizationRemarkEmitter &ORE) const {
BasicBlock *EntryBlock = &F.front();
DominatorTree DT(F);
LoopInfo LI(DT);
BranchProbabilityInfo BPI(F, LI);
std::unique_ptr<BlockFrequencyInfo> ScopedBFI;
BlockFrequencyInfo *BFI;
if (!GetBFI) {
ScopedBFI.reset(new BlockFrequencyInfo(F, BPI, LI));
BFI = ScopedBFI.get();
} else
BFI = &(GetBFI(F));
// Return if we don't have profiling information.
if (!PSI.hasInstrumentationProfile())
return std::unique_ptr<FunctionOutliningMultiRegionInfo>();
std::unique_ptr<FunctionOutliningMultiRegionInfo> OutliningInfo =
std::make_unique<FunctionOutliningMultiRegionInfo>();
auto IsSingleExit =
[&ORE](SmallVectorImpl<BasicBlock *> &BlockList) -> BasicBlock * {
BasicBlock *ExitBlock = nullptr;
for (auto *Block : BlockList) {
for (BasicBlock *Succ : successors(Block)) {
if (!is_contained(BlockList, Succ)) {
if (ExitBlock) {
ORE.emit([&]() {
return OptimizationRemarkMissed(DEBUG_TYPE, "MultiExitRegion",
&Succ->front())
<< "Region dominated by "
<< ore::NV("Block", BlockList.front()->getName())
<< " has more than one region exit edge.";
});
return nullptr;
}
ExitBlock = Block;
}
}
}
return ExitBlock;
};
auto BBProfileCount = [BFI](BasicBlock *BB) {
return BFI->getBlockProfileCount(BB)
? BFI->getBlockProfileCount(BB).getValue()
: 0;
};
// Use the same computeBBInlineCost function to compute the cost savings of
// the outlining the candidate region.
TargetTransformInfo *FTTI = &GetTTI(F);
InstructionCost OverallFunctionCost = 0;
for (auto &BB : F)
OverallFunctionCost += computeBBInlineCost(&BB, FTTI);
LLVM_DEBUG(dbgs() << "OverallFunctionCost = " << OverallFunctionCost
<< "\n";);
InstructionCost MinOutlineRegionCost = OverallFunctionCost.map(
[&](auto Cost) { return Cost * MinRegionSizeRatio; });
BranchProbability MinBranchProbability(
static_cast<int>(ColdBranchRatio * MinBlockCounterExecution),
MinBlockCounterExecution);
bool ColdCandidateFound = false;
BasicBlock *CurrEntry = EntryBlock;
std::vector<BasicBlock *> DFS;
DenseMap<BasicBlock *, bool> VisitedMap;
DFS.push_back(CurrEntry);
VisitedMap[CurrEntry] = true;
// Use Depth First Search on the basic blocks to find CFG edges that are
// considered cold.
// Cold regions considered must also have its inline cost compared to the
// overall inline cost of the original function. The region is outlined only
// if it reduced the inline cost of the function by 'MinOutlineRegionCost' or
// more.
while (!DFS.empty()) {
auto *ThisBB = DFS.back();
DFS.pop_back();
// Only consider regions with predecessor blocks that are considered
// not-cold (default: part of the top 99.99% of all block counters)
// AND greater than our minimum block execution count (default: 100).
if (PSI.isColdBlock(ThisBB, BFI) ||
BBProfileCount(ThisBB) < MinBlockCounterExecution)
continue;
for (auto SI = succ_begin(ThisBB); SI != succ_end(ThisBB); ++SI) {
if (VisitedMap[*SI])
continue;
VisitedMap[*SI] = true;
DFS.push_back(*SI);
// If branch isn't cold, we skip to the next one.
BranchProbability SuccProb = BPI.getEdgeProbability(ThisBB, *SI);
if (SuccProb > MinBranchProbability)
continue;
LLVM_DEBUG(dbgs() << "Found cold edge: " << ThisBB->getName() << "->"
<< SI->getName()
<< "\nBranch Probability = " << SuccProb << "\n";);
SmallVector<BasicBlock *, 8> DominateVector;
DT.getDescendants(*SI, DominateVector);
assert(!DominateVector.empty() &&
"SI should be reachable and have at least itself as descendant");
// We can only outline single entry regions (for now).
if (!DominateVector.front()->hasNPredecessors(1)) {
LLVM_DEBUG(dbgs() << "ABORT: Block " << SI->getName()
<< " doesn't have a single predecessor in the "
"dominator tree\n";);
continue;
}
BasicBlock *ExitBlock = nullptr;
// We can only outline single exit regions (for now).
if (!(ExitBlock = IsSingleExit(DominateVector))) {
LLVM_DEBUG(dbgs() << "ABORT: Block " << SI->getName()
<< " doesn't have a unique successor\n";);
continue;
}
InstructionCost OutlineRegionCost = 0;
for (auto *BB : DominateVector)
OutlineRegionCost += computeBBInlineCost(BB, &GetTTI(*BB->getParent()));
LLVM_DEBUG(dbgs() << "OutlineRegionCost = " << OutlineRegionCost
<< "\n";);
if (!SkipCostAnalysis && OutlineRegionCost < MinOutlineRegionCost) {
ORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "TooCostly",
&SI->front())
<< ore::NV("Callee", &F)
<< " inline cost-savings smaller than "
<< ore::NV("Cost", MinOutlineRegionCost);
});
LLVM_DEBUG(dbgs() << "ABORT: Outline region cost is smaller than "
<< MinOutlineRegionCost << "\n";);
continue;
}
// For now, ignore blocks that belong to a SISE region that is a
// candidate for outlining. In the future, we may want to look
// at inner regions because the outer region may have live-exit
// variables.
for (auto *BB : DominateVector)
VisitedMap[BB] = true;
// ReturnBlock here means the block after the outline call
BasicBlock *ReturnBlock = ExitBlock->getSingleSuccessor();
FunctionOutliningMultiRegionInfo::OutlineRegionInfo RegInfo(
DominateVector, DominateVector.front(), ExitBlock, ReturnBlock);
OutliningInfo->ORI.push_back(RegInfo);
LLVM_DEBUG(dbgs() << "Found Cold Candidate starting at block: "
<< DominateVector.front()->getName() << "\n";);
ColdCandidateFound = true;
NumColdRegionsFound++;
}
}
if (ColdCandidateFound)
return OutliningInfo;
return std::unique_ptr<FunctionOutliningMultiRegionInfo>();
}
std::unique_ptr<FunctionOutliningInfo>
PartialInlinerImpl::computeOutliningInfo(Function &F) const {
BasicBlock *EntryBlock = &F.front();
BranchInst *BR = dyn_cast<BranchInst>(EntryBlock->getTerminator());
if (!BR || BR->isUnconditional())
return std::unique_ptr<FunctionOutliningInfo>();
// Returns true if Succ is BB's successor
auto IsSuccessor = [](BasicBlock *Succ, BasicBlock *BB) {
return is_contained(successors(BB), Succ);
};
auto IsReturnBlock = [](BasicBlock *BB) {
Instruction *TI = BB->getTerminator();
return isa<ReturnInst>(TI);
};
auto GetReturnBlock = [&](BasicBlock *Succ1, BasicBlock *Succ2) {
if (IsReturnBlock(Succ1))
return std::make_tuple(Succ1, Succ2);
if (IsReturnBlock(Succ2))
return std::make_tuple(Succ2, Succ1);
return std::make_tuple<BasicBlock *, BasicBlock *>(nullptr, nullptr);
};
// Detect a triangular shape:
auto GetCommonSucc = [&](BasicBlock *Succ1, BasicBlock *Succ2) {
if (IsSuccessor(Succ1, Succ2))
return std::make_tuple(Succ1, Succ2);
if (IsSuccessor(Succ2, Succ1))
return std::make_tuple(Succ2, Succ1);
return std::make_tuple<BasicBlock *, BasicBlock *>(nullptr, nullptr);
};
std::unique_ptr<FunctionOutliningInfo> OutliningInfo =
std::make_unique<FunctionOutliningInfo>();
BasicBlock *CurrEntry = EntryBlock;
bool CandidateFound = false;
do {
// The number of blocks to be inlined has already reached
// the limit. When MaxNumInlineBlocks is set to 0 or 1, this
// disables partial inlining for the function.
if (OutliningInfo->getNumInlinedBlocks() >= MaxNumInlineBlocks)
break;
if (succ_size(CurrEntry) != 2)
break;
BasicBlock *Succ1 = *succ_begin(CurrEntry);
BasicBlock *Succ2 = *(succ_begin(CurrEntry) + 1);
BasicBlock *ReturnBlock, *NonReturnBlock;
std::tie(ReturnBlock, NonReturnBlock) = GetReturnBlock(Succ1, Succ2);
if (ReturnBlock) {
OutliningInfo->Entries.push_back(CurrEntry);
OutliningInfo->ReturnBlock = ReturnBlock;
OutliningInfo->NonReturnBlock = NonReturnBlock;
CandidateFound = true;
break;
}
BasicBlock *CommSucc, *OtherSucc;
std::tie(CommSucc, OtherSucc) = GetCommonSucc(Succ1, Succ2);
if (!CommSucc)
break;
OutliningInfo->Entries.push_back(CurrEntry);
CurrEntry = OtherSucc;
} while (true);
if (!CandidateFound)
return std::unique_ptr<FunctionOutliningInfo>();
// Do sanity check of the entries: threre should not
// be any successors (not in the entry set) other than
// {ReturnBlock, NonReturnBlock}
assert(OutliningInfo->Entries[0] == &F.front() &&
"Function Entry must be the first in Entries vector");
DenseSet<BasicBlock *> Entries;
for (BasicBlock *E : OutliningInfo->Entries)
Entries.insert(E);
// Returns true of BB has Predecessor which is not
// in Entries set.
auto HasNonEntryPred = [Entries](BasicBlock *BB) {
for (auto *Pred : predecessors(BB)) {
if (!Entries.count(Pred))
return true;
}
return false;
};
auto CheckAndNormalizeCandidate =
[Entries, HasNonEntryPred](FunctionOutliningInfo *OutliningInfo) {
for (BasicBlock *E : OutliningInfo->Entries) {
for (auto *Succ : successors(E)) {
if (Entries.count(Succ))
continue;
if (Succ == OutliningInfo->ReturnBlock)
OutliningInfo->ReturnBlockPreds.push_back(E);
else if (Succ != OutliningInfo->NonReturnBlock)
return false;
}
// There should not be any outside incoming edges either:
if (HasNonEntryPred(E))
return false;
}
return true;
};
if (!CheckAndNormalizeCandidate(OutliningInfo.get()))
return std::unique_ptr<FunctionOutliningInfo>();
// Now further growing the candidate's inlining region by
// peeling off dominating blocks from the outlining region:
while (OutliningInfo->getNumInlinedBlocks() < MaxNumInlineBlocks) {
BasicBlock *Cand = OutliningInfo->NonReturnBlock;
if (succ_size(Cand) != 2)
break;
if (HasNonEntryPred(Cand))
break;
BasicBlock *Succ1 = *succ_begin(Cand);
BasicBlock *Succ2 = *(succ_begin(Cand) + 1);
BasicBlock *ReturnBlock, *NonReturnBlock;
std::tie(ReturnBlock, NonReturnBlock) = GetReturnBlock(Succ1, Succ2);
if (!ReturnBlock || ReturnBlock != OutliningInfo->ReturnBlock)
break;
if (NonReturnBlock->getSinglePredecessor() != Cand)
break;
// Now grow and update OutlininigInfo:
OutliningInfo->Entries.push_back(Cand);
OutliningInfo->NonReturnBlock = NonReturnBlock;
OutliningInfo->ReturnBlockPreds.push_back(Cand);
Entries.insert(Cand);
}
return OutliningInfo;
}
// Check if there is PGO data or user annotated branch data:
static bool hasProfileData(const Function &F, const FunctionOutliningInfo &OI) {
if (F.hasProfileData())
return true;
// Now check if any of the entry block has MD_prof data:
for (auto *E : OI.Entries) {
BranchInst *BR = dyn_cast<BranchInst>(E->getTerminator());
if (!BR || BR->isUnconditional())
continue;
uint64_t T, F;
if (BR->extractProfMetadata(T, F))
return true;
}
return false;
}
BranchProbability PartialInlinerImpl::getOutliningCallBBRelativeFreq(
FunctionCloner &Cloner) const {
BasicBlock *OutliningCallBB = Cloner.OutlinedFunctions.back().second;
auto EntryFreq =
Cloner.ClonedFuncBFI->getBlockFreq(&Cloner.ClonedFunc->getEntryBlock());
auto OutliningCallFreq =
Cloner.ClonedFuncBFI->getBlockFreq(OutliningCallBB);
// FIXME Hackery needed because ClonedFuncBFI is based on the function BEFORE
// we outlined any regions, so we may encounter situations where the
// OutliningCallFreq is *slightly* bigger than the EntryFreq.
if (OutliningCallFreq.getFrequency() > EntryFreq.getFrequency())
OutliningCallFreq = EntryFreq;
auto OutlineRegionRelFreq = BranchProbability::getBranchProbability(
OutliningCallFreq.getFrequency(), EntryFreq.getFrequency());
if (hasProfileData(*Cloner.OrigFunc, *Cloner.ClonedOI.get()))
return OutlineRegionRelFreq;
// When profile data is not available, we need to be conservative in
// estimating the overall savings. Static branch prediction can usually
// guess the branch direction right (taken/non-taken), but the guessed
// branch probability is usually not biased enough. In case when the
// outlined region is predicted to be likely, its probability needs
// to be made higher (more biased) to not under-estimate the cost of
// function outlining. On the other hand, if the outlined region
// is predicted to be less likely, the predicted probablity is usually
// higher than the actual. For instance, the actual probability of the
// less likely target is only 5%, but the guessed probablity can be
// 40%. In the latter case, there is no need for further adjustement.
// FIXME: add an option for this.
if (OutlineRegionRelFreq < BranchProbability(45, 100))
return OutlineRegionRelFreq;
OutlineRegionRelFreq = std::max(
OutlineRegionRelFreq, BranchProbability(OutlineRegionFreqPercent, 100));
return OutlineRegionRelFreq;
}
bool PartialInlinerImpl::shouldPartialInline(
CallBase &CB, FunctionCloner &Cloner, BlockFrequency WeightedOutliningRcost,
OptimizationRemarkEmitter &ORE) const {
using namespace ore;
Function *Callee = CB.getCalledFunction();
assert(Callee == Cloner.ClonedFunc);
if (SkipCostAnalysis)
return isInlineViable(*Callee).isSuccess();
Function *Caller = CB.getCaller();
auto &CalleeTTI = GetTTI(*Callee);
bool RemarksEnabled =
Callee->getContext().getDiagHandlerPtr()->isMissedOptRemarkEnabled(
DEBUG_TYPE);
InlineCost IC =
getInlineCost(CB, getInlineParams(), CalleeTTI, GetAssumptionCache,
GetTLI, GetBFI, &PSI, RemarksEnabled ? &ORE : nullptr);
if (IC.isAlways()) {
ORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "AlwaysInline", &CB)
<< NV("Callee", Cloner.OrigFunc)
<< " should always be fully inlined, not partially";
});
return false;
}
if (IC.isNever()) {
ORE.emit([&]() {
return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline", &CB)
<< NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
<< NV("Caller", Caller)
<< " because it should never be inlined (cost=never)";
});
return false;
}
if (!IC) {
ORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "TooCostly", &CB)
<< NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
<< NV("Caller", Caller) << " because too costly to inline (cost="
<< NV("Cost", IC.getCost()) << ", threshold="
<< NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")";
});
return false;
}
const DataLayout &DL = Caller->getParent()->getDataLayout();
// The savings of eliminating the call:
int NonWeightedSavings = getCallsiteCost(CB, DL);
BlockFrequency NormWeightedSavings(NonWeightedSavings);
// Weighted saving is smaller than weighted cost, return false
if (NormWeightedSavings < WeightedOutliningRcost) {
ORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "OutliningCallcostTooHigh",
&CB)
<< NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
<< NV("Caller", Caller) << " runtime overhead (overhead="
<< NV("Overhead", (unsigned)WeightedOutliningRcost.getFrequency())
<< ", savings="
<< NV("Savings", (unsigned)NormWeightedSavings.getFrequency())
<< ")"
<< " of making the outlined call is too high";
});
return false;
}
ORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "CanBePartiallyInlined", &CB)
<< NV("Callee", Cloner.OrigFunc) << " can be partially inlined into "
<< NV("Caller", Caller) << " with cost=" << NV("Cost", IC.getCost())
<< " (threshold="
<< NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")";
});
return true;
}
// TODO: Ideally we should share Inliner's InlineCost Analysis code.
// For now use a simplified version. The returned 'InlineCost' will be used
// to esimate the size cost as well as runtime cost of the BB.
InstructionCost
PartialInlinerImpl::computeBBInlineCost(BasicBlock *BB,
TargetTransformInfo *TTI) {
InstructionCost InlineCost = 0;
const DataLayout &DL = BB->getParent()->getParent()->getDataLayout();
for (Instruction &I : BB->instructionsWithoutDebug()) {
// Skip free instructions.
switch (I.getOpcode()) {
case Instruction::BitCast:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::Alloca:
case Instruction::PHI:
continue;
case Instruction::GetElementPtr:
if (cast<GetElementPtrInst>(&I)->hasAllZeroIndices())
continue;
break;
default:
break;
}
if (I.isLifetimeStartOrEnd())
continue;
if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
Intrinsic::ID IID = II->getIntrinsicID();
SmallVector<Type *, 4> Tys;
FastMathFlags FMF;
for (Value *Val : II->args())
Tys.push_back(Val->getType());
if (auto *FPMO = dyn_cast<FPMathOperator>(II))
FMF = FPMO->getFastMathFlags();
IntrinsicCostAttributes ICA(IID, II->getType(), Tys, FMF);
InlineCost += TTI->getIntrinsicInstrCost(ICA, TTI::TCK_SizeAndLatency);
continue;
}
if (CallInst *CI = dyn_cast<CallInst>(&I)) {
InlineCost += getCallsiteCost(*CI, DL);
continue;
}
if (InvokeInst *II = dyn_cast<InvokeInst>(&I)) {
InlineCost += getCallsiteCost(*II, DL);
continue;
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(&I)) {
InlineCost += (SI->getNumCases() + 1) * InlineConstants::InstrCost;
continue;
}
InlineCost += InlineConstants::InstrCost;
}
return InlineCost;
}
std::tuple<InstructionCost, InstructionCost>
PartialInlinerImpl::computeOutliningCosts(FunctionCloner &Cloner) const {
InstructionCost OutliningFuncCallCost = 0, OutlinedFunctionCost = 0;
for (auto FuncBBPair : Cloner.OutlinedFunctions) {
Function *OutlinedFunc = FuncBBPair.first;
BasicBlock* OutliningCallBB = FuncBBPair.second;
// Now compute the cost of the call sequence to the outlined function
// 'OutlinedFunction' in BB 'OutliningCallBB':
auto *OutlinedFuncTTI = &GetTTI(*OutlinedFunc);
OutliningFuncCallCost +=
computeBBInlineCost(OutliningCallBB, OutlinedFuncTTI);
// Now compute the cost of the extracted/outlined function itself:
for (BasicBlock &BB : *OutlinedFunc)
OutlinedFunctionCost += computeBBInlineCost(&BB, OutlinedFuncTTI);
}
assert(OutlinedFunctionCost >= Cloner.OutlinedRegionCost &&
"Outlined function cost should be no less than the outlined region");
// The code extractor introduces a new root and exit stub blocks with
// additional unconditional branches. Those branches will be eliminated
// later with bb layout. The cost should be adjusted accordingly:
OutlinedFunctionCost -=
2 * InlineConstants::InstrCost * Cloner.OutlinedFunctions.size();
InstructionCost OutliningRuntimeOverhead =
OutliningFuncCallCost +
(OutlinedFunctionCost - Cloner.OutlinedRegionCost) +
ExtraOutliningPenalty.getValue();
return std::make_tuple(OutliningFuncCallCost, OutliningRuntimeOverhead);
}
// Create the callsite to profile count map which is
// used to update the original function's entry count,
// after the function is partially inlined into the callsite.
void PartialInlinerImpl::computeCallsiteToProfCountMap(
Function *DuplicateFunction,
DenseMap<User *, uint64_t> &CallSiteToProfCountMap) const {
std::vector<User *> Users(DuplicateFunction->user_begin(),
DuplicateFunction->user_end());
Function *CurrentCaller = nullptr;
std::unique_ptr<BlockFrequencyInfo> TempBFI;
BlockFrequencyInfo *CurrentCallerBFI = nullptr;
auto ComputeCurrBFI = [&,this](Function *Caller) {
// For the old pass manager:
if (!GetBFI) {
DominatorTree DT(*Caller);
LoopInfo LI(DT);
BranchProbabilityInfo BPI(*Caller, LI);
TempBFI.reset(new BlockFrequencyInfo(*Caller, BPI, LI));
CurrentCallerBFI = TempBFI.get();
} else {
// New pass manager:
CurrentCallerBFI = &(GetBFI(*Caller));
}
};
for (User *User : Users) {
CallBase *CB = getSupportedCallBase(User);
Function *Caller = CB->getCaller();
if (CurrentCaller != Caller) {
CurrentCaller = Caller;
ComputeCurrBFI(Caller);
} else {
assert(CurrentCallerBFI && "CallerBFI is not set");
}
BasicBlock *CallBB = CB->getParent();
auto Count = CurrentCallerBFI->getBlockProfileCount(CallBB);
if (Count)
CallSiteToProfCountMap[User] = *Count;
else
CallSiteToProfCountMap[User] = 0;
}
}
PartialInlinerImpl::FunctionCloner::FunctionCloner(
Function *F, FunctionOutliningInfo *OI, OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC,
function_ref<TargetTransformInfo &(Function &)> GetTTI)
: OrigFunc(F), ORE(ORE), LookupAC(LookupAC), GetTTI(GetTTI) {
ClonedOI = std::make_unique<FunctionOutliningInfo>();
// Clone the function, so that we can hack away on it.
ValueToValueMapTy VMap;
ClonedFunc = CloneFunction(F, VMap);
ClonedOI->ReturnBlock = cast<BasicBlock>(VMap[OI->ReturnBlock]);
ClonedOI->NonReturnBlock = cast<BasicBlock>(VMap[OI->NonReturnBlock]);
for (BasicBlock *BB : OI->Entries)
ClonedOI->Entries.push_back(cast<BasicBlock>(VMap[BB]));
for (BasicBlock *E : OI->ReturnBlockPreds) {
BasicBlock *NewE = cast<BasicBlock>(VMap[E]);
ClonedOI->ReturnBlockPreds.push_back(NewE);
}
// Go ahead and update all uses to the duplicate, so that we can just
// use the inliner functionality when we're done hacking.
F->replaceAllUsesWith(ClonedFunc);
}
PartialInlinerImpl::FunctionCloner::FunctionCloner(
Function *F, FunctionOutliningMultiRegionInfo *OI,
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC,
function_ref<TargetTransformInfo &(Function &)> GetTTI)
: OrigFunc(F), ORE(ORE), LookupAC(LookupAC), GetTTI(GetTTI) {
ClonedOMRI = std::make_unique<FunctionOutliningMultiRegionInfo>();
// Clone the function, so that we can hack away on it.
ValueToValueMapTy VMap;
ClonedFunc = CloneFunction(F, VMap);
// Go through all Outline Candidate Regions and update all BasicBlock
// information.
for (FunctionOutliningMultiRegionInfo::OutlineRegionInfo RegionInfo :
OI->ORI) {
SmallVector<BasicBlock *, 8> Region;
for (BasicBlock *BB : RegionInfo.Region)
Region.push_back(cast<BasicBlock>(VMap[BB]));
BasicBlock *NewEntryBlock = cast<BasicBlock>(VMap[RegionInfo.EntryBlock]);
BasicBlock *NewExitBlock = cast<BasicBlock>(VMap[RegionInfo.ExitBlock]);
BasicBlock *NewReturnBlock = nullptr;
if (RegionInfo.ReturnBlock)
NewReturnBlock = cast<BasicBlock>(VMap[RegionInfo.ReturnBlock]);
FunctionOutliningMultiRegionInfo::OutlineRegionInfo MappedRegionInfo(
Region, NewEntryBlock, NewExitBlock, NewReturnBlock);
ClonedOMRI->ORI.push_back(MappedRegionInfo);
}
// Go ahead and update all uses to the duplicate, so that we can just
// use the inliner functionality when we're done hacking.
F->replaceAllUsesWith(ClonedFunc);
}
void PartialInlinerImpl::FunctionCloner::normalizeReturnBlock() const {
auto GetFirstPHI = [](BasicBlock *BB) {
BasicBlock::iterator I = BB->begin();
PHINode *FirstPhi = nullptr;
while (I != BB->end()) {
PHINode *Phi = dyn_cast<PHINode>(I);
if (!Phi)
break;
if (!FirstPhi) {
FirstPhi = Phi;
break;
}
}
return FirstPhi;
};
// Shouldn't need to normalize PHIs if we're not outlining non-early return
// blocks.
if (!ClonedOI)
return;
// Special hackery is needed with PHI nodes that have inputs from more than
// one extracted block. For simplicity, just split the PHIs into a two-level
// sequence of PHIs, some of which will go in the extracted region, and some
// of which will go outside.
BasicBlock *PreReturn = ClonedOI->ReturnBlock;
// only split block when necessary:
PHINode *FirstPhi = GetFirstPHI(PreReturn);
unsigned NumPredsFromEntries = ClonedOI->ReturnBlockPreds.size();
if (!FirstPhi || FirstPhi->getNumIncomingValues() <= NumPredsFromEntries + 1)
return;
auto IsTrivialPhi = [](PHINode *PN) -> Value * {
Value *CommonValue = PN->getIncomingValue(0);
if (all_of(PN->incoming_values(),
[&](Value *V) { return V == CommonValue; }))
return CommonValue;
return nullptr;
};
ClonedOI->ReturnBlock = ClonedOI->ReturnBlock->splitBasicBlock(
ClonedOI->ReturnBlock->getFirstNonPHI()->getIterator());
BasicBlock::iterator I = PreReturn->begin();
Instruction *Ins = &ClonedOI->ReturnBlock->front();
SmallVector<Instruction *, 4> DeadPhis;
while (I != PreReturn->end()) {
PHINode *OldPhi = dyn_cast<PHINode>(I);
if (!OldPhi)
break;
PHINode *RetPhi =
PHINode::Create(OldPhi->getType(), NumPredsFromEntries + 1, "", Ins);
OldPhi->replaceAllUsesWith(RetPhi);
Ins = ClonedOI->ReturnBlock->getFirstNonPHI();
RetPhi->addIncoming(&*I, PreReturn);
for (BasicBlock *E : ClonedOI->ReturnBlockPreds) {
RetPhi->addIncoming(OldPhi->getIncomingValueForBlock(E), E);
OldPhi->removeIncomingValue(E);
}
// After incoming values splitting, the old phi may become trivial.
// Keeping the trivial phi can introduce definition inside the outline
// region which is live-out, causing necessary overhead (load, store
// arg passing etc).
if (auto *OldPhiVal = IsTrivialPhi(OldPhi)) {
OldPhi->replaceAllUsesWith(OldPhiVal);
DeadPhis.push_back(OldPhi);
}
++I;
}
for (auto *DP : DeadPhis)
DP->eraseFromParent();
for (auto *E : ClonedOI->ReturnBlockPreds)
E->getTerminator()->replaceUsesOfWith(PreReturn, ClonedOI->ReturnBlock);
}
bool PartialInlinerImpl::FunctionCloner::doMultiRegionFunctionOutlining() {
auto ComputeRegionCost =
[&](SmallVectorImpl<BasicBlock *> &Region) -> InstructionCost {
InstructionCost Cost = 0;
for (BasicBlock* BB : Region)
Cost += computeBBInlineCost(BB, &GetTTI(*BB->getParent()));
return Cost;
};
assert(ClonedOMRI && "Expecting OutlineInfo for multi region outline");
if (ClonedOMRI->ORI.empty())
return false;
// The CodeExtractor needs a dominator tree.
DominatorTree DT;
DT.recalculate(*ClonedFunc);
// Manually calculate a BlockFrequencyInfo and BranchProbabilityInfo.
LoopInfo LI(DT);
BranchProbabilityInfo BPI(*ClonedFunc, LI);
ClonedFuncBFI.reset(new BlockFrequencyInfo(*ClonedFunc, BPI, LI));
// Cache and recycle the CodeExtractor analysis to avoid O(n^2) compile-time.
CodeExtractorAnalysisCache CEAC(*ClonedFunc);
SetVector<Value *> Inputs, Outputs, Sinks;
for (FunctionOutliningMultiRegionInfo::OutlineRegionInfo RegionInfo :
ClonedOMRI->ORI) {
InstructionCost CurrentOutlinedRegionCost =
ComputeRegionCost(RegionInfo.Region);
CodeExtractor CE(RegionInfo.Region, &DT, /*AggregateArgs*/ false,
ClonedFuncBFI.get(), &BPI,
LookupAC(*RegionInfo.EntryBlock->getParent()),
/* AllowVarargs */ false);
CE.findInputsOutputs(Inputs, Outputs, Sinks);
LLVM_DEBUG({
dbgs() << "inputs: " << Inputs.size() << "\n";
dbgs() << "outputs: " << Outputs.size() << "\n";
for (Value *value : Inputs)
dbgs() << "value used in func: " << *value << "\n";
for (Value *output : Outputs)
dbgs() << "instr used in func: " << *output << "\n";
});
// Do not extract regions that have live exit variables.
if (Outputs.size() > 0 && !ForceLiveExit)
continue;
if (Function *OutlinedFunc = CE.extractCodeRegion(CEAC)) {
CallBase *OCS = PartialInlinerImpl::getOneCallSiteTo(*OutlinedFunc);
BasicBlock *OutliningCallBB = OCS->getParent();
assert(OutliningCallBB->getParent() == ClonedFunc);
OutlinedFunctions.push_back(std::make_pair(OutlinedFunc,OutliningCallBB));
NumColdRegionsOutlined++;
OutlinedRegionCost += CurrentOutlinedRegionCost;
if (MarkOutlinedColdCC) {
OutlinedFunc->setCallingConv(CallingConv::Cold);
OCS->setCallingConv(CallingConv::Cold);
}
} else
ORE.emit([&]() {
return OptimizationRemarkMissed(DEBUG_TYPE, "ExtractFailed",
&RegionInfo.Region.front()->front())
<< "Failed to extract region at block "
<< ore::NV("Block", RegionInfo.Region.front());
});
}
return !OutlinedFunctions.empty();
}
Function *
PartialInlinerImpl::FunctionCloner::doSingleRegionFunctionOutlining() {
// Returns true if the block is to be partial inlined into the caller
// (i.e. not to be extracted to the out of line function)
auto ToBeInlined = [&, this](BasicBlock *BB) {
return BB == ClonedOI->ReturnBlock ||
llvm::is_contained(ClonedOI->Entries, BB);
};
assert(ClonedOI && "Expecting OutlineInfo for single region outline");
// The CodeExtractor needs a dominator tree.
DominatorTree DT;
DT.recalculate(*ClonedFunc);
// Manually calculate a BlockFrequencyInfo and BranchProbabilityInfo.
LoopInfo LI(DT);
BranchProbabilityInfo BPI(*ClonedFunc, LI);
ClonedFuncBFI.reset(new BlockFrequencyInfo(*ClonedFunc, BPI, LI));
// Gather up the blocks that we're going to extract.
std::vector<BasicBlock *> ToExtract;
auto *ClonedFuncTTI = &GetTTI(*ClonedFunc);
ToExtract.push_back(ClonedOI->NonReturnBlock);
OutlinedRegionCost += PartialInlinerImpl::computeBBInlineCost(
ClonedOI->NonReturnBlock, ClonedFuncTTI);
for (BasicBlock &BB : *ClonedFunc)
if (!ToBeInlined(&BB) && &BB != ClonedOI->NonReturnBlock) {
ToExtract.push_back(&BB);
// FIXME: the code extractor may hoist/sink more code
// into the outlined function which may make the outlining
// overhead (the difference of the outlined function cost
// and OutliningRegionCost) look larger.
OutlinedRegionCost += computeBBInlineCost(&BB, ClonedFuncTTI);
}
// Extract the body of the if.
CodeExtractorAnalysisCache CEAC(*ClonedFunc);
Function *OutlinedFunc =
CodeExtractor(ToExtract, &DT, /*AggregateArgs*/ false,
ClonedFuncBFI.get(), &BPI, LookupAC(*ClonedFunc),
/* AllowVarargs */ true)
.extractCodeRegion(CEAC);
if (OutlinedFunc) {
BasicBlock *OutliningCallBB =
PartialInlinerImpl::getOneCallSiteTo(*OutlinedFunc)->getParent();
assert(OutliningCallBB->getParent() == ClonedFunc);
OutlinedFunctions.push_back(std::make_pair(OutlinedFunc, OutliningCallBB));
} else
ORE.emit([&]() {
return OptimizationRemarkMissed(DEBUG_TYPE, "ExtractFailed",
&ToExtract.front()->front())
<< "Failed to extract region at block "
<< ore::NV("Block", ToExtract.front());
});
return OutlinedFunc;
}
PartialInlinerImpl::FunctionCloner::~FunctionCloner() {
// Ditch the duplicate, since we're done with it, and rewrite all remaining
// users (function pointers, etc.) back to the original function.
ClonedFunc->replaceAllUsesWith(OrigFunc);
ClonedFunc->eraseFromParent();
if (!IsFunctionInlined) {
// Remove each function that was speculatively created if there is no
// reference.
for (auto FuncBBPair : OutlinedFunctions) {
Function *Func = FuncBBPair.first;
Func->eraseFromParent();
}
}
}
std::pair<bool, Function *> PartialInlinerImpl::unswitchFunction(Function &F) {
if (F.hasAddressTaken())
return {false, nullptr};
// Let inliner handle it
if (F.hasFnAttribute(Attribute::AlwaysInline))
return {false, nullptr};
if (F.hasFnAttribute(Attribute::NoInline))
return {false, nullptr};
if (PSI.isFunctionEntryCold(&F))
return {false, nullptr};
if (F.users().empty())
return {false, nullptr};
OptimizationRemarkEmitter ORE(&F);
// Only try to outline cold regions if we have a profile summary, which
// implies we have profiling information.
if (PSI.hasProfileSummary() && F.hasProfileData() &&
!DisableMultiRegionPartialInline) {
std::unique_ptr<FunctionOutliningMultiRegionInfo> OMRI =
computeOutliningColdRegionsInfo(F, ORE);
if (OMRI) {
FunctionCloner Cloner(&F, OMRI.get(), ORE, LookupAssumptionCache, GetTTI);
LLVM_DEBUG({
dbgs() << "HotCountThreshold = " << PSI.getHotCountThreshold() << "\n";
dbgs() << "ColdCountThreshold = " << PSI.getColdCountThreshold()
<< "\n";
});
bool DidOutline = Cloner.doMultiRegionFunctionOutlining();
if (DidOutline) {
LLVM_DEBUG({
dbgs() << ">>>>>> Outlined (Cloned) Function >>>>>>\n";
Cloner.ClonedFunc->print(dbgs());
dbgs() << "<<<<<< Outlined (Cloned) Function <<<<<<\n";
});
if (tryPartialInline(Cloner))
return {true, nullptr};
}
}
}
// Fall-thru to regular partial inlining if we:
// i) can't find any cold regions to outline, or
// ii) can't inline the outlined function anywhere.
std::unique_ptr<FunctionOutliningInfo> OI = computeOutliningInfo(F);
if (!OI)
return {false, nullptr};
FunctionCloner Cloner(&F, OI.get(), ORE, LookupAssumptionCache, GetTTI);
Cloner.normalizeReturnBlock();
Function *OutlinedFunction = Cloner.doSingleRegionFunctionOutlining();
if (!OutlinedFunction)
return {false, nullptr};
if (tryPartialInline(Cloner))
return {true, OutlinedFunction};
return {false, nullptr};
}
bool PartialInlinerImpl::tryPartialInline(FunctionCloner &Cloner) {
if (Cloner.OutlinedFunctions.empty())
return false;
int SizeCost = 0;
BlockFrequency WeightedRcost;
int NonWeightedRcost;
auto OutliningCosts = computeOutliningCosts(Cloner);
assert(std::get<0>(OutliningCosts).isValid() &&
std::get<1>(OutliningCosts).isValid() && "Expected valid costs");
SizeCost = *std::get<0>(OutliningCosts).getValue();
NonWeightedRcost = *std::get<1>(OutliningCosts).getValue();
// Only calculate RelativeToEntryFreq when we are doing single region
// outlining.
BranchProbability RelativeToEntryFreq;
if (Cloner.ClonedOI)
RelativeToEntryFreq = getOutliningCallBBRelativeFreq(Cloner);
else
// RelativeToEntryFreq doesn't make sense when we have more than one
// outlined call because each call will have a different relative frequency
// to the entry block. We can consider using the average, but the
// usefulness of that information is questionable. For now, assume we never
// execute the calls to outlined functions.
RelativeToEntryFreq = BranchProbability(0, 1);
WeightedRcost = BlockFrequency(NonWeightedRcost) * RelativeToEntryFreq;
// The call sequence(s) to the outlined function(s) are larger than the sum of
// the original outlined region size(s), it does not increase the chances of
// inlining the function with outlining (The inliner uses the size increase to
// model the cost of inlining a callee).
if (!SkipCostAnalysis && Cloner.OutlinedRegionCost < SizeCost) {
OptimizationRemarkEmitter OrigFuncORE(Cloner.OrigFunc);
DebugLoc DLoc;
BasicBlock *Block;
std::tie(DLoc, Block) = getOneDebugLoc(*Cloner.ClonedFunc);
OrigFuncORE.emit([&]() {
return OptimizationRemarkAnalysis(DEBUG_TYPE, "OutlineRegionTooSmall",
DLoc, Block)
<< ore::NV("Function", Cloner.OrigFunc)
<< " not partially inlined into callers (Original Size = "
<< ore::NV("OutlinedRegionOriginalSize", Cloner.OutlinedRegionCost)
<< ", Size of call sequence to outlined function = "
<< ore::NV("NewSize", SizeCost) << ")";
});
return false;
}
assert(Cloner.OrigFunc->users().empty() &&
"F's users should all be replaced!");
std::vector<User *> Users(Cloner.ClonedFunc->user_begin(),
Cloner.ClonedFunc->user_end());
DenseMap<User *, uint64_t> CallSiteToProfCountMap;
auto CalleeEntryCount = Cloner.OrigFunc->getEntryCount();
if (CalleeEntryCount)
computeCallsiteToProfCountMap(Cloner.ClonedFunc, CallSiteToProfCountMap);
uint64_t CalleeEntryCountV =
(CalleeEntryCount ? CalleeEntryCount.getCount() : 0);
bool AnyInline = false;
for (User *User : Users) {
CallBase *CB = getSupportedCallBase(User);
if (isLimitReached())
continue;
OptimizationRemarkEmitter CallerORE(CB->getCaller());
if (!shouldPartialInline(*CB, Cloner, WeightedRcost, CallerORE))
continue;
// Construct remark before doing the inlining, as after successful inlining
// the callsite is removed.
OptimizationRemark OR(DEBUG_TYPE, "PartiallyInlined", CB);
OR << ore::NV("Callee", Cloner.OrigFunc) << " partially inlined into "
<< ore::NV("Caller", CB->getCaller());
InlineFunctionInfo IFI(nullptr, GetAssumptionCache, &PSI);
// We can only forward varargs when we outlined a single region, else we
// bail on vararg functions.
if (!InlineFunction(*CB, IFI, nullptr, true,
(Cloner.ClonedOI ? Cloner.OutlinedFunctions.back().first
: nullptr))
.isSuccess())
continue;
CallerORE.emit(OR);
// Now update the entry count:
if (CalleeEntryCountV && CallSiteToProfCountMap.count(User)) {
uint64_t CallSiteCount = CallSiteToProfCountMap[User];
CalleeEntryCountV -= std::min(CalleeEntryCountV, CallSiteCount);
}
AnyInline = true;
NumPartialInlining++;
// Update the stats
if (Cloner.ClonedOI)
NumPartialInlined++;
else
NumColdOutlinePartialInlined++;
}
if (AnyInline) {
Cloner.IsFunctionInlined = true;
if (CalleeEntryCount)
Cloner.OrigFunc->setEntryCount(
CalleeEntryCount.setCount(CalleeEntryCountV));
OptimizationRemarkEmitter OrigFuncORE(Cloner.OrigFunc);
OrigFuncORE.emit([&]() {
return OptimizationRemark(DEBUG_TYPE, "PartiallyInlined", Cloner.OrigFunc)
<< "Partially inlined into at least one caller";
});
}
return AnyInline;
}
bool PartialInlinerImpl::run(Module &M) {
if (DisablePartialInlining)
return false;
std::vector<Function *> Worklist;
Worklist.reserve(M.size());
for (Function &F : M)
if (!F.use_empty() && !F.isDeclaration())
Worklist.push_back(&F);
bool Changed = false;
while (!Worklist.empty()) {
Function *CurrFunc = Worklist.back();
Worklist.pop_back();
if (CurrFunc->use_empty())
continue;
bool Recursive = false;
for (User *U : CurrFunc->users())
if (Instruction *I = dyn_cast<Instruction>(U))
if (I->getParent()->getParent() == CurrFunc) {
Recursive = true;
break;
}
if (Recursive)
continue;
std::pair<bool, Function *> Result = unswitchFunction(*CurrFunc);
if (Result.second)
Worklist.push_back(Result.second);
Changed |= Result.first;
}
return Changed;
}
char PartialInlinerLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(PartialInlinerLegacyPass, "partial-inliner",
"Partial Inliner", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(PartialInlinerLegacyPass, "partial-inliner",
"Partial Inliner", false, false)
ModulePass *llvm::createPartialInliningPass() {
return new PartialInlinerLegacyPass();
}
PreservedAnalyses PartialInlinerPass::run(Module &M,
ModuleAnalysisManager &AM) {
auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
auto GetAssumptionCache = [&FAM](Function &F) -> AssumptionCache & {
return FAM.getResult<AssumptionAnalysis>(F);
};
auto LookupAssumptionCache = [&FAM](Function &F) -> AssumptionCache * {
return FAM.getCachedResult<AssumptionAnalysis>(F);
};
auto GetBFI = [&FAM](Function &F) -> BlockFrequencyInfo & {
return FAM.getResult<BlockFrequencyAnalysis>(F);
};
auto GetTTI = [&FAM](Function &F) -> TargetTransformInfo & {
return FAM.getResult<TargetIRAnalysis>(F);
};
auto GetTLI = [&FAM](Function &F) -> TargetLibraryInfo & {
return FAM.getResult<TargetLibraryAnalysis>(F);
};
ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
if (PartialInlinerImpl(GetAssumptionCache, LookupAssumptionCache, GetTTI,
GetTLI, PSI, GetBFI)
.run(M))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}
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