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llvm-mirror/lib/Analysis/ModuleSummaryAnalysis.cpp
Teresa Johnson 1bdb8a9032 [ThinLTO] Subsume all importing checks into a single flag 
Summary:
This adds a new summary flag NotEligibleToImport that subsumes
several existing flags (NoRename, HasInlineAsmMaybeReferencingInternal
and IsNotViableToInline). It also subsumes the checking of references
on the summary that was being done during the thin link by
eligibleForImport() for each candidate. It is much more efficient to
do that checking once during the per-module summary build and record
it in the summary.

Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28169

llvm-svn: 291108
2017-01-05 14:32:16 +00:00

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//===- ModuleSummaryAnalysis.cpp - Module summary index builder -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass builds a ModuleSummaryIndex object for the module, to be written
// to bitcode or LLVM assembly.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/IndirectCallPromotionAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/TypeMetadataUtils.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Pass.h"
using namespace llvm;
#define DEBUG_TYPE "module-summary-analysis"
// Walk through the operands of a given User via worklist iteration and populate
// the set of GlobalValue references encountered. Invoked either on an
// Instruction or a GlobalVariable (which walks its initializer).
static void findRefEdges(const User *CurUser, SetVector<ValueInfo> &RefEdges,
SmallPtrSet<const User *, 8> &Visited) {
SmallVector<const User *, 32> Worklist;
Worklist.push_back(CurUser);
while (!Worklist.empty()) {
const User *U = Worklist.pop_back_val();
if (!Visited.insert(U).second)
continue;
ImmutableCallSite CS(U);
for (const auto &OI : U->operands()) {
const User *Operand = dyn_cast<User>(OI);
if (!Operand)
continue;
if (isa<BlockAddress>(Operand))
continue;
if (auto *GV = dyn_cast<GlobalValue>(Operand)) {
// We have a reference to a global value. This should be added to
// the reference set unless it is a callee. Callees are handled
// specially by WriteFunction and are added to a separate list.
if (!(CS && CS.isCallee(&OI)))
RefEdges.insert(GV);
continue;
}
Worklist.push_back(Operand);
}
}
}
static CalleeInfo::HotnessType getHotness(uint64_t ProfileCount,
ProfileSummaryInfo *PSI) {
if (!PSI)
return CalleeInfo::HotnessType::Unknown;
if (PSI->isHotCount(ProfileCount))
return CalleeInfo::HotnessType::Hot;
if (PSI->isColdCount(ProfileCount))
return CalleeInfo::HotnessType::Cold;
return CalleeInfo::HotnessType::None;
}
static bool isNonRenamableLocal(const GlobalValue &GV) {
return GV.hasSection() && GV.hasLocalLinkage();
}
static void
computeFunctionSummary(ModuleSummaryIndex &Index, const Module &M,
const Function &F, BlockFrequencyInfo *BFI,
ProfileSummaryInfo *PSI, bool HasLocalsInUsed,
SmallPtrSet<GlobalValue::GUID, 8> &CantBePromoted) {
// Summary not currently supported for anonymous functions, they should
// have been named.
assert(F.hasName());
unsigned NumInsts = 0;
// Map from callee ValueId to profile count. Used to accumulate profile
// counts for all static calls to a given callee.
MapVector<ValueInfo, CalleeInfo> CallGraphEdges;
SetVector<ValueInfo> RefEdges;
SetVector<GlobalValue::GUID> TypeTests;
ICallPromotionAnalysis ICallAnalysis;
bool HasInlineAsmMaybeReferencingInternal = false;
SmallPtrSet<const User *, 8> Visited;
for (const BasicBlock &BB : F)
for (const Instruction &I : BB) {
if (isa<DbgInfoIntrinsic>(I))
continue;
++NumInsts;
findRefEdges(&I, RefEdges, Visited);
auto CS = ImmutableCallSite(&I);
if (!CS)
continue;
const auto *CI = dyn_cast<CallInst>(&I);
// Since we don't know exactly which local values are referenced in inline
// assembly, conservatively mark the function as possibly referencing
// a local value from inline assembly to ensure we don't export a
// reference (which would require renaming and promotion of the
// referenced value).
if (HasLocalsInUsed && CI && CI->isInlineAsm())
HasInlineAsmMaybeReferencingInternal = true;
auto *CalledValue = CS.getCalledValue();
auto *CalledFunction = CS.getCalledFunction();
// Check if this is an alias to a function. If so, get the
// called aliasee for the checks below.
if (auto *GA = dyn_cast<GlobalAlias>(CalledValue)) {
assert(!CalledFunction && "Expected null called function in callsite for alias");
CalledFunction = dyn_cast<Function>(GA->getBaseObject());
}
// Check if this is a direct call to a known function or a known
// intrinsic, or an indirect call with profile data.
if (CalledFunction) {
if (CalledFunction->isIntrinsic()) {
if (CalledFunction->getIntrinsicID() != Intrinsic::type_test)
continue;
// Produce a summary from type.test intrinsics. We only summarize
// type.test intrinsics that are used other than by an llvm.assume
// intrinsic. Intrinsics that are assumed are relevant only to the
// devirtualization pass, not the type test lowering pass.
bool HasNonAssumeUses = llvm::any_of(CI->uses(), [](const Use &CIU) {
auto *AssumeCI = dyn_cast<CallInst>(CIU.getUser());
if (!AssumeCI)
return true;
Function *F = AssumeCI->getCalledFunction();
return !F || F->getIntrinsicID() != Intrinsic::assume;
});
if (HasNonAssumeUses) {
auto *TypeMDVal = cast<MetadataAsValue>(CI->getArgOperand(1));
if (auto *TypeId = dyn_cast<MDString>(TypeMDVal->getMetadata()))
TypeTests.insert(GlobalValue::getGUID(TypeId->getString()));
}
}
// We should have named any anonymous globals
assert(CalledFunction->hasName());
auto ScaledCount = BFI ? BFI->getBlockProfileCount(&BB) : None;
auto Hotness = ScaledCount ? getHotness(ScaledCount.getValue(), PSI)
: CalleeInfo::HotnessType::Unknown;
// Use the original CalledValue, in case it was an alias. We want
// to record the call edge to the alias in that case. Eventually
// an alias summary will be created to associate the alias and
// aliasee.
CallGraphEdges[cast<GlobalValue>(CalledValue)].updateHotness(Hotness);
} else {
// Skip inline assembly calls.
if (CI && CI->isInlineAsm())
continue;
// Skip direct calls.
if (!CS.getCalledValue() || isa<Constant>(CS.getCalledValue()))
continue;
uint32_t NumVals, NumCandidates;
uint64_t TotalCount;
auto CandidateProfileData =
ICallAnalysis.getPromotionCandidatesForInstruction(
&I, NumVals, TotalCount, NumCandidates);
for (auto &Candidate : CandidateProfileData)
CallGraphEdges[Candidate.Value].updateHotness(
getHotness(Candidate.Count, PSI));
}
}
bool NonRenamableLocal = isNonRenamableLocal(F);
bool NotEligibleForImport =
NonRenamableLocal || HasInlineAsmMaybeReferencingInternal ||
// Inliner doesn't handle variadic functions.
// FIXME: refactor this to use the same code that inliner is using.
F.isVarArg();
GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport);
auto FuncSummary = llvm::make_unique<FunctionSummary>(
Flags, NumInsts, RefEdges.takeVector(), CallGraphEdges.takeVector(),
TypeTests.takeVector());
if (NonRenamableLocal)
CantBePromoted.insert(F.getGUID());
Index.addGlobalValueSummary(F.getName(), std::move(FuncSummary));
}
static void
computeVariableSummary(ModuleSummaryIndex &Index, const GlobalVariable &V,
SmallPtrSet<GlobalValue::GUID, 8> &CantBePromoted) {
SetVector<ValueInfo> RefEdges;
SmallPtrSet<const User *, 8> Visited;
findRefEdges(&V, RefEdges, Visited);
bool NonRenamableLocal = isNonRenamableLocal(V);
GlobalValueSummary::GVFlags Flags(V.getLinkage(), NonRenamableLocal);
auto GVarSummary =
llvm::make_unique<GlobalVarSummary>(Flags, RefEdges.takeVector());
if (NonRenamableLocal)
CantBePromoted.insert(V.getGUID());
Index.addGlobalValueSummary(V.getName(), std::move(GVarSummary));
}
static void
computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
SmallPtrSet<GlobalValue::GUID, 8> &CantBePromoted) {
bool NonRenamableLocal = isNonRenamableLocal(A);
GlobalValueSummary::GVFlags Flags(A.getLinkage(), NonRenamableLocal);
auto AS = llvm::make_unique<AliasSummary>(Flags, ArrayRef<ValueInfo>{});
auto *Aliasee = A.getBaseObject();
auto *AliaseeSummary = Index.getGlobalValueSummary(*Aliasee);
assert(AliaseeSummary && "Alias expects aliasee summary to be parsed");
AS->setAliasee(AliaseeSummary);
if (NonRenamableLocal)
CantBePromoted.insert(A.getGUID());
Index.addGlobalValueSummary(A.getName(), std::move(AS));
}
ModuleSummaryIndex llvm::buildModuleSummaryIndex(
const Module &M,
std::function<BlockFrequencyInfo *(const Function &F)> GetBFICallback,
ProfileSummaryInfo *PSI) {
ModuleSummaryIndex Index;
// Identify the local values in the llvm.used and llvm.compiler.used sets,
// which should not be exported as they would then require renaming and
// promotion, but we may have opaque uses e.g. in inline asm. We collect them
// here because we use this information to mark functions containing inline
// assembly calls as not importable.
SmallPtrSet<GlobalValue *, 8> LocalsUsed;
SmallPtrSet<GlobalValue *, 8> Used;
// First collect those in the llvm.used set.
collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
// Next collect those in the llvm.compiler.used set.
collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ true);
SmallPtrSet<GlobalValue::GUID, 8> CantBePromoted;
for (auto *V : Used) {
if (V->hasLocalLinkage()) {
LocalsUsed.insert(V);
CantBePromoted.insert(V->getGUID());
}
}
// Compute summaries for all functions defined in module, and save in the
// index.
for (auto &F : M) {
if (F.isDeclaration())
continue;
BlockFrequencyInfo *BFI = nullptr;
std::unique_ptr<BlockFrequencyInfo> BFIPtr;
if (GetBFICallback)
BFI = GetBFICallback(F);
else if (F.getEntryCount().hasValue()) {
LoopInfo LI{DominatorTree(const_cast<Function &>(F))};
BranchProbabilityInfo BPI{F, LI};
BFIPtr = llvm::make_unique<BlockFrequencyInfo>(F, BPI, LI);
BFI = BFIPtr.get();
}
computeFunctionSummary(Index, M, F, BFI, PSI, !LocalsUsed.empty(),
CantBePromoted);
}
// Compute summaries for all variables defined in module, and save in the
// index.
for (const GlobalVariable &G : M.globals()) {
if (G.isDeclaration())
continue;
computeVariableSummary(Index, G, CantBePromoted);
}
// Compute summaries for all aliases defined in module, and save in the
// index.
for (const GlobalAlias &A : M.aliases())
computeAliasSummary(Index, A, CantBePromoted);
for (auto *V : LocalsUsed) {
auto *Summary = Index.getGlobalValueSummary(*V);
assert(Summary && "Missing summary for global value");
Summary->setNotEligibleToImport();
}
if (!M.getModuleInlineAsm().empty()) {
// Collect the local values defined by module level asm, and set up
// summaries for these symbols so that they can be marked as NoRename,
// to prevent export of any use of them in regular IR that would require
// renaming within the module level asm. Note we don't need to create a
// summary for weak or global defs, as they don't need to be flagged as
// NoRename, and defs in module level asm can't be imported anyway.
// Also, any values used but not defined within module level asm should
// be listed on the llvm.used or llvm.compiler.used global and marked as
// referenced from there.
ModuleSymbolTable::CollectAsmSymbols(
Triple(M.getTargetTriple()), M.getModuleInlineAsm(),
[&M, &Index, &CantBePromoted](StringRef Name,
object::BasicSymbolRef::Flags Flags) {
// Symbols not marked as Weak or Global are local definitions.
if (Flags & (object::BasicSymbolRef::SF_Weak |
object::BasicSymbolRef::SF_Global))
return;
GlobalValue *GV = M.getNamedValue(Name);
if (!GV)
return;
assert(GV->isDeclaration() && "Def in module asm already has definition");
GlobalValueSummary::GVFlags GVFlags(GlobalValue::InternalLinkage,
/* NotEligibleToImport */ true);
CantBePromoted.insert(GlobalValue::getGUID(Name));
// Create the appropriate summary type.
if (isa<Function>(GV)) {
std::unique_ptr<FunctionSummary> Summary =
llvm::make_unique<FunctionSummary>(
GVFlags, 0, ArrayRef<ValueInfo>{},
ArrayRef<FunctionSummary::EdgeTy>{},
ArrayRef<GlobalValue::GUID>{});
Index.addGlobalValueSummary(Name, std::move(Summary));
} else {
std::unique_ptr<GlobalVarSummary> Summary =
llvm::make_unique<GlobalVarSummary>(GVFlags,
ArrayRef<ValueInfo>{});
Index.addGlobalValueSummary(Name, std::move(Summary));
}
});
}
for (auto &GlobalList : Index) {
assert(GlobalList.second.size() == 1 &&
"Expected module's index to have one summary per GUID");
auto &Summary = GlobalList.second[0];
bool AllRefsCanBeExternallyReferenced =
llvm::all_of(Summary->refs(), [&](const ValueInfo &VI) {
return !CantBePromoted.count(VI.getValue()->getGUID());
});
if (!AllRefsCanBeExternallyReferenced) {
Summary->setNotEligibleToImport();
continue;
}
if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) {
bool AllCallsCanBeExternallyReferenced = llvm::all_of(
FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) {
auto GUID = Edge.first.isGUID() ? Edge.first.getGUID()
: Edge.first.getValue()->getGUID();
return !CantBePromoted.count(GUID);
});
if (!AllCallsCanBeExternallyReferenced)
Summary->setNotEligibleToImport();
}
}
return Index;
}
AnalysisKey ModuleSummaryIndexAnalysis::Key;
ModuleSummaryIndex
ModuleSummaryIndexAnalysis::run(Module &M, ModuleAnalysisManager &AM) {
ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
return buildModuleSummaryIndex(
M,
[&FAM](const Function &F) {
return &FAM.getResult<BlockFrequencyAnalysis>(
*const_cast<Function *>(&F));
},
&PSI);
}
char ModuleSummaryIndexWrapperPass::ID = 0;
INITIALIZE_PASS_BEGIN(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
"Module Summary Analysis", false, true)
INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
INITIALIZE_PASS_END(ModuleSummaryIndexWrapperPass, "module-summary-analysis",
"Module Summary Analysis", false, true)
ModulePass *llvm::createModuleSummaryIndexWrapperPass() {
return new ModuleSummaryIndexWrapperPass();
}
ModuleSummaryIndexWrapperPass::ModuleSummaryIndexWrapperPass()
: ModulePass(ID) {
initializeModuleSummaryIndexWrapperPassPass(*PassRegistry::getPassRegistry());
}
bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) {
auto &PSI = *getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
Index = buildModuleSummaryIndex(
M,
[this](const Function &F) {
return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>(
*const_cast<Function *>(&F))
.getBFI());
},
&PSI);
return false;
}
bool ModuleSummaryIndexWrapperPass::doFinalization(Module &M) {
Index.reset();
return false;
}
void ModuleSummaryIndexWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<BlockFrequencyInfoWrapperPass>();
AU.addRequired<ProfileSummaryInfoWrapperPass>();
}
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