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ThinLTO: Move the ODR resolution to be based purely on the summary.
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This is a requirement for the cache handling in D18494

Differential Revision: http://reviews.llvm.org/D18908

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266519
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@joker-eph
joker-eph committed Apr 16, 2016
1 parent 71c8440 commit 1aafabf
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Showing 5 changed files with 135 additions and 85 deletions.
6 changes: 6 additions & 0 deletions llvm/include/llvm/IR/ModuleSummaryIndex.h
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Expand Up @@ -466,6 +466,12 @@ class ModuleSummaryIndex {
void collectDefinedFunctionsForModule(
StringRef ModulePath,
std::map<GlobalValue::GUID, GlobalValueSummary *> &FunctionInfoMap) const;

/// Collect for each module the list of Summaries it defines (GUID ->
/// Summary).
void collectDefinedGVSummariesPerModule(
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>> &
ModuleToDefinedGVSummaries) const;
};

} // End llvm namespace
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6 changes: 6 additions & 0 deletions llvm/include/llvm/Transforms/IPO/FunctionImport.h
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Expand Up @@ -19,6 +19,7 @@

namespace llvm {
class LLVMContext;
class GlobalValueSummary;
class Module;
class ModuleSummaryIndex;

Expand Down Expand Up @@ -59,6 +60,9 @@ class FunctionImporter {

/// Compute all the imports and exports for every module in the Index.
///
/// \p ModuleToDefinedGVSummaries contains for each Module a map
/// (GUID -> Summary) for every global defined in the module.
///
/// \p ImportLists will be populated with an entry for every Module we are
/// importing into. This entry is itself a map that can be passed to
/// FunctionImporter::importFunctions() above (see description there).
Expand All @@ -68,6 +72,8 @@ class FunctionImporter {
/// is the set of globals that need to be promoted/renamed appropriately.
void ComputeCrossModuleImport(
const ModuleSummaryIndex &Index,
const StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>> &
ModuleToDefinedGVSummaries,
StringMap<FunctionImporter::ImportMapTy> &ImportLists,
StringMap<FunctionImporter::ExportSetTy> &ExportLists);

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13 changes: 13 additions & 0 deletions llvm/lib/IR/ModuleSummaryIndex.cpp
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Expand Up @@ -89,6 +89,19 @@ void ModuleSummaryIndex::collectDefinedFunctionsForModule(
}
}

// Collect for each module the list of function it defines (GUID -> Summary).
void ModuleSummaryIndex::collectDefinedGVSummariesPerModule(
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>> &
Module2FunctionInfoMap) const {
for (auto &GlobalList : *this) {
auto GUID = GlobalList.first;
for (auto &GlobInfo : GlobalList.second) {
auto *Summary = GlobInfo->summary();
Module2FunctionInfoMap[Summary->modulePath()][GUID] = Summary;
}
}
}

GlobalValueInfo *
ModuleSummaryIndex::getGlobalValueInfo(uint64_t ValueGUID,
bool PerModuleIndex) const {
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138 changes: 91 additions & 47 deletions llvm/lib/LTO/ThinLTOCodeGenerator.cpp
View file
Expand Up @@ -30,6 +30,7 @@
#include "llvm/Linker/Linker.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Object/ModuleSummaryIndexObjectFile.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/ThreadPool.h"
Expand All @@ -42,6 +43,8 @@

using namespace llvm;

#define DEBUG_TYPE "thinlto"

namespace llvm {
// Flags -discard-value-names, defined in LTOCodeGenerator.cpp
extern cl::opt<bool> LTODiscardValueNames;
Expand Down Expand Up @@ -119,24 +122,15 @@ bool IsFirstDefinitionForLinker(const GlobalValueInfoList &GVInfo,
return true;
}

static void ResolveODR(GlobalValue &GV, const ModuleSummaryIndex &Index,
StringRef ModulePath) {
if (GV.isDeclaration())
return;

static GlobalValue::LinkageTypes ResolveODR(const ModuleSummaryIndex &Index,
StringRef ModuleIdentifier,
GlobalValue::GUID GUID,
const GlobalValueSummary &GV) {
auto HasMultipleCopies =
[&](const GlobalValueInfoList &GVInfo) { return GVInfo.size() > 1; };

auto getGVInfo = [&](GlobalValue &GV) -> const GlobalValueInfoList *{
auto GUID = Function::getGlobalIdentifier(GV.getName(), GV.getLinkage(),
ModulePath);
auto It = Index.findGlobalValueInfoList(GV.getName());
if (It == Index.end())
return nullptr;
return &It->second;
};

switch (GV.getLinkage()) {
auto OriginalLinkage = GV.linkage();
switch (OriginalLinkage) {
case GlobalValue::ExternalLinkage:
case GlobalValue::AvailableExternallyLinkage:
case GlobalValue::AppendingLinkage:
Expand All @@ -149,20 +143,19 @@ static void ResolveODR(GlobalValue &GV, const ModuleSummaryIndex &Index,
break;
case GlobalValue::LinkOnceODRLinkage:
case GlobalValue::WeakODRLinkage: {
auto *GVInfo = getGVInfo(GV);
if (!GVInfo)
break;
auto &GVInfo = Index.findGlobalValueInfoList(GUID)->second;
// We need to emit only one of these, the first module will keep
// it, but turned into a weak while the others will drop it.
if (!HasMultipleCopies(*GVInfo))
if (!HasMultipleCopies(GVInfo))
break;
if (IsFirstDefinitionForLinker(*GVInfo, Index, ModulePath))
GV.setLinkage(GlobalValue::WeakODRLinkage);
if (IsFirstDefinitionForLinker(GVInfo, Index, ModuleIdentifier))
return GlobalValue::WeakODRLinkage;
else
GV.setLinkage(GlobalValue::AvailableExternallyLinkage);
return GlobalValue::AvailableExternallyLinkage;
break;
}
}
return OriginalLinkage;
}

/// Resolve LinkOnceODR and WeakODR.
Expand All @@ -171,29 +164,54 @@ static void ResolveODR(GlobalValue &GV, const ModuleSummaryIndex &Index,
/// current module. However there is a chance that another module is still
/// referencing them because of the import. We make sure we always emit at least
/// one copy.
static void ResolveODR(Module &TheModule,
const ModuleSummaryIndex &Index) {
static void ResolveODR(
const ModuleSummaryIndex &Index,
const std::map<GlobalValue::GUID, GlobalValueSummary *> &DefinedGlobals,
StringRef ModuleIdentifier,
DenseMap<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR) {
if (Index.modulePaths().size() == 1)
// Nothing to do if we don't have multiple modules
return;

// We won't optimize the globals that are referenced by an alias for now
// Ideally we should turn the alias into a global and duplicate the definition
// when needed.
DenseSet<GlobalValue *> GlobalInvolvedWithAlias;
for (auto &GA : TheModule.aliases()) {
auto *GO = GA.getBaseObject();
if (auto *GV = dyn_cast<GlobalValue>(GO))
GlobalInvolvedWithAlias.insert(GV);
DenseSet<GlobalValueSummary *> GlobalInvolvedWithAlias;
for (auto &GA : DefinedGlobals) {
if (auto AS = dyn_cast<AliasSummary>(GA.second))
GlobalInvolvedWithAlias.insert(&AS->getAliasee());
}

for (auto &GV : DefinedGlobals) {
if (GlobalInvolvedWithAlias.count(GV.second))
continue;
auto NewLinkage = ResolveODR(Index, ModuleIdentifier, GV.first, *GV.second);
if (NewLinkage != GV.second->linkage()) {
ResolvedODR[GV.first] = NewLinkage;
}
}
}

/// Fixup linkage, see ResolveODR() above.
void fixupODR(
Module &TheModule,
const DenseMap<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR) {
// Process functions and global now
for (auto &GV : TheModule) {
if (!GlobalInvolvedWithAlias.count(&GV))
ResolveODR(GV, Index, TheModule.getModuleIdentifier());
auto NewLinkage = ResolvedODR.find(GV.getGUID());
if (NewLinkage == ResolvedODR.end())
continue;
DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName() << "` from "
<< GV.getLinkage() << " to " << NewLinkage->second << "\n");
GV.setLinkage(NewLinkage->second);
}
for (auto &GV : TheModule.globals()) {
if (!GlobalInvolvedWithAlias.count(&GV))
ResolveODR(GV, Index, TheModule.getModuleIdentifier());
auto NewLinkage = ResolvedODR.find(GV.getGUID());
if (NewLinkage == ResolvedODR.end())
continue;
DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName() << "` from "
<< GV.getLinkage() << " to " << NewLinkage->second << "\n");
GV.setLinkage(NewLinkage->second);
}
}

Expand Down Expand Up @@ -291,13 +309,13 @@ std::unique_ptr<MemoryBuffer> codegenModule(Module &TheModule,
return make_unique<ObjectMemoryBuffer>(std::move(OutputBuffer));
}

static std::unique_ptr<MemoryBuffer>
ProcessThinLTOModule(Module &TheModule, const ModuleSummaryIndex &Index,
StringMap<MemoryBufferRef> &ModuleMap, TargetMachine &TM,
const FunctionImporter::ImportMapTy &ImportList,
ThinLTOCodeGenerator::CachingOptions CacheOptions,
bool DisableCodeGen, StringRef SaveTempsDir,
unsigned count) {
static std::unique_ptr<MemoryBuffer> ProcessThinLTOModule(
Module &TheModule, const ModuleSummaryIndex &Index,
StringMap<MemoryBufferRef> &ModuleMap, TargetMachine &TM,
const FunctionImporter::ImportMapTy &ImportList,
DenseMap<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
ThinLTOCodeGenerator::CachingOptions CacheOptions, bool DisableCodeGen,
StringRef SaveTempsDir, unsigned count) {

// Save temps: after IPO.
saveTempBitcode(TheModule, SaveTempsDir, count, ".1.IPO.bc");
Expand All @@ -311,7 +329,7 @@ ProcessThinLTOModule(Module &TheModule, const ModuleSummaryIndex &Index,
// Resolve the LinkOnce/Weak ODR, trying to turn them into
// "available_externally" when possible.
// This is a compile-time optimization.
ResolveODR(TheModule, Index);
fixupODR(TheModule, ResolvedODR);

// Save temps: after promotion.
saveTempBitcode(TheModule, SaveTempsDir, count, ".2.promoted.bc");
Expand Down Expand Up @@ -435,10 +453,19 @@ std::unique_ptr<ModuleSummaryIndex> ThinLTOCodeGenerator::linkCombinedIndex() {
*/
void ThinLTOCodeGenerator::promote(Module &TheModule,
ModuleSummaryIndex &Index) {
auto ModuleIdentifier = TheModule.getModuleIdentifier();
// Collect for each module the list of function it defines (GUID -> Summary).
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
ModuleToDefinedGVSummaries;
Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);

// Resolve the LinkOnceODR, trying to turn them into "available_externally"
// where possible.
ResolveODR(TheModule, Index);
// This is a compile-time optimization.
DenseMap<GlobalValue::GUID, GlobalValue::LinkageTypes> ResolvedODR;
ResolveODR(Index, ModuleToDefinedGVSummaries[ModuleIdentifier],
ModuleIdentifier, ResolvedODR);
fixupODR(TheModule, ResolvedODR);

promoteModule(TheModule, Index);
}
Expand All @@ -449,12 +476,18 @@ void ThinLTOCodeGenerator::promote(Module &TheModule,
void ThinLTOCodeGenerator::crossModuleImport(Module &TheModule,
ModuleSummaryIndex &Index) {
auto ModuleMap = generateModuleMap(Modules);
auto ModuleCount = Index.modulePaths().size();

// Collect for each module the list of function it defines (GUID -> Summary).
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
ModuleToDefinedGVSummaries(ModuleCount);
Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);

// Generate import/export list
auto ModuleCount = Index.modulePaths().size();
StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
ComputeCrossModuleImport(Index, ImportLists, ExportLists);
ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
ExportLists);
auto &ImportList = ImportLists[TheModule.getModuleIdentifier()];

crossImportIntoModule(TheModule, Index, ModuleMap, ImportList);
Expand Down Expand Up @@ -522,11 +555,17 @@ void ThinLTOCodeGenerator::run() {
auto ModuleMap = generateModuleMap(Modules);
auto ModuleCount = Modules.size();

// Collect for each module the list of function it defines (GUID -> Summary).
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
ModuleToDefinedGVSummaries(ModuleCount);
Index->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);

// Collect the import/export lists for all modules from the call-graph in the
// combined index.
StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
ComputeCrossModuleImport(*Index, ImportLists, ExportLists);
ComputeCrossModuleImport(*Index, ModuleToDefinedGVSummaries, ImportLists,
ExportLists);

// Parallel optimizer + codegen
{
Expand All @@ -536,6 +575,11 @@ void ThinLTOCodeGenerator::run() {
Pool.async([&](int count) {
LLVMContext Context;
Context.setDiscardValueNames(LTODiscardValueNames);
auto ModuleIdentifier = ModuleBuffer.getBufferIdentifier();

DenseMap<GlobalValue::GUID, GlobalValue::LinkageTypes> ResolvedODR;
ResolveODR(*Index, ModuleToDefinedGVSummaries[ModuleIdentifier],
ModuleIdentifier, ResolvedODR);

// Parse module now
auto TheModule = loadModuleFromBuffer(ModuleBuffer, Context, false);
Expand All @@ -545,10 +589,10 @@ void ThinLTOCodeGenerator::run() {
saveTempBitcode(*TheModule, SaveTempsDir, count, ".0.original.bc");
}

auto &ImportList = ImportLists[TheModule->getModuleIdentifier()];
auto &ImportList = ImportLists[ModuleIdentifier];
ProducedBinaries[count] = ProcessThinLTOModule(
*TheModule, *Index, ModuleMap, *TMBuilder.create(), ImportList,
CacheOptions, DisableCodeGen, SaveTempsDir, count);
ResolvedODR, CacheOptions, DisableCodeGen, SaveTempsDir, count);
}, count);
count++;
}
Expand Down

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