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[ThinLTO] Add correctness check for RO/WO variable import

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This patch adds an assertion check for exported read/write-only
variables to be also in import list for module. If they aren't
we may face linker errors, because read/write-only variables are
internalized in their source modules. The patch also changes
export lists to store ValueInfo instead of GUID for performance
considerations.

Differential revision: https://reviews.llvm.org/D70128
This commit is contained in:
evgeny 2019-11-14 12:24:05 +03:00
parent 74f7478d2b
commit 3ab27f6ce8
8 changed files with 68 additions and 41 deletions
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2
include/llvm/LTO/LTO.h
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@ -59,7 +59,7 @@ void thinLTOResolvePrevailingInIndex(
/// must apply the changes to the Module via thinLTOInternalizeModule.
void thinLTOInternalizeAndPromoteInIndex(
ModuleSummaryIndex &Index,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
function_ref<bool(StringRef, ValueInfo)> isExported,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing);

2
include/llvm/Transforms/IPO/FunctionImport.h
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@ -98,7 +98,7 @@ public:
using ImportMapTy = StringMap<FunctionsToImportTy>;
/// The set contains an entry for every global value the module exports.
using ExportSetTy = std::unordered_set<GlobalValue::GUID>;
using ExportSetTy = DenseSet<ValueInfo>;
/// A function of this type is used to load modules referenced by the index.
using ModuleLoaderTy =

2
include/llvm/Transforms/IPO/WholeProgramDevirt.h
View File

@ -251,7 +251,7 @@ void runWholeProgramDevirtOnIndex(
/// devirt target names for any locals that were exported.
void updateIndexWPDForExports(
ModuleSummaryIndex &Summary,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
function_ref<bool(StringRef, ValueInfo)> isExported,
std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap);
} // end namespace llvm

27
lib/LTO/LTO.cpp
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@ -146,9 +146,11 @@ void llvm::computeLTOCacheKey(
// Include the hash for the current module
auto ModHash = Index.getModuleHash(ModuleID);
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
for (auto F : ExportList)
for (const auto &VI : ExportList) {
auto GUID = VI.getGUID();
// The export list can impact the internalization, be conservative here
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&F, sizeof(F)));
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&GUID, sizeof(GUID)));
}
// Include the hash for every module we import functions from. The set of
// imported symbols for each module may affect code generation and is
@ -383,12 +385,12 @@ static bool isWeakObjectWithRWAccess(GlobalValueSummary *GVS) {
}
static void thinLTOInternalizeAndPromoteGUID(
GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
GlobalValueSummaryList &GVSummaryList, ValueInfo VI,
function_ref<bool(StringRef, ValueInfo)> isExported,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing) {
for (auto &S : GVSummaryList) {
if (isExported(S->modulePath(), GUID)) {
if (isExported(S->modulePath(), VI)) {
if (GlobalValue::isLocalLinkage(S->linkage()))
S->setLinkage(GlobalValue::ExternalLinkage);
} else if (EnableLTOInternalization &&
@ -396,7 +398,7 @@ static void thinLTOInternalizeAndPromoteGUID(
// doesn't resolve them.
!GlobalValue::isLocalLinkage(S->linkage()) &&
(!GlobalValue::isInterposableLinkage(S->linkage()) ||
isPrevailing(GUID, S.get())) &&
isPrevailing(VI.getGUID(), S.get())) &&
S->linkage() != GlobalValue::AppendingLinkage &&
// We can't internalize available_externally globals because this
// can break function pointer equality.
@ -415,12 +417,12 @@ static void thinLTOInternalizeAndPromoteGUID(
// as external and non-exported values as internal.
void llvm::thinLTOInternalizeAndPromoteInIndex(
ModuleSummaryIndex &Index,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
function_ref<bool(StringRef, ValueInfo)> isExported,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing) {
for (auto &I : Index)
thinLTOInternalizeAndPromoteGUID(I.second.SummaryList, I.first, isExported,
isPrevailing);
thinLTOInternalizeAndPromoteGUID(
I.second.SummaryList, Index.getValueInfo(I), isExported, isPrevailing);
}
// Requires a destructor for std::vector<InputModule>.
@ -1330,11 +1332,10 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
ExportedGUIDs.insert(
GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(Def)));
auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
auto isExported = [&](StringRef ModuleIdentifier, ValueInfo VI) {
const auto &ExportList = ExportLists.find(ModuleIdentifier);
return (ExportList != ExportLists.end() &&
ExportList->second.count(GUID)) ||
ExportedGUIDs.count(GUID);
return (ExportList != ExportLists.end() && ExportList->second.count(VI)) ||
ExportedGUIDs.count(VI.getGUID());
};
// Update local devirtualized targets that were exported by cross-module

7
lib/LTO/ThinLTOCodeGenerator.cpp
View File

@ -589,11 +589,10 @@ struct IsExported {
const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols)
: ExportLists(ExportLists), GUIDPreservedSymbols(GUIDPreservedSymbols) {}
bool operator()(StringRef ModuleIdentifier, GlobalValue::GUID GUID) const {
bool operator()(StringRef ModuleIdentifier, ValueInfo VI) const {
const auto &ExportList = ExportLists.find(ModuleIdentifier);
return (ExportList != ExportLists.end() &&
ExportList->second.count(GUID)) ||
GUIDPreservedSymbols.count(GUID);
return (ExportList != ExportLists.end() && ExportList->second.count(VI)) ||
GUIDPreservedSymbols.count(VI.getGUID());
}
};

59
lib/Transforms/IPO/FunctionImport.cpp
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@ -308,7 +308,7 @@ static void computeImportForReferencedGlobals(
auto MarkExported = [&](const ValueInfo &VI, const GlobalValueSummary *S) {
if (ExportLists)
(*ExportLists)[S->modulePath()].insert(VI.getGUID());
(*ExportLists)[S->modulePath()].insert(VI);
};
for (auto &RefSummary : VI.getSummaryList())
@ -497,7 +497,7 @@ static void computeImportForFunction(
// Make exports in the source module.
if (ExportLists) {
auto &ExportList = (*ExportLists)[ExportModulePath];
ExportList.insert(VI.getGUID());
ExportList.insert(VI);
if (!PreviouslyImported) {
// This is the first time this function was exported from its source
// module, so mark all functions and globals it references as exported
@ -505,14 +505,11 @@ static void computeImportForFunction(
// For efficiency, we unconditionally add all the referenced GUIDs
// to the ExportList for this module, and will prune out any not
// defined in the module later in a single pass.
for (auto &Edge : ResolvedCalleeSummary->calls()) {
auto CalleeGUID = Edge.first.getGUID();
ExportList.insert(CalleeGUID);
}
for (auto &Ref : ResolvedCalleeSummary->refs()) {
auto GUID = Ref.getGUID();
ExportList.insert(GUID);
}
for (auto &Edge : ResolvedCalleeSummary->calls())
ExportList.insert(Edge.first);
for (auto &Ref : ResolvedCalleeSummary->refs())
ExportList.insert(Ref);
}
}
}
@ -630,6 +627,37 @@ static unsigned numGlobalVarSummaries(const ModuleSummaryIndex &Index,
}
#endif
static bool
checkVariableImport(const ModuleSummaryIndex &Index,
StringMap<FunctionImporter::ImportMapTy> &ImportLists,
StringMap<FunctionImporter::ExportSetTy> &ExportLists) {
DenseSet<GlobalValue::GUID> FlattenedImports;
for (auto &ImportPerModule : ImportLists)
for (auto &ExportPerModule : ImportPerModule.second)
FlattenedImports.insert(ExportPerModule.second.begin(),
ExportPerModule.second.end());
// Checks that all GUIDs of read/writeonly vars we see in export lists
// are also in the import lists. Otherwise we my face linker undefs,
// because readonly and writeonly vars are internalized in their
// source modules.
auto IsReadOrWriteOnlyVar = [&](StringRef ModulePath, const ValueInfo &VI) {
auto *GVS = dyn_cast_or_null<GlobalVarSummary>(
Index.findSummaryInModule(VI, ModulePath));
return GVS && (Index.isReadOnly(GVS) || Index.isWriteOnly(GVS));
};
for (auto &ExportPerModule : ExportLists)
for (auto &VI : ExportPerModule.second)
if (!FlattenedImports.count(VI.getGUID()) &&
IsReadOrWriteOnlyVar(ExportPerModule.first(), VI))
return false;
return true;
}
/// Compute all the import and export for every module using the Index.
void llvm::ComputeCrossModuleImport(
const ModuleSummaryIndex &Index,
@ -654,14 +682,13 @@ void llvm::ComputeCrossModuleImport(
for (auto &ELI : ExportLists) {
const auto &DefinedGVSummaries =
ModuleToDefinedGVSummaries.lookup(ELI.first());
for (auto EI = ELI.second.begin(); EI != ELI.second.end();) {
if (!DefinedGVSummaries.count(*EI))
EI = ELI.second.erase(EI);
else
++EI;
}
std::remove_if(ELI.second.begin(), ELI.second.end(),
[&](const ValueInfo &VI) {
return !DefinedGVSummaries.count(VI.getGUID());
});
}
assert(checkVariableImport(Index, ImportLists, ExportLists));
#ifndef NDEBUG
LLVM_DEBUG(dbgs() << "Import/Export lists for " << ImportLists.size()
<< " modules:\n");

4
lib/Transforms/IPO/WholeProgramDevirt.cpp
View File

@ -710,7 +710,7 @@ void runWholeProgramDevirtOnIndex(
void updateIndexWPDForExports(
ModuleSummaryIndex &Summary,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
function_ref<bool(StringRef, ValueInfo)> isExported,
std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
for (auto &T : LocalWPDTargetsMap) {
auto &VI = T.first;
@ -718,7 +718,7 @@ void updateIndexWPDForExports(
assert(VI.getSummaryList().size() == 1 &&
"Devirt of local target has more than one copy");
auto &S = VI.getSummaryList()[0];
if (!isExported(S->modulePath(), VI.getGUID()))
if (!isExported(S->modulePath(), VI))
continue;
// It's been exported by a cross module import.

6
lib/Transforms/Utils/FunctionImportUtils.cpp
View File

@ -250,12 +250,12 @@ void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
// contains summaries from the source modules if they are being imported.
// We might have a non-null VI and get here even in that case if the name
// matches one in this module (e.g. weak or appending linkage).
auto* GVS = dyn_cast_or_null<GlobalVarSummary>(
ImportIndex.findSummaryInModule(VI, M.getModuleIdentifier()));
auto *GVS = dyn_cast_or_null<GlobalVarSummary>(
ImportIndex.findSummaryInModule(VI, M.getModuleIdentifier()));
if (GVS &&
(ImportIndex.isReadOnly(GVS) || ImportIndex.isWriteOnly(GVS))) {
V->addAttribute("thinlto-internalize");
// Objects referenced by writeonly GV initializer should not be
// Objects referenced by writeonly GV initializer should not be
// promoted, because there is no any kind of read access to them
// on behalf of this writeonly GV. To avoid promotion we convert
// GV initializer to 'zeroinitializer'. This effectively drops