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[ThinLTO] Add summary entries for index-based WPD

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Summary:
If LTOUnit splitting is disabled, the module summary analysis computes
the summary information necessary to perform single implementation
devirtualization during the thin link with the index and no IR. The
information collected from the regular LTO IR in the current hybrid WPD
algorithm is summarized, including:
1) For vtable definitions, record the function pointers and their offset
within the vtable initializer (subsumes the information collected from
IR by tryFindVirtualCallTargets).
2) A record for each type metadata summarizing the vtable definitions
decorated with that metadata (subsumes the TypeIdentiferMap collected
from IR).

Also added are the necessary bitcode records, and the corresponding
assembly support.

The index-based WPD will be sent as a follow-on.

Depends on D53890.

Reviewers: pcc

Subscribers: mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits

Differential Revision: https://reviews.llvm.org/D54815

llvm-svn: 351453
This commit is contained in:
Teresa Johnson
2019-01-17 15:49:03 +00:00
parent e50d9cb364
commit 4fcf3b1621
14 changed files with 721 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
View File

@@ -215,7 +215,8 @@ private:
const Function &F);
void writeModuleLevelReferences(const GlobalVariable &V,
SmallVector<uint64_t, 64> &NameVals,
unsigned FSModRefsAbbrev);
unsigned FSModRefsAbbrev,
unsigned FSModVTableRefsAbbrev);
void assignValueId(GlobalValue::GUID ValGUID) {
GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
@@ -3528,6 +3529,18 @@ static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
W.second);
}
static void writeTypeIdMetadataSummaryRecord(
SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
const std::string &Id, const TypeIdGVInfo &Summary, ValueEnumerator &VE) {
NameVals.push_back(StrtabBuilder.add(Id));
NameVals.push_back(Id.size());
for (auto &P : Summary) {
NameVals.push_back(P.first);
NameVals.push_back(VE.getValueID(P.second.getValue()));
}
}
// Helper to emit a single function summary record.
void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
@@ -3572,7 +3585,7 @@ void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
// and emit them in a summary record.
void ModuleBitcodeWriterBase::writeModuleLevelReferences(
const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
unsigned FSModRefsAbbrev) {
unsigned FSModRefsAbbrev, unsigned FSModVTableRefsAbbrev) {
auto VI = Index->getValueInfo(V.getGUID());
if (!VI || VI.getSummaryList().empty()) {
// Only declarations should not have a summary (a declaration might however
@@ -3586,6 +3599,10 @@ void ModuleBitcodeWriterBase::writeModuleLevelReferences(
NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
auto VTableFuncs = VS->vTableFuncs();
if (!VTableFuncs.empty())
NameVals.push_back(VS->refs().size());
unsigned SizeBeforeRefs = NameVals.size();
for (auto &RI : VS->refs())
NameVals.push_back(VE.getValueID(RI.getValue()));
@@ -3593,8 +3610,20 @@ void ModuleBitcodeWriterBase::writeModuleLevelReferences(
// been initialized from a DenseSet.
llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
FSModRefsAbbrev);
if (!VTableFuncs.empty()) {
// VTableFuncs pairs should already be sorted by offset.
for (auto &P : VTableFuncs) {
NameVals.push_back(VE.getValueID(P.first.getValue()));
NameVals.push_back(P.second);
}
}
if (VTableFuncs.empty())
Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
FSModRefsAbbrev);
else
Stream.EmitRecord(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS, NameVals,
FSModVTableRefsAbbrev);
NameVals.clear();
}
@@ -3675,6 +3704,17 @@ void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
// Abbrev for FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS.
Abbv = std::make_shared<BitCodeAbbrev>();
Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numrefs
// numrefs x valueid, n x (valueid , offset)
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
unsigned FSModVTableRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
// Abbrev for FS_ALIAS.
Abbv = std::make_shared<BitCodeAbbrev>();
Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
@@ -3707,7 +3747,8 @@ void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
// Capture references from GlobalVariable initializers, which are outside
// of a function scope.
for (const GlobalVariable &G : M.globals())
writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev,
FSModVTableRefsAbbrev);
for (const GlobalAlias &A : M.aliases()) {
auto *Aliasee = A.getBaseObject();
@@ -3725,6 +3766,16 @@ void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
NameVals.clear();
}
if (!Index->typeIdMetadataMap().empty()) {
SmallVector<uint64_t, 64> NameVals;
for (auto &S : Index->typeIdMetadataMap()) {
writeTypeIdMetadataSummaryRecord(NameVals, StrtabBuilder, S.first,
S.second, VE);
Stream.EmitRecord(bitc::FS_TYPE_ID_METADATA, NameVals);
NameVals.clear();
}
}
Stream.ExitBlock();
}