[ThinLTO] Shrink GlobalValueSummary by 8 bytes (#107342)

During the ThinLTO indexing step for one of our large applications, we
create 7.5 million instances of GlobalValueSummary.

Changing:

  std::vector<ValueInfo> RefEdgeList;

to:

  SmallVector<ValueInfo, 0> RefEdgeList;

in GlobalValueSummary reduces the size of each instance by 8 bytes.
The rest of the patch makes the same change to other places so that
the types stay compatible across function boundaries.

1 files changed, 9 insertions, 9 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index f887c9b..e52757f 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -985,7 +985,7 @@ private:
   Error parseValueSymbolTable(
       uint64_t Offset,
       DenseMap<unsigned, GlobalValue::LinkageTypes> &ValueIdToLinkageMap);
-  std::vector<ValueInfo> makeRefList(ArrayRef<uint64_t> Record);
+  SmallVector<ValueInfo, 0> makeRefList(ArrayRef<uint64_t> Record);
   std::vector<FunctionSummary::EdgeTy> makeCallList(ArrayRef<uint64_t> Record,
                                                     bool IsOldProfileFormat,
                                                     bool HasProfile,
@@ -7369,9 +7369,9 @@ Error ModuleSummaryIndexBitcodeReader::parseModule() {
   }
 }
 
-std::vector<ValueInfo>
+SmallVector<ValueInfo, 0>
 ModuleSummaryIndexBitcodeReader::makeRefList(ArrayRef<uint64_t> Record) {
-  std::vector<ValueInfo> Ret;
+  SmallVector<ValueInfo, 0> Ret;
   Ret.reserve(Record.size());
   for (uint64_t RefValueId : Record)
     Ret.push_back(std::get<0>(getValueInfoFromValueId(RefValueId)));
@@ -7516,7 +7516,7 @@ void ModuleSummaryIndexBitcodeReader::parseTypeIdCompatibleVtableSummaryRecord(
     parseTypeIdCompatibleVtableInfo(Record, Slot, TypeId);
 }
 
-static void setSpecialRefs(std::vector<ValueInfo> &Refs, unsigned ROCnt,
+static void setSpecialRefs(SmallVectorImpl<ValueInfo> &Refs, unsigned ROCnt,
                            unsigned WOCnt) {
   // Readonly and writeonly refs are in the end of the refs list.
   assert(ROCnt + WOCnt <= Refs.size());
@@ -7666,7 +7666,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
              "Record size inconsistent with number of references");
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       bool HasProfile = (BitCode == bitc::FS_PERMODULE_PROFILE);
       bool HasRelBF = (BitCode == bitc::FS_PERMODULE_RELBF);
@@ -7741,7 +7741,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
         GVF = getDecodedGVarFlags(Record[2]);
         RefArrayStart = 3;
       }
-      std::vector<ValueInfo> Refs =
+      SmallVector<ValueInfo, 0> Refs =
           makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
       auto FS =
           std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));
@@ -7762,7 +7762,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       unsigned RefListStartIndex = 4;
       unsigned VTableListStartIndex = RefListStartIndex + NumRefs;
       auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       VTableFuncList VTableFuncs;
       for (unsigned I = VTableListStartIndex, E = Record.size(); I != E; ++I) {
@@ -7823,7 +7823,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
              "Record size inconsistent with number of references");
-      std::vector<ValueInfo> Refs = makeRefList(
+      SmallVector<ValueInfo, 0> Refs = makeRefList(
           ArrayRef<uint64_t>(Record).slice(RefListStartIndex, NumRefs));
       bool HasProfile = (BitCode == bitc::FS_COMBINED_PROFILE);
       std::vector<FunctionSummary::EdgeTy> Edges = makeCallList(
@@ -7883,7 +7883,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
         GVF = getDecodedGVarFlags(Record[3]);
         RefArrayStart = 4;
       }
-      std::vector<ValueInfo> Refs =
+      SmallVector<ValueInfo, 0> Refs =
           makeRefList(ArrayRef<uint64_t>(Record).slice(RefArrayStart));
       auto FS =
           std::make_unique<GlobalVarSummary>(Flags, GVF, std::move(Refs));