Add a version field in the bitcode for the summary

[mehdi_amini]

(update tests)

[mehdi_amini]

r267318

include/llvm/Bitcode/LLVMBitCodes.h

enum GlobalValueSummarySymtabCodes {
   // COMBINED_GLOBALVAR_INIT_REFS: [modid, linkage, n x valueid]
   FS_COMBINED_GLOBALVAR_INIT_REFS = 6,
   // ALIAS: [valueid, linkage, valueid]
   FS_ALIAS = 7,
   // COMBINED_ALIAS: [modid, linkage, offset]
   FS_COMBINED_ALIAS = 8,
   // COMBINED_ORIGINAL_NAME: [original_name_hash]
   FS_COMBINED_ORIGINAL_NAME = 9,
+  // VERSION of the summary, bumped when adding flags for instance.
+  FS_VERSION = 10,
 };
 
 enum MetadataCodes {
   METADATA_STRING_OLD = 1,       // MDSTRING:      [values]
   METADATA_VALUE = 2,            // VALUE:         [type num, value num]
   METADATA_NODE = 3,             // NODE:          [n x md num]
   METADATA_NAME = 4,             // STRING:        [values]
   METADATA_DISTINCT_NODE = 5,    // DISTINCT_NODE: [n x md num]

lib/Bitcode/Reader/BitcodeReader.cpp

std::error_code ModuleSummaryIndexBitcodeReader::parseModule() {
   }
 }
 
 // Eagerly parse the entire summary block. This populates the GlobalValueSummary
 // objects in the index.
 std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
   if (Stream.EnterSubBlock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID))
     return error("Invalid record");
-
   SmallVector<uint64_t, 64> Record;
+
+  // Parse version
+  {
+    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
+    if (Entry.Kind != BitstreamEntry::Record)
+      return error("Invalid Summary Block: record for version expected");
+    if (Stream.readRecord(Entry.ID, Record) != bitc::FS_VERSION)
+      return error("Invalid Summary Block: version expected");
+  }
+  const uint64_t Version = Record[0];
+  if (Version != 1)
+    return error("Invalid summary version " + Twine(Version) + ", 1 expected");
+  Record.clear();
+
   // Keep around the last seen summary to be used when we see an optional
   // "OriginalName" attachement.
   GlobalValueSummary *LastSeenSummary = nullptr;
   bool Combined = false;
   while (1) {
     BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
 
     switch (Entry.Kind) {

lib/Bitcode/Writer/BitcodeWriter.cpp

void ModuleBitcodeWriter::writeModuleLevelReferences(
   GlobalVarSummary *VS = cast<GlobalVarSummary>(Info->summary());
   for (auto Ref : VS->refs())
     NameVals.push_back(VE.getValueID(Ref.getValue()));
   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
                     FSModRefsAbbrev);
   NameVals.clear();
 }
 
+// Current version for the summary.
+// This is bumped whenever we introduce changes in the way some record are
+// interpreted, like flags for instance.
+static const uint64_t INDEX_VERSION = 1;
+
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
   if (M.empty())
     return;
 
   if (Index->begin() == Index->end())
     return;
 
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
 
+  Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
+
   // Abbrev for FS_PERMODULE.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   // numrefs x valueid, n x (valueid, callsitecount)
void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
   }
 
   Stream.ExitBlock();
 }
 
 /// Emit the combined summary section into the combined index file.
 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
+  Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
 
   // Abbrev for FS_COMBINED.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs

test/Bitcode/summary_version.ll

+; Check summary versioning
+; RUN: opt  -module-summary  %s -o - | llvm-bcanalyzer -dump | FileCheck %s
+
+; CHECK: <GLOBALVAL_SUMMARY_BLOCK
+; CHECK: <VERSION op0=1/>
+
+
+
+; Need a function for the summary to be populated.
+define void @foo() {
+    ret void
+}

tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp

default:
       STRINGIFY_CODE(FS, PERMODULE_PROFILE)
       STRINGIFY_CODE(FS, PERMODULE_GLOBALVAR_INIT_REFS)
       STRINGIFY_CODE(FS, COMBINED)
       STRINGIFY_CODE(FS, COMBINED_PROFILE)
       STRINGIFY_CODE(FS, COMBINED_GLOBALVAR_INIT_REFS)
       STRINGIFY_CODE(FS, ALIAS)
       STRINGIFY_CODE(FS, COMBINED_ALIAS)
       STRINGIFY_CODE(FS, COMBINED_ORIGINAL_NAME)
+      STRINGIFY_CODE(FS, VERSION)
     }
   case bitc::METADATA_ATTACHMENT_ID:
     switch(CodeID) {
     default:return nullptr;
       STRINGIFY_CODE(METADATA, ATTACHMENT)
     }
   case bitc::METADATA_BLOCK_ID:
     switch(CodeID) {