[ThinLTO] Compute synthetic function entry count

Summary:
This patch computes the synthetic function entry count on the whole
program callgraph (based on module summary) and writes the entry counts
to the summary. After function importing, this count gets attached to
the IR as metadata. Since it adds a new field to the summary, this bumps
up the version.

Reviewers: tejohnson

Subscribers: mehdi_amini, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D43521

llvm-svn: 349076

2 files changed, 26 insertions, 11 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index f9b3c930b05..846ce3a4f7a 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5247,9 +5247,9 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
   }
   const uint64_t Version = Record[0];
   const bool IsOldProfileFormat = Version == 1;
-  if (Version < 1 || Version > 5)
+  if (Version < 1 || Version > 6)
     return error("Invalid summary version " + Twine(Version) +
-                 ", 1, 2, 3, 4 or 5 expected");
+                 ". Version should be in the range [1-6].");
   Record.clear();
 
   // Keep around the last seen summary to be used when we see an optional
@@ -5303,6 +5303,9 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       // 1 bit: SkipModuleByDistributedBackend flag.
       if (Flags & 0x2)
         TheIndex.setSkipModuleByDistributedBackend();
+      // 1 bit: HasSyntheticEntryCounts flag.
+      if (Flags & 0x4)
+        TheIndex.setHasSyntheticEntryCounts();
       break;
     }
     case bitc::FS_VALUE_GUID: { // [valueid, refguid]
@@ -5358,8 +5361,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
           IsOldProfileFormat, HasProfile, HasRelBF);
       setImmutableRefs(Refs, NumImmutableRefs);
       auto FS = llvm::make_unique<FunctionSummary>(
-          Flags, InstCount, getDecodedFFlags(RawFunFlags), std::move(Refs),
-          std::move(Calls), std::move(PendingTypeTests),
+          Flags, InstCount, getDecodedFFlags(RawFunFlags), /*EntryCount=*/0,
+          std::move(Refs), std::move(Calls), std::move(PendingTypeTests),
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),
@@ -5437,18 +5440,25 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       uint64_t RawFlags = Record[2];
       unsigned InstCount = Record[3];
       uint64_t RawFunFlags = 0;
+      uint64_t EntryCount = 0;
       unsigned NumRefs = Record[4];
       unsigned NumImmutableRefs = 0;
       int RefListStartIndex = 5;
 
       if (Version >= 4) {
         RawFunFlags = Record[4];
-        NumRefs = Record[5];
         RefListStartIndex = 6;
+        size_t NumRefsIndex = 5;
         if (Version >= 5) {
-          NumImmutableRefs = Record[6];
           RefListStartIndex = 7;
+          if (Version >= 6) {
+            NumRefsIndex = 6;
+            EntryCount = Record[5];
+            RefListStartIndex = 8;
+          }
+          NumImmutableRefs = Record[RefListStartIndex - 1];
         }
+        NumRefs = Record[NumRefsIndex];
       }
 
       auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
@@ -5464,8 +5474,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       ValueInfo VI = getValueInfoFromValueId(ValueID).first;
       setImmutableRefs(Refs, NumImmutableRefs);
       auto FS = llvm::make_unique<FunctionSummary>(
-          Flags, InstCount, getDecodedFFlags(RawFunFlags), std::move(Refs),
-          std::move(Edges), std::move(PendingTypeTests),
+          Flags, InstCount, getDecodedFFlags(RawFunFlags), EntryCount,
+          std::move(Refs), std::move(Edges), std::move(PendingTypeTests),
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 29d0f87d826..68d79edceaf 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -3601,7 +3601,7 @@ void ModuleBitcodeWriterBase::writeModuleLevelReferences(
 // 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 = 5;
+static const uint64_t INDEX_VERSION = 6;
 
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
@@ -3732,6 +3732,8 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     Flags |= 0x1;
   if (Index.skipModuleByDistributedBackend())
     Flags |= 0x2;
+  if (Index.hasSyntheticEntryCounts())
+    Flags |= 0x4;
   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
 
   for (const auto &GVI : valueIds()) {
@@ -3747,6 +3749,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // immutablerefcnt
   // numrefs x valueid, n x (valueid)
@@ -3861,6 +3864,8 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
     NameVals.push_back(FS->instCount());
     NameVals.push_back(getEncodedFFlags(FS->fflags()));
+    NameVals.push_back(FS->entryCount());
+
     // Fill in below
     NameVals.push_back(0); // numrefs
     NameVals.push_back(0); // immutablerefcnt
@@ -3875,8 +3880,8 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
         ImmutableRefCnt++;
       Count++;
     }
-    NameVals[5] = Count;
-    NameVals[6] = ImmutableRefCnt;
+    NameVals[6] = Count;
+    NameVals[7] = ImmutableRefCnt;
 
     bool HasProfileData = false;
     for (auto &EI : FS->calls()) {