[SampleFDO] Add indexing for function profiles so they can be loaded on demand

in ExtBinary format

Currently for Text, Binary and ExtBinary format profiles, when we compile a
module with samplefdo, even if there is no function showing up in the profile,
we have to load all the function profiles from the profile input. That is a
waste of compile time.

CompactBinary format profile has already had the support of loading function
profiles on demand. In this patch, we add the support to load profile on
demand for ExtBinary format. It will work no matter the sections in ExtBinary
format profile are compressed or not. Experiment shows it reduces the time to
compile a server benchmark by 30%.

When profile remapping and loading function profiles on demand are both used,
extra work needs to be done so that the loading on demand process will take
the name remapping into consideration. It will be addressed in a follow-up
patch.

Differential Revision: https://reviews.llvm.org/D68601

llvm-svn: 374233

1 files changed, 81 insertions, 21 deletions

diff --git a/llvm/lib/ProfileData/SampleProfReader.cpp b/llvm/lib/ProfileData/SampleProfReader.cpp
index 6d00404b0bb..cf3e56728e2 100644
--- a/llvm/lib/ProfileData/SampleProfReader.cpp
+++ b/llvm/lib/ProfileData/SampleProfReader.cpp
@@ -439,7 +439,9 @@ SampleProfileReaderBinary::readProfile(FunctionSamples &FProfile) {
   return sampleprof_error::success;
 }
 
-std::error_code SampleProfileReaderBinary::readFuncProfile() {
+std::error_code
+SampleProfileReaderBinary::readFuncProfile(const uint8_t *Start) {
+  Data = Start;
   auto NumHeadSamples = readNumber<uint64_t>();
   if (std::error_code EC = NumHeadSamples.getError())
     return EC;
@@ -461,7 +463,7 @@ std::error_code SampleProfileReaderBinary::readFuncProfile() {
 
 std::error_code SampleProfileReaderBinary::read() {
   while (!at_eof()) {
-    if (std::error_code EC = readFuncProfile())
+    if (std::error_code EC = readFuncProfile(Data))
       return EC;
   }
 
@@ -483,13 +485,15 @@ SampleProfileReaderExtBinary::readOneSection(const uint8_t *Start,
       return EC;
     break;
   case SecLBRProfile:
-    while (Data < Start + Size) {
-      if (std::error_code EC = readFuncProfile())
-        return EC;
-    }
+    if (std::error_code EC = readFuncProfiles())
+      return EC;
     break;
   case SecProfileSymbolList:
-    if (std::error_code EC = readProfileSymbolList(Size))
+    if (std::error_code EC = readProfileSymbolList())
+      return EC;
+    break;
+  case SecFuncOffsetTable:
+    if (std::error_code EC = readFuncOffsetTable())
       return EC;
     break;
   default:
@@ -498,15 +502,65 @@ SampleProfileReaderExtBinary::readOneSection(const uint8_t *Start,
   return sampleprof_error::success;
 }
 
-std::error_code
-SampleProfileReaderExtBinary::readProfileSymbolList(uint64_t Size) {
+void SampleProfileReaderExtBinary::collectFuncsFrom(const Module &M) {
+  UseAllFuncs = false;
+  FuncsToUse.clear();
+  for (auto &F : M)
+    FuncsToUse.insert(FunctionSamples::getCanonicalFnName(F));
+}
+
+std::error_code SampleProfileReaderExtBinary::readFuncOffsetTable() {
+  auto Size = readNumber<uint64_t>();
+  if (std::error_code EC = Size.getError())
+    return EC;
+
+  FuncOffsetTable.reserve(*Size);
+  for (uint32_t I = 0; I < *Size; ++I) {
+    auto FName(readStringFromTable());
+    if (std::error_code EC = FName.getError())
+      return EC;
+
+    auto Offset = readNumber<uint64_t>();
+    if (std::error_code EC = Offset.getError())
+      return EC;
+
+    FuncOffsetTable[*FName] = *Offset;
+  }
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderExtBinary::readFuncProfiles() {
+  const uint8_t *Start = Data;
+  if (UseAllFuncs) {
+    while (Data < End) {
+      if (std::error_code EC = readFuncProfile(Data))
+        return EC;
+    }
+    assert(Data == End && "More data is read than expected");
+    return sampleprof_error::success;
+  }
+
+  for (auto Name : FuncsToUse) {
+    auto iter = FuncOffsetTable.find(Name);
+    if (iter == FuncOffsetTable.end())
+      continue;
+    const uint8_t *FuncProfileAddr = Start + iter->second;
+    assert(FuncProfileAddr < End && "out of LBRProfile section");
+    if (std::error_code EC = readFuncProfile(FuncProfileAddr))
+      return EC;
+  }
+  Data = End;
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderExtBinary::readProfileSymbolList() {
   if (!ProfSymList)
     ProfSymList = std::make_unique<ProfileSymbolList>();
 
-  if (std::error_code EC = ProfSymList->read(Data, Size))
+  if (std::error_code EC = ProfSymList->read(Data, End - Data))
     return EC;
 
-  Data = Data + Size;
+  Data = End;
   return sampleprof_error::success;
 }
 
@@ -600,9 +654,9 @@ std::error_code SampleProfileReaderCompactBinary::read() {
 
   for (auto Offset : OffsetsToUse) {
     const uint8_t *SavedData = Data;
-    Data = reinterpret_cast<const uint8_t *>(Buffer->getBufferStart()) +
-           Offset;
-    if (std::error_code EC = readFuncProfile())
+    if (std::error_code EC = readFuncProfile(
+            reinterpret_cast<const uint8_t *>(Buffer->getBufferStart()) +
+            Offset))
       return EC;
     Data = SavedData;
   }
@@ -719,8 +773,16 @@ uint64_t SampleProfileReaderExtBinaryBase::getSectionSize(SecType Type) {
 }
 
 uint64_t SampleProfileReaderExtBinaryBase::getFileSize() {
-  auto &LastEntry = SecHdrTable.back();
-  return LastEntry.Offset + LastEntry.Size;
+  // Sections in SecHdrTable is not necessarily in the same order as
+  // sections in the profile because section like FuncOffsetTable needs
+  // to be written after section LBRProfile but needs to be read before
+  // section LBRProfile, so we cannot simply use the last entry in
+  // SecHdrTable to calculate the file size.
+  uint64_t FileSize = 0;
+  for (auto &Entry : SecHdrTable) {
+    FileSize = std::max(Entry.Offset + Entry.Size, FileSize);
+  }
+  return FileSize;
 }
 
 bool SampleProfileReaderExtBinaryBase::dumpSectionInfo(raw_ostream &OS) {
@@ -812,13 +874,11 @@ std::error_code SampleProfileReaderCompactBinary::readFuncOffsetTable() {
   return sampleprof_error::success;
 }
 
-void SampleProfileReaderCompactBinary::collectFuncsToUse(const Module &M) {
+void SampleProfileReaderCompactBinary::collectFuncsFrom(const Module &M) {
   UseAllFuncs = false;
   FuncsToUse.clear();
-  for (auto &F : M) {
-    StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
-    FuncsToUse.insert(CanonName);
-  }
+  for (auto &F : M)
+    FuncsToUse.insert(FunctionSamples::getCanonicalFnName(F));
 }
 
 std::error_code SampleProfileReaderBinary::readSummaryEntry(