[SampleFDO] Add FunctionOffsetTable in compact binary format profile.

The patch saves a function offset table which maps function name index to the
offset of its function profile to the start of the binary profile. By using
the function offset table, for those function profiles which will not be used
when compiling a module, the profile reader does't have to read them. For
profile size around 10~20M, it saves ~10% compile time.

Differential Revision: https://reviews.llvm.org/D51863

llvm-svn: 342283

1 files changed, 98 insertions, 13 deletions

diff --git a/llvm/lib/ProfileData/SampleProfReader.cpp b/llvm/lib/ProfileData/SampleProfReader.cpp
index 5503104c1ef..2b4551b9849 100644
--- a/llvm/lib/ProfileData/SampleProfReader.cpp
+++ b/llvm/lib/ProfileData/SampleProfReader.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/LineIterator.h"
+#include "llvm/Support/MD5.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -320,6 +321,21 @@ ErrorOr<StringRef> SampleProfileReaderBinary::readString() {
 }
 
 template <typename T>
+ErrorOr<T> SampleProfileReaderBinary::readUnencodedNumber() {
+  std::error_code EC;
+
+  if (Data + sizeof(T) > End) {
+    EC = sampleprof_error::truncated;
+    reportError(0, EC.message());
+    return EC;
+  }
+
+  using namespace support;
+  T Val = endian::readNext<T, little, unaligned>(Data);
+  return Val;
+}
+
+template <typename T>
 inline ErrorOr<uint32_t> SampleProfileReaderBinary::readStringIndex(T &Table) {
   std::error_code EC;
   auto Idx = readNumber<uint32_t>();
@@ -423,29 +439,51 @@ SampleProfileReaderBinary::readProfile(FunctionSamples &FProfile) {
   return sampleprof_error::success;
 }
 
-std::error_code SampleProfileReaderBinary::read() {
-  while (!at_eof()) {
-    auto NumHeadSamples = readNumber<uint64_t>();
-    if (std::error_code EC = NumHeadSamples.getError())
-      return EC;
+std::error_code SampleProfileReaderBinary::readFuncProfile() {
+  auto NumHeadSamples = readNumber<uint64_t>();
+  if (std::error_code EC = NumHeadSamples.getError())
+    return EC;
 
-    auto FName(readStringFromTable());
-    if (std::error_code EC = FName.getError())
-      return EC;
+  auto FName(readStringFromTable());
+  if (std::error_code EC = FName.getError())
+    return EC;
 
-    Profiles[*FName] = FunctionSamples();
-    FunctionSamples &FProfile = Profiles[*FName];
-    FProfile.setName(*FName);
+  Profiles[*FName] = FunctionSamples();
+  FunctionSamples &FProfile = Profiles[*FName];
+  FProfile.setName(*FName);
 
-    FProfile.addHeadSamples(*NumHeadSamples);
+  FProfile.addHeadSamples(*NumHeadSamples);
+
+  if (std::error_code EC = readProfile(FProfile))
+    return EC;
+  return sampleprof_error::success;
+}
 
-    if (std::error_code EC = readProfile(FProfile))
+std::error_code SampleProfileReaderBinary::read() {
+  while (!at_eof()) {
+    if (std::error_code EC = readFuncProfile())
       return EC;
   }
 
   return sampleprof_error::success;
 }
 
+std::error_code SampleProfileReaderCompactBinary::read() {
+  for (auto Name : FuncsToUse) {
+    auto GUID = std::to_string(MD5Hash(Name));
+    auto iter = FuncOffsetTable.find(StringRef(GUID));
+    if (iter == FuncOffsetTable.end())
+      continue;
+    const uint8_t *SavedData = Data;
+    Data = reinterpret_cast<const uint8_t *>(Buffer->getBufferStart()) +
+           iter->second;
+    if (std::error_code EC = readFuncProfile())
+      return EC;
+    Data = SavedData;
+  }
+  return sampleprof_error::success;
+}
+
 std::error_code SampleProfileReaderRawBinary::verifySPMagic(uint64_t Magic) {
   if (Magic == SPMagic())
     return sampleprof_error::success;
@@ -514,6 +552,53 @@ std::error_code SampleProfileReaderBinary::readHeader() {
   return sampleprof_error::success;
 }
 
+std::error_code SampleProfileReaderCompactBinary::readHeader() {
+  SampleProfileReaderBinary::readHeader();
+  if (std::error_code EC = readFuncOffsetTable())
+    return EC;
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderCompactBinary::readFuncOffsetTable() {
+  auto TableOffset = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = TableOffset.getError())
+    return EC;
+
+  const uint8_t *SavedData = Data;
+  const uint8_t *TableStart =
+      reinterpret_cast<const uint8_t *>(Buffer->getBufferStart()) +
+      *TableOffset;
+  Data = TableStart;
+
+  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;
+  }
+  End = TableStart;
+  Data = SavedData;
+  return sampleprof_error::success;
+}
+
+void SampleProfileReaderCompactBinary::collectFuncsToUse(const Module &M) {
+  FuncsToUse.clear();
+  for (auto &F : M) {
+    StringRef Fname = F.getName().split('.').first;
+    FuncsToUse.insert(Fname);
+  }
+}
+
 std::error_code SampleProfileReaderBinary::readSummaryEntry(
     std::vector<ProfileSummaryEntry> &Entries) {
   auto Cutoff = readNumber<uint64_t>();