[llvm] r303407 - [CodeView] Reduce memory usage in TypeSerializer.

[Zachary Turner via llvm-commits]

Author: zturner
Date: Thu May 18 23:56:48 2017
New Revision: 303407

URL: http://llvm.org/viewvc/llvm-project?rev=303407&view=rev
Log:
[CodeView] Reduce memory usage in TypeSerializer.

We were using a BumpPtrAllocator to allocate stable storage for
a record, then trying to insert that into a hash table.  If a
collision occurred, the bytes were never inserted and the
allocation was unnecessary.  At the cost of an extra hash
computation, check first if it exists, and only if it does do
we allocate and insert.

Modified:
    llvm/trunk/include/llvm/DebugInfo/CodeView/TypeSerializer.h
    llvm/trunk/lib/DebugInfo/CodeView/TypeSerializer.cpp

Modified: llvm/trunk/include/llvm/DebugInfo/CodeView/TypeSerializer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/DebugInfo/CodeView/TypeSerializer.h?rev=303407&r1=303406&r2=303407&view=diff
==============================================================================
--- llvm/trunk/include/llvm/DebugInfo/CodeView/TypeSerializer.h (original)
+++ llvm/trunk/include/llvm/DebugInfo/CodeView/TypeSerializer.h Thu May 18 23:56:48 2017
@@ -70,6 +70,8 @@ class TypeSerializer : public TypeVisito
   MutableArrayRef<uint8_t> getCurrentRecordData();
   Error writeRecordPrefix(TypeLeafKind Kind);
   TypeIndex insertRecordBytesPrivate(MutableArrayRef<uint8_t> Record);
+  TypeIndex insertRecordBytesWithCopy(CVType &Record,
+                                      MutableArrayRef<uint8_t> Data);
 
   Expected<MutableArrayRef<uint8_t>>
   addPadding(MutableArrayRef<uint8_t> Record);

Modified: llvm/trunk/lib/DebugInfo/CodeView/TypeSerializer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/CodeView/TypeSerializer.cpp?rev=303407&r1=303406&r2=303407&view=diff
==============================================================================
--- llvm/trunk/lib/DebugInfo/CodeView/TypeSerializer.cpp (original)
+++ llvm/trunk/lib/DebugInfo/CodeView/TypeSerializer.cpp Thu May 18 23:56:48 2017
@@ -66,6 +66,31 @@ TypeSerializer::insertRecordBytesPrivate
   return Result.first->getValue();
 }
 
+TypeIndex
+TypeSerializer::insertRecordBytesWithCopy(CVType &Record,
+                                          MutableArrayRef<uint8_t> Data) {
+  assert(Data.size() % 4 == 0 && "Record is not aligned to 4 bytes!");
+
+  StringRef S(reinterpret_cast<const char *>(Data.data()), Data.size());
+
+  // Do a two state lookup / insert so that we don't have to allocate unless
+  // we're going
+  // to do an insert.  This is a big memory savings.
+  auto Iter = HashedRecords.find(S);
+  if (Iter != HashedRecords.end())
+    return Iter->second;
+
+  LastTypeIndex = calcNextTypeIndex();
+  uint8_t *Copy = RecordStorage.Allocate<uint8_t>(Data.size());
+  ::memcpy(Copy, Data.data(), Data.size());
+  Data = MutableArrayRef<uint8_t>(Copy, Data.size());
+  S = StringRef(reinterpret_cast<const char *>(Data.data()), Data.size());
+  HashedRecords.insert(std::make_pair(S, LastTypeIndex));
+  SeenRecords.push_back(Data);
+  Record.RecordData = Data;
+  return LastTypeIndex;
+}
+
 Expected<MutableArrayRef<uint8_t>>
 TypeSerializer::addPadding(MutableArrayRef<uint8_t> Record) {
   uint32_t Align = Record.size() % 4;
@@ -137,11 +162,9 @@ Expected<TypeIndex> TypeSerializer::visi
       reinterpret_cast<RecordPrefix *>(ThisRecordData.data());
   Prefix->RecordLen = ThisRecordData.size() - sizeof(uint16_t);
 
-  uint8_t *Copy = RecordStorage.Allocate<uint8_t>(ThisRecordData.size());
-  ::memcpy(Copy, ThisRecordData.data(), ThisRecordData.size());
-  ThisRecordData = MutableArrayRef<uint8_t>(Copy, ThisRecordData.size());
-  Record = CVType(*TypeKind, ThisRecordData);
-  TypeIndex InsertedTypeIndex = insertRecordBytesPrivate(ThisRecordData);
+  Record.Type = *TypeKind;
+  TypeIndex InsertedTypeIndex =
+      insertRecordBytesWithCopy(Record, ThisRecordData);
 
   // Write out each additional segment in reverse order, and update each
   // record's continuation index to point to the previous one.