Updated Deserializer class to provide more information about the current

block that is being visited in the bitstream.  The client can also now
skip blocks before reading them, and query the current abbreviation number
as seen from the perspective of the Deserializer.  This allows the client
to be more interactive in the deserialization process (if they so choose).

llvm-svn: 43916

include/llvm/Bitcode/Deserialize.h

@@ -88,12 +88,14 @@ public:
 
 private:
   BitstreamReader& Stream;
-  SmallVector<uint64_t,10> Record;
+  SmallVector<uint64_t,20> Record;
   unsigned RecIdx;
   BumpPtrAllocator Allocator;
   BPNode* FreeList;
   MapTy BPatchMap;
-  llvm::SmallVector<uint64_t,5> BlockLocs;
+  llvm::SmallVector<std::pair<Location,unsigned>,5> BlockStack;
+  unsigned AbbrevNo;
+  unsigned RecordCode;
   
   //===----------------------------------------------------------===//
   // Public Interface.
@@ -231,14 +233,22 @@ public:
     RegisterPtr(PtrID,&x);
   }  
   
-  Location GetCurrentBlockLocation();
+  Location getCurrentBlockLocation();
+  unsigned getCurrentBlockID();
+  unsigned getAbbrevNo();
+  
   bool FinishedBlock(Location BlockLoc);
   
   bool AtEnd();
   bool inRecord();
+  void SkipBlock();
+  
+  unsigned getRecordCode();
   
 private:
-  void ReadRecord();  
+  bool AdvanceStream();  
+  void ReadRecord();
+  
   uintptr_t ReadInternalRefPtr();
   
   static inline bool HasFinalPtr(MapTy::value_type& V) {

lib/Bitcode/Reader/Deserialize.cpp

@@ -20,14 +20,14 @@
 using namespace llvm;
 
 Deserializer::Deserializer(BitstreamReader& stream)
-  : Stream(stream), RecIdx(0), FreeList(NULL) {
+  : Stream(stream), RecIdx(0), FreeList(NULL), AbbrevNo(0), RecordCode(0) {
 }
 
 Deserializer::~Deserializer() {
   assert (RecIdx >= Record.size() && 
           "Still scanning bitcode record when deserialization completed.");
  
-#ifdef NDEBUG
+#ifdef DEBUG_BACKPATCH
   for (MapTy::iterator I=BPatchMap.begin(), E=BPatchMap.end(); I!=E; ++I)
     assert (I->first.hasFinalPtr() &&
             "Some pointers were not backpatched.");
@@ -40,82 +40,131 @@ bool Deserializer::inRecord() {
     if (RecIdx >= Record.size()) {
       RecIdx = 0;
       Record.clear();
+      AbbrevNo = 0;
       return false;
     }
-    else return true;
+    else
+      return true;
   }
-  else return false;
+
+  return false;
+}
+
+bool Deserializer::AdvanceStream() {
+  assert (!inRecord() && 
+          "Cannot advance stream.  Still processing a record.");
+  
+  if (AbbrevNo == bitc::ENTER_SUBBLOCK ||
+      AbbrevNo >= bitc::UNABBREV_RECORD)
+    return true;
+  
+  while (!Stream.AtEndOfStream()) {
+    
+    AbbrevNo = Stream.ReadCode();    
+  
+    switch (AbbrevNo) {        
+      case bitc::ENTER_SUBBLOCK: {
+        unsigned id = Stream.ReadSubBlockID();
+        BlockStack.push_back(std::make_pair(Stream.GetCurrentBitNo(),id));
+        break;
+      } 
+        
+      case bitc::END_BLOCK: {
+        bool x = Stream.ReadBlockEnd();
+        assert (!x && "Error at block end.");
+        BlockStack.pop_back();
+        continue;
+      }
+        
+      case bitc::DEFINE_ABBREV:
+        Stream.ReadAbbrevRecord();
+        continue;
+
+      default:
+        break;
+    }
+    
+    return true;
+  }
+  
+  return false;
 }
 
 void Deserializer::ReadRecord() {
-  // FIXME: Check if we haven't run off the edge of the stream.
-  // FIXME: Handle abbreviations.
-
-  assert (Record.size() == 0);
   
-  unsigned Code;
-
-  while (true) {
-    
-    if (Stream.AtEndOfStream())
-      return;
-    
-    Code = Stream.ReadCode();
-  
-    if (Code == bitc::ENTER_SUBBLOCK) {
-      BlockLocs.push_back(Stream.GetCurrentBitNo());
-      unsigned id = Stream.ReadSubBlockID();
-      Stream.EnterSubBlock(id);
-      continue;
-    }
-
-    if (Code == bitc::END_BLOCK) {      
-      bool x = Stream.ReadBlockEnd();
-      assert (!x && "Error at block end.");
-      BlockLocs.pop_back();
-      continue;
-    }
-    
-    if (Code == bitc::DEFINE_ABBREV) {
-      Stream.ReadAbbrevRecord();
-      continue;
-    }
-    
-    break;
+  while (AdvanceStream() && AbbrevNo == bitc::ENTER_SUBBLOCK) {
+    assert (!BlockStack.empty());
+    Stream.EnterSubBlock(BlockStack.back().second);
+    AbbrevNo = 0;
   }
+
+  if (Stream.AtEndOfStream())
+    return;
   
-  assert (Record.size() == 0);  
-  Stream.ReadRecord(Code,Record);  
-  assert (Record.size() > 0 || Stream.AtEndOfStream());
+  assert (Record.size() == 0);
+  assert (AbbrevNo >= bitc::UNABBREV_RECORD);
+  RecordCode = Stream.ReadRecord(AbbrevNo,Record);
+  assert (Record.size() > 0);
 }
 
-Deserializer::Location Deserializer::GetCurrentBlockLocation() {
+void Deserializer::SkipBlock() {
+  assert (!inRecord());
+  assert (AbbrevNo == bitc::ENTER_SUBBLOCK);  
+  Stream.SkipBlock();
+  AbbrevNo = 0;
+}
+
+Deserializer::Location Deserializer::getCurrentBlockLocation() {
   if (!inRecord())
-    ReadRecord();
+    AdvanceStream();
   
-  assert (!BlockLocs.empty());
-  return BlockLocs.back();
+  return BlockStack.back().first;
+}
+
+unsigned Deserializer::getCurrentBlockID() { 
+  if (!inRecord())
+    AdvanceStream();
+  
+  return BlockStack.back().second;
+}
+
+unsigned Deserializer::getRecordCode() {
+  if (!inRecord()) {
+    AdvanceStream();
+    assert (AbbrevNo >= bitc::UNABBREV_RECORD);
+    ReadRecord();
+  }
+  
+  return RecordCode;
 }
 
 bool Deserializer::FinishedBlock(Location BlockLoc) {
   if (!inRecord())
-    ReadRecord();
-  
-  for (llvm::SmallVector<Location,5>::reverse_iterator
-       I=BlockLocs.rbegin(), E=BlockLocs.rend(); I!=E; ++I)
-    if (*I == BlockLoc)
-      return false;
+    AdvanceStream();
+
+  for (llvm::SmallVector<std::pair<Location,unsigned>,5>::reverse_iterator
+        I=BlockStack.rbegin(), E=BlockStack.rend(); I!=E; ++I)
+      if (I->first == BlockLoc)
+        return false;
   
   return true;
 }
 
+unsigned Deserializer::getAbbrevNo() {
+  if (!inRecord())
+    AdvanceStream();
+  
+  return AbbrevNo;
+}
+
 bool Deserializer::AtEnd() {
   if (inRecord())
     return false;
   
-  ReadRecord();
+  if (!AdvanceStream())
+    return true;
   
-  return Stream.AtEndOfStream();
+  return false;
 }
 
 uint64_t Deserializer::ReadInt() {