Add special case bitcode support for DebugLoc. This avoids

having the bitcode writer materialize mdnodes for all the
debug location tuples when writing out the bc file and 
stores the information in a more compact form.  For example,
the -O0 -g bc file for combine.c in 176.gcc shrinks from
739392 to 512096 bytes.

This concludes my planned short-term debug info work.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100261 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Bitcode/LLVMBitCodes.h

@@ -240,7 +240,10 @@ namespace bitc {
     // new select on i1 or [N x i1]
     FUNC_CODE_INST_VSELECT     = 29, // VSELECT:    [ty,opval,opval,predty,pred]
     FUNC_CODE_INST_INBOUNDS_GEP= 30, // INBOUNDS_GEP: [n x operands]
-    FUNC_CODE_INST_INDIRECTBR  = 31  // INDIRECTBR: [opty, op0, op1, ...]
+    FUNC_CODE_INST_INDIRECTBR  = 31, // INDIRECTBR: [opty, op0, op1, ...]
+    
+    FUNC_CODE_DEBUG_LOC        = 32, // DEBUG_LOC: [Line,Col,ScopeVal, IAVal]
+    FUNC_CODE_DEBUG_LOC_AGAIN  = 33  // DEBUG_LOC_AGAIN
   };
 } // End bitc namespace
 } // End llvm namespace

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1644,6 +1644,8 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
   BasicBlock *CurBB = 0;
   unsigned CurBBNo = 0;
 
+  DebugLoc LastLoc;
+  
   // Read all the records.
   SmallVector<uint64_t, 64> Record;
   while (1) {
@@ -1699,6 +1701,46 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
       CurBB = FunctionBBs[0];
       continue;
 
+        
+    case bitc::FUNC_CODE_DEBUG_LOC_AGAIN:  // DEBUG_LOC_AGAIN
+      // This record indicates that the last instruction is at the same
+      // location as the previous instruction with a location.
+      I = 0;
+        
+      // Get the last instruction emitted.
+      if (CurBB && !CurBB->empty())
+        I = &CurBB->back();
+      else if (CurBBNo && FunctionBBs[CurBBNo-1] &&
+               !FunctionBBs[CurBBNo-1]->empty())
+        I = &FunctionBBs[CurBBNo-1]->back();
+        
+      if (I == 0) return Error("Invalid DEBUG_LOC_AGAIN record");
+      I->setDebugLoc(LastLoc);
+      I = 0;
+      continue;
+        
+    case bitc::FUNC_CODE_DEBUG_LOC: {      // DEBUG_LOC: [line, col, scope, ia]
+      I = 0;     // Get the last instruction emitted.
+      if (CurBB && !CurBB->empty())
+        I = &CurBB->back();
+      else if (CurBBNo && FunctionBBs[CurBBNo-1] &&
+               !FunctionBBs[CurBBNo-1]->empty())
+        I = &FunctionBBs[CurBBNo-1]->back();
+      if (I == 0 || Record.size() < 4)
+        return Error("Invalid FUNC_CODE_DEBUG_LOC record");
+      
+      unsigned Line = Record[0], Col = Record[1];
+      unsigned ScopeID = Record[2], IAID = Record[3];
+      
+      MDNode *Scope = 0, *IA = 0;
+      if (ScopeID) Scope = cast<MDNode>(MDValueList.getValueFwdRef(ScopeID-1));
+      if (IAID)    IA = cast<MDNode>(MDValueList.getValueFwdRef(IAID-1));
+      LastLoc = DebugLoc::get(Line, Col, Scope, IA);
+      I->setDebugLoc(LastLoc);
+      I = 0;
+      continue;
+    }
+
     case bitc::FUNC_CODE_INST_BINOP: {    // BINOP: [opval, ty, opval, opcode]
       unsigned OpNum = 0;
       Value *LHS, *RHS;
@@ -2285,8 +2327,6 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
 
   // See if anything took the address of blocks in this function.  If so,
   // resolve them now.
-  /// BlockAddrFwdRefs - These are blockaddr references to basic blocks.  These
-  /// are resolved lazily when functions are loaded.
   DenseMap<Function*, std::vector<BlockAddrRefTy> >::iterator BAFRI =
     BlockAddrFwdRefs.find(F);
   if (BAFRI != BlockAddrFwdRefs.end()) {

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -596,7 +596,8 @@ static void WriteFunctionLocalMetadata(const Function &F,
 static void WriteMetadataAttachment(const Function &F,
                                     const ValueEnumerator &VE,
                                     BitstreamWriter &Stream) {
-  bool StartedMetadataBlock = false;
+  Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
+
   SmallVector<uint64_t, 64> Record;
 
   // Write metadata attachments
@@ -607,7 +608,7 @@ static void WriteMetadataAttachment(const Function &F,
     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
          I != E; ++I) {
       MDs.clear();
-      I->getAllMetadata(MDs);
+      I->getAllMetadataOtherThanDebugLoc(MDs);
       
       // If no metadata, ignore instruction.
       if (MDs.empty()) continue;
@@ -618,16 +619,11 @@ static void WriteMetadataAttachment(const Function &F,
         Record.push_back(MDs[i].first);
         Record.push_back(VE.getValueID(MDs[i].second));
       }
-      if (!StartedMetadataBlock)  {
-        Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
-        StartedMetadataBlock = true;
-      }
       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
       Record.clear();
     }
 
-  if (StartedMetadataBlock)
-    Stream.ExitBlock();
+  Stream.ExitBlock();
 }
 
 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
@@ -1256,19 +1252,49 @@ static void WriteFunction(const Function &F, ValueEnumerator &VE,
   // Keep a running idea of what the instruction ID is.
   unsigned InstID = CstEnd;
 
+  bool NeedsMetadataAttachment = false;
+  
+  DebugLoc LastDL;
+  
   // Finally, emit all the instructions, in order.
   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
          I != E; ++I) {
       WriteInstruction(*I, InstID, VE, Stream, Vals);
+      
       if (!I->getType()->isVoidTy())
         ++InstID;
+      
+      // If the instruction has metadata, write a metadata attachment later.
+      NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
+      
+      // If the instruction has a debug location, emit it.
+      DebugLoc DL = I->getDebugLoc();
+      if (DL.isUnknown()) {
+        // nothing todo.
+      } else if (DL == LastDL) {
+        // Just repeat the same debug loc as last time.
+        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
+      } else {
+        MDNode *Scope, *IA;
+        DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
+        
+        Vals.push_back(DL.getLine());
+        Vals.push_back(DL.getCol());
+        Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
+        Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
+        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
+        Vals.clear();
+        
+        LastDL = DL;
+      }
     }
 
   // Emit names for all the instructions etc.
   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
 
-  WriteMetadataAttachment(F, VE, Stream);
+  if (NeedsMetadataAttachment)
+    WriteMetadataAttachment(F, VE, Stream);
   VE.purgeFunction();
   Stream.ExitBlock();
 }

lib/Bitcode/Writer/ValueEnumerator.cpp

@@ -104,9 +104,16 @@ ValueEnumerator::ValueEnumerator(const Module *M) {
 
         // Enumerate metadata attached with this instruction.
         MDs.clear();
-        I->getAllMetadata(MDs);
+        I->getAllMetadataOtherThanDebugLoc(MDs);
         for (unsigned i = 0, e = MDs.size(); i != e; ++i)
           EnumerateMetadata(MDs[i].second);
+        
+        if (!I->getDebugLoc().isUnknown()) {
+          MDNode *Scope, *IA;
+          I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
+          if (Scope) EnumerateMetadata(Scope);
+          if (IA) EnumerateMetadata(IA);
+        }
       }
   }
 

tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp

@@ -237,6 +237,8 @@ static const char *GetCodeName(unsigned CodeID, unsigned BlockID,
     case bitc::FUNC_CODE_INST_INSERTVAL:    return "INST_INSERTVAL";
     case bitc::FUNC_CODE_INST_CMP2:         return "INST_CMP2";
     case bitc::FUNC_CODE_INST_VSELECT:      return "INST_VSELECT";
+    case bitc::FUNC_CODE_DEBUG_LOC:         return "DEBUG_LOC";
+    case bitc::FUNC_CODE_DEBUG_LOC_AGAIN:   return "DEBUG_LOC_AGAIN";
     }
   case bitc::TYPE_SYMTAB_BLOCK_ID:
     switch (CodeID) {