Each input file is encoded as a separate compile unit in LLVM debugging

information output. However, many target specific tool chains prefer to encode
only one compile unit in an object file. In this situation, the LLVM code
generator will include  debugging information entities in the compile unit 
that is marked as main compile unit. The code generator accepts maximum one main
compile unit per module. If a module does not contain any main compile unit 
then the code generator will emit multiple compile units in the output object 
file.

[Part 1]

Update DebugInfo APIs to accept optional boolean value while creating DICompileUnit  to mark the unit as "main" unit. By defaults all units are considered  non-main.  Update SourceLevelDebugging.html to document "main" compile unit.

Update DebugInfo APIs to not accept and encode separate source file/directory entries while creating various llvm.dbg.* entities. There was a recent, yet to be documented, change to include this additional information so no documentation changes are required here.

Update DwarfDebug to handle "main" compile unit. If "main" compile unit is seen then all DIEs are inserted into "main" compile unit. All other compile units are used to find source location for llvm.dbg.* values. If there is not any "main" compile unit then create unique compile unit DIEs for each llvm.dbg.compile_unit.

[Part 2]

Create separate llvm.dbg.compile_unit for each input file. Mark compile unit create for main_input_filename as "main" compile unit. Use appropriate compile unit, based on source location information collected from the tree node, while creating llvm.dbg.* values using DebugInfo APIs.

---

This is Part 1.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63400 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 46 insertions, 34 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
index b2a52cabe0..95990cfe67 100644
--- a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
@@ -1274,6 +1274,9 @@ private:
   /// of each entry in this vector corresponds to the sources in MMI.
   DenseMap<Value *, CompileUnit *> DW_CUs;
 
+  /// MainCU - Some platform prefers one compile unit per .o file. In such
+  /// cases, all dies are inserted in MainCU.
+  CompileUnit *MainCU;
   /// AbbreviationsSet - Used to uniquely define abbreviations.
   ///
   FoldingSet<DIEAbbrev> AbbreviationsSet;
@@ -1559,16 +1562,8 @@ private:
   void AddSourceLine(DIE *Die, const DIVariable *V) {
     unsigned FileID = 0;
     unsigned Line = V->getLineNumber();
-    if (V->getVersion() <= LLVMDebugVersion6) {
-      // Version6 or earlier. Use compile unit info to get file id.
-      CompileUnit *Unit = FindCompileUnit(V->getCompileUnit());
-      FileID = Unit->getID();
-    } else {
-      // Version7 or newer, use filename and directory info from DIVariable
-      // directly.
-      unsigned DID = Directories.idFor(V->getDirectory());
-      FileID = SrcFiles.idFor(SrcFileInfo(DID, V->getFilename()));
-    }
+    CompileUnit *Unit = FindCompileUnit(V->getCompileUnit());
+    FileID = Unit->getID();
     AddUInt(Die, DW_AT_decl_file, 0, FileID);
     AddUInt(Die, DW_AT_decl_line, 0, Line);
   }
@@ -1578,16 +1573,8 @@ private:
   void AddSourceLine(DIE *Die, const DIGlobal *G) {
     unsigned FileID = 0;
     unsigned Line = G->getLineNumber();
-    if (G->getVersion() <= LLVMDebugVersion6) {
-      // Version6 or earlier. Use compile unit info to get file id.
-      CompileUnit *Unit = FindCompileUnit(G->getCompileUnit());
-      FileID = Unit->getID();
-    } else {
-      // Version7 or newer, use filename and directory info from DIGlobal
-      // directly.
-      unsigned DID = Directories.idFor(G->getDirectory());
-      FileID = SrcFiles.idFor(SrcFileInfo(DID, G->getFilename()));
-    }
+    CompileUnit *Unit = FindCompileUnit(G->getCompileUnit());
+    FileID = Unit->getID();
     AddUInt(Die, DW_AT_decl_file, 0, FileID);
     AddUInt(Die, DW_AT_decl_line, 0, Line);
   }
@@ -1595,16 +1582,11 @@ private:
   void AddSourceLine(DIE *Die, const DIType *Ty) {
     unsigned FileID = 0;
     unsigned Line = Ty->getLineNumber();
-    if (Ty->getVersion() <= LLVMDebugVersion6) {
-      // Version6 or earlier. Use compile unit info to get file id.
-      CompileUnit *Unit = FindCompileUnit(Ty->getCompileUnit());
-      FileID = Unit->getID();
-    } else {
-      // Version7 or newer, use filename and directory info from DIType
-      // directly.
-      unsigned DID = Directories.idFor(Ty->getDirectory());
-      FileID = SrcFiles.idFor(SrcFileInfo(DID, Ty->getFilename()));
-    }
+    DICompileUnit CU = Ty->getCompileUnit();
+    if (CU.isNull())
+      return;
+    CompileUnit *Unit = FindCompileUnit(CU);
+    FileID = Unit->getID();
     AddUInt(Die, DW_AT_decl_file, 0, FileID);
     AddUInt(Die, DW_AT_decl_line, 0, Line);
   }
@@ -2091,7 +2073,9 @@ private:
     DISubprogram SPD(Desc.getGV());
 
     // Get the compile unit context.
-    CompileUnit *Unit = FindCompileUnit(SPD.getCompileUnit());
+    CompileUnit *Unit = MainCU;
+    if (!Unit)
+      Unit = FindCompileUnit(SPD.getCompileUnit());
 
     // Get the subprogram die.
     DIE *SPDie = Unit->getDieMapSlotFor(SPD.getGV());
@@ -2122,7 +2106,9 @@ private:
 
       if (SPD.getName() == MF->getFunction()->getName()) {
         // Get the compile unit context.
-        CompileUnit *Unit = FindCompileUnit(SPD.getCompileUnit());
+        CompileUnit *Unit = MainCU;
+        if (!Unit)
+          Unit = FindCompileUnit(SPD.getCompileUnit());
 
         // Get the subprogram die.
         DIE *SPDie = Unit->getDieMapSlotFor(SPD.getGV());
@@ -2294,6 +2280,15 @@ private:
   ///
   void SizeAndOffsets() {
     // Process base compile unit.
+    if (MainCU) {
+      // Compute size of compile unit header
+      unsigned Offset = sizeof(int32_t) + // Length of Compilation Unit Info
+        sizeof(int16_t) + // DWARF version number
+        sizeof(int32_t) + // Offset Into Abbrev. Section
+        sizeof(int8_t);   // Pointer Size (in bytes)
+      SizeAndOffsetDie(MainCU->getDie(), Offset, true);
+      return;
+    }
     for (DenseMap<Value *, CompileUnit *>::iterator CI = DW_CUs.begin(),
            CE = DW_CUs.end(); CI != CE; ++CI) {
       CompileUnit *Unit = CI->second;
@@ -2315,6 +2310,8 @@ private:
     for (DenseMap<Value *, CompileUnit *>::iterator CI = DW_CUs.begin(),
            CE = DW_CUs.end(); CI != CE; ++CI) {
       CompileUnit *Unit = CI->second;
+      if (MainCU)
+        Unit = MainCU;
       DIE *Die = Unit->getDie();
       // Emit the compile units header.
       EmitLabel("info_begin", Unit->getID());
@@ -2340,6 +2337,8 @@ private:
       EmitLabel("info_end", Unit->getID());
       
       Asm->EOL();
+      if (MainCU)
+        return;
     }
   }
 
@@ -2639,6 +2638,8 @@ private:
     for (DenseMap<Value *, CompileUnit *>::iterator CI = DW_CUs.begin(),
            CE = DW_CUs.end(); CI != CE; ++CI) {
       CompileUnit *Unit = CI->second;
+      if (MainCU)
+        Unit = MainCU;
 
       EmitDifference("pubnames_end", Unit->getID(),
                      "pubnames_begin", Unit->getID(), true);
@@ -2672,6 +2673,8 @@ private:
       EmitLabel("pubnames_end", Unit->getID());
       
       Asm->EOL();
+      if (MainCU)
+        return;
     }
   }
 
@@ -2789,6 +2792,10 @@ private:
         AddString(Die, DW_AT_APPLE_flags, DW_FORM_string, Flags);
 
       CompileUnit *Unit = new CompileUnit(ID, Die);
+      if (DIUnit.isMain()) {
+        assert (!MainCU && "Multiple main compile units are found!");
+        MainCU = Unit;
+      }
       DW_CUs[DIUnit.getGV()] = Unit;
     }
   }
@@ -2802,7 +2809,9 @@ private:
     for (std::vector<GlobalVariable *>::iterator GVI = Result.begin(),
            GVE = Result.end(); GVI != GVE; ++GVI) {
       DIGlobalVariable DI_GV(*GVI);
-      CompileUnit *DW_Unit = FindCompileUnit(DI_GV.getCompileUnit());
+      CompileUnit *DW_Unit = MainCU;
+      if (!DW_Unit)
+        DW_Unit = FindCompileUnit(DI_GV.getCompileUnit());
 
       // Check for pre-existence.
       DIE *&Slot = DW_Unit->getDieMapSlotFor(DI_GV.getGV());
@@ -2839,7 +2848,9 @@ private:
            RE = Result.end(); RI != RE; ++RI) {
 
       DISubprogram SP(*RI);
-      CompileUnit *Unit = FindCompileUnit(SP.getCompileUnit());
+      CompileUnit *Unit = MainCU;
+      if (!Unit)
+        Unit = FindCompileUnit(SP.getCompileUnit());
 
       // Check for pre-existence.
       DIE *&Slot = Unit->getDieMapSlotFor(SP.getGV());
@@ -2862,6 +2873,7 @@ public:
   //
   DwarfDebug(raw_ostream &OS, AsmPrinter *A, const TargetAsmInfo *T)
   : Dwarf(OS, A, T, "dbg")
+  , MainCU(NULL)
   , AbbreviationsSet(InitAbbreviationsSetSize)
   , Abbreviations()
   , ValuesSet(InitValuesSetSize)