Dwarf: support for LTO where a single object file can have multiple line tables

We generate one line table for each compilation unit in the object file.
Reviewed by Eric and Kevin.

rdar://problem/13067005


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174445 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 44 insertions, 6 deletions

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index f6ae6479c5..20d52ebb3e 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -144,6 +144,10 @@ namespace llvm {
     /// We need a deterministic iteration order, so we remember the order
     /// the elements were added.
     std::vector<const MCSection *> MCLineSectionOrder;
+    /// The Compile Unit ID that we are currently processing.
+    unsigned DwarfCompileUnitID;
+    /// The line table start symbol for each Compile Unit.
+    DenseMap<unsigned, MCSymbol *> MCLineTableSymbols;
 
     void *MachOUniquingMap, *ELFUniquingMap, *COFFUniquingMap;
 
@@ -304,6 +308,25 @@ namespace llvm {
       MCLineSections[Sec] = Line;
       MCLineSectionOrder.push_back(Sec);
     }
+    unsigned getDwarfCompileUnitID() {
+      return DwarfCompileUnitID;
+    }
+    void setDwarfCompileUnitID(unsigned CUIndex) {
+      DwarfCompileUnitID = CUIndex;
+    }
+    const DenseMap<unsigned, MCSymbol *> &getMCLineTableSymbols() const {
+      return MCLineTableSymbols;
+    }
+    MCSymbol *getMCLineTableSymbol(unsigned ID) const {
+      DenseMap<unsigned, MCSymbol *>::const_iterator CIter =
+        MCLineTableSymbols.find(ID);
+      if (CIter == MCLineTableSymbols.end())
+        return NULL;
+      return CIter->second;
+    }
+    void setMCLineTableSymbol(MCSymbol *Sym, unsigned ID) {
+      MCLineTableSymbols[ID] = Sym;
+    }
 
     /// setCurrentDwarfLoc - saves the information from the currently parsed
     /// dwarf .loc directive and sets DwarfLocSeen.  When the next instruction
diff --git a/include/llvm/MC/MCDwarf.h b/include/llvm/MC/MCDwarf.h
index 3160b616f7..1a392e8755 100644
--- a/include/llvm/MC/MCDwarf.h
+++ b/include/llvm/MC/MCDwarf.h
@@ -19,6 +19,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/raw_ostream.h"
+#include <map>
 #include <vector>
 
 namespace llvm {
@@ -186,29 +187,43 @@ namespace llvm {
     MCLineSection() {}
 
     // addLineEntry - adds an entry to this MCLineSection's line entries
-    void addLineEntry(const MCLineEntry &LineEntry) {
-      MCLineEntries.push_back(LineEntry);
+    void addLineEntry(const MCLineEntry &LineEntry, unsigned CUID) {
+      MCLineDivisions[CUID].push_back(LineEntry);
     }
 
     typedef std::vector<MCLineEntry> MCLineEntryCollection;
     typedef MCLineEntryCollection::iterator iterator;
     typedef MCLineEntryCollection::const_iterator const_iterator;
+    typedef std::map<unsigned, MCLineEntryCollection> MCLineDivisionMap;
 
   private:
-    MCLineEntryCollection MCLineEntries;
+    // A collection of MCLineEntry for each Compile Unit ID.
+    MCLineDivisionMap MCLineDivisions;
 
   public:
-    const MCLineEntryCollection *getMCLineEntries() const {
-      return &MCLineEntries;
+    // Returns whether MCLineSection contains entries for a given Compile
+    // Unit ID.
+    bool containEntriesForID(unsigned CUID) const {
+      return MCLineDivisions.count(CUID);
+    }
+    // Returns the collection of MCLineEntry for a given Compile Unit ID.
+    const MCLineEntryCollection &getMCLineEntries(unsigned CUID) const {
+      MCLineDivisionMap::const_iterator CIter = MCLineDivisions.find(CUID);
+      assert(CIter != MCLineDivisions.end());
+      return CIter->second;
     }
   };
 
   class MCDwarfFileTable {
   public:
     //
-    // This emits the Dwarf file and the line tables.
+    // This emits the Dwarf file and the line tables for all Compile Units.
     //
     static const MCSymbol *Emit(MCStreamer *MCOS);
+    //
+    // This emits the Dwarf file and the line tables for a given Compile Unit.
+    //
+    static const MCSymbol *EmitCU(MCStreamer *MCOS, unsigned ID);
   };
 
   class MCDwarfLineAddr {