DebugInfo: Push header handling down into CompileUnit

This is a preliminary step to handling type units by abstracting over
all (type or compile) units.

llvm-svn: 193714

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -22,6 +22,8 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCStreamer.h"
 #include "llvm/Target/Mangler.h"
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetMachine.h"
@@ -1900,3 +1902,14 @@ DIE *CompileUnit::getOrCreateStaticMemberDIE(const DIDerivedType DT) {
 
   return StaticMemberDIE;
 }
+
+void CompileUnit::emitHeader(const MCSection *ASection,
+                             const MCSymbol *ASectionSym) {
+  Asm->OutStreamer.AddComment("DWARF version number");
+  Asm->EmitInt16(DD->getDwarfVersion());
+  Asm->OutStreamer.AddComment("Offset Into Abbrev. Section");
+  Asm->EmitSectionOffset(Asm->GetTempSymbol(ASection->getLabelBeginName()),
+                         ASectionSym);
+  Asm->OutStreamer.AddComment("Address Size (in bytes)");
+  Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+}

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h

@@ -315,6 +315,17 @@ public:
   /// call insertDIE if MD is not null.
   DIE *createAndAddDIE(unsigned Tag, DIE &Parent, const MDNode *MD = NULL);
 
+  /// Compute the size of a header for this unit, not including the initial
+  /// length field.
+  unsigned getHeaderSize() const {
+    return sizeof(int16_t) + // DWARF version number
+           sizeof(int32_t) + // Offset Into Abbrev. Section
+           sizeof(int8_t);   // Pointer Size (in bytes)
+  }
+
+  /// Emit the header for this unit, not including the initial length field.
+  void emitHeader(const MCSection *ASection, const MCSymbol *ASectionSym);
+
 private:
   /// constructTypeDIE - Construct basic type die from DIBasicType.
   void constructTypeDIE(DIE &Buffer, DIBasicType BTy);

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1972,11 +1972,8 @@ void DwarfUnits::computeSizeAndOffsets() {
     (*I)->setDebugInfoOffset(SecOffset);
 
     // CU-relative offset is reset to 0 here.
-    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)
+    unsigned Offset = sizeof(int32_t) + // Length of Unit Info
+                      (*I)->getHeaderSize(); // Unit-specific headers
 
     // EndOffset here is CU-relative, after laying out
     // all of the CU DIE.
@@ -2163,20 +2160,10 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
                                     TheCU->getUniqueID()));
 
     // Emit size of content not including length itself
-    unsigned ContentSize = Die->getSize() +
-      sizeof(int16_t) + // DWARF version number
-      sizeof(int32_t) + // Offset Into Abbrev. Section
-      sizeof(int8_t);   // Pointer Size (in bytes)
+    Asm->OutStreamer.AddComment("Length of Unit");
+    Asm->EmitInt32(TheCU->getHeaderSize() + Die->getSize());
 
-    Asm->OutStreamer.AddComment("Length of Compilation Unit Info");
-    Asm->EmitInt32(ContentSize);
-    Asm->OutStreamer.AddComment("DWARF version number");
-    Asm->EmitInt16(DD->getDwarfVersion());
-    Asm->OutStreamer.AddComment("Offset Into Abbrev. Section");
-    Asm->EmitSectionOffset(Asm->GetTempSymbol(ASection->getLabelBeginName()),
-                           ASectionSym);
-    Asm->OutStreamer.AddComment("Address Size (in bytes)");
-    Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+    TheCU->emitHeader(ASection, ASectionSym);
 
     DD->emitDIE(Die, Abbreviations);
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol(USection->getLabelEndName(),