Add support for producing .deubg_frame sections.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131121 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCDwarf.h

@@ -281,7 +281,8 @@ namespace llvm {
     //
     // This emits the frame info section.
     //
-    static void Emit(MCStreamer &streamer, bool usingCFI);
+    static void Emit(MCStreamer &streamer, bool usingCFI,
+                     bool isEH);
     static void EmitAdvanceLoc(MCStreamer &Streamer, uint64_t AddrDelta);
     static void EncodeAdvanceLoc(uint64_t AddrDelta, raw_ostream &OS);
   };

include/llvm/Target/TargetAsmInfo.h

@@ -58,6 +58,10 @@ public:
     return TLOF->getEHFrameSection();
   }
 
+  const MCSection *getDwarfFrameSection() const {
+    return TLOF->getDwarfFrameSection();
+  }
+
   unsigned getFDEEncoding(bool CFI) const {
     return TLOF->getFDEEncoding(CFI);
   }

lib/MC/MCDwarf.cpp

@@ -501,10 +501,12 @@ namespace {
     int CFAOffset;
     int CIENum;
     bool UsingCFI;
+    bool IsEH;
 
   public:
-    FrameEmitterImpl(bool usingCFI) : CFAOffset(0), CIENum(0),
+    FrameEmitterImpl(bool usingCFI, bool isEH) : CFAOffset(0), CIENum(0),
-                     UsingCFI(usingCFI) {
+                                                 UsingCFI(usingCFI),
+                                                 IsEH(isEH) {
     }
 
     const MCSymbol &EmitCIE(MCStreamer &streamer,
@@ -647,13 +649,15 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
   streamer.EmitAbsValue(Length, 4);
 
   // CIE ID
-  streamer.EmitIntValue(0, 4);
+  unsigned CIE_ID = IsEH ? 0 : -1;
+  streamer.EmitIntValue(CIE_ID, 4);
 
   // Version
   streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
 
   // Augmentation String
   SmallString<8> Augmentation;
+  if (IsEH) {
     Augmentation += "z";
     if (personality)
       Augmentation += "P";
@@ -661,6 +665,7 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
       Augmentation += "L";
     Augmentation += "R";
     streamer.EmitBytes(Augmentation.str(), 0);
+  }
   streamer.EmitIntValue(0, 1);
 
   // Code Alignment Factor
@@ -675,6 +680,7 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
   // Augmentation Data Length (optional)
 
   unsigned augmentationLength = 0;
+  if (IsEH) {
     if (personality) {
       // Personality Encoding
       augmentationLength += 1;
@@ -699,6 +705,7 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
       streamer.EmitIntValue(lsdaEncoding, 1); // LSDA Encoding
     // Encoding of the FDE pointers
     streamer.EmitIntValue(asmInfo.getFDEEncoding(UsingCFI), 1);
+  }
 
   // Initial Instructions
 
@@ -718,7 +725,7 @@ const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
   EmitCFIInstructions(streamer, Instructions, NULL);
 
   // Padding
-  streamer.EmitValueToAlignment(4);
+  streamer.EmitValueToAlignment(IsEH ? 4 : asmInfo.getPointerSize());
 
   streamer.EmitLabel(sectionEnd);
   return *sectionStart;
@@ -752,13 +759,16 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
   unsigned size = getSizeForEncoding(streamer, fdeEncoding);
 
   // PC Begin
-  EmitSymbol(streamer, *frame.Begin, fdeEncoding);
+  unsigned PCBeginEncoding = IsEH ? fdeEncoding : dwarf::DW_EH_PE_absptr;
+  unsigned PCBeginSize = getSizeForEncoding(streamer, PCBeginEncoding);
+  EmitSymbol(streamer, *frame.Begin, PCBeginEncoding);
 
   // PC Range
   const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
                                               *frame.End, 0);
   streamer.EmitAbsValue(Range, size);
 
+  if (IsEH) {
     // Augmentation Data Length
     unsigned augmentationLength = 0;
 
@@ -770,13 +780,14 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
     // Augmentation Data
     if (frame.Lsda)
       EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding);
+  }
 
   // Call Frame Instructions
 
   EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
 
   // Padding
-  streamer.EmitValueToAlignment(size);
+  streamer.EmitValueToAlignment(PCBeginSize);
 
   return fdeEnd;
 }
@@ -823,21 +834,24 @@ namespace llvm {
 }
 
 void MCDwarfFrameEmitter::Emit(MCStreamer &streamer,
-                               bool usingCFI) {
+                               bool usingCFI,
+                               bool isEH) {
   const MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
-  const MCSection &section = *asmInfo.getEHFrameSection();
+  const MCSection &section = isEH ?
+    *asmInfo.getEHFrameSection() : *asmInfo.getDwarfFrameSection();
   streamer.SwitchSection(&section);
 
   MCSymbol *fdeEnd = NULL;
   DenseMap<CIEKey, const MCSymbol*> CIEStarts;
-  FrameEmitterImpl Emitter(usingCFI);
+  FrameEmitterImpl Emitter(usingCFI, isEH);
 
+  const MCSymbol *DummyDebugKey = NULL;
   for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
     const MCDwarfFrameInfo &frame = streamer.getFrameInfo(i);
     CIEKey key(frame.Personality, frame.PersonalityEncoding,
                frame.LsdaEncoding);
-    const MCSymbol *&cieStart = CIEStarts[key];
+    const MCSymbol *&cieStart = isEH ? CIEStarts[key] : DummyDebugKey;
     if (!cieStart)
       cieStart = &Emitter.EmitCIE(streamer, frame.Personality,
                                   frame.PersonalityEncoding, frame.Lsda,

lib/MC/MCStreamer.cpp

@@ -369,5 +369,8 @@ void MCStreamer::EmitFrames(bool usingCFI) {
     return;
 
   if (EmitEHFrame)
-    MCDwarfFrameEmitter::Emit(*this, usingCFI);
+    MCDwarfFrameEmitter::Emit(*this, usingCFI, true);
+
+  if (EmitDebugFrame)
+    MCDwarfFrameEmitter::Emit(*this, usingCFI, false);
 }

test/MC/ELF/cfi-sections.s

@@ -0,0 +1,42 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_64 %s
+// RUN: llvm-mc -filetype=obj -triple i686-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_32 %s
+
+
+// The only difference in gas' output in this test is that we don't produce
+// the relocations to .debug_frame (we know their values).
+
+.cfi_sections .debug_frame
+
+f1:
+        .cfi_startproc
+        nop
+        .cfi_endproc
+
+f2:
+        .cfi_startproc
+        nop
+        .cfi_endproc
+
+// ELF_64:      (('sh_name', 0x00000011) # '.debug_frame'
+// ELF_64-NEXT:  ('sh_type', 0x00000001)
+// ELF_64-NEXT:  ('sh_flags', 0x00000000)
+// ELF_64-NEXT:  ('sh_addr', 0x00000000)
+// ELF_64-NEXT:  ('sh_offset', 0x00000048)
+// ELF_64-NEXT:  ('sh_size', 0x00000048)
+// ELF_64-NEXT:  ('sh_link', 0x00000000)
+// ELF_64-NEXT:  ('sh_info', 0x00000000)
+// ELF_64-NEXT:  ('sh_addralign', 0x00000008)
+// ELF_64-NEXT:  ('sh_entsize', 0x00000000)
+// ELF_64-NEXT:  ('_section_data', '14000000 ffffffff 01000178 100c0708 90010000 00000000 14000000 1c000000 00000000 00000000 01000000 00000000 14000000 34000000 00000000 00000000 01000000 00000000')
+
+// ELF_32:      (('sh_name', 0x00000010) # '.debug_frame'
+// ELF_32-NEXT:  ('sh_type', 0x00000001)
+// ELF_32-NEXT:  ('sh_flags', 0x00000000)
+// ELF_32-NEXT:  ('sh_addr', 0x00000000)
+// ELF_32-NEXT:  ('sh_offset', 0x00000038)
+// ELF_32-NEXT:  ('sh_size', 0x00000034)
+// ELF_32-NEXT:  ('sh_link', 0x00000000)
+// ELF_32-NEXT:  ('sh_info', 0x00000000)
+// ELF_32-NEXT:  ('sh_addralign', 0x00000004)
+// ELF_32-NEXT:  ('sh_entsize', 0x00000000)
+// ELF_32-NEXT:  ('_section_data', '10000000 ffffffff 0100017c 080c0404 88010000 0c000000 18000000 00000000 01000000 0c000000 28000000 01000000 01000000')