Some skeleton code to emit the compact unwind. If the information is unable to

[oota-llvm.git] / lib / MC / MCDwarf.cpp

diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index d0eaf2074c616b48aaeaaa368ab08a568766376b..937dad41026be6bff73b52c138773edc8c7aa0b2 100644 (file)
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -354,10 +354,7 @@ void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
       OS << char(dwarf::DW_LNS_const_add_pc);
     else {
       OS << char(dwarf::DW_LNS_advance_pc);
-      SmallString<32> Tmp;
-      raw_svector_ostream OSE(Tmp);
-      MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
-      OS << OSE.str();
+      MCObjectWriter::EncodeULEB128(AddrDelta, OS);
     }
     OS << char(dwarf::DW_LNS_extended_op);
     OS << char(1);
@@ -502,13 +499,20 @@ namespace {
     int CIENum;
     bool UsingCFI;
     bool IsEH;
+    const MCSymbol *SectionStart;
 
   public:
-    FrameEmitterImpl(bool usingCFI, bool isEH) : CFAOffset(0), CIENum(0),
-                                                 UsingCFI(usingCFI),
-                                                 IsEH(isEH) {
+    FrameEmitterImpl(bool usingCFI, bool isEH, const MCSymbol *sectionStart) :
+      CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
+      SectionStart(sectionStart) {
     }
 
+    /// EmitCompactUnwind - Emit the unwind information in a compact way. If
+    /// we're successful, return 'true'. Otherwise, return 'false' and it will
+    /// emit the normal CIE and FDE.
+    bool EmitCompactUnwind(MCStreamer &streamer,
+                           const MCDwarfFrameInfo &frame);
+
     const MCSymbol &EmitCIE(MCStreamer &streamer,
                             const MCSymbol *personality,
                             unsigned personalityEncoding,
@@ -538,8 +542,6 @@ void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
 
     // If advancing cfa.
     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
-      assert(!Src.isReg() && "Machine move not supported yet.");
-
       if (Src.getReg() == MachineLocation::VirtualFP) {
         Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
       } else {
@@ -624,6 +626,55 @@ void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
   }
 }
 
+/// EmitCompactUnwind - Emit the unwind information in a compact way. If we're
+/// successful, return 'true'. Otherwise, return 'false' and it will emit the
+/// normal CIE and FDE.
+bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
+                                         const MCDwarfFrameInfo &Frame) {
+#if 1
+  return false;
+#else
+  MCContext &Context = Streamer.getContext();
+  const TargetAsmInfo &TAI = Context.getTargetAsmInfo();
+  Streamer.SwitchSection(TAI.getCompactUnwindSection());
+
+  unsigned FDEEncoding = TAI.getFDEEncoding(UsingCFI);
+  unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
+
+  // range-start range-length  compact-unwind-enc personality-func   lsda
+  //  _foo       LfooEnd-_foo  0x00000023          0                 0
+  //  _bar       LbarEnd-_bar  0x00000025         __gxx_personality  except_tab1
+  //
+  //   .section __LD,__compact_unwind,regular,debug
+  //
+  //   # compact unwind for _foo
+  //   .quad _foo
+  //   .set L1,LfooEnd-_foo
+  //   .long L1
+  //   .long 0x01010001
+  //   .quad 0
+  //   .quad 0
+  //
+  //   # compact unwind for _bar
+  //   .quad _bar
+  //   .set L2,LbarEnd-_bar
+  //   .long L2
+  //   .long 0x01020011
+  //   .quad __gxx_personality
+  //   .quad except_tab1
+
+  // Range Start
+  EmitSymbol(Streamer, *Frame.Begin, FDEEncoding);
+
+  // Range Length
+  const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
+                                              *Frame.End, 0);
+  Streamer.EmitAbsValue(Range, Size);
+
+  return true;
+#endif
+}
+
 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
                                           const MCSymbol *personality,
                                           unsigned personalityEncoding,
@@ -737,9 +788,9 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
   MCContext &context = streamer.getContext();
   MCSymbol *fdeStart = context.CreateTempSymbol();
   MCSymbol *fdeEnd = context.CreateTempSymbol();
-  const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
+  const TargetAsmInfo &TAsmInfo = context.getTargetAsmInfo();
 
-  if (!asmInfo.isFunctionEHFrameSymbolPrivate() && IsEH) {
+  if (!TAsmInfo.isFunctionEHFrameSymbolPrivate() && IsEH) {
     MCSymbol *EHSym = context.GetOrCreateSymbol(
       frame.Function->getName() + Twine(".eh"));
     streamer.EmitEHSymAttributes(frame.Function, EHSym);
@@ -751,19 +802,26 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
   streamer.EmitAbsValue(Length, 4);
 
   streamer.EmitLabel(fdeStart);
+
   // CIE Pointer
+  const MCAsmInfo &asmInfo = context.getAsmInfo();
   if (IsEH) {
     const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
                                                  0);
     streamer.EmitAbsValue(offset, 4);
+  } else if (!asmInfo.doesDwarfRequireRelocationForSectionOffset()) {
+    const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
+                                                 cieStart, 0);
+    streamer.EmitAbsValue(offset, 4);
   } else {
     streamer.EmitSymbolValue(&cieStart, 4);
   }
-  unsigned fdeEncoding = asmInfo.getFDEEncoding(UsingCFI);
+  unsigned fdeEncoding = TAsmInfo.getFDEEncoding(UsingCFI);
   unsigned size = getSizeForEncoding(streamer, fdeEncoding);
 
   // PC Begin
-  unsigned PCBeginEncoding = IsEH ? fdeEncoding : dwarf::DW_EH_PE_absptr;
+  unsigned PCBeginEncoding = IsEH ? fdeEncoding :
+    (unsigned)dwarf::DW_EH_PE_absptr;
   unsigned PCBeginSize = getSizeForEncoding(streamer, PCBeginEncoding);
   EmitSymbol(streamer, *frame.Begin, PCBeginEncoding);
 
@@ -840,15 +898,18 @@ namespace llvm {
 void MCDwarfFrameEmitter::Emit(MCStreamer &streamer,
                                bool usingCFI,
                                bool isEH) {
-  const MCContext &context = streamer.getContext();
+  MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
   const MCSection &section = isEH ?
-    *asmInfo.getEHFrameSection() : *asmInfo.getDwarfFrameSection();
+    *asmInfo.getEHFrameSection() :
+    *asmInfo.getDwarfFrameSection();
   streamer.SwitchSection(&section);
+  MCSymbol *SectionStart = context.CreateTempSymbol();
+  streamer.EmitLabel(SectionStart);
 
   MCSymbol *fdeEnd = NULL;
   DenseMap<CIEKey, const MCSymbol*> CIEStarts;
-  FrameEmitterImpl Emitter(usingCFI, isEH);
+  FrameEmitterImpl Emitter(usingCFI, isEH, SectionStart);
 
   const MCSymbol *DummyDebugKey = NULL;
   for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
@@ -856,11 +917,17 @@ void MCDwarfFrameEmitter::Emit(MCStreamer &streamer,
     CIEKey key(frame.Personality, frame.PersonalityEncoding,
                frame.LsdaEncoding);
     const MCSymbol *&cieStart = isEH ? CIEStarts[key] : DummyDebugKey;
+    if (isEH && asmInfo.getSupportsCompactUnwindInfo() &&
+        Emitter.EmitCompactUnwind(streamer, frame))
+      continue;
+
     if (!cieStart)
       cieStart = &Emitter.EmitCIE(streamer, frame.Personality,
                                   frame.PersonalityEncoding, frame.Lsda,
                                   frame.LsdaEncoding);
+
     fdeEnd = Emitter.EmitFDE(streamer, *cieStart, frame);
+
     if (i != n - 1)
       streamer.EmitLabel(fdeEnd);
   }