Initial support for DWARF CFI parsing and dumping in LLVM

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174463 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 195 insertions, 0 deletions

diff --git a/lib/DebugInfo/DWARFDebugFrame.cpp b/lib/DebugInfo/DWARFDebugFrame.cpp
new file mode 100644
index 0000000000..0b78cce1dd
--- /dev/null
+++ b/lib/DebugInfo/DWARFDebugFrame.cpp
@@ -0,0 +1,195 @@
+//===-- DWARFDebugFrame.h - Parsing of .debug_frame -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFDebugFrame.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Format.h"
+
+using namespace llvm;
+using namespace dwarf;
+
+
+class llvm::FrameEntry {
+public:
+  enum FrameKind {FK_CIE, FK_FDE};
+  FrameEntry(FrameKind K, DataExtractor D, uint64_t Offset, uint64_t Length)
+    : Kind(K), Data(D), Offset(Offset), Length(Length)
+  {}
+
+  FrameKind getKind() const { return Kind; }
+
+  virtual void dumpHeader(raw_ostream &OS) const = 0;
+protected:
+  const FrameKind Kind;
+  DataExtractor Data;
+  uint64_t Offset;
+  uint64_t Length;
+};
+
+
+class CIE : public FrameEntry {
+public:
+  // CIEs (and FDEs) are simply container classes, so the only sensible way to
+  // create them is by providing the full parsed contents in the constructor.
+  CIE(DataExtractor D, uint64_t Offset, uint64_t Length, uint8_t Version,
+      SmallString<8> Augmentation, uint64_t CodeAlignmentFactor,
+      int64_t DataAlignmentFactor, uint64_t ReturnAddressRegister)
+   : FrameEntry(FK_CIE, D, Offset, Length), Version(Version),
+     Augmentation(Augmentation), CodeAlignmentFactor(CodeAlignmentFactor),
+     DataAlignmentFactor(DataAlignmentFactor),
+     ReturnAddressRegister(ReturnAddressRegister)
+  {}
+
+  void dumpHeader(raw_ostream &OS) const {
+    OS << format("%08x %08x %08x CIE", Offset, Length, DW_CIE_ID) << "\n";
+    OS << format("  Version:               %d\n", Version);
+    OS << "  Augmentation:          \"" << Augmentation << "\"\n";
+    OS << format("  Code alignment factor: %u\n", CodeAlignmentFactor);
+    OS << format("  Data alignment factor: %d\n", DataAlignmentFactor);
+    OS << format("  Return address column: %d\n", ReturnAddressRegister);
+    OS << "\n";
+  }
+
+  static bool classof(const FrameEntry *FE) {
+    return FE->getKind() == FK_CIE;
+  } 
+private:
+  uint8_t Version;
+  SmallString<8> Augmentation;
+  uint64_t CodeAlignmentFactor;
+  int64_t DataAlignmentFactor;
+  uint64_t ReturnAddressRegister;
+};
+
+
+class FDE : public FrameEntry {
+public:
+  // Each FDE has a CIE it's "linked to". Our FDE contains is constructed with
+  // an offset to the CIE (provided by parsing the FDE header). The CIE itself
+  // is obtained lazily once it's actually required.
+  FDE(DataExtractor D, uint64_t Offset, uint64_t Length, int64_t LinkedCIEOffset,
+      uint64_t InitialLocation, uint64_t AddressRange)
+   : FrameEntry(FK_FDE, D, Offset, Length), LinkedCIEOffset(LinkedCIEOffset),
+     InitialLocation(InitialLocation), AddressRange(AddressRange),
+     LinkedCIE(NULL)
+  {}
+
+  void dumpHeader(raw_ostream &OS) const {
+    OS << format("%08x %08x %08x FDE ", Offset, Length, LinkedCIEOffset);
+    OS << format("cie=%08x pc=%08x...%08x\n",
+                 LinkedCIEOffset, InitialLocation,
+                 InitialLocation + AddressRange);
+    OS << "\n";
+  }
+
+  static bool classof(const FrameEntry *FE) {
+    return FE->getKind() == FK_FDE;
+  } 
+private:
+  uint64_t LinkedCIEOffset;
+  uint64_t InitialLocation;
+  uint64_t AddressRange;
+  CIE *LinkedCIE;
+};
+
+
+DWARFDebugFrame::DWARFDebugFrame()
+{
+}
+
+
+DWARFDebugFrame::~DWARFDebugFrame()
+{
+  for (EntryVector::iterator I = Entries.begin(), E = Entries.end();
+       I != E; ++I) {
+    delete *I;
+  }
+}
+
+
+static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
+                                              uint32_t Offset, int Length) {
+  errs() << "DUMP: ";
+  for (int i = 0; i < Length; ++i) {
+    uint8_t c = Data.getU8(&Offset);
+    errs().write_hex(c); errs() << " ";
+  }
+  errs() << "\n";
+}
+
+
+void DWARFDebugFrame::parse(DataExtractor Data) {
+  uint32_t Offset = 0;
+
+  while (Data.isValidOffset(Offset)) {
+    uint32_t StartOffset = Offset;
+
+    bool IsDWARF64 = false;
+    uint64_t Length = Data.getU32(&Offset);
+    uint64_t Id;
+
+    if (Length == UINT32_MAX) {
+      // DWARF-64 is distinguished by the first 32 bits of the initial length
+      // field being 0xffffffff. Then, the next 64 bits are the actual entry
+      // length.
+      IsDWARF64 = true;
+      Length = Data.getU64(&Offset);
+    }
+
+    // At this point, Offset points to the next field after Length.
+    // Length is the structure size excluding itself. Compute an offset one
+    // past the end of the structure (needed to know how many instructions to
+    // read).
+    // TODO: For honest DWARF64 support, DataExtractor will have to treat
+    //       offset_ptr as uint64_t*
+    uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);
+
+    // The Id field's size depends on the DWARF format
+    Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
+    bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);
+
+    if (IsCIE) {
+      // Note: this is specifically DWARFv3 CIE header structure. It was
+      // changed in DWARFv4.
+      uint8_t Version = Data.getU8(&Offset);
+      const char *Augmentation = Data.getCStr(&Offset);
+      uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
+      int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
+      uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);
+
+      CIE *NewCIE = new CIE(Data, StartOffset, Length, Version,
+                            StringRef(Augmentation), CodeAlignmentFactor,
+                            DataAlignmentFactor, ReturnAddressRegister);
+      Entries.push_back(NewCIE);
+    } else {
+      // FDE
+      uint64_t CIEPointer = Id;
+      uint64_t InitialLocation = Data.getAddress(&Offset);
+      uint64_t AddressRange = Data.getAddress(&Offset);
+
+      FDE *NewFDE = new FDE(Data, StartOffset, Length, CIEPointer,
+                            InitialLocation, AddressRange);
+      Entries.push_back(NewFDE);
+    }
+
+    Offset = EndStructureOffset;
+  }
+}
+
+
+void DWARFDebugFrame::dump(raw_ostream &OS) const {
+  OS << "\n";
+  for (EntryVector::const_iterator I = Entries.begin(), E = Entries.end();
+       I != E; ++I) {
+    (*I)->dumpHeader(OS);
+  }
+}
+