text: // Copyright (c) 2010, Google Inc.
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
  
  // cfi_assembler.cc: Implementation of google_breakpad::CFISection class.
  // See cfi_assembler.h for details.
  
  #include "common/dwarf/cfi_assembler.h"
  
  #include <assert.h>
  #include <stdlib.h>
  
  namespace google_breakpad {
  
  using dwarf2reader::DwarfPointerEncoding;
    
  CFISection &CFISection::CIEHeader(uint64_t code_alignment_factor,
                                    int data_alignment_factor,
                                    unsigned return_address_register,
                                    uint8_t version,
                                    const string &augmentation,
                                    bool dwarf64,
                                    uint8_t address_size,
                                    uint8_t segment_size) {
    assert(!entry_length_);
    entry_length_ = new PendingLength();
    in_fde_ = false;
  
    if (dwarf64) {
      D32(kDwarf64InitialLengthMarker);
      D64(entry_length_->length);
      entry_length_->start = Here();
      D64(eh_frame_ ? kEHFrame64CIEIdentifier : kDwarf64CIEIdentifier);
    } else {
      D32(entry_length_->length);
      entry_length_->start = Here();
      D32(eh_frame_ ? kEHFrame32CIEIdentifier : kDwarf32CIEIdentifier);
    }
    D8(version);
    AppendCString(augmentation);
    if (version >= 4) {
      D8(address_size);
      D8(segment_size);
    }
    ULEB128(code_alignment_factor);
    LEB128(data_alignment_factor);
    if (version == 1)
      D8(return_address_register);
    else
      ULEB128(return_address_register);
    return *this;
  }
  
  CFISection &CFISection::FDEHeader(Label cie_pointer,
                                    uint64_t initial_location,
                                    uint64_t address_range,
                                    bool dwarf64) {
    assert(!entry_length_);
    entry_length_ = new PendingLength();
    in_fde_ = true;
    fde_start_address_ = initial_location;
  
    if (dwarf64) {
      D32(0xffffffff);
      D64(entry_length_->length);
      entry_length_->start = Here();
      if (eh_frame_)
        D64(Here() - cie_pointer);
      else
        D64(cie_pointer);
    } else {
      D32(entry_length_->length);
      entry_length_->start = Here();
      if (eh_frame_)
        D32(Here() - cie_pointer);
      else
        D32(cie_pointer);
    }
    EncodedPointer(initial_location);
    // The FDE length in an .eh_frame section uses the same encoding as the
    // initial location, but ignores the base address (selected by the upper
    // nybble of the encoding), as it's a length, not an address that can be
    // made relative.
    EncodedPointer(address_range,
                   DwarfPointerEncoding(pointer_encoding_ & 0x0f));
    return *this;
  }
  
  CFISection &CFISection::FinishEntry() {
    assert(entry_length_);
    Align(address_size_, dwarf2reader::DW_CFA_nop);
    entry_length_->length = Here() - entry_length_->start;
    delete entry_length_;
    entry_length_ = NULL;
    in_fde_ = false;
    return *this;
  }
  
  CFISection &CFISection::EncodedPointer(uint64_t address,
                                         DwarfPointerEncoding encoding,
                                         const EncodedPointerBases &bases) {
    // Omitted data is extremely easy to emit.
    if (encoding == dwarf2reader::DW_EH_PE_omit)
      return *this;
  
    // If (encoding & dwarf2reader::DW_EH_PE_indirect) != 0, then we assume
    // that ADDRESS is the address at which the pointer is stored --- in
    // other words, that bit has no effect on how we write the pointer.
    encoding = DwarfPointerEncoding(encoding & ~dwarf2reader::DW_EH_PE_indirect);
  
    // Find the base address to which this pointer is relative. The upper
    // nybble of the encoding specifies this.
    uint64_t base;
    switch (encoding & 0xf0) {
      case dwarf2reader::DW_EH_PE_absptr:  base = 0;                  break;
      case dwarf2reader::DW_EH_PE_pcrel:   base = bases.cfi + Size(); break;
      case dwarf2reader::DW_EH_PE_textrel: base = bases.text;         break;
      case dwarf2reader::DW_EH_PE_datarel: base = bases.data;         break;
      case dwarf2reader::DW_EH_PE_funcrel: base = fde_start_address_; break;
      case dwarf2reader::DW_EH_PE_aligned: base = 0;                  break;
      default: abort();
    };
  
    // Make ADDRESS relative. Yes, this is appropriate even for "absptr"
    // values; see gcc/unwind-pe.h.
    address -= base;
  
    // Align the pointer, if required.
    if ((encoding & 0xf0) == dwarf2reader::DW_EH_PE_aligned)
      Align(AddressSize());
  
    // Append ADDRESS to this section in the appropriate form. For the
    // fixed-width forms, we don't need to differentiate between signed and
    // unsigned encodings, because ADDRESS has already been extended to 64
    // bits before it was passed to us.
    switch (encoding & 0x0f) {
      case dwarf2reader::DW_EH_PE_absptr:
        Address(address);
        break;
  
      case dwarf2reader::DW_EH_PE_uleb128:
        ULEB128(address);
        break;
  
      case dwarf2reader::DW_EH_PE_sleb128:
        LEB128(address);
        break;
  
      case dwarf2reader::DW_EH_PE_udata2:
      case dwarf2reader::DW_EH_PE_sdata2:
        D16(address);
        break;
  
      case dwarf2reader::DW_EH_PE_udata4:
      case dwarf2reader::DW_EH_PE_sdata4:
        D32(address);
        break;
  
      case dwarf2reader::DW_EH_PE_udata8:
      case dwarf2reader::DW_EH_PE_sdata8:
        D64(address);
        break;
  
      default:
        abort();
    }
  
    return *this;
  };
  
  const uint32_t CFISection::kDwarf64InitialLengthMarker;
  const uint32_t CFISection::kDwarf32CIEIdentifier;
  const uint64_t CFISection::kDwarf64CIEIdentifier;
  const uint32_t CFISection::kEHFrame32CIEIdentifier;
  const uint64_t CFISection::kEHFrame64CIEIdentifier;
  
  } // namespace google_breakpad
  