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 // 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) {

   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);

   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