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//===- DWARFDataExtractor.cpp ---------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
#include "llvm/DebugInfo/DWARF/DWARFObject.h"
#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
#include "llvm/Support/Errc.h"
using namespace llvm;
std::pair<uint64_t, dwarf::DwarfFormat>
DWARFDataExtractor::getInitialLength(uint64_t *Off, Error *Err) const {
ErrorAsOutParameter ErrAsOut(Err);
if (Err && *Err)
return {0, dwarf::DWARF32};
Cursor C(*Off);
uint64_t Length = getRelocatedValue(C, 4);
dwarf::DwarfFormat Format = dwarf::DWARF32;
if (Length == dwarf::DW_LENGTH_DWARF64) {
Length = getRelocatedValue(C, 8);
Format = dwarf::DWARF64;
} else if (Length >= dwarf::DW_LENGTH_lo_reserved) {
cantFail(C.takeError());
if (Err)
*Err = createStringError(
errc::invalid_argument,
"unsupported reserved unit length of value 0x%8.8" PRIx64, Length);
return {0, dwarf::DWARF32};
}
if (C) {
*Off = C.tell();
return {Length, Format};
}
if (Err)
*Err = C.takeError();
else
consumeError(C.takeError());
return {0, dwarf::DWARF32};
}
uint64_t DWARFDataExtractor::getRelocatedValue(uint32_t Size, uint64_t *Off,
uint64_t *SecNdx,
Error *Err) const {
if (SecNdx)
*SecNdx = object::SectionedAddress::UndefSection;
if (!Section)
return getUnsigned(Off, Size, Err);
ErrorAsOutParameter ErrAsOut(Err);
std::optional<RelocAddrEntry> E = Obj->find(*Section, *Off);
uint64_t LocData = getUnsigned(Off, Size, Err);
if (!E || (Err && *Err))
return LocData;
if (SecNdx)
*SecNdx = E->SectionIndex;
uint64_t R =
object::resolveRelocation(E->Resolver, E->Reloc, E->SymbolValue, LocData);
if (E->Reloc2)
R = object::resolveRelocation(E->Resolver, *E->Reloc2, E->SymbolValue2, R);
return R;
}
std::optional<uint64_t>
DWARFDataExtractor::getEncodedPointer(uint64_t *Offset, uint8_t Encoding,
uint64_t PCRelOffset) const {
if (Encoding == dwarf::DW_EH_PE_omit)
return std::nullopt;
uint64_t Result = 0;
uint64_t OldOffset = *Offset;
// First get value
switch (Encoding & 0x0F) {
case dwarf::DW_EH_PE_absptr:
switch (getAddressSize()) {
case 2:
case 4:
case 8:
Result = getUnsigned(Offset, getAddressSize());
break;
default:
return std::nullopt;
}
break;
case dwarf::DW_EH_PE_uleb128:
Result = getULEB128(Offset);
break;
case dwarf::DW_EH_PE_sleb128:
Result = getSLEB128(Offset);
break;
case dwarf::DW_EH_PE_udata2:
Result = getUnsigned(Offset, 2);
break;
case dwarf::DW_EH_PE_udata4:
Result = getUnsigned(Offset, 4);
break;
case dwarf::DW_EH_PE_udata8:
Result = getUnsigned(Offset, 8);
break;
case dwarf::DW_EH_PE_sdata2:
Result = getSigned(Offset, 2);
break;
case dwarf::DW_EH_PE_sdata4:
Result = SignExtend64<32>(getRelocatedValue(4, Offset));
break;
case dwarf::DW_EH_PE_sdata8:
Result = getRelocatedValue(8, Offset);
break;
default:
return std::nullopt;
}
// Then add relative offset, if required
switch (Encoding & 0x70) {
case dwarf::DW_EH_PE_absptr:
// do nothing
break;
case dwarf::DW_EH_PE_pcrel:
Result += PCRelOffset;
break;
case dwarf::DW_EH_PE_datarel:
case dwarf::DW_EH_PE_textrel:
case dwarf::DW_EH_PE_funcrel:
case dwarf::DW_EH_PE_aligned:
default:
*Offset = OldOffset;
return std::nullopt;
}
return Result;
}
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