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Refactor data-in-code annotations.

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Use a dedicated MachO load command to annotate data-in-code regions.
This is the same format the linker produces for final executable images,
allowing consistency of representation and use of introspection tools
for both object and executable files.

Data-in-code regions are annotated via ".data_region"/".end_data_region"
directive pairs, with an optional region type.

data_region_directive := ".data_region" { region_type }
region_type := "jt8" | "jt16" | "jt32" | "jta32"
end_data_region_directive := ".end_data_region"

The previous handling of ARM-style "$d.*" labels was broken and has
been removed. Specifically, it didn't handle ARM vs. Thumb mode when
marking the end of the section.

rdar://11459456

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157062 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach
2012-05-18 19:12:01 +00:00
parent 18e2f6e94c
commit 3e96531186
28 changed files with 411 additions and 215 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
lib/MC/MachObjectWriter.cpp
View File

@ -21,6 +21,7 @@
#include "llvm/MC/MCMachOSymbolFlags.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Object/MachOFormat.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include <vector>
@ -351,6 +352,21 @@ void MachObjectWriter::WriteNlist(MachSymbolData &MSD,
Write32(Address);
}
void MachObjectWriter::WriteLinkeditLoadCommand(uint32_t Type,
uint32_t DataOffset,
uint32_t DataSize) {
uint64_t Start = OS.tell();
(void) Start;
Write32(Type);
Write32(macho::LinkeditLoadCommandSize);
Write32(DataOffset);
Write32(DataSize);
assert(OS.tell() - Start == macho::LinkeditLoadCommandSize);
}
void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
@ -654,6 +670,13 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
macho::DysymtabLoadCommandSize);
}
// Add the data-in-code load command size, if used.
unsigned NumDataRegions = Asm.getDataRegions().size();
if (NumDataRegions) {
++NumLoadCommands;
LoadCommandsSize += macho::LinkeditLoadCommandSize;
}
// Compute the total size of the section data, as well as its file size and vm
// size.
uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
@ -701,6 +724,15 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
RelocTableEnd += NumRelocs * macho::RelocationInfoSize;
}
// Write the data-in-code load command, if used.
uint64_t DataInCodeTableEnd = RelocTableEnd + NumDataRegions * 8;
if (NumDataRegions) {
uint64_t DataRegionsOffset = RelocTableEnd;
uint64_t DataRegionsSize = NumDataRegions * 8;
WriteLinkeditLoadCommand(macho::LCT_DataInCode, DataRegionsOffset,
DataRegionsSize);
}
// Write the symbol table load command, if used.
if (NumSymbols) {
unsigned FirstLocalSymbol = 0;
@ -717,10 +749,10 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
// If used, the indirect symbols are written after the section data.
if (NumIndirectSymbols)
IndirectSymbolOffset = RelocTableEnd;
IndirectSymbolOffset = DataInCodeTableEnd;
// The symbol table is written after the indirect symbol data.
uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
uint64_t SymbolTableOffset = DataInCodeTableEnd + IndirectSymbolSize;
// The string table is written after symbol table.
uint64_t StringTableOffset =
@ -760,6 +792,23 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
}
}
// Write out the data-in-code region payload, if there is one.
for (MCAssembler::const_data_region_iterator
it = Asm.data_region_begin(), ie = Asm.data_region_end();
it != ie; ++it) {
const DataRegionData *Data = &(*it);
uint64_t Start = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start), Layout);
uint64_t End = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End), Layout);
DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
<< " start: " << Start << "(" << Data->Start->getName() << ")"
<< " end: " << End << "(" << Data->End->getName() << ")"
<< " size: " << End - Start
<< "\n");
Write32(Start);
Write16(End - Start);
Write16(Data->Kind);
}
// Write the symbol table data, if used.
if (NumSymbols) {
// Write the indirect symbol entries.