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//===- lib/MC/MCNaCl.cpp - NaCl-specific MC implementation ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCNaCl.h"
#include "llvm/ADT/Triple.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ELF.h"
static const char NoteNamespace[] = "NaCl";
namespace llvm {
cl::opt<bool>
FlagSfiData("sfi-data", cl::desc("use illegal at data bundle beginning"));
cl::opt<bool>
FlagSfiLoad("sfi-load", cl::desc("enable sandboxing for load"));
cl::opt<bool>
FlagSfiStore("sfi-store", cl::desc("enable sandboxing for stores"));
cl::opt<bool>
FlagSfiStack("sfi-stack", cl::desc("enable sandboxing for stack changes"));
cl::opt<bool>
FlagSfiBranch("sfi-branch", cl::desc("enable sandboxing for branches"));
void initializeNaClMCStreamer(MCStreamer &Streamer, MCContext &Ctx,
const Triple &TheTriple) {
assert(TheTriple.isOSNaCl());
const char *NoteName;
const char *NoteArch;
unsigned BundleAlign;
switch (TheTriple.getArch()) {
case Triple::arm:
NoteName = ".note.NaCl.ABI.arm";
NoteArch = "arm";
BundleAlign = 4;
break;
case Triple::mipsel:
NoteName = ".note.NaCl.ABI.mipsel";
NoteArch = "mipsel";
BundleAlign = 4;
break;
case Triple::x86:
NoteName = ".note.NaCl.ABI.x86-32";
NoteArch = "x86-32";
BundleAlign = 5;
break;
case Triple::x86_64:
NoteName = ".note.NaCl.ABI.x86-64";
NoteArch = "x86-64";
BundleAlign = 5;
break;
default:
report_fatal_error("Unsupported architecture for NaCl");
}
// Set bundle-alignment as required by the NaCl ABI for the target.
Streamer.EmitBundleAlignMode(BundleAlign);
// Emit an ELF Note section in its own COMDAT group which identifies NaCl
// object files to the gold linker, so it can use the NaCl layout.
const MCSection *Note = Ctx.getELFSection(
NoteName, ELF::SHT_NOTE, ELF::SHF_ALLOC | ELF::SHF_GROUP,
SectionKind::getReadOnly(), 0, NoteName);
// TODO(dschuff) This should probably use PushSection and PopSection, but
// PopSection will assert if there haven't been any other sections switched to
// yet.
Streamer.SwitchSection(Note);
Streamer.EmitIntValue(strlen(NoteNamespace) + 1, 4);
Streamer.EmitIntValue(strlen(NoteArch) + 1, 4);
Streamer.EmitIntValue(ELF::NT_VERSION, 4);
Streamer.EmitBytes(NoteNamespace);
Streamer.EmitIntValue(0, 1); // NUL terminator
Streamer.EmitValueToAlignment(4);
Streamer.EmitBytes(NoteArch);
Streamer.EmitIntValue(0, 1); // NUL terminator
Streamer.EmitValueToAlignment(4);
}
} // namespace llvm
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