Rebased PNaCl localmods in LLVM to 223109

lib/MC/MCNaCl.cpp

+//===- 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 {
+
+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);
+
+  // For gas, override the size of DWARF address values generated by .loc
+  // directives.
+  if (TheTriple.getArch() == Triple::x86_64 &&
+      Streamer.hasRawTextSupport()) {
+    Streamer.EmitRawText("\t.dwarf_addr_size 4\n");
+  }
+  // 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);
+
+  Streamer.PushSection();
+  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);
+  Streamer.PopSection();
+}
+
+} // namespace llvm