I added a new file ARMAsmBackend which stubs out in similar ways to

the eqv X86 class.
For now, I split the ELFARMAsmBackend from the DarwinARMAsmBackend
(also mimicking X86)

Tested against -r115126



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115129 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/ARMAsmBackend.cpp

@@ -0,0 +1,143 @@
+//===-- ARMAsmBackend.cpp - ARM Assembler Backend -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetAsmBackend.h"
+#include "ARM.h"
+//FIXME: add #include "ARMFixupKinds.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/MC/ELFObjectWriter.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSectionCOFF.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCSectionMachO.h"
+#include "llvm/MC/MachObjectWriter.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetRegistry.h"
+#include "llvm/Target/TargetAsmBackend.h"
+using namespace llvm;
+
+namespace {
+class ARMAsmBackend : public TargetAsmBackend {
+public:
+  ARMAsmBackend(const Target &T)
+    : TargetAsmBackend(T) {    
+  }
+
+  bool MayNeedRelaxation(const MCInst &Inst) const;
+
+  void RelaxInstruction(const MCInst &Inst, MCInst &Res) const;
+
+  bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const;
+};
+
+bool ARMAsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
+  // FIXME: Thumb targets, different move constant targets..
+  return false;
+}
+
+void ARMAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
+  assert(0 && "ARMAsmBackend::RelaxInstruction() unimplemented");
+  return;
+}
+
+bool ARMAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const {
+  assert(0 && "ARMAsmBackend::WriteNopData() unimplemented");
+  if ((Count % 4) != 0) {    
+    // Fixme: % 2 for Thumb?
+    return false;
+  }
+  return false;
+};
+} // end anonymous namespace
+
+namespace {
+// FIXME: This should be in a separate file.
+// ELF is an ELF of course...
+class ELFARMAsmBackend : public ARMAsmBackend {
+public:
+  Triple::OSType OSType;
+  ELFARMAsmBackend(const Target &T, Triple::OSType _OSType)
+    : ARMAsmBackend(T), OSType(_OSType) {
+    HasAbsolutizedSet = true;
+    HasScatteredSymbols = true;
+  }
+
+  void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
+                  uint64_t Value) const;
+
+  bool isVirtualSection(const MCSection &Section) const {
+    const MCSectionELF &SE = static_cast<const MCSectionELF&>(Section);
+    return SE.getType() == MCSectionELF::SHT_NOBITS;
+  }
+
+  MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
+    return new ELFObjectWriter(OS, /*Is64Bit=*/false,
+                               OSType,
+                               /*IsLittleEndian=*/true,
+                               /*HasRelocationAddend=*/false);
+  }
+};
+
+// Fixme: can we raise this to share code bet. Darwin and ELF?
+void ELFARMAsmBackend::ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
+                                  uint64_t Value) const {
+  assert(0 && "ELFARMAsmBackend::ApplyFixup() unimplemented");
+}
+
+// FIXME: This should be in a separate file.
+class DarwinARMAsmBackend : public ARMAsmBackend {
+public:
+  DarwinARMAsmBackend(const Target &T)
+    : ARMAsmBackend(T) {
+    HasAbsolutizedSet = true;
+    HasScatteredSymbols = true;
+    assert(0 && "DarwinARMAsmBackend::DarwinARMAsmBackend() unimplemented");
+  }
+
+  void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
+                  uint64_t Value) const;
+
+  bool isVirtualSection(const MCSection &Section) const {
+    const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
+    return (SMO.getType() == MCSectionMachO::S_ZEROFILL ||
+            SMO.getType() == MCSectionMachO::S_GB_ZEROFILL ||
+            SMO.getType() == MCSectionMachO::S_THREAD_LOCAL_ZEROFILL);
+  }
+
+  MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
+    return new MachObjectWriter(OS, /*Is64Bit=*/false);
+  }
+
+  virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
+    return false;
+  }
+};
+
+void DarwinARMAsmBackend::ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF,
+                                  uint64_t Value) const {
+  assert(0 && "DarwinARMAsmBackend::ApplyFixup() unimplemented");
+}
+} // end anonymous namespace 
+
+TargetAsmBackend *llvm::createARMAsmBackend(const Target &T,
+                                            const std::string &TT) {
+  switch (Triple(TT).getOS()) {
+  case Triple::Darwin:
+    return new DarwinARMAsmBackend(T);
+  case Triple::MinGW32:
+  case Triple::Cygwin:
+  case Triple::Win32:
+    assert(0 && "Windows not supported on ARM");
+  default:
+    return new ELFARMAsmBackend(T, Triple(TT).getOS());
+  }
+}