1 files changed, 418 insertions, 0 deletions
diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
new file mode 100644
index 000000000000..418971df3292
--- /dev/null
+++ b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -0,0 +1,418 @@
+//===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file assembles .s files and emits ARM ELF .o object files. Different
+// from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
+// delimit regions of data and code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARMUnwindOp.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCELF.h"
+#include "llvm/MC/MCELFStreamer.h"
+#include "llvm/MC/MCELFSymbolFlags.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCObjectStreamer.h"
+#include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+namespace {
+
+/// Extend the generic ELFStreamer class so that it can emit mapping symbols at
+/// the appropriate points in the object files. These symbols are defined in the
+/// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
+///
+/// In brief: $a, $t or $d should be emitted at the start of each contiguous
+/// region of ARM code, Thumb code or data in a section. In practice, this
+/// emission does not rely on explicit assembler directives but on inherent
+/// properties of the directives doing the emission (e.g. ".byte" is data, "add
+/// r0, r0, r0" an instruction).
+///
+/// As a result this system is orthogonal to the DataRegion infrastructure used
+/// by MachO. Beware!
+class ARMELFStreamer : public MCELFStreamer {
+public:
+  ARMELFStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &OS,
+                 MCCodeEmitter *Emitter, bool IsThumb)
+      : MCELFStreamer(SK_ARMELFStreamer, Context, TAB, OS, Emitter),
+        IsThumb(IsThumb), MappingSymbolCounter(0), LastEMS(EMS_None), ExTab(0),
+        FnStart(0), Personality(0), CantUnwind(false) {}
+
+  ~ARMELFStreamer() {}
+
+  // ARM exception handling directives
+  virtual void EmitFnStart();
+  virtual void EmitFnEnd();
+  virtual void EmitCantUnwind();
+  virtual void EmitPersonality(const MCSymbol *Per);
+  virtual void EmitHandlerData();
+  virtual void EmitSetFP(unsigned NewFpReg,
+                         unsigned NewSpReg,
+                         int64_t Offset = 0);
+  virtual void EmitPad(int64_t Offset);
+  virtual void EmitRegSave(const SmallVectorImpl<unsigned> &RegList,
+                           bool isVector);
+
+  virtual void ChangeSection(const MCSection *Section) {
+    // We have to keep track of the mapping symbol state of any sections we
+    // use. Each one should start off as EMS_None, which is provided as the
+    // default constructor by DenseMap::lookup.
+    LastMappingSymbols[getPreviousSection()] = LastEMS;
+    LastEMS = LastMappingSymbols.lookup(Section);
+
+    MCELFStreamer::ChangeSection(Section);
+  }
+
+  /// This function is the one used to emit instruction data into the ELF
+  /// streamer. We override it to add the appropriate mapping symbol if
+  /// necessary.
+  virtual void EmitInstruction(const MCInst& Inst) {
+    if (IsThumb)
+      EmitThumbMappingSymbol();
+    else
+      EmitARMMappingSymbol();
+
+    MCELFStreamer::EmitInstruction(Inst);
+  }
+
+  /// This is one of the functions used to emit data into an ELF section, so the
+  /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
+  /// necessary.
+  virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {
+    EmitDataMappingSymbol();
+    MCELFStreamer::EmitBytes(Data, AddrSpace);
+  }
+
+  /// This is one of the functions used to emit data into an ELF section, so the
+  /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
+  /// necessary.
+  virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
+                             unsigned AddrSpace) {
+    EmitDataMappingSymbol();
+    MCELFStreamer::EmitValueImpl(Value, Size, AddrSpace);
+  }
+
+  virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {
+    MCELFStreamer::EmitAssemblerFlag(Flag);
+
+    switch (Flag) {
+    case MCAF_SyntaxUnified:
+      return; // no-op here.
+    case MCAF_Code16:
+      IsThumb = true;
+      return; // Change to Thumb mode
+    case MCAF_Code32:
+      IsThumb = false;
+      return; // Change to ARM mode
+    case MCAF_Code64:
+      return;
+    case MCAF_SubsectionsViaSymbols:
+      return;
+    }
+  }
+
+  static bool classof(const MCStreamer *S) {
+    return S->getKind() == SK_ARMELFStreamer;
+  }
+
+private:
+  enum ElfMappingSymbol {
+    EMS_None,
+    EMS_ARM,
+    EMS_Thumb,
+    EMS_Data
+  };
+
+  void EmitDataMappingSymbol() {
+    if (LastEMS == EMS_Data) return;
+    EmitMappingSymbol("$d");
+    LastEMS = EMS_Data;
+  }
+
+  void EmitThumbMappingSymbol() {
+    if (LastEMS == EMS_Thumb) return;
+    EmitMappingSymbol("$t");
+    LastEMS = EMS_Thumb;
+  }
+
+  void EmitARMMappingSymbol() {
+    if (LastEMS == EMS_ARM) return;
+    EmitMappingSymbol("$a");
+    LastEMS = EMS_ARM;
+  }
+
+  void EmitMappingSymbol(StringRef Name) {
+    MCSymbol *Start = getContext().CreateTempSymbol();
+    EmitLabel(Start);
+
+    MCSymbol *Symbol =
+      getContext().GetOrCreateSymbol(Name + "." +
+                                     Twine(MappingSymbolCounter++));
+
+    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
+    MCELF::SetType(SD, ELF::STT_NOTYPE);
+    MCELF::SetBinding(SD, ELF::STB_LOCAL);
+    SD.setExternal(false);
+    Symbol->setSection(*getCurrentSection());
+
+    const MCExpr *Value = MCSymbolRefExpr::Create(Start, getContext());
+    Symbol->setVariableValue(Value);
+  }
+
+  void EmitThumbFunc(MCSymbol *Func) {
+    // FIXME: Anything needed here to flag the function as thumb?
+
+    getAssembler().setIsThumbFunc(Func);
+
+    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Func);
+    SD.setFlags(SD.getFlags() | ELF_Other_ThumbFunc);
+  }
+
+  // Helper functions for ARM exception handling directives
+  void Reset();
+
+  void EmitPersonalityFixup(StringRef Name);
+
+  void SwitchToEHSection(const char *Prefix, unsigned Type, unsigned Flags,
+                         SectionKind Kind, const MCSymbol &Fn);
+  void SwitchToExTabSection(const MCSymbol &FnStart);
+  void SwitchToExIdxSection(const MCSymbol &FnStart);
+
+  bool IsThumb;
+  int64_t MappingSymbolCounter;
+
+  DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
+  ElfMappingSymbol LastEMS;
+
+  // ARM Exception Handling Frame Information
+  MCSymbol *ExTab;
+  MCSymbol *FnStart;
+  const MCSymbol *Personality;
+  bool CantUnwind;
+};
+}
+
+inline void ARMELFStreamer::SwitchToEHSection(const char *Prefix,
+                                              unsigned Type,
+                                              unsigned Flags,
+                                              SectionKind Kind,
+                                              const MCSymbol &Fn) {
+  const MCSectionELF &FnSection =
+    static_cast<const MCSectionELF &>(Fn.getSection());
+
+  // Create the name for new section
+  StringRef FnSecName(FnSection.getSectionName());
+  SmallString<128> EHSecName(Prefix);
+  if (FnSecName != ".text") {
+    EHSecName += FnSecName;
+  }
+
+  // Get .ARM.extab or .ARM.exidx section
+  const MCSectionELF *EHSection = NULL;
+  if (const MCSymbol *Group = FnSection.getGroup()) {
+    EHSection = getContext().getELFSection(
+      EHSecName, Type, Flags | ELF::SHF_GROUP, Kind,
+      FnSection.getEntrySize(), Group->getName());
+  } else {
+    EHSection = getContext().getELFSection(EHSecName, Type, Flags, Kind);
+  }
+  assert(EHSection);
+
+  // Switch to .ARM.extab or .ARM.exidx section
+  SwitchSection(EHSection);
+  EmitCodeAlignment(4, 0);
+}
+
+inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
+  SwitchToEHSection(".ARM.extab",
+                    ELF::SHT_PROGBITS,
+                    ELF::SHF_ALLOC,
+                    SectionKind::getDataRel(),
+                    FnStart);
+}
+
+inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
+  SwitchToEHSection(".ARM.exidx",
+                    ELF::SHT_ARM_EXIDX,
+                    ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
+                    SectionKind::getDataRel(),
+                    FnStart);
+}
+
+void ARMELFStreamer::Reset() {
+  ExTab = NULL;
+  FnStart = NULL;
+  Personality = NULL;
+  CantUnwind = false;
+}
+
+// Add the R_ARM_NONE fixup at the same position
+void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
+  const MCSymbol *PersonalitySym = getContext().GetOrCreateSymbol(Name);
+
+  const MCSymbolRefExpr *PersonalityRef =
+    MCSymbolRefExpr::Create(PersonalitySym,
+                            MCSymbolRefExpr::VK_ARM_NONE,
+                            getContext());
+
+  AddValueSymbols(PersonalityRef);
+  MCDataFragment *DF = getOrCreateDataFragment();
+  DF->getFixups().push_back(
+    MCFixup::Create(DF->getContents().size(), PersonalityRef,
+                    MCFixup::getKindForSize(4, false)));
+}
+
+void ARMELFStreamer::EmitFnStart() {
+  assert(FnStart == 0);
+  FnStart = getContext().CreateTempSymbol();
+  EmitLabel(FnStart);
+}
+
+void ARMELFStreamer::EmitFnEnd() {
+  assert(FnStart && ".fnstart must preceeds .fnend");
+
+  // Emit unwind opcodes if there is no .handlerdata directive
+  int PersonalityIndex = -1;
+  if (!ExTab && !CantUnwind) {
+    // For __aeabi_unwind_cpp_pr1, we have to emit opcodes in .ARM.extab.
+    SwitchToExTabSection(*FnStart);
+
+    // Create .ARM.extab label for offset in .ARM.exidx
+    ExTab = getContext().CreateTempSymbol();
+    EmitLabel(ExTab);
+
+    PersonalityIndex = 1;
+
+    uint32_t Entry = 0;
+    uint32_t NumExtraEntryWords = 0;
+    Entry |= NumExtraEntryWords << 24;
+    Entry |= (EHT_COMPACT | PersonalityIndex) << 16;
+
+    // TODO: This should be generated according to .save, .vsave, .setfp
+    // directives.  Currently, we are simply generating FINISH opcode.
+    Entry |= UNWIND_OPCODE_FINISH << 8;
+    Entry |= UNWIND_OPCODE_FINISH;
+
+    EmitIntValue(Entry, 4, 0);
+  }
+
+  // Emit the exception index table entry
+  SwitchToExIdxSection(*FnStart);
+
+  if (PersonalityIndex == 1)
+    EmitPersonalityFixup("__aeabi_unwind_cpp_pr1");
+
+  const MCSymbolRefExpr *FnStartRef =
+    MCSymbolRefExpr::Create(FnStart,
+                            MCSymbolRefExpr::VK_ARM_PREL31,
+                            getContext());
+
+  EmitValue(FnStartRef, 4, 0);
+
+  if (CantUnwind) {
+    EmitIntValue(EXIDX_CANTUNWIND, 4, 0);
+  } else {
+    const MCSymbolRefExpr *ExTabEntryRef =
+      MCSymbolRefExpr::Create(ExTab,
+                              MCSymbolRefExpr::VK_ARM_PREL31,
+                              getContext());
+    EmitValue(ExTabEntryRef, 4, 0);
+  }
+
+  // Clean exception handling frame information
+  Reset();
+}
+
+void ARMELFStreamer::EmitCantUnwind() {
+  CantUnwind = true;
+}
+
+void ARMELFStreamer::EmitHandlerData() {
+  SwitchToExTabSection(*FnStart);
+
+  // Create .ARM.extab label for offset in .ARM.exidx
+  assert(!ExTab);
+  ExTab = getContext().CreateTempSymbol();
+  EmitLabel(ExTab);
+
+  // Emit Personality
+  assert(Personality && ".personality directive must preceed .handlerdata");
+
+  const MCSymbolRefExpr *PersonalityRef =
+    MCSymbolRefExpr::Create(Personality,
+                            MCSymbolRefExpr::VK_ARM_PREL31,
+                            getContext());
+
+  EmitValue(PersonalityRef, 4, 0);
+
+  // Emit unwind opcodes
+  uint32_t Entry = 0;
+  uint32_t NumExtraEntryWords = 0;
+
+  // TODO: This should be generated according to .save, .vsave, .setfp
+  // directives.  Currently, we are simply generating FINISH opcode.
+  Entry |= NumExtraEntryWords << 24;
+  Entry |= UNWIND_OPCODE_FINISH << 16;
+  Entry |= UNWIND_OPCODE_FINISH << 8;
+  Entry |= UNWIND_OPCODE_FINISH;
+
+  EmitIntValue(Entry, 4, 0);
+}
+
+void ARMELFStreamer::EmitPersonality(const MCSymbol *Per) {
+  Personality = Per;
+}
+
+void ARMELFStreamer::EmitSetFP(unsigned NewFpReg,
+                               unsigned NewSpReg,
+                               int64_t Offset) {
+  // TODO: Not implemented
+}
+
+void ARMELFStreamer::EmitPad(int64_t Offset) {
+  // TODO: Not implemented
+}
+
+void ARMELFStreamer::EmitRegSave(const SmallVectorImpl<unsigned> &RegList,
+                                 bool IsVector) {
+  // TODO: Not implemented
+}
+
+namespace llvm {
+  MCELFStreamer* createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
+                                      raw_ostream &OS, MCCodeEmitter *Emitter,
+                                      bool RelaxAll, bool NoExecStack,
+                                      bool IsThumb) {
+    ARMELFStreamer *S = new ARMELFStreamer(Context, TAB, OS, Emitter, IsThumb);
+    if (RelaxAll)
+      S->getAssembler().setRelaxAll(true);
+    if (NoExecStack)
+      S->getAssembler().setNoExecStack(true);
+    return S;
+  }
+
+}
+
+