MC: Split MCObjectWriter out of MCAssembler.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98949 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 184 insertions, 17 deletions

diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
index 1c21bbaf32..41e751549c 100644
--- a/include/llvm/MC/MCAssembler.h
+++ b/include/llvm/MC/MCAssembler.h
@@ -26,6 +26,7 @@ class MCAssembler;
 class MCContext;
 class MCExpr;
 class MCFragment;
+class MCObjectWriter;
 class MCSection;
 class MCSectionData;
 class MCSymbol;
@@ -618,6 +619,23 @@ private:
   unsigned SubsectionsViaSymbols : 1;
 
 private:
+  /// Evaluate a fixup to a relocatable expression and the value which should be
+  /// placed into the fixup.
+  ///
+  /// \param Layout The layout to use for evaluation.
+  /// \param Fixup The fixup to evaluate.
+  /// \param DF The fragment the fixup is inside.
+  /// \param Target [out] On return, the relocatable expression the fixup
+  /// evaluates to.
+  /// \param Value [out] On return, the value of the fixup as currently layed
+  /// out.
+  /// \return Whether the fixup value was fully resolved. This is true if the
+  /// \arg Value result is fixed, otherwise the value may change due to
+  /// relocation.
+  bool EvaluateFixup(const MCAsmLayout &Layout,
+                     MCAsmFixup &Fixup, MCDataFragment *DF,
+                     MCValue &Target, uint64_t &Value) const;
+
   /// Check whether a fixup can be satisfied, or whether it needs to be relaxed
   /// (increased in size, in order to hold its value correctly).
   bool FixupNeedsRelaxation(MCAsmFixup &Fixup, MCDataFragment *DF);
@@ -631,7 +649,6 @@ private:
   /// were adjusted.
   bool LayoutOnce();
 
-  // FIXME: Make protected once we factor out object writer classes.
 public:
   /// Find the symbol which defines the atom containing given address, inside
   /// the given section, or null if there is no such symbol.
@@ -652,22 +669,10 @@ public:
   /// defining a separate atom.
   bool isSymbolLinkerVisible(const MCSymbolData *SD) const;
 
-  /// Evaluate a fixup to a relocatable expression and the value which should be
-  /// placed into the fixup.
-  ///
-  /// \param Layout The layout to use for evaluation.
-  /// \param Fixup The fixup to evaluate.
-  /// \param DF The fragment the fixup is inside.
-  /// \param Target [out] On return, the relocatable expression the fixup
-  /// evaluates to.
-  /// \param Value [out] On return, the value of the fixup as currently layed
-  /// out.
-  /// \return Whether the fixup value was fully resolved. This is true if the
-  /// \arg Value result is fixed, otherwise the value may change due to
-  /// relocation.
-  bool EvaluateFixup(const MCAsmLayout &Layout,
-                     MCAsmFixup &Fixup, MCDataFragment *DF,
-                     MCValue &Target, uint64_t &Value) const;
+  /// Emit the section contents using the given object writer.
+  //
+  // FIXME: Should MCAssembler always have a reference to the object writer?
+  void WriteSectionData(const MCSectionData *Section, MCObjectWriter *OW) const;
 
 public:
   /// Construct a new assembler instance.
diff --git a/include/llvm/MC/MCObjectWriter.h b/include/llvm/MC/MCObjectWriter.h
new file mode 100644
index 0000000000..d4fab0ea47
--- /dev/null
+++ b/include/llvm/MC/MCObjectWriter.h
@@ -0,0 +1,162 @@
+//===-- llvm/MC/MCObjectWriter.h - Object File Writer Interface -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCOBJECTWRITER_H
+#define LLVM_MC_MCOBJECTWRITER_H
+
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/System/DataTypes.h"
+#include <cassert>
+
+namespace llvm {
+class MCAsmFixup;
+class MCAssembler;
+class MCDataFragment;
+class MCValue;
+class raw_ostream;
+
+/// MCObjectWriter - Defines the object file and target independent interfaces
+/// used by the assembler backend to write native file format object files.
+///
+/// The object writer contains a few callbacks used by the assembler to allow
+/// the object writer to modify the assembler data structures at appropriate
+/// points. Once assembly is complete, the object writer is given the
+/// MCAssembler instance, which contains all the symbol and section data which
+/// should be emitted as part of WriteObject().
+///
+/// The object writer also contains a number of helper methods for writing
+/// binary data to the output stream.
+class MCObjectWriter {
+  MCObjectWriter(const MCObjectWriter &); // DO NOT IMPLEMENT
+  void operator=(const MCObjectWriter &); // DO NOT IMPLEMENT
+
+protected:
+  raw_ostream &OS;
+
+  unsigned IsLittleEndian : 1;
+
+protected: // Can only create subclasses.
+  MCObjectWriter(raw_ostream &_OS, bool _IsLittleEndian)
+    : OS(_OS), IsLittleEndian(_IsLittleEndian) {}
+
+public:
+  virtual ~MCObjectWriter();
+
+  bool isLittleEndian() { return IsLittleEndian; }
+
+  raw_ostream &getStream() { return OS; }
+
+  /// @name High-Level API
+  /// @{
+
+  /// Perform any late binding of symbols (for example, to assign symbol indices
+  /// for use when generating relocations).
+  ///
+  /// This routine is called by the assembler after layout and relaxation is
+  /// complete.
+  virtual void ExecutePostLayoutBinding(MCAssembler &Asm) = 0;
+
+  /// Record a relocation entry.
+  ///
+  /// This routine is called by the assembler after layout and relaxation, and
+  /// post layout binding. The implementation is responsible for storing
+  /// information about the relocation so that it can be emitted during
+  /// WriteObject().
+  virtual void RecordRelocation(const MCAssembler &Asm,
+                                const MCDataFragment &Fragment,
+                                const MCAsmFixup &Fixup, MCValue Target,
+                                uint64_t &FixedValue) = 0;
+
+  /// Write the object file.
+  ///
+  /// This routine is called by the assembler after layout and relaxation is
+  /// complete, fixups have been evaluate and applied, and relocations
+  /// generated.
+  virtual void WriteObject(const MCAssembler &Asm) = 0;
+
+  /// @}
+  /// @name Binary Output
+  /// @{
+
+  void Write8(uint8_t Value) {
+    OS << char(Value);
+  }
+
+  void WriteLE16(uint16_t Value) {
+    Write8(uint8_t(Value >> 0));
+    Write8(uint8_t(Value >> 8));
+  }
+
+  void WriteLE32(uint32_t Value) {
+    WriteLE16(uint16_t(Value >> 0));
+    WriteLE16(uint16_t(Value >> 16));
+  }
+
+  void WriteLE64(uint64_t Value) {
+    WriteLE32(uint32_t(Value >> 0));
+    WriteLE32(uint32_t(Value >> 32));
+  }
+
+  void WriteBE16(uint16_t Value) {
+    Write8(uint8_t(Value >> 8));
+    Write8(uint8_t(Value >> 0));
+  }
+
+  void WriteBE32(uint32_t Value) {
+    WriteBE16(uint16_t(Value >> 16));
+    WriteBE16(uint16_t(Value >> 0));
+  }
+
+  void WriteBE64(uint64_t Value) {
+    WriteBE32(uint32_t(Value >> 32));
+    WriteBE32(uint32_t(Value >> 0));
+  }
+
+  void Write16(uint16_t Value) {
+    if (IsLittleEndian)
+      WriteLE16(Value);
+    else
+      WriteBE16(Value);
+  }
+
+  void Write32(uint32_t Value) {
+    if (IsLittleEndian)
+      WriteLE32(Value);
+    else
+      WriteBE32(Value);
+  }
+
+  void Write64(uint64_t Value) {
+    if (IsLittleEndian)
+      WriteLE64(Value);
+    else
+      WriteBE64(Value);
+  }
+
+  void WriteZeros(unsigned N) {
+    const char Zeros[16] = { 0 };
+
+    for (unsigned i = 0, e = N / 16; i != e; ++i)
+      OS << StringRef(Zeros, 16);
+
+    OS << StringRef(Zeros, N % 16);
+  }
+
+  void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) {
+    OS << Str;
+    if (ZeroFillSize)
+      WriteZeros(ZeroFillSize - Str.size());
+  }
+
+  /// @}
+};
+
+} // End llvm namespace
+
+#endif