7 files changed, 142 insertions, 20 deletions
diff --git a/lib/MC/CMakeLists.txt b/lib/MC/CMakeLists.txt
index 9ead33b..4cf71dc 100644
--- a/lib/MC/CMakeLists.txt
+++ b/lib/MC/CMakeLists.txt
@@ -18,4 +18,5 @@ add_llvm_library(LLVMMC
   MCStreamer.cpp
   MCSymbol.cpp
   MCValue.cpp
+  TargetAsmBackend.cpp
   )
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 6add1b4..66a0a24 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -134,6 +134,9 @@ public:
                                     unsigned ValueSize = 1,
                                     unsigned MaxBytesToEmit = 0);
 
+  virtual void EmitCodeAlignment(unsigned ByteAlignment,
+                                 unsigned MaxBytesToEmit = 0);
+
   virtual void EmitValueToOffset(const MCExpr *Offset,
                                  unsigned char Value = 0);
 
@@ -513,6 +516,13 @@ void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitCodeAlignment(unsigned ByteAlignment,
+                                      unsigned MaxBytesToEmit) {
+  // Emit with a text fill value.
+  EmitValueToAlignment(ByteAlignment, MAI.getTextAlignFillValue(),
+                       1, MaxBytesToEmit);
+}
+
 void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
                                       unsigned char Value) {
   // FIXME: Verify that Offset is associated with the current section.
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 653fbf2..96227db 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -42,6 +42,8 @@ STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
 static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
                           MachObjectWriter &MOW);
 
+static uint64_t WriteNopData(uint64_t Count, MachObjectWriter &MOW);
+
 /// isVirtualSection - Check if this is a section which does not actually exist
 /// in the object file.
 static bool isVirtualSection(const MCSection &Section) {
@@ -51,7 +53,7 @@ static bool isVirtualSection(const MCSection &Section) {
   return (Type == MCSectionMachO::S_ZEROFILL);
 }
 
-static unsigned getFixupKindLog2Size(MCFixupKind Kind) {
+static unsigned getFixupKindLog2Size(unsigned Kind) {
   switch (Kind) {
   default: llvm_unreachable("invalid fixup kind!");
   case X86::reloc_pcrel_1byte:
@@ -64,7 +66,7 @@ static unsigned getFixupKindLog2Size(MCFixupKind Kind) {
   }
 }
 
-static bool isFixupKindPCRel(MCFixupKind Kind) {
+static bool isFixupKindPCRel(unsigned Kind) {
   switch (Kind) {
   default:
     return false;
@@ -439,6 +441,7 @@ public:
                                      std::vector<MachRelocationEntry> &Relocs) {
     uint32_t Address = Fragment.getOffset() + Fixup.Offset;
     unsigned IsPCRel = 0;
+    unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
     unsigned Type = RIT_Vanilla;
 
     // See <reloc.h>.
@@ -454,12 +457,10 @@ public:
       Value2 = SD->getFragment()->getAddress() + SD->getOffset();
     }
 
-    unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
-
     // The value which goes in the fixup is current value of the expression.
     Fixup.FixedValue = Value - Value2 + Target.getConstant();
     if (isFixupKindPCRel(Fixup.Kind)) {
-      Fixup.FixedValue -= Address + (1 << Log2Size);
+      Fixup.FixedValue -= Address;
       IsPCRel = 1;
     }
 
@@ -507,6 +508,7 @@ public:
     uint32_t Value = 0;
     unsigned Index = 0;
     unsigned IsPCRel = 0;
+    unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
     unsigned IsExtern = 0;
     unsigned Type = 0;
 
@@ -544,10 +546,8 @@ public:
     // The value which goes in the fixup is current value of the expression.
     Fixup.FixedValue = Value + Target.getConstant();
 
-    unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
-
     if (isFixupKindPCRel(Fixup.Kind)) {
-      Fixup.FixedValue -= Address + (1<<Log2Size);
+      Fixup.FixedValue -= Address;
       IsPCRel = 1;
     }
 
@@ -1060,6 +1060,64 @@ void MCAssembler::LayoutSection(MCSectionData &SD) {
     SD.setFileSize(Address - SD.getAddress());
 }
 
+/// WriteNopData - Write optimal nops to the output file for the \arg Count
+/// bytes.  This returns the number of bytes written.  It may return 0 if
+/// the \arg Count is more than the maximum optimal nops.
+///
+/// FIXME this is X86 32-bit specific and should move to a better place.
+static uint64_t WriteNopData(uint64_t Count, MachObjectWriter &MOW) {
+  static const uint8_t Nops[16][16] = {
+    // nop
+    {0x90},
+    // xchg %ax,%ax
+    {0x66, 0x90},
+    // nopl (%[re]ax)
+    {0x0f, 0x1f, 0x00},
+    // nopl 0(%[re]ax)
+    {0x0f, 0x1f, 0x40, 0x00},
+    // nopl 0(%[re]ax,%[re]ax,1)
+    {0x0f, 0x1f, 0x44, 0x00, 0x00},
+    // nopw 0(%[re]ax,%[re]ax,1)
+    {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+    // nopl 0L(%[re]ax)
+    {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+    // nopl 0L(%[re]ax,%[re]ax,1)
+    {0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+    // nopw 0L(%[re]ax,%[re]ax,1)
+    {0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+    // nopw %cs:0L(%[re]ax,%[re]ax,1)
+    {0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+    // nopl 0(%[re]ax,%[re]ax,1)
+    // nopw 0(%[re]ax,%[re]ax,1)
+    {0x0f, 0x1f, 0x44, 0x00, 0x00,
+     0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+    // nopw 0(%[re]ax,%[re]ax,1)
+    // nopw 0(%[re]ax,%[re]ax,1)
+    {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
+     0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+    // nopw 0(%[re]ax,%[re]ax,1)
+    // nopl 0L(%[re]ax) */
+    {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
+     0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+    // nopl 0L(%[re]ax)
+    // nopl 0L(%[re]ax)
+    {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
+     0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+    // nopl 0L(%[re]ax)
+    // nopl 0L(%[re]ax,%[re]ax,1)
+    {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
+     0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}
+  };
+
+  if (Count > 15)
+    return 0;
+
+  for (uint64_t i = 0; i < Count; i++)
+    MOW.Write8 (uint8_t(Nops[Count - 1][i]));
+
+  return Count;
+}
+
 /// WriteFileData - Write the \arg F data to the output file.
 static void WriteFileData(raw_ostream &OS, const MCFragment &F,
                           MachObjectWriter &MOW) {
@@ -1083,6 +1141,14 @@ static void WriteFileData(raw_ostream &OS, const MCFragment &F,
                         "' is not a divisor of padding size '" +
                         Twine(AF.getFileSize()) + "'");
 
+    // See if we are aligning with nops, and if so do that first to try to fill
+    // the Count bytes.  Then if that did not fill any bytes or there are any
+    // bytes left to fill use the the Value and ValueSize to fill the rest.
+    if (AF.getEmitNops()) {
+      uint64_t NopByteCount = WriteNopData(Count, MOW);
+      Count -= NopByteCount;
+    }
+
     for (uint64_t i = 0; i != Count; ++i) {
       switch (AF.getValueSize()) {
       default:
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 0c9627d..a7a8a5d 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -137,6 +137,8 @@ public:
   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
                                     unsigned ValueSize = 1,
                                     unsigned MaxBytesToEmit = 0);
+  virtual void EmitCodeAlignment(unsigned ByteAlignment,
+                                 unsigned MaxBytesToEmit = 0);
   virtual void EmitValueToOffset(const MCExpr *Offset,
                                  unsigned char Value = 0);
   
@@ -333,15 +335,13 @@ void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
 
 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
                                 unsigned AddrSpace) {
-  // Assume the front-end will have evaluate things absolute expressions, so
-  // just create data + fixup.
   MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
   if (!DF)
     DF = new MCDataFragment(CurSectionData);
 
   // Avoid fixups when possible.
   int64_t AbsValue;
-  if (Value->EvaluateAsAbsolute(AbsValue)) {
+  if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
     // FIXME: Endianness assumption.
     for (unsigned i = 0; i != Size; ++i)
       DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
@@ -359,7 +359,20 @@ void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
   if (MaxBytesToEmit == 0)
     MaxBytesToEmit = ByteAlignment;
   new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
-                      CurSectionData);
+                      false /* EmitNops */, CurSectionData);
+
+  // Update the maximum alignment on the current section if necessary.
+  if (ByteAlignment > CurSectionData->getAlignment())
+    CurSectionData->setAlignment(ByteAlignment);
+}
+
+void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
+                                        unsigned MaxBytesToEmit) {
+  if (MaxBytesToEmit == 0)
+    MaxBytesToEmit = ByteAlignment;
+  // FIXME the 0x90 is the default x86 1 byte nop opcode.
+  new MCAlignFragment(ByteAlignment, 0x90, 1, MaxBytesToEmit,
+                      true /* EmitNops */, CurSectionData);
 
   // Update the maximum alignment on the current section if necessary.
   if (ByteAlignment > CurSectionData->getAlignment())
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index 46e9ebf..ab61799 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -55,6 +55,9 @@ namespace {
                                       unsigned ValueSize = 1,
                                       unsigned MaxBytesToEmit = 0) {}
 
+    virtual void EmitCodeAlignment(unsigned ByteAlignment,
+                                   unsigned MaxBytesToEmit = 0) {}
+
     virtual void EmitValueToOffset(const MCExpr *Offset,
                                    unsigned char Value = 0) {}
     
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 51ad5d1..6185c30 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -146,7 +146,7 @@ bool AsmParser::Run() {
   // FIXME: Target hook & command line option for initial section.
   Out.SwitchSection(getMachOSection("__TEXT", "__text",
                                     MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
-                                    0, SectionKind()));
+                                    0, SectionKind::getText()));
 
 
   // Prime the lexer.
@@ -914,8 +914,10 @@ bool AsmParser::ParseDirectiveDarwinSection() {
     return Error(Loc, ErrorStr.c_str());
   
   // FIXME: Arch specific.
+  bool isText = Segment == "__TEXT";  // FIXME: Hack.
   Out.SwitchSection(getMachOSection(Segment, Section, TAA, StubSize,
-                                    SectionKind()));
+                                    isText ? SectionKind::getText()
+                                           : SectionKind::getDataRel()));
   return false;
 }
 
@@ -929,8 +931,10 @@ bool AsmParser::ParseDirectiveSectionSwitch(const char *Segment,
   Lex();
   
   // FIXME: Arch specific.
+  bool isText = StringRef(Segment) == "__TEXT";  // FIXME: Hack.
   Out.SwitchSection(getMachOSection(Segment, Section, TAA, StubSize,
-                                    SectionKind()));
+                                    isText ? SectionKind::getText()
+                                    : SectionKind::getDataRel()));
 
   // Set the implicit alignment, if any.
   //
@@ -1237,8 +1241,14 @@ bool AsmParser::ParseDirectiveAlign(bool IsPow2, unsigned ValueSize) {
     }
   }
 
-  // FIXME: Target specific behavior about how the "extra" bytes are filled.
-  Out.EmitValueToAlignment(Alignment, FillExpr, ValueSize, MaxBytesToFill);
+  // FIXME: hard code the parser to use EmitCodeAlignment for text when using
+  // the TextAlignFillValue.
+  if(Out.getCurrentSection()->getKind().isText() && 
+     Lexer.getMAI().getTextAlignFillValue() == FillExpr)
+    Out.EmitCodeAlignment(Alignment, MaxBytesToFill);
+  else
+    // FIXME: Target specific behavior about how the "extra" bytes are filled.
+    Out.EmitValueToAlignment(Alignment, FillExpr, ValueSize, MaxBytesToFill);
 
   return false;
 }
@@ -1362,7 +1372,7 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
   if (IsLocal) {
     Out.EmitZerofill(getMachOSection("__DATA", "__bss",
                                      MCSectionMachO::S_ZEROFILL, 0,
-                                     SectionKind()),
+                                     SectionKind::getBSS()),
                      Sym, Size, 1 << Pow2Alignment);
     return false;
   }
@@ -1398,7 +1408,7 @@ bool AsmParser::ParseDirectiveDarwinZerofill() {
     // Create the zerofill section but no symbol
     Out.EmitZerofill(getMachOSection(Segment, Section,
                                      MCSectionMachO::S_ZEROFILL, 0,
-                                     SectionKind()));
+                                     SectionKind::getBSS()));
     return false;
   }
 
@@ -1456,7 +1466,7 @@ bool AsmParser::ParseDirectiveDarwinZerofill() {
   // FIXME: Arch specific.
   Out.EmitZerofill(getMachOSection(Segment, Section,
                                  MCSectionMachO::S_ZEROFILL, 0,
-                                 SectionKind()),
+                                 SectionKind::getBSS()),
                    Sym, Size, 1 << Pow2Alignment);
 
   return false;
diff --git a/lib/MC/TargetAsmBackend.cpp b/lib/MC/TargetAsmBackend.cpp
new file mode 100644
index 0000000..918d272
--- /dev/null
+++ b/lib/MC/TargetAsmBackend.cpp
@@ -0,0 +1,19 @@
+//===-- TargetAsmBackend.cpp - Target Assembly 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"
+using namespace llvm;
+
+TargetAsmBackend::TargetAsmBackend(const Target &T)
+  : TheTarget(T)
+{
+}
+
+TargetAsmBackend::~TargetAsmBackend() {
+}