Revert "Add an API to MCSectionData that tracks known offsets for text emitted into a"

This reverts commit 4c5c9165c7175ee84c68a589a1b7b68fde48a86a.

It is causing mysterious validation failures in "test-arm-pic".

BUG= http://code.google.com/p/nativeclient/issues/detail?id=2545

Review URL: https://chromiumcodereview.appspot.com/10832307

3 files changed, 17 insertions, 88 deletions

diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
index 7c1ba4ef6c..b577f92ae8 100644
--- a/include/llvm/MC/MCAssembler.h
+++ b/include/llvm/MC/MCAssembler.h
@@ -532,26 +532,18 @@ private:
   unsigned HasInstructions : 1;
 
   // @LOCALMOD-BEGIN
-  bool BundlingEnabled : 1;
-  bool BundleLocked : 1;
+  bool BundlingEnabled;
+  bool BundleLocked;
 
   // Because ".bundle_lock" occurs before the fragment it applies to exists,
   // we need to keep this flag around so we know to mark the next fragment
   // as the start of a bundle group. A similar flag is not necessary for the
   // last fragment, because when a .bundle_unlock occurs, the last fragment
   // in the group already exists and can be marked directly.
-  bool BundleGroupFirstFrag : 1;
+  bool BundleGroupFirstFrag;
 
   typedef MCFragment::BundleAlignType BundleAlignType;
-  BundleAlignType BundleAlignNext : 2;
-
-  // Optimization to reduce the number of fragments generated (for memory
-  // savings).  Keep track of when we know the offset of the next point to
-  // emit an instruction.  If we know the offset from a known alignment point,
-  // we can just append to the previous fragment.
-  bool BundleOffsetKnown : 1;
-  unsigned BundleSize;
-  unsigned BundleOffset;
+  BundleAlignType BundleAlignNext;
   // @LOCALMOD-END
 
   /// @}
@@ -564,7 +556,7 @@ public:
   const MCSection &getSection() const { return *Section; }
 
   unsigned getAlignment() const { return Alignment; }
-  void setAlignment(unsigned Value); // @LOCALMOD
+  void setAlignment(unsigned Value) { Alignment = Value; }
 
   bool hasInstructions() const { return HasInstructions; }
   void setHasInstructions(bool Value) { HasInstructions = Value; }
@@ -587,10 +579,6 @@ public:
 
   BundleAlignType getBundleAlignNext() const { return BundleAlignNext; }
   void setBundleAlignNext(BundleAlignType Value) { BundleAlignNext = Value; }
-
-  void MarkBundleOffsetUnknown();
-  bool ShouldCreateNewFragment(size_t Size);
-  void UpdateBundleOffset(size_t Size);
   // @LOCALMOD-END
 
   /// @name Fragment Access
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 76dac99850..321b2832b9 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -186,14 +186,13 @@ MCFragment::~MCFragment() {
 }
 
 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
-  : Kind(_Kind),
+  : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0)),
     // @LOCALMOD-BEGIN
     BundleAlign(BundleAlignNone),
     BundleGroupStart(false),
     BundleGroupEnd(false),
-    BundlePadding(~UINT8_C(0)),
+    BundlePadding(~UINT8_C(0))
     // @LOCALMOD-END
-    Parent(_Parent), Atom(0), Offset(~UINT64_C(0))
 {
   if (Parent)
     Parent->getFragmentList().push_back(this);
@@ -227,16 +226,14 @@ MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
     BundlingEnabled(false),
     BundleLocked(false),
     BundleGroupFirstFrag(false),
-    BundleAlignNext(MCFragment::BundleAlignNone),
-    BundleOffsetKnown(false),
-    BundleOffset(0)
+    BundleAlignNext(MCFragment::BundleAlignNone)
 // @LOCALMOD-END
 {
   if (A)
     A->getSectionList().push_back(this);
 
   // @LOCALMOD-BEGIN
-  BundleSize = A->getBackend().getBundleSize();
+  unsigned BundleSize = A->getBackend().getBundleSize();
   if (BundleSize && _Section.UseCodeAlign()) {
     BundlingEnabled = true;
     setAlignment(BundleSize);
@@ -244,65 +241,6 @@ MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
   // @LOCALMOD-END
 }
 
-// @LOCALMOD-BEGIN
-void MCSectionData::setAlignment(unsigned Value) {
-  Alignment = Value;
-  // If the alignment is at least as big as a bundle, then we know the offset
-  // relative to the start of a bundle.
-  if (Alignment >= BundleSize) {
-    BundleOffsetKnown = true;
-    BundleOffset = 0;
-  } else {
-    BundleOffsetKnown = false;
-    BundleOffset = 0;
-  }
-}
-
-void MCSectionData::MarkBundleOffsetUnknown() {
-  BundleOffsetKnown = false;
-  BundleOffset = 0;
-}
-
-// Only create a new fragment if:
-// 1) we are emitting the first instruction of a bundle locked sequence.
-// 2) we are not currently emitting a bundle locked sequence and we cannot
-//    guarantee the instruction would not span a bundle boundary.
-// Otherwise, append to the current fragment to reduce the number of fragments.
-bool MCSectionData::ShouldCreateNewFragment(size_t Size) {
-  // The first instruction of a bundle locked region starts a new fragment.
-  if (isBundleLocked() && isBundleGroupFirstFrag())
-    return true;
-  // Unless we know the relative offset of the end of the current fragment,
-  // we need to create a new fragment.
-  if (!isBundleLocked() && !BundleOffsetKnown)
-    return true;
-  assert(BundleSize != 0 && "BundleSize needs to be non-zero");
-  assert(Size < BundleSize && "Instruction size must be less than BundleSize");
-  // If inserting the instruction would overlap a bundle boundary, start a
-  // new fragment.
-  // TODO(sehr): we could still explicitly insert a NOP and continue here.
-  if (BundleOffset + (unsigned) Size > BundleSize)
-    return true;
-  return false;
-}
-
-void MCSectionData::UpdateBundleOffset(size_t Size) {
-  // A bundle locked fragment could move if it spans a bundle boundary.
-  if (isBundleLocked()) {
-    BundleOffsetKnown = false;
-    return;
-  }
-  // If inserting the instruction would overlap a bundle boundary, starting a
-  // new fragment moves the known offset to the end of the instruction in the
-  // next bundle.
-  // TODO(sehr): we could insert a NOP and continue the fragment.
-  if (BundleOffset + (unsigned) Size > BundleSize)
-    BundleOffset = Size;
-  else
-    BundleOffset = BundleOffset + Size;
-}
-// @LOCALMOD-END
-
 /* *** */
 
 MCSymbolData::MCSymbolData() : Symbol(0) {}
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 6d7c78bb22..26b171ed21 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -359,7 +359,6 @@ void MCELFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
   // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
   // MCObjectStreamer.
   getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
-  getCurrentSectionData()->MarkBundleOffsetUnknown();  // @LOCALMOD
 }
 
 void MCELFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
@@ -396,7 +395,6 @@ void MCELFStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
                                   unsigned AddrSpace) {
   fixSymbolsInTLSFixups(Value);
   MCObjectStreamer::EmitValueImpl(Value, Size, AddrSpace);
-  getCurrentSectionData()->MarkBundleOffsetUnknown();  // @LOCALMOD
 }
 
 
@@ -465,7 +463,6 @@ void MCELFStreamer::EmitInstToFragment(const MCInst &Inst) {
 
   for (unsigned i = 0, e = F.getFixups().size(); i != e; ++i)
     fixSymbolsInTLSFixups(F.getFixups()[i].getValue());
-  getCurrentSectionData()->MarkBundleOffsetUnknown();  // @LOCALMOD
 }
 
 void MCELFStreamer::EmitInstToData(const MCInst &Inst) {
@@ -490,12 +487,18 @@ void MCELFStreamer::EmitInstToData(const MCInst &Inst) {
     }
     DF->getContents().append(Code.begin(), Code.end());
   } else {
+    // Only create a new fragment if:
+    // 1) there is no current fragment,
+    // 2) we are not currently emitting a bundle locked sequence, or
+    // 3) we are emitting the first instruction of a bundle locked sequence.
+    // Otherwise, append to the current fragment to reduce the number of
+    // fragments.
     MCTinyFragment *TF = dyn_cast_or_null<MCTinyFragment>(getCurrentFragment());
     MCSectionData *SD = getCurrentSectionData();
-    if (!TF || SD->ShouldCreateNewFragment(Code.size()))
+    if (!TF || !SD->isBundleLocked() || SD->isBundleGroupFirstFrag()) {
       TF = new MCTinyFragment(SD);
+    }
     TF->getContents().append(Code.begin(), Code.end());
-    SD->UpdateBundleOffset(Code.size());
   }
   // @LOCALMOD-END
 }