Add the align_to_end option to .bundle_lock in the MC implementation of aligned

bundling. The document describing this feature and the implementation has also
been updated:

https://sites.google.com/a/chromium.org/dev/nativeclient/pnacl/aligned-bundling-support-in-llvm


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171797 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 32 insertions, 10 deletions

diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
index 6c2fdc5..1e953c9 100644
--- a/include/llvm/MC/MCAssembler.h
+++ b/include/llvm/MC/MCAssembler.h
@@ -100,9 +100,12 @@ public:
   void setLayoutOrder(unsigned Value) { LayoutOrder = Value; }
 
   /// \brief Does this fragment have instructions emitted into it? By default
-  ///  this is false, but specific fragment types may set it to true.
+  /// this is false, but specific fragment types may set it to true.
   virtual bool hasInstructions() const { return false; }
 
+  /// \brief Should this fragment be placed at the end of an aligned bundle?
+  virtual bool alignToBundleEnd() const { return false; }
+
   /// \brief Get the padding size that must be inserted before this fragment.
   /// Used for bundling. By default, no padding is inserted.
   /// Note that padding size is restricted to 8 bits. This is an optimization
@@ -165,6 +168,9 @@ class MCDataFragment : public MCEncodedFragment {
   /// \brief Does this fragment contain encoded instructions anywhere in it?
   bool HasInstructions;
 
+  /// \brief Should this fragment be aligned to the end of a bundle?
+  bool AlignToBundleEnd;
+
   SmallVector<char, 32> Contents;
 
   /// Fixups - The list of fixups in this fragment.
@@ -172,7 +178,7 @@ class MCDataFragment : public MCEncodedFragment {
 public:
   MCDataFragment(MCSectionData *SD = 0)
     : MCEncodedFragment(FT_Data, SD),
-      HasInstructions(false)
+      HasInstructions(false), AlignToBundleEnd(false)
   {
   }
 
@@ -190,6 +196,9 @@ public:
   virtual bool hasInstructions() const { return HasInstructions; }
   virtual void setHasInstructions(bool V) { HasInstructions = V; }
 
+  virtual bool alignToBundleEnd() const { return AlignToBundleEnd; }
+  virtual void setAlignToBundleEnd(bool V) { AlignToBundleEnd = V; }
+
   fixup_iterator fixup_begin() { return Fixups.begin(); }
   const_fixup_iterator fixup_begin() const { return Fixups.begin(); }
 
@@ -476,6 +485,12 @@ public:
   typedef FragmentListType::const_reverse_iterator const_reverse_iterator;
   typedef FragmentListType::reverse_iterator reverse_iterator;
 
+  /// \brief Express the state of bundle locked groups while emitting code.
+  enum BundleLockStateType {
+    NotBundleLocked,
+    BundleLocked,
+    BundleLockedAlignToEnd
+  };
 private:
   FragmentListType Fragments;
   const MCSection *Section;
@@ -489,8 +504,8 @@ private:
   /// Alignment - The maximum alignment seen in this section.
   unsigned Alignment;
 
-  /// \brief We're currently inside a bundle-locked group.
-  bool BundleLocked;
+  /// \brief Keeping track of bundle-locked state.
+  BundleLockStateType BundleLockState; 
 
   /// \brief We've seen a bundle_lock directive but not its first instruction
   /// yet.
@@ -549,11 +564,15 @@ public:
   bool empty() const { return Fragments.empty(); }
 
   bool isBundleLocked() const {
-    return BundleLocked;
+    return BundleLockState != NotBundleLocked;
+  }
+
+  BundleLockStateType getBundleLockState() const {
+    return BundleLockState;
   }
 
-  void setBundleLocked(bool IsLocked) {
-    BundleLocked = IsLocked;
+  void setBundleLockState(BundleLockStateType NewState) {
+    BundleLockState = NewState;
   }
 
   bool isBundleGroupBeforeFirstInst() const {
diff --git a/include/llvm/MC/MCELFStreamer.h b/include/llvm/MC/MCELFStreamer.h
index 5e148c3..ab20ee8 100644
--- a/include/llvm/MC/MCELFStreamer.h
+++ b/include/llvm/MC/MCELFStreamer.h
@@ -85,7 +85,7 @@ private:
   virtual void EmitInstToData(const MCInst &Inst);
 
   virtual void EmitBundleAlignMode(unsigned AlignPow2);
-  virtual void EmitBundleLock();
+  virtual void EmitBundleLock(bool AlignToEnd);
   virtual void EmitBundleUnlock();
 
   void fixSymbolsInTLSFixups(const MCExpr *expr);
diff --git a/include/llvm/MC/MCObjectStreamer.h b/include/llvm/MC/MCObjectStreamer.h
index 4bc24d4..0ece092 100644
--- a/include/llvm/MC/MCObjectStreamer.h
+++ b/include/llvm/MC/MCObjectStreamer.h
@@ -84,7 +84,7 @@ public:
   virtual void EmitInstToFragment(const MCInst &Inst);
 
   virtual void EmitBundleAlignMode(unsigned AlignPow2);
-  virtual void EmitBundleLock();
+  virtual void EmitBundleLock(bool AlignToEnd);
   virtual void EmitBundleUnlock();
   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
   virtual void EmitValueToAlignment(unsigned ByteAlignment,
diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 8be46b5..05a33c5 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -562,7 +562,10 @@ namespace llvm {
     virtual void EmitBundleAlignMode(unsigned AlignPow2) = 0;
 
     /// \brief The following instructions are a bundle-locked group.
-    virtual void EmitBundleLock() = 0;
+    ///
+    /// \param AlignToEnd - If true, the bundle-locked group will be aligned to
+    ///                     the end of a bundle.
+    virtual void EmitBundleLock(bool AlignToEnd) = 0;
 
     /// \brief Ends a bundle-locked group.
     virtual void EmitBundleUnlock() = 0;