MC CFG: Split MCBasicBlocks to mirror atom splitting.

When an MCTextAtom is split, all MCBasicBlocks backed by it are
automatically split, with a fallthrough between both blocks, and
the successors moved to the second block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188881 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 0 deletions

diff --git a/include/llvm/MC/MCFunction.h b/include/llvm/MC/MCFunction.h
index 697b5006a9..3fccaac29b 100644
--- a/include/llvm/MC/MCFunction.h
+++ b/include/llvm/MC/MCFunction.h
@@ -70,6 +70,14 @@ public:
 
   void addPredecessor(const MCBasicBlock *MCBB);
   bool isPredecessor(const MCBasicBlock *MCBB) const;
+
+  /// \brief Split block, mirrorring NewAtom = Insts->split(..).
+  /// This moves all successors to \p SplitBB, and
+  /// adds a fallthrough to it.
+  /// \p SplitBB The result of splitting Insts, a basic block directly following
+  /// this basic block.
+  /// \returns A new basic block, backed by \p SplitBB.
+  void splitBasicBlock(MCBasicBlock *SplitBB);
   /// @}
 };
 
diff --git a/include/llvm/MC/MCModule.h b/include/llvm/MC/MCModule.h
index c0c242c21a..63635c7478 100644
--- a/include/llvm/MC/MCModule.h
+++ b/include/llvm/MC/MCModule.h
@@ -56,6 +56,21 @@ class MCModule {
   void map(MCAtom *NewAtom);
   /// @}
 
+  /// \name Basic block tracking
+  /// @{
+  typedef std::vector<MCBasicBlock*> BBsByAtomTy;
+  BBsByAtomTy BBsByAtom;
+
+  // For access to basic block > atom tracking.
+  friend class MCBasicBlock;
+  friend class MCTextAtom;
+
+  /// \brief Keep track of \p BBBackedByAtom as being backed by \p Atom.
+  /// This is used to update succs/preds when \p Atom is split.
+  void trackBBForAtom(const MCTextAtom *Atom, MCBasicBlock *BBBackedByAtom);
+  void splitBasicBlocksForAtom(const MCTextAtom *TA, const MCTextAtom *NewTA);
+  /// @}
+
   /// \name Function tracking
   /// @{
   typedef std::vector<MCFunction*> FunctionListTy;