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.

llvm-svn: 188881

1 files changed, 27 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCModule.cpp b/llvm/lib/MC/MCModule.cpp
index bdd5cc6b1cd..7e9e18a5a91 100644
--- a/llvm/lib/MC/MCModule.cpp
+++ b/llvm/lib/MC/MCModule.cpp
@@ -103,6 +103,33 @@ MCFunction *MCModule::createFunction(StringRef Name) {
   return Functions.back();
 }
 
+static bool CompBBToAtom(MCBasicBlock *BB, const MCTextAtom *Atom) {
+  return BB->getInsts() < Atom;
+}
+
+void MCModule::splitBasicBlocksForAtom(const MCTextAtom *TA,
+                                       const MCTextAtom *NewTA) {
+  BBsByAtomTy::iterator
+    I = std::lower_bound(BBsByAtom.begin(), BBsByAtom.end(),
+                         TA, CompBBToAtom);
+  for (; I != BBsByAtom.end() && (*I)->getInsts() == TA; ++I) {
+    MCBasicBlock *BB = *I;
+    MCBasicBlock *NewBB = &BB->getParent()->createBlock(*NewTA);
+    BB->splitBasicBlock(NewBB);
+  }
+}
+
+void MCModule::trackBBForAtom(const MCTextAtom *Atom, MCBasicBlock *BB) {
+  assert(Atom == BB->getInsts() && "Text atom doesn't back the basic block!");
+  BBsByAtomTy::iterator I = std::lower_bound(BBsByAtom.begin(),
+                                             BBsByAtom.end(),
+                                             Atom, CompBBToAtom);
+  for (; I != BBsByAtom.end() && (*I)->getInsts() == Atom; ++I)
+    if (*I == BB)
+      return;
+  BBsByAtom.insert(I, BB);
+}
+
 MCModule::~MCModule() {
   for (AtomListTy::iterator AI = atom_begin(),
                             AE = atom_end();