Introduce llvm::SplitAllCriticalEdges

Summary:
move the code from BreakCriticalEdges::runOnFunction()
into a separate utility function llvm::SplitAllCriticalEdges()
so that it can be used independently.
No functionality change intended.

Test Plan: check-llvm

Reviewers: nlewycky

Reviewed By: nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6313

llvm-svn: 222288

3 files changed, 22 insertions, 19 deletions

diff --git a/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h b/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
index bcafda657c2..19acf5b2db8 100644
--- a/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
+++ b/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
@@ -133,6 +133,11 @@ inline BasicBlock *SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst,
   }
 }
 
+// SplitAllCriticalEdges - Loop over all of the edges in the CFG,
+// breaking critical edges as they are found. Pass P must not be NULL.
+// Returns the number of broken edges.
+unsigned SplitAllCriticalEdges(Function &F, Pass *P);
+
 /// SplitEdge -  Split the edge connecting specified block. Pass P must
 /// not be NULL.
 BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To, Pass *P);
diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 602e8ba5510..983f025a1a3 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -265,6 +265,18 @@ BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) {
   return SplitBlock(BB, BB->getTerminator(), P);
 }
 
+unsigned llvm::SplitAllCriticalEdges(Function &F, Pass *P) {
+  unsigned NumBroken = 0;
+  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+    TerminatorInst *TI = I->getTerminator();
+    if (TI->getNumSuccessors() > 1 && !isa<IndirectBrInst>(TI))
+      for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+        if (SplitCriticalEdge(TI, i, P))
+          ++NumBroken;
+  }
+  return NumBroken;
+}
+
 /// SplitBlock - Split the specified block at the specified instruction - every
 /// thing before SplitPt stays in Old and everything starting with SplitPt moves
 /// to a new block.  The two blocks are joined by an unconditional branch and
diff --git a/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp b/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
index 80bd5163751..eda22cfc1ba 100644
--- a/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
+++ b/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -40,7 +40,11 @@ namespace {
       initializeBreakCriticalEdgesPass(*PassRegistry::getPassRegistry());
     }
 
-    bool runOnFunction(Function &F) override;
+    bool runOnFunction(Function &F) override {
+      unsigned N = SplitAllCriticalEdges(F, this);
+      NumBroken += N;
+      return N > 0;
+    }
 
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.addPreserved<DominatorTreeWrapperPass>();
@@ -62,24 +66,6 @@ FunctionPass *llvm::createBreakCriticalEdgesPass() {
   return new BreakCriticalEdges();
 }
 
-// runOnFunction - Loop over all of the edges in the CFG, breaking critical
-// edges as they are found.
-//
-bool BreakCriticalEdges::runOnFunction(Function &F) {
-  bool Changed = false;
-  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
-    TerminatorInst *TI = I->getTerminator();
-    if (TI->getNumSuccessors() > 1 && !isa<IndirectBrInst>(TI))
-      for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
-        if (SplitCriticalEdge(TI, i, this)) {
-          ++NumBroken;
-          Changed = true;
-        }
-  }
-
-  return Changed;
-}
-
 //===----------------------------------------------------------------------===//
 //    Implementation of the external critical edge manipulation functions
 //===----------------------------------------------------------------------===//