Changes to support PHINode::removeIncoming changes

[oota-llvm.git] / lib / Transforms / Utils / UnifyFunctionExitNodes.cpp

diff --git a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index efc7676bb714095d078a6c520add646b5eb22542..3c522b53ab03e1300210a2ba8dcd12256eb0140b 100644 (file)
--- a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
+++ b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -1,47 +1,55 @@
-//===- SimplifyCFG.cpp - CFG Simplification Routines -------------*- C++ -*--=//
+//===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
 //
-// This file provides several routines that are useful for simplifying CFGs in
-// various ways...
+// This pass is used to ensure that functions have at most one return
+// instruction in them.  Additionally, it keeps track of which node is the new
+// exit node of the CFG.  If there are no exit nodes in the CFG, the getExitNode
+// method will return a null pointer.
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Analysis/SimplifyCFG.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
 #include "llvm/BasicBlock.h"
-#include "llvm/Method.h"
+#include "llvm/Function.h"
 #include "llvm/iTerminators.h"
 #include "llvm/iPHINode.h"
 #include "llvm/Type.h"
+using std::vector;
+
+static RegisterOpt<UnifyFunctionExitNodes>
+X("mergereturn", "Unify function exit nodes");
 
 // UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
 // BasicBlock, and converting all returns to unconditional branches to this
 // new basic block.  The singular exit node is returned.
 //
-// If there are no return stmts in the Method, a null pointer is returned.
+// If there are no return stmts in the Function, a null pointer is returned.
 //
-BasicBlock *cfg::UnifyAllExitNodes(Method *M) {
-  vector<BasicBlock*> ReturningBlocks;
-
-  // Loop over all of the blocks in a method, tracking all of the blocks that
+bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
+  // Loop over all of the blocks in a function, tracking all of the blocks that
   // return.
   //
-  for(Method::iterator I = M->begin(), E = M->end(); I != E; ++I)
-    if ((*I)->getTerminator()->getOpcode() == Instruction::Ret)
-      ReturningBlocks.push_back(*I);
+  vector<BasicBlock*> ReturningBlocks;
+  for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+    if (isa<ReturnInst>(I->getTerminator()))
+      ReturningBlocks.push_back(I);
 
-  if (ReturningBlocks.size() == 0) 
-    return 0;                          // No blocks return
-  else if (ReturningBlocks.size() == 1)
-    return ReturningBlocks.front();    // Already has a single return block
+  if (ReturningBlocks.empty()) {
+    ExitNode = 0;
+    return false;                          // No blocks return
+  } else if (ReturningBlocks.size() == 1) {
+    ExitNode = ReturningBlocks.front();    // Already has a single return block
+    return false;
+  }
 
-  // Otherwise, we need to insert a new basic block into the method, add a PHI
+  // Otherwise, we need to insert a new basic block into the function, add a PHI
   // node (if the function returns a value), and convert all of the return 
   // instructions into unconditional branches.
   //
-  BasicBlock *NewRetBlock = new BasicBlock("", M);
+  BasicBlock *NewRetBlock = new BasicBlock("UnifiedExitNode", &F);
 
-  if (M->getReturnType() != Type::VoidTy) {
-    // If the method doesn't return void... add a PHI node to the block...
-    PHINode *PN = new PHINode(M->getReturnType());
+  if (F.getReturnType() != Type::VoidTy) {
+    // If the function doesn't return void... add a PHI node to the block...
+    PHINode *PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
     NewRetBlock->getInstList().push_back(PN);
 
     // Add an incoming element to the PHI node for every return instruction that
@@ -62,8 +70,9 @@ BasicBlock *cfg::UnifyAllExitNodes(Method *M) {
   //
   for (vector<BasicBlock*>::iterator I = ReturningBlocks.begin(), 
                                      E = ReturningBlocks.end(); I != E; ++I) {
-    delete (*I)->getInstList().pop_back();  // Remove the return insn
+    (*I)->getInstList().pop_back();  // Remove the return insn
     (*I)->getInstList().push_back(new BranchInst(NewRetBlock));
   }
-  return NewRetBlock;
+  ExitNode = NewRetBlock;
+  return true;
 }