-//===- 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...
//
//===----------------------------------------------------------------------===//
-#include "llvm/Analysis/SimplifyCFG.h"
+#include "llvm/Transforms/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;
+
+AnalysisID UnifyFunctionExitNodes::ID(AnalysisID::create<UnifyFunctionExitNodes>());
+
// 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::doit(Function *M, BasicBlock *&ExitNode) {
+ // 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)
+ vector<BasicBlock*> ReturningBlocks;
+ for(Function::iterator I = M->begin(), E = M->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", M);
if (M->getReturnType() != Type::VoidTy) {
- // If the method doesn't return void... add a PHI node to the block...
+ // If the function doesn't return void... add a PHI node to the block...
PHINode *PN = new PHINode(M->getReturnType());
NewRetBlock->getInstList().push_back(PN);
delete (*I)->getInstList().pop_back(); // Remove the return insn
(*I)->getInstList().push_back(new BranchInst(NewRetBlock));
}
- return NewRetBlock;
+ ExitNode = NewRetBlock;
+ return true;
}