//===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
-//
+//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
//===----------------------------------------------------------------------===//
//
// This pass is used to ensure that functions have at most one return
#include "llvm/Transforms/Scalar.h"
#include "llvm/BasicBlock.h"
#include "llvm/Function.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iPHINode.h"
+#include "llvm/Instructions.h"
#include "llvm/Type.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+using namespace llvm;
-namespace llvm {
-
-static RegisterOpt<UnifyFunctionExitNodes>
+char UnifyFunctionExitNodes::ID = 0;
+static RegisterPass<UnifyFunctionExitNodes>
X("mergereturn", "Unify function exit nodes");
-Pass *createUnifyFunctionExitNodesPass() {
+int UnifyFunctionExitNodes::stub;
+
+Pass *llvm::createUnifyFunctionExitNodesPass() {
return new UnifyFunctionExitNodes();
}
void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
// We preserve the non-critical-edgeness property
AU.addPreservedID(BreakCriticalEdgesID);
+ // This is a cluster of orthogonal Transforms
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSwitchID);
}
// UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
//
std::vector<BasicBlock*> ReturningBlocks;
std::vector<BasicBlock*> UnwindingBlocks;
+ std::vector<BasicBlock*> UnreachableBlocks;
for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (isa<ReturnInst>(I->getTerminator()))
ReturningBlocks.push_back(I);
else if (isa<UnwindInst>(I->getTerminator()))
UnwindingBlocks.push_back(I);
+ else if (isa<UnreachableInst>(I->getTerminator()))
+ UnreachableBlocks.push_back(I);
- // Handle unwinding blocks first...
+ // Handle unwinding blocks first.
if (UnwindingBlocks.empty()) {
UnwindBlock = 0;
} else if (UnwindingBlocks.size() == 1) {
UnwindBlock = UnwindingBlocks.front();
} else {
- UnwindBlock = new BasicBlock("UnifiedUnwindBlock", &F);
- UnwindBlock->getInstList().push_back(new UnwindInst());
+ UnwindBlock = BasicBlock::Create("UnifiedUnwindBlock", &F);
+ new UnwindInst(UnwindBlock);
- for (std::vector<BasicBlock*>::iterator I = UnwindingBlocks.begin(),
+ for (std::vector<BasicBlock*>::iterator I = UnwindingBlocks.begin(),
E = UnwindingBlocks.end(); I != E; ++I) {
BasicBlock *BB = *I;
- BB->getInstList().pop_back(); // Remove the return insn
- BB->getInstList().push_back(new BranchInst(UnwindBlock));
+ BB->getInstList().pop_back(); // Remove the unwind insn
+ BranchInst::Create(UnwindBlock, BB);
}
}
- // Now handle return blocks...
+ // Then unreachable blocks.
+ if (UnreachableBlocks.empty()) {
+ UnreachableBlock = 0;
+ } else if (UnreachableBlocks.size() == 1) {
+ UnreachableBlock = UnreachableBlocks.front();
+ } else {
+ UnreachableBlock = BasicBlock::Create("UnifiedUnreachableBlock", &F);
+ new UnreachableInst(UnreachableBlock);
+
+ for (std::vector<BasicBlock*>::iterator I = UnreachableBlocks.begin(),
+ E = UnreachableBlocks.end(); I != E; ++I) {
+ BasicBlock *BB = *I;
+ BB->getInstList().pop_back(); // Remove the unreachable inst.
+ BranchInst::Create(UnreachableBlock, BB);
+ }
+ }
+
+ // Now handle return blocks.
if (ReturningBlocks.empty()) {
ReturnBlock = 0;
return false; // No blocks return
}
// 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
+ // nodes (if the function returns values), and convert all of the return
// instructions into unconditional branches.
//
- BasicBlock *NewRetBlock = new BasicBlock("UnifiedReturnBlock", &F);
+ BasicBlock *NewRetBlock = BasicBlock::Create("UnifiedReturnBlock", &F);
- PHINode *PN = 0;
- if (F.getReturnType() != Type::VoidTy) {
+ SmallVector<Value *, 4> Phis;
+ unsigned NumRetVals = ReturningBlocks[0]->getTerminator()->getNumOperands();
+ if (NumRetVals == 0)
+ ReturnInst::Create(NULL, NewRetBlock);
+ else if (const StructType *STy = dyn_cast<StructType>(F.getReturnType())) {
+ Instruction *InsertPt = NewRetBlock->getFirstNonPHI();
+ for (unsigned i = 0; i < NumRetVals; ++i) {
+ PHINode *PN = PHINode::Create(STy->getElementType(i), "UnifiedRetVal."
+ + utostr(i), InsertPt);
+ Phis.push_back(PN);
+ }
+ ReturnInst::Create(&Phis[0], NumRetVals);
+ }
+ else {
// If the function doesn't return void... add a PHI node to the block...
- PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+ PHINode *PN = PHINode::Create(F.getReturnType(), "UnifiedRetVal");
NewRetBlock->getInstList().push_back(PN);
- NewRetBlock->getInstList().push_back(new ReturnInst(PN));
- } else {
- // If it returns void, just add a return void instruction to the block
- NewRetBlock->getInstList().push_back(new ReturnInst());
+ Phis.push_back(PN);
+ ReturnInst::Create(PN, NewRetBlock);
}
// Loop over all of the blocks, replacing the return instruction with an
// unconditional branch.
//
- for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
+ for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
E = ReturningBlocks.end(); I != E; ++I) {
BasicBlock *BB = *I;
// Add an incoming element to the PHI node for every return instruction that
// is merging into this new block...
- if (PN) PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
+ if (!Phis.empty()) {
+ for (unsigned i = 0; i < NumRetVals; ++i)
+ cast<PHINode>(Phis[i])->addIncoming(BB->getTerminator()->getOperand(i),
+ BB);
+ }
BB->getInstList().pop_back(); // Remove the return insn
- BB->getInstList().push_back(new BranchInst(NewRetBlock));
+ BranchInst::Create(NewRetBlock, BB);
}
ReturnBlock = NewRetBlock;
return true;
}
-
-} // End llvm namespace
projects / oota-llvm.git / blobdiff