//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/Constant.h"
+#include "llvm/DataLayout.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
-#include "llvm/Constant.h"
-#include "llvm/Type.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ValueHandle.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Type.h"
#include <algorithm>
using namespace llvm;
/// any single-entry PHI nodes in it, fold them away. This handles the case
/// when all entries to the PHI nodes in a block are guaranteed equal, such as
/// when the block has exactly one predecessor.
-void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) {
+void llvm::FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P) {
+ if (!isa<PHINode>(BB->begin())) return;
+
+ AliasAnalysis *AA = 0;
+ MemoryDependenceAnalysis *MemDep = 0;
+ if (P) {
+ AA = P->getAnalysisIfAvailable<AliasAnalysis>();
+ MemDep = P->getAnalysisIfAvailable<MemoryDependenceAnalysis>();
+ }
+
while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
if (PN->getIncomingValue(0) != PN)
PN->replaceAllUsesWith(PN->getIncomingValue(0));
else
PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+
+ if (MemDep)
+ MemDep->removeInstruction(PN); // Memdep updates AA itself.
+ else if (AA && isa<PointerType>(PN->getType()))
+ AA->deleteValue(PN);
+
PN->eraseFromParent();
}
}
/// is dead. Also recursively delete any operands that become dead as
/// a result. This includes tracing the def-use list from the PHI to see if
/// it is ultimately unused or if it reaches an unused cycle.
-bool llvm::DeleteDeadPHIs(BasicBlock *BB) {
+bool llvm::DeleteDeadPHIs(BasicBlock *BB, const TargetLibraryInfo *TLI) {
// Recursively deleting a PHI may cause multiple PHIs to be deleted
// or RAUW'd undef, so use an array of WeakVH for the PHIs to delete.
SmallVector<WeakVH, 8> PHIs;
bool Changed = false;
for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
- Changed |= RecursivelyDeleteDeadPHINode(PN);
+ Changed |= RecursivelyDeleteDeadPHINode(PN, TLI);
return Changed;
}
/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
/// if possible. The return value indicates success or failure.
bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) {
- pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
- // Can't merge the entry block. Don't merge away blocks who have their
- // address taken: this is a bug if the predecessor block is the entry node
- // (because we'd end up taking the address of the entry) and undesirable in
- // any case.
- if (pred_begin(BB) == pred_end(BB) ||
- BB->hasAddressTaken()) return false;
-
- BasicBlock *PredBB = *PI++;
- for (; PI != PE; ++PI) // Search all predecessors, see if they are all same
- if (*PI != PredBB) {
- PredBB = 0; // There are multiple different predecessors...
- break;
- }
+ // Don't merge away blocks who have their address taken.
+ if (BB->hasAddressTaken()) return false;
- // Can't merge if there are multiple predecessors.
+ // Can't merge if there are multiple predecessors, or no predecessors.
+ BasicBlock *PredBB = BB->getUniquePredecessor();
if (!PredBB) return false;
+
// Don't break self-loops.
if (PredBB == BB) return false;
// Don't break invokes.
if (isa<InvokeInst>(PredBB->getTerminator())) return false;
succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
- BasicBlock* OnlySucc = BB;
+ BasicBlock *OnlySucc = BB;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
OnlySucc = 0; // There are multiple distinct successors!
}
// Begin by getting rid of unneeded PHIs.
- while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
- PN->replaceAllUsesWith(PN->getIncomingValue(0));
- BB->getInstList().pop_front(); // Delete the phi node...
- }
+ if (isa<PHINode>(BB->front()))
+ FoldSingleEntryPHINodes(BB, P);
// Delete the unconditional branch from the predecessor...
PredBB->getInstList().pop_back();
- // Move all definitions in the successor to the predecessor...
- PredBB->getInstList().splice(PredBB->end(), BB->getInstList());
-
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(PredBB);
+ // Move all definitions in the successor to the predecessor...
+ PredBB->getInstList().splice(PredBB->end(), BB->getInstList());
+
// Inherit predecessors name if it exists.
if (!PredBB->hasName())
PredBB->takeName(BB);
// Finally, erase the old block and update dominator info.
if (P) {
- if (DominatorTree* DT = P->getAnalysisIfAvailable<DominatorTree>()) {
- DomTreeNode* DTN = DT->getNode(BB);
- DomTreeNode* PredDTN = DT->getNode(PredBB);
-
- if (DTN) {
- SmallPtrSet<DomTreeNode*, 8> Children(DTN->begin(), DTN->end());
- for (SmallPtrSet<DomTreeNode*, 8>::iterator DI = Children.begin(),
+ if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) {
+ if (DomTreeNode *DTN = DT->getNode(BB)) {
+ DomTreeNode *PredDTN = DT->getNode(PredBB);
+ SmallVector<DomTreeNode*, 8> Children(DTN->begin(), DTN->end());
+ for (SmallVector<DomTreeNode*, 8>::iterator DI = Children.begin(),
DE = Children.end(); DI != DE; ++DI)
DT->changeImmediateDominator(*DI, PredDTN);
DT->eraseNode(BB);
}
+
+ if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>())
+ LI->removeBlock(BB);
+
+ if (MemoryDependenceAnalysis *MD =
+ P->getAnalysisIfAvailable<MemoryDependenceAnalysis>())
+ MD->invalidateCachedPredecessors();
}
}
BB->eraseFromParent();
-
-
return true;
}
ReplaceInstWithInst(From->getParent()->getInstList(), BI, To);
}
-/// RemoveSuccessor - Change the specified terminator instruction such that its
-/// successor SuccNum no longer exists. Because this reduces the outgoing
-/// degree of the current basic block, the actual terminator instruction itself
-/// may have to be changed. In the case where the last successor of the block
-/// is deleted, a return instruction is inserted in its place which can cause a
-/// surprising change in program behavior if it is not expected.
-///
-void llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) {
- assert(SuccNum < TI->getNumSuccessors() &&
- "Trying to remove a nonexistant successor!");
-
- // If our old successor block contains any PHI nodes, remove the entry in the
- // PHI nodes that comes from this branch...
- //
- BasicBlock *BB = TI->getParent();
- TI->getSuccessor(SuccNum)->removePredecessor(BB);
-
- TerminatorInst *NewTI = 0;
- switch (TI->getOpcode()) {
- case Instruction::Br:
- // If this is a conditional branch... convert to unconditional branch.
- if (TI->getNumSuccessors() == 2) {
- cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum));
- } else { // Otherwise convert to a return instruction...
- Value *RetVal = 0;
-
- // Create a value to return... if the function doesn't return null...
- if (!BB->getParent()->getReturnType()->isVoidTy())
- RetVal = Constant::getNullValue(BB->getParent()->getReturnType());
-
- // Create the return...
- NewTI = ReturnInst::Create(TI->getContext(), RetVal);
- }
- break;
-
- case Instruction::Invoke: // Should convert to call
- case Instruction::Switch: // Should remove entry
- default:
- case Instruction::Ret: // Cannot happen, has no successors!
- llvm_unreachable("Unhandled terminator instruction type in RemoveSuccessor!");
- }
-
- if (NewTI) // If it's a different instruction, replace.
- ReplaceInstWithInst(TI, NewTI);
-}
-
/// GetSuccessorNumber - Search for the specified successor of basic block BB
/// and return its position in the terminator instruction's list of
/// successors. It is an error to call this with a block that is not a
if (Term->getSuccessor(i) == Succ)
return i;
}
- return 0;
}
/// SplitEdge - Split the edge connecting specified block. Pass P must
assert(SP == BB && "CFG broken");
SP = NULL;
return SplitBlock(Succ, Succ->begin(), P);
- } else {
- // Otherwise, if BB has a single successor, split it at the bottom of the
- // block.
- assert(BB->getTerminator()->getNumSuccessors() == 1 &&
- "Should have a single succ!");
- return SplitBlock(BB, BB->getTerminator(), P);
}
+
+ // Otherwise, if BB has a single successor, split it at the bottom of the
+ // block.
+ assert(BB->getTerminator()->getNumSuccessors() == 1 &&
+ "Should have a single succ!");
+ return SplitBlock(BB, BB->getTerminator(), P);
}
/// SplitBlock - Split the specified block at the specified instruction - every
///
BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) {
BasicBlock::iterator SplitIt = SplitPt;
- while (isa<PHINode>(SplitIt))
+ while (isa<PHINode>(SplitIt) || isa<LandingPadInst>(SplitIt))
++SplitIt;
BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split");
// The new block lives in whichever loop the old one did. This preserves
// LCSSA as well, because we force the split point to be after any PHI nodes.
- if (LoopInfo* LI = P->getAnalysisIfAvailable<LoopInfo>())
+ if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>())
if (Loop *L = LI->getLoopFor(Old))
L->addBasicBlockToLoop(New, LI->getBase());
if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) {
- // Old dominates New. New node domiantes all other nodes dominated by Old.
- DomTreeNode *OldNode = DT->getNode(Old);
- std::vector<DomTreeNode *> Children;
- for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end();
- I != E; ++I)
- Children.push_back(*I);
+ // Old dominates New. New node dominates all other nodes dominated by Old.
+ if (DomTreeNode *OldNode = DT->getNode(Old)) {
+ std::vector<DomTreeNode *> Children;
+ for (DomTreeNode::iterator I = OldNode->begin(), E = OldNode->end();
+ I != E; ++I)
+ Children.push_back(*I);
DomTreeNode *NewNode = DT->addNewBlock(New,Old);
for (std::vector<DomTreeNode *>::iterator I = Children.begin(),
E = Children.end(); I != E; ++I)
DT->changeImmediateDominator(*I, NewNode);
+ }
}
- if (DominanceFrontier *DF = P->getAnalysisIfAvailable<DominanceFrontier>())
- DF->splitBlock(Old);
-
return New;
}
+/// UpdateAnalysisInformation - Update DominatorTree, LoopInfo, and LCCSA
+/// analysis information.
+static void UpdateAnalysisInformation(BasicBlock *OldBB, BasicBlock *NewBB,
+ ArrayRef<BasicBlock *> Preds,
+ Pass *P, bool &HasLoopExit) {
+ if (!P) return;
-/// SplitBlockPredecessors - This method transforms BB by introducing a new
-/// basic block into the function, and moving some of the predecessors of BB to
-/// be predecessors of the new block. The new predecessors are indicated by the
-/// Preds array, which has NumPreds elements in it. The new block is given a
-/// suffix of 'Suffix'.
-///
-/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
-/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
-/// In particular, it does not preserve LoopSimplify (because it's
-/// complicated to handle the case where one of the edges being split
-/// is an exit of a loop with other exits).
-///
-BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
- BasicBlock *const *Preds,
- unsigned NumPreds, const char *Suffix,
- Pass *P) {
- // Create new basic block, insert right before the original block.
- BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix,
- BB->getParent(), BB);
-
- // The new block unconditionally branches to the old block.
- BranchInst *BI = BranchInst::Create(BB, NewBB);
-
- LoopInfo *LI = P ? P->getAnalysisIfAvailable<LoopInfo>() : 0;
- Loop *L = LI ? LI->getLoopFor(BB) : 0;
- bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID);
+ LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>();
+ Loop *L = LI ? LI->getLoopFor(OldBB) : 0;
- // Move the edges from Preds to point to NewBB instead of BB.
- // While here, if we need to preserve loop analyses, collect
- // some information about how this split will affect loops.
- bool HasLoopExit = false;
+ // If we need to preserve loop analyses, collect some information about how
+ // this split will affect loops.
bool IsLoopEntry = !!L;
bool SplitMakesNewLoopHeader = false;
- for (unsigned i = 0; i != NumPreds; ++i) {
- // This is slightly more strict than necessary; the minimum requirement
- // is that there be no more than one indirectbr branching to BB. And
- // all BlockAddress uses would need to be updated.
- assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) &&
- "Cannot split an edge from an IndirectBrInst");
-
- Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
-
- if (LI) {
- // If we need to preserve LCSSA, determine if any of
- // the preds is a loop exit.
+ if (LI) {
+ bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID);
+ for (ArrayRef<BasicBlock*>::iterator
+ i = Preds.begin(), e = Preds.end(); i != e; ++i) {
+ BasicBlock *Pred = *i;
+
+ // If we need to preserve LCSSA, determine if any of the preds is a loop
+ // exit.
if (PreserveLCSSA)
- if (Loop *PL = LI->getLoopFor(Preds[i]))
- if (!PL->contains(BB))
+ if (Loop *PL = LI->getLoopFor(Pred))
+ if (!PL->contains(OldBB))
HasLoopExit = true;
- // If we need to preserve LoopInfo, note whether any of the
- // preds crosses an interesting loop boundary.
- if (L) {
- if (L->contains(Preds[i]))
- IsLoopEntry = false;
- else
- SplitMakesNewLoopHeader = true;
- }
+
+ // If we need to preserve LoopInfo, note whether any of the preds crosses
+ // an interesting loop boundary.
+ if (!L) continue;
+ if (L->contains(Pred))
+ IsLoopEntry = false;
+ else
+ SplitMakesNewLoopHeader = true;
}
}
- // Update dominator tree and dominator frontier if available.
- DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0;
+ // Update dominator tree if available.
+ DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>();
if (DT)
DT->splitBlock(NewBB);
- if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0)
- DF->splitBlock(NewBB);
- // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI
- // node becomes an incoming value for BB's phi node. However, if the Preds
- // list is empty, we need to insert dummy entries into the PHI nodes in BB to
- // account for the newly created predecessor.
- if (NumPreds == 0) {
- // Insert dummy values as the incoming value.
- for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I)
- cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
- return NewBB;
+ if (!L) return;
+
+ if (IsLoopEntry) {
+ // Add the new block to the nearest enclosing loop (and not an adjacent
+ // loop). To find this, examine each of the predecessors and determine which
+ // loops enclose them, and select the most-nested loop which contains the
+ // loop containing the block being split.
+ Loop *InnermostPredLoop = 0;
+ for (ArrayRef<BasicBlock*>::iterator
+ i = Preds.begin(), e = Preds.end(); i != e; ++i) {
+ BasicBlock *Pred = *i;
+ if (Loop *PredLoop = LI->getLoopFor(Pred)) {
+ // Seek a loop which actually contains the block being split (to avoid
+ // adjacent loops).
+ while (PredLoop && !PredLoop->contains(OldBB))
+ PredLoop = PredLoop->getParentLoop();
+
+ // Select the most-nested of these loops which contains the block.
+ if (PredLoop && PredLoop->contains(OldBB) &&
+ (!InnermostPredLoop ||
+ InnermostPredLoop->getLoopDepth() < PredLoop->getLoopDepth()))
+ InnermostPredLoop = PredLoop;
+ }
+ }
+
+ if (InnermostPredLoop)
+ InnermostPredLoop->addBasicBlockToLoop(NewBB, LI->getBase());
+ } else {
+ L->addBasicBlockToLoop(NewBB, LI->getBase());
+ if (SplitMakesNewLoopHeader)
+ L->moveToHeader(NewBB);
}
+}
+/// UpdatePHINodes - Update the PHI nodes in OrigBB to include the values coming
+/// from NewBB. This also updates AliasAnalysis, if available.
+static void UpdatePHINodes(BasicBlock *OrigBB, BasicBlock *NewBB,
+ ArrayRef<BasicBlock*> Preds, BranchInst *BI,
+ Pass *P, bool HasLoopExit) {
+ // Otherwise, create a new PHI node in NewBB for each PHI node in OrigBB.
AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0;
-
- if (L) {
- if (IsLoopEntry) {
- // Add the new block to the nearest enclosing loop (and not an
- // adjacent loop). To find this, examine each of the predecessors and
- // determine which loops enclose them, and select the most-nested loop
- // which contains the loop containing the block being split.
- Loop *InnermostPredLoop = 0;
- for (unsigned i = 0; i != NumPreds; ++i)
- if (Loop *PredLoop = LI->getLoopFor(Preds[i])) {
- // Seek a loop which actually contains the block being split (to
- // avoid adjacent loops).
- while (PredLoop && !PredLoop->contains(BB))
- PredLoop = PredLoop->getParentLoop();
- // Select the most-nested of these loops which contains the block.
- if (PredLoop &&
- PredLoop->contains(BB) &&
- (!InnermostPredLoop ||
- InnermostPredLoop->getLoopDepth() < PredLoop->getLoopDepth()))
- InnermostPredLoop = PredLoop;
- }
- if (InnermostPredLoop)
- InnermostPredLoop->addBasicBlockToLoop(NewBB, LI->getBase());
- } else {
- L->addBasicBlockToLoop(NewBB, LI->getBase());
- if (SplitMakesNewLoopHeader)
- L->moveToHeader(NewBB);
- }
- }
-
- // Otherwise, create a new PHI node in NewBB for each PHI node in BB.
- for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) {
+ for (BasicBlock::iterator I = OrigBB->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I++);
-
+
// Check to see if all of the values coming in are the same. If so, we
// don't need to create a new PHI node, unless it's needed for LCSSA.
Value *InVal = 0;
if (!HasLoopExit) {
InVal = PN->getIncomingValueForBlock(Preds[0]);
- for (unsigned i = 1; i != NumPreds; ++i)
+ for (unsigned i = 1, e = Preds.size(); i != e; ++i)
if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
InVal = 0;
break;
// If all incoming values for the new PHI would be the same, just don't
// make a new PHI. Instead, just remove the incoming values from the old
// PHI.
- for (unsigned i = 0; i != NumPreds; ++i)
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i)
PN->removeIncomingValue(Preds[i], false);
} else {
// If the values coming into the block are not the same, we need a PHI.
// Create the new PHI node, insert it into NewBB at the end of the block
PHINode *NewPHI =
- PHINode::Create(PN->getType(), PN->getName()+".ph", BI);
+ PHINode::Create(PN->getType(), Preds.size(), PN->getName() + ".ph", BI);
if (AA) AA->copyValue(PN, NewPHI);
// Move all of the PHI values for 'Preds' to the new PHI.
- for (unsigned i = 0; i != NumPreds; ++i) {
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
Value *V = PN->removeIncomingValue(Preds[i], false);
NewPHI->addIncoming(V, Preds[i]);
}
+
InVal = NewPHI;
}
-
+
// Add an incoming value to the PHI node in the loop for the preheader
// edge.
PN->addIncoming(InVal, NewBB);
}
+}
+
+/// SplitBlockPredecessors - This method transforms BB by introducing a new
+/// basic block into the function, and moving some of the predecessors of BB to
+/// be predecessors of the new block. The new predecessors are indicated by the
+/// Preds array, which has NumPreds elements in it. The new block is given a
+/// suffix of 'Suffix'.
+///
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
+/// LoopInfo, and LCCSA but no other analyses. In particular, it does not
+/// preserve LoopSimplify (because it's complicated to handle the case where one
+/// of the edges being split is an exit of a loop with other exits).
+///
+BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
+ ArrayRef<BasicBlock*> Preds,
+ const char *Suffix, Pass *P) {
+ // Create new basic block, insert right before the original block.
+ BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix,
+ BB->getParent(), BB);
+
+ // The new block unconditionally branches to the old block.
+ BranchInst *BI = BranchInst::Create(BB, NewBB);
+ // Move the edges from Preds to point to NewBB instead of BB.
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
+ // This is slightly more strict than necessary; the minimum requirement
+ // is that there be no more than one indirectbr branching to BB. And
+ // all BlockAddress uses would need to be updated.
+ assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) &&
+ "Cannot split an edge from an IndirectBrInst");
+ Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
+ }
+
+ // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI
+ // node becomes an incoming value for BB's phi node. However, if the Preds
+ // list is empty, we need to insert dummy entries into the PHI nodes in BB to
+ // account for the newly created predecessor.
+ if (Preds.size() == 0) {
+ // Insert dummy values as the incoming value.
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I)
+ cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
+ return NewBB;
+ }
+
+ // Update DominatorTree, LoopInfo, and LCCSA analysis information.
+ bool HasLoopExit = false;
+ UpdateAnalysisInformation(BB, NewBB, Preds, P, HasLoopExit);
+
+ // Update the PHI nodes in BB with the values coming from NewBB.
+ UpdatePHINodes(BB, NewBB, Preds, BI, P, HasLoopExit);
return NewBB;
}
+/// SplitLandingPadPredecessors - This method transforms the landing pad,
+/// OrigBB, by introducing two new basic blocks into the function. One of those
+/// new basic blocks gets the predecessors listed in Preds. The other basic
+/// block gets the remaining predecessors of OrigBB. The landingpad instruction
+/// OrigBB is clone into both of the new basic blocks. The new blocks are given
+/// the suffixes 'Suffix1' and 'Suffix2', and are returned in the NewBBs vector.
+///
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
+/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses. In particular,
+/// it does not preserve LoopSimplify (because it's complicated to handle the
+/// case where one of the edges being split is an exit of a loop with other
+/// exits).
+///
+void llvm::SplitLandingPadPredecessors(BasicBlock *OrigBB,
+ ArrayRef<BasicBlock*> Preds,
+ const char *Suffix1, const char *Suffix2,
+ Pass *P,
+ SmallVectorImpl<BasicBlock*> &NewBBs) {
+ assert(OrigBB->isLandingPad() && "Trying to split a non-landing pad!");
+
+ // Create a new basic block for OrigBB's predecessors listed in Preds. Insert
+ // it right before the original block.
+ BasicBlock *NewBB1 = BasicBlock::Create(OrigBB->getContext(),
+ OrigBB->getName() + Suffix1,
+ OrigBB->getParent(), OrigBB);
+ NewBBs.push_back(NewBB1);
+
+ // The new block unconditionally branches to the old block.
+ BranchInst *BI1 = BranchInst::Create(OrigBB, NewBB1);
+
+ // Move the edges from Preds to point to NewBB1 instead of OrigBB.
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
+ // This is slightly more strict than necessary; the minimum requirement
+ // is that there be no more than one indirectbr branching to BB. And
+ // all BlockAddress uses would need to be updated.
+ assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) &&
+ "Cannot split an edge from an IndirectBrInst");
+ Preds[i]->getTerminator()->replaceUsesOfWith(OrigBB, NewBB1);
+ }
+
+ // Update DominatorTree, LoopInfo, and LCCSA analysis information.
+ bool HasLoopExit = false;
+ UpdateAnalysisInformation(OrigBB, NewBB1, Preds, P, HasLoopExit);
+
+ // Update the PHI nodes in OrigBB with the values coming from NewBB1.
+ UpdatePHINodes(OrigBB, NewBB1, Preds, BI1, P, HasLoopExit);
+
+ // Move the remaining edges from OrigBB to point to NewBB2.
+ SmallVector<BasicBlock*, 8> NewBB2Preds;
+ for (pred_iterator i = pred_begin(OrigBB), e = pred_end(OrigBB);
+ i != e; ) {
+ BasicBlock *Pred = *i++;
+ if (Pred == NewBB1) continue;
+ assert(!isa<IndirectBrInst>(Pred->getTerminator()) &&
+ "Cannot split an edge from an IndirectBrInst");
+ NewBB2Preds.push_back(Pred);
+ e = pred_end(OrigBB);
+ }
+
+ BasicBlock *NewBB2 = 0;
+ if (!NewBB2Preds.empty()) {
+ // Create another basic block for the rest of OrigBB's predecessors.
+ NewBB2 = BasicBlock::Create(OrigBB->getContext(),
+ OrigBB->getName() + Suffix2,
+ OrigBB->getParent(), OrigBB);
+ NewBBs.push_back(NewBB2);
+
+ // The new block unconditionally branches to the old block.
+ BranchInst *BI2 = BranchInst::Create(OrigBB, NewBB2);
+
+ // Move the remaining edges from OrigBB to point to NewBB2.
+ for (SmallVectorImpl<BasicBlock*>::iterator
+ i = NewBB2Preds.begin(), e = NewBB2Preds.end(); i != e; ++i)
+ (*i)->getTerminator()->replaceUsesOfWith(OrigBB, NewBB2);
+
+ // Update DominatorTree, LoopInfo, and LCCSA analysis information.
+ HasLoopExit = false;
+ UpdateAnalysisInformation(OrigBB, NewBB2, NewBB2Preds, P, HasLoopExit);
+
+ // Update the PHI nodes in OrigBB with the values coming from NewBB2.
+ UpdatePHINodes(OrigBB, NewBB2, NewBB2Preds, BI2, P, HasLoopExit);
+ }
+
+ LandingPadInst *LPad = OrigBB->getLandingPadInst();
+ Instruction *Clone1 = LPad->clone();
+ Clone1->setName(Twine("lpad") + Suffix1);
+ NewBB1->getInstList().insert(NewBB1->getFirstInsertionPt(), Clone1);
+
+ if (NewBB2) {
+ Instruction *Clone2 = LPad->clone();
+ Clone2->setName(Twine("lpad") + Suffix2);
+ NewBB2->getInstList().insert(NewBB2->getFirstInsertionPt(), Clone2);
+
+ // Create a PHI node for the two cloned landingpad instructions.
+ PHINode *PN = PHINode::Create(LPad->getType(), 2, "lpad.phi", LPad);
+ PN->addIncoming(Clone1, NewBB1);
+ PN->addIncoming(Clone2, NewBB2);
+ LPad->replaceAllUsesWith(PN);
+ LPad->eraseFromParent();
+ } else {
+ // There is no second clone. Just replace the landing pad with the first
+ // clone.
+ LPad->replaceAllUsesWith(Clone1);
+ LPad->eraseFromParent();
+ }
+}
+
/// FindFunctionBackedges - Analyze the specified function to find all of the
/// loop backedges in the function and return them. This is a relatively cheap
/// (compared to computing dominators and loop info) analysis.
// Go up one level.
InStack.erase(VisitStack.pop_back_val().first);
}
- } while (!VisitStack.empty());
-
-
+ } while (!VisitStack.empty());
+}
+
+/// FoldReturnIntoUncondBranch - This method duplicates the specified return
+/// instruction into a predecessor which ends in an unconditional branch. If
+/// the return instruction returns a value defined by a PHI, propagate the
+/// right value into the return. It returns the new return instruction in the
+/// predecessor.
+ReturnInst *llvm::FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
+ BasicBlock *Pred) {
+ Instruction *UncondBranch = Pred->getTerminator();
+ // Clone the return and add it to the end of the predecessor.
+ Instruction *NewRet = RI->clone();
+ Pred->getInstList().push_back(NewRet);
+
+ // If the return instruction returns a value, and if the value was a
+ // PHI node in "BB", propagate the right value into the return.
+ for (User::op_iterator i = NewRet->op_begin(), e = NewRet->op_end();
+ i != e; ++i) {
+ Value *V = *i;
+ Instruction *NewBC = 0;
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(V)) {
+ // Return value might be bitcasted. Clone and insert it before the
+ // return instruction.
+ V = BCI->getOperand(0);
+ NewBC = BCI->clone();
+ Pred->getInstList().insert(NewRet, NewBC);
+ *i = NewBC;
+ }
+ if (PHINode *PN = dyn_cast<PHINode>(V)) {
+ if (PN->getParent() == BB) {
+ if (NewBC)
+ NewBC->setOperand(0, PN->getIncomingValueForBlock(Pred));
+ else
+ *i = PN->getIncomingValueForBlock(Pred);
+ }
+ }
+ }
+
+ // Update any PHI nodes in the returning block to realize that we no
+ // longer branch to them.
+ BB->removePredecessor(Pred);
+ UncondBranch->eraseFromParent();
+ return cast<ReturnInst>(NewRet);
+}
+
+/// SplitBlockAndInsertIfThen - Split the containing block at the
+/// specified instruction - everything before and including Cmp stays
+/// in the old basic block, and everything after Cmp is moved to a
+/// new block. The two blocks are connected by a conditional branch
+/// (with value of Cmp being the condition).
+/// Before:
+/// Head
+/// Cmp
+/// Tail
+/// After:
+/// Head
+/// Cmp
+/// if (Cmp)
+/// ThenBlock
+/// Tail
+///
+/// If Unreachable is true, then ThenBlock ends with
+/// UnreachableInst, otherwise it branches to Tail.
+/// Returns the NewBasicBlock's terminator.
+
+TerminatorInst *llvm::SplitBlockAndInsertIfThen(Instruction *Cmp,
+ bool Unreachable, MDNode *BranchWeights) {
+ Instruction *SplitBefore = Cmp->getNextNode();
+ BasicBlock *Head = SplitBefore->getParent();
+ BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
+ TerminatorInst *HeadOldTerm = Head->getTerminator();
+ LLVMContext &C = Head->getContext();
+ BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
+ TerminatorInst *CheckTerm;
+ if (Unreachable)
+ CheckTerm = new UnreachableInst(C, ThenBlock);
+ else
+ CheckTerm = BranchInst::Create(Tail, ThenBlock);
+ BranchInst *HeadNewTerm =
+ BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cmp);
+ HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
+ ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
+ return CheckTerm;
}
projects / oota-llvm.git / blobdiff