//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/BasicBlockUtils.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/Dominators.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/ValueHandle.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
using namespace llvm;
// Can delete self loop.
BB->getSinglePredecessor() == BB) && "Block is not dead!");
TerminatorInst *BBTerm = BB->getTerminator();
-
+
// Loop through all of our successors and make sure they know that one
// of their predecessors is going away.
for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i)
BBTerm->getSuccessor(i)->removePredecessor(BB);
-
+
// Zap all the instructions in the block.
while (!BB->empty()) {
Instruction &I = BB->back();
I.replaceAllUsesWith(UndefValue::get(I.getType()));
BB->getInstList().pop_back();
}
-
+
// Zap the block!
BB->eraseFromParent();
}
/// when the block has exactly one predecessor.
void llvm::FoldSingleEntryPHINodes(BasicBlock *BB, Pass *P) {
if (!isa<PHINode>(BB->begin())) return;
-
- AliasAnalysis *AA = 0;
- MemoryDependenceAnalysis *MemDep = 0;
+
+ AliasAnalysis *AA = nullptr;
+ MemoryDependenceAnalysis *MemDep = nullptr;
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;
}
bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) {
// Don't merge away blocks who have their address taken.
if (BB->hasAddressTaken()) return false;
-
+
// Can't merge if there are multiple predecessors, or no predecessors.
BasicBlock *PredBB = BB->getUniquePredecessor();
if (!PredBB) return false;
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;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
- OnlySucc = 0; // There are multiple distinct successors!
+ OnlySucc = nullptr; // There are multiple distinct successors!
break;
}
-
+
// Can't merge if there are multiple successors.
if (!OnlySucc) return false;
// Begin by getting rid of unneeded PHIs.
if (isa<PHINode>(BB->front()))
FoldSingleEntryPHINodes(BB, P);
-
+
// Delete the unconditional branch from the predecessor...
PredBB->getInstList().pop_back();
-
+
// 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>()) {
- if (DomTreeNode *DTN = DT->getNode(BB)) {
- DomTreeNode *PredDTN = DT->getNode(PredBB);
+ if (DominatorTreeWrapperPass *DTWP =
+ P->getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
+ DominatorTree &DT = DTWP->getDomTree();
+ 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(),
+ for (SmallVectorImpl<DomTreeNode *>::iterator DI = Children.begin(),
DE = Children.end(); DI != DE; ++DI)
- DT->changeImmediateDominator(*DI, PredDTN);
+ DT.changeImmediateDominator(*DI, PredDTN);
- DT->eraseNode(BB);
+ DT.eraseNode(BB);
}
-
+
if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>())
LI->removeBlock(BB);
-
+
if (MemoryDependenceAnalysis *MD =
P->getAnalysisIfAvailable<MemoryDependenceAnalysis>())
MD->invalidateCachedPredecessors();
}
}
-
+
BB->eraseFromParent();
return true;
}
///
void llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL,
BasicBlock::iterator &BI, Instruction *I) {
- assert(I->getParent() == 0 &&
+ assert(I->getParent() == nullptr &&
"ReplaceInstWithInst: Instruction already inserted into basic block!");
// Insert the new instruction into the basic block...
ReplaceInstWithInst(From->getParent()->getInstList(), BI, To);
}
-/// 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
-/// successor.
-unsigned llvm::GetSuccessorNumber(BasicBlock *BB, BasicBlock *Succ) {
- TerminatorInst *Term = BB->getTerminator();
-#ifndef NDEBUG
- unsigned e = Term->getNumSuccessors();
-#endif
- for (unsigned i = 0; ; ++i) {
- assert(i != e && "Didn't find edge?");
- if (Term->getSuccessor(i) == Succ)
- return i;
- }
- return 0;
-}
-
-/// SplitEdge - Split the edge connecting specified block. Pass P must
-/// not be NULL.
+/// SplitEdge - Split the edge connecting specified block. Pass P must
+/// not be NULL.
BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) {
unsigned SuccNum = GetSuccessorNumber(BB, Succ);
-
+
// If this is a critical edge, let SplitCriticalEdge do it.
TerminatorInst *LatchTerm = BB->getTerminator();
if (SplitCriticalEdge(LatchTerm, SuccNum, P))
// If the edge isn't critical, then BB has a single successor or Succ has a
// single pred. Split the block.
- BasicBlock::iterator SplitPoint;
if (BasicBlock *SP = Succ->getSinglePredecessor()) {
// If the successor only has a single pred, split the top of the successor
// block.
assert(SP == BB && "CFG broken");
- SP = NULL;
+ SP = nullptr;
return SplitBlock(Succ, Succ->begin(), 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!");
+ "Should have a single succ!");
return SplitBlock(BB, BB->getTerminator(), P);
}
if (Loop *L = LI->getLoopFor(Old))
L->addBasicBlockToLoop(New, LI->getBase());
- if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) {
+ if (DominatorTreeWrapperPass *DTWP =
+ P->getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
+ DominatorTree &DT = DTWP->getDomTree();
// Old dominates New. New node dominates 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);
+ 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);
+ DomTreeNode *NewNode = DT.addNewBlock(New, Old);
for (std::vector<DomTreeNode *>::iterator I = Children.begin(),
- E = Children.end(); I != E; ++I)
- DT->changeImmediateDominator(*I, NewNode);
+ E = Children.end(); I != E; ++I)
+ DT.changeImmediateDominator(*I, NewNode);
+ }
}
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;
+
+ LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>();
+ Loop *L = LI ? LI->getLoopFor(OldBB) : nullptr;
+
+ // If we need to preserve loop analyses, collect some information about how
+ // this split will affect loops.
+ bool IsLoopEntry = !!L;
+ bool SplitMakesNewLoopHeader = false;
+ 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(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) continue;
+ if (L->contains(Pred))
+ IsLoopEntry = false;
+ else
+ SplitMakesNewLoopHeader = true;
+ }
+ }
+
+ // Update dominator tree if available.
+ if (DominatorTreeWrapperPass *DTWP =
+ P->getAnalysisIfAvailable<DominatorTreeWrapperPass>())
+ DTWP->getDomTree().splitBlock(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 = nullptr;
+ 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>() : nullptr;
+ SmallPtrSet<BasicBlock *, 16> PredSet(Preds.begin(), Preds.end());
+ 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 = nullptr;
+ if (!HasLoopExit) {
+ InVal = PN->getIncomingValueForBlock(Preds[0]);
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ if (!PredSet.count(PN->getIncomingBlock(i)))
+ continue;
+ if (!InVal)
+ InVal = PN->getIncomingValue(i);
+ else if (InVal != PN->getIncomingValue(i)) {
+ InVal = nullptr;
+ break;
+ }
+ }
+ }
+
+ if (InVal) {
+ // 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.
+
+ // NOTE! This loop walks backwards for a reason! First off, this minimizes
+ // the cost of removal if we end up removing a large number of values, and
+ // second off, this ensures that the indices for the incoming values
+ // aren't invalidated when we remove one.
+ for (int64_t i = PN->getNumIncomingValues() - 1; i >= 0; --i)
+ if (PredSet.count(PN->getIncomingBlock(i)))
+ PN->removeIncomingValue(i, false);
+
+ // Add an incoming value to the PHI node in the loop for the preheader
+ // edge.
+ PN->addIncoming(InVal, NewBB);
+ continue;
+ }
+
+ // If the values coming into the block are not the same, we need a new
+ // PHI.
+ // Create the new PHI node, insert it into NewBB at the end of the block
+ PHINode *NewPHI =
+ PHINode::Create(PN->getType(), Preds.size(), PN->getName() + ".ph", BI);
+ if (AA)
+ AA->copyValue(PN, NewPHI);
+
+ // NOTE! This loop walks backwards for a reason! First off, this minimizes
+ // the cost of removal if we end up removing a large number of values, and
+ // second off, this ensures that the indices for the incoming values aren't
+ // invalidated when we remove one.
+ for (int64_t i = PN->getNumIncomingValues() - 1; i >= 0; --i) {
+ BasicBlock *IncomingBB = PN->getIncomingBlock(i);
+ if (PredSet.count(IncomingBB)) {
+ Value *V = PN->removeIncomingValue(i, false);
+ NewPHI->addIncoming(V, IncomingBB);
+ }
+ }
+
+ PN->addIncoming(NewPHI, NewBB);
+ }
+}
/// SplitBlockPredecessors - This method transforms BB by introducing a new
/// basic block into the function, and moving some of the predecessors of BB to
/// 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) {
+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);
-
- LoopInfo *LI = P ? P->getAnalysisIfAvailable<LoopInfo>() : 0;
- Loop *L = LI ? LI->getLoopFor(BB) : 0;
- bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID);
// 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;
- bool IsLoopEntry = !!L;
- bool SplitMakesNewLoopHeader = false;
- for (unsigned i = 0; i != NumPreds; ++i) {
+ 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);
-
- if (LI) {
- // 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))
- 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;
- }
- }
}
- // Update dominator tree if available.
- DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0;
- if (DT)
- DT->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) {
+ 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;
}
- 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); ) {
- 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)
- if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
- InVal = 0;
- break;
- }
- }
+ // Update DominatorTree, LoopInfo, and LCCSA analysis information.
+ bool HasLoopExit = false;
+ UpdateAnalysisInformation(BB, NewBB, Preds, P, HasLoopExit);
- if (InVal) {
- // 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)
- 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(), NumPreds, 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) {
- 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);
- }
-
+ // Update the PHI nodes in BB with the values coming from NewBB.
+ UpdatePHINodes(BB, NewBB, Preds, BI, P, HasLoopExit);
return NewBB;
}
-/// 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.
+/// 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.
///
-/// The output is added to Result, as pairs of <from,to> edge info.
-void llvm::FindFunctionBackedges(const Function &F,
- SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) {
- const BasicBlock *BB = &F.getEntryBlock();
- if (succ_begin(BB) == succ_end(BB))
- return;
-
- SmallPtrSet<const BasicBlock*, 8> Visited;
- SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack;
- SmallPtrSet<const BasicBlock*, 8> InStack;
-
- Visited.insert(BB);
- VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
- InStack.insert(BB);
- do {
- std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back();
- const BasicBlock *ParentBB = Top.first;
- succ_const_iterator &I = Top.second;
-
- bool FoundNew = false;
- while (I != succ_end(ParentBB)) {
- BB = *I++;
- if (Visited.insert(BB)) {
- FoundNew = true;
- break;
- }
- // Successor is in VisitStack, it's a back edge.
- if (InStack.count(BB))
- Result.push_back(std::make_pair(ParentBB, BB));
- }
-
- if (FoundNew) {
- // Go down one level if there is a unvisited successor.
- InStack.insert(BB);
- VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
- } else {
- // Go up one level.
- InStack.erase(VisitStack.pop_back_val().first);
- }
- } while (!VisitStack.empty());
+/// 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 = nullptr;
+ 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();
+ }
}
/// FoldReturnIntoUncondBranch - This method duplicates the specified return
// 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)
- if (PHINode *PN = dyn_cast<PHINode>(*i))
- if (PN->getParent() == BB)
- *i = PN->getIncomingValueForBlock(Pred);
-
+ i != e; ++i) {
+ Value *V = *i;
+ Instruction *NewBC = nullptr;
+ 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);
return cast<ReturnInst>(NewRet);
}
-/// GetFirstDebugLocInBasicBlock - Return first valid DebugLoc entry in a
-/// given basic block.
-DebugLoc llvm::GetFirstDebugLocInBasicBlock(const BasicBlock *BB) {
- if (const Instruction *I = BB->getFirstNonPHI())
- return I->getDebugLoc();
- // Scanning entire block may be too expensive, if the first instruction
- // does not have valid location info.
- return DebugLoc();
+/// SplitBlockAndInsertIfThen - Split the containing block at the
+/// specified instruction - everything before and including SplitBefore stays
+/// in the old basic block, and everything after SplitBefore is moved to a
+/// new block. The two blocks are connected by a conditional branch
+/// (with value of Cmp being the condition).
+/// Before:
+/// Head
+/// SplitBefore
+/// Tail
+/// After:
+/// Head
+/// if (Cond)
+/// ThenBlock
+/// SplitBefore
+/// Tail
+///
+/// If Unreachable is true, then ThenBlock ends with
+/// UnreachableInst, otherwise it branches to Tail.
+/// Returns the NewBasicBlock's terminator.
+
+TerminatorInst *llvm::SplitBlockAndInsertIfThen(Value *Cond,
+ Instruction *SplitBefore,
+ bool Unreachable,
+ MDNode *BranchWeights,
+ DominatorTree *DT) {
+ 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);
+ CheckTerm->setDebugLoc(SplitBefore->getDebugLoc());
+ BranchInst *HeadNewTerm =
+ BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cond);
+ HeadNewTerm->setDebugLoc(SplitBefore->getDebugLoc());
+ HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
+ ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
+
+ if (DT) {
+ if (DomTreeNode *OldNode = DT->getNode(Head)) {
+ std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
+
+ DomTreeNode *NewNode = DT->addNewBlock(Tail, Head);
+ for (auto Child : Children)
+ DT->changeImmediateDominator(Child, NewNode);
+
+ // Head dominates ThenBlock.
+ DT->addNewBlock(ThenBlock, Head);
+ }
+ }
+
+ return CheckTerm;
+}
+
+/// SplitBlockAndInsertIfThenElse is similar to SplitBlockAndInsertIfThen,
+/// but also creates the ElseBlock.
+/// Before:
+/// Head
+/// SplitBefore
+/// Tail
+/// After:
+/// Head
+/// if (Cond)
+/// ThenBlock
+/// else
+/// ElseBlock
+/// SplitBefore
+/// Tail
+void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+ TerminatorInst **ThenTerm,
+ TerminatorInst **ElseTerm,
+ MDNode *BranchWeights) {
+ 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);
+ BasicBlock *ElseBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
+ *ThenTerm = BranchInst::Create(Tail, ThenBlock);
+ (*ThenTerm)->setDebugLoc(SplitBefore->getDebugLoc());
+ *ElseTerm = BranchInst::Create(Tail, ElseBlock);
+ (*ElseTerm)->setDebugLoc(SplitBefore->getDebugLoc());
+ BranchInst *HeadNewTerm =
+ BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/ElseBlock, Cond);
+ HeadNewTerm->setDebugLoc(SplitBefore->getDebugLoc());
+ HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
+ ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
+}
+
+
+/// GetIfCondition - Given a basic block (BB) with two predecessors,
+/// check to see if the merge at this block is due
+/// to an "if condition". If so, return the boolean condition that determines
+/// which entry into BB will be taken. Also, return by references the block
+/// that will be entered from if the condition is true, and the block that will
+/// be entered if the condition is false.
+///
+/// This does no checking to see if the true/false blocks have large or unsavory
+/// instructions in them.
+Value *llvm::GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
+ BasicBlock *&IfFalse) {
+ PHINode *SomePHI = dyn_cast<PHINode>(BB->begin());
+ BasicBlock *Pred1 = nullptr;
+ BasicBlock *Pred2 = nullptr;
+
+ if (SomePHI) {
+ if (SomePHI->getNumIncomingValues() != 2)
+ return nullptr;
+ Pred1 = SomePHI->getIncomingBlock(0);
+ Pred2 = SomePHI->getIncomingBlock(1);
+ } else {
+ pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+ if (PI == PE) // No predecessor
+ return nullptr;
+ Pred1 = *PI++;
+ if (PI == PE) // Only one predecessor
+ return nullptr;
+ Pred2 = *PI++;
+ if (PI != PE) // More than two predecessors
+ return nullptr;
+ }
+
+ // We can only handle branches. Other control flow will be lowered to
+ // branches if possible anyway.
+ BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator());
+ BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator());
+ if (!Pred1Br || !Pred2Br)
+ return nullptr;
+
+ // Eliminate code duplication by ensuring that Pred1Br is conditional if
+ // either are.
+ if (Pred2Br->isConditional()) {
+ // If both branches are conditional, we don't have an "if statement". In
+ // reality, we could transform this case, but since the condition will be
+ // required anyway, we stand no chance of eliminating it, so the xform is
+ // probably not profitable.
+ if (Pred1Br->isConditional())
+ return nullptr;
+
+ std::swap(Pred1, Pred2);
+ std::swap(Pred1Br, Pred2Br);
+ }
+
+ if (Pred1Br->isConditional()) {
+ // The only thing we have to watch out for here is to make sure that Pred2
+ // doesn't have incoming edges from other blocks. If it does, the condition
+ // doesn't dominate BB.
+ if (!Pred2->getSinglePredecessor())
+ return nullptr;
+
+ // If we found a conditional branch predecessor, make sure that it branches
+ // to BB and Pred2Br. If it doesn't, this isn't an "if statement".
+ if (Pred1Br->getSuccessor(0) == BB &&
+ Pred1Br->getSuccessor(1) == Pred2) {
+ IfTrue = Pred1;
+ IfFalse = Pred2;
+ } else if (Pred1Br->getSuccessor(0) == Pred2 &&
+ Pred1Br->getSuccessor(1) == BB) {
+ IfTrue = Pred2;
+ IfFalse = Pred1;
+ } else {
+ // We know that one arm of the conditional goes to BB, so the other must
+ // go somewhere unrelated, and this must not be an "if statement".
+ return nullptr;
+ }
+
+ return Pred1Br->getCondition();
+ }
+
+ // Ok, if we got here, both predecessors end with an unconditional branch to
+ // BB. Don't panic! If both blocks only have a single (identical)
+ // predecessor, and THAT is a conditional branch, then we're all ok!
+ BasicBlock *CommonPred = Pred1->getSinglePredecessor();
+ if (CommonPred == nullptr || CommonPred != Pred2->getSinglePredecessor())
+ return nullptr;
+
+ // Otherwise, if this is a conditional branch, then we can use it!
+ BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator());
+ if (!BI) return nullptr;
+
+ assert(BI->isConditional() && "Two successors but not conditional?");
+ if (BI->getSuccessor(0) == Pred1) {
+ IfTrue = Pred1;
+ IfFalse = Pred2;
+ } else {
+ IfTrue = Pred2;
+ IfFalse = Pred1;
+ }
+ return BI->getCondition();
}
projects / oota-llvm.git / blobdiff