//
// 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.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/DominatorInternals.h"
#include "llvm/Instructions.h"
-#include "llvm/Support/Streams.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/CommandLine.h"
#include <algorithm>
using namespace llvm;
-namespace llvm {
-static std::ostream &operator<<(std::ostream &o,
- const std::set<BasicBlock*> &BBs) {
- for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
- I != E; ++I)
- if (*I)
- WriteAsOperand(o, *I, false);
- else
- o << " <<exit node>>";
- return o;
-}
-}
+// Always verify dominfo if expensive checking is enabled.
+#ifdef XDEBUG
+static bool VerifyDomInfo = true;
+#else
+static bool VerifyDomInfo = false;
+#endif
+static cl::opt<bool,true>
+VerifyDomInfoX("verify-dom-info", cl::location(VerifyDomInfo),
+ cl::desc("Verify dominator info (time consuming)"));
//===----------------------------------------------------------------------===//
// DominatorTree Implementation
//
//===----------------------------------------------------------------------===//
-TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
-TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
+TEMPLATE_INSTANTIATION(class llvm::DomTreeNodeBase<BasicBlock>);
+TEMPLATE_INSTANTIATION(class llvm::DominatorTreeBase<BasicBlock>);
char DominatorTree::ID = 0;
-static RegisterPass<DominatorTree>
-E("domtree", "Dominator Tree Construction", true);
+INITIALIZE_PASS(DominatorTree, "domtree",
+ "Dominator Tree Construction", true, true);
bool DominatorTree::runOnFunction(Function &F) {
- reset(); // Reset from the last time we were run...
+ DT->recalculate(F);
+ return false;
+}
+
+void DominatorTree::verifyAnalysis() const {
+ if (!VerifyDomInfo) return;
+
+ Function &F = *getRoot()->getParent();
+
+ DominatorTree OtherDT;
+ OtherDT.getBase().recalculate(F);
+ assert(!compare(OtherDT) && "Invalid DominatorTree info!");
+}
+
+void DominatorTree::print(raw_ostream &OS, const Module *) const {
+ DT->print(OS);
+}
+
+// dominates - Return true if A dominates a use in B. This performs the
+// special checks necessary if A and B are in the same basic block.
+bool DominatorTree::dominates(const Instruction *A, const Instruction *B) const{
+ const BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
- // Initialize roots
- Roots.push_back(&F.getEntryBlock());
- IDoms[&F.getEntryBlock()] = 0;
- DomTreeNodes[&F.getEntryBlock()] = 0;
- Vertex.push_back(0);
+ // If A is an invoke instruction, its value is only available in this normal
+ // successor block.
+ if (const InvokeInst *II = dyn_cast<InvokeInst>(A))
+ BBA = II->getNormalDest();
- Calculate<BasicBlock*, GraphTraits<BasicBlock*> >(*this, F);
+ if (BBA != BBB) return dominates(BBA, BBB);
- updateDFSNumbers();
+ // It is not possible to determine dominance between two PHI nodes
+ // based on their ordering.
+ if (isa<PHINode>(A) && isa<PHINode>(B))
+ return false;
- return false;
+ // Loop through the basic block until we find A or B.
+ BasicBlock::const_iterator I = BBA->begin();
+ for (; &*I != A && &*I != B; ++I)
+ /*empty*/;
+
+ return &*I == A;
}
+
+
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
//===----------------------------------------------------------------------===//
char DominanceFrontier::ID = 0;
-static RegisterPass<DominanceFrontier>
-G("domfrontier", "Dominance Frontier Construction", true);
+INITIALIZE_PASS(DominanceFrontier, "domfrontier",
+ "Dominance Frontier Construction", true, true);
+
+void DominanceFrontier::verifyAnalysis() const {
+ if (!VerifyDomInfo) return;
+
+ DominatorTree &DT = getAnalysis<DominatorTree>();
-// NewBB is split and now it has one successor. Update dominace frontier to
+ DominanceFrontier OtherDF;
+ const std::vector<BasicBlock*> &DTRoots = DT.getRoots();
+ OtherDF.calculate(DT, DT.getNode(DTRoots[0]));
+ assert(!compare(OtherDF) && "Invalid DominanceFrontier info!");
+}
+
+// NewBB is split and now it has one successor. Update dominance frontier to
// reflect this change.
void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
- assert(NewBB->getTerminator()->getNumSuccessors() == 1
- && "NewBB should have a single successor!");
+ assert(NewBB->getTerminator()->getNumSuccessors() == 1 &&
+ "NewBB should have a single successor!");
BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
- std::vector<BasicBlock*> PredBlocks;
- for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
- PI != PE; ++PI)
- PredBlocks.push_back(*PI);
-
- if (PredBlocks.empty())
- // If NewBB does not have any predecessors then it is a entry block.
- // In this case, NewBB and its successor NewBBSucc dominates all
- // other blocks.
- return;
-
// NewBBSucc inherits original NewBB frontier.
DominanceFrontier::iterator NewBBI = find(NewBB);
- if (NewBBI != end()) {
- DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
- DominanceFrontier::DomSetType NewBBSuccSet;
- NewBBSuccSet.insert(NewBBSet.begin(), NewBBSet.end());
- addBasicBlock(NewBBSucc, NewBBSuccSet);
- }
+ if (NewBBI != end())
+ addBasicBlock(NewBBSucc, NewBBI->second);
// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
- // DF(PredBlocks[0]) without the stuff that the new block does not dominate
+ // DF(NewBBSucc) without the stuff that the new block does not dominate
// a predecessor of.
DominatorTree &DT = getAnalysis<DominatorTree>();
- if (DT.dominates(NewBB, NewBBSucc)) {
- DominanceFrontier::iterator DFI = find(PredBlocks[0]);
+ DomTreeNode *NewBBNode = DT.getNode(NewBB);
+ DomTreeNode *NewBBSuccNode = DT.getNode(NewBBSucc);
+ if (DT.dominates(NewBBNode, NewBBSuccNode)) {
+ DominanceFrontier::iterator DFI = find(NewBBSucc);
if (DFI != end()) {
DominanceFrontier::DomSetType Set = DFI->second;
// Filter out stuff in Set that we do not dominate a predecessor of.
bool DominatesPred = false;
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
PI != E; ++PI)
- if (DT.dominates(NewBB, *PI))
+ if (DT.dominates(NewBBNode, DT.getNode(*PI))) {
DominatesPred = true;
+ break;
+ }
if (!DominatesPred)
Set.erase(SetI++);
else
NewDFSet.insert(NewBBSucc);
addBasicBlock(NewBB, NewDFSet);
}
-
- // Now we must loop over all of the dominance frontiers in the function,
- // replacing occurrences of NewBBSucc with NewBB in some cases. All
- // blocks that dominate a block in PredBlocks and contained NewBBSucc in
- // their dominance frontier must be updated to contain NewBB instead.
- //
- for (Function::iterator FI = NewBB->getParent()->begin(),
- FE = NewBB->getParent()->end(); FI != FE; ++FI) {
- DominanceFrontier::iterator DFI = find(FI);
- if (DFI == end()) continue; // unreachable block.
-
- // Only consider nodes that have NewBBSucc in their dominator frontier.
- if (!DFI->second.count(NewBBSucc)) continue;
-
- // Verify whether this block dominates a block in predblocks. If not, do
- // not update it.
- bool BlockDominatesAny = false;
- for (std::vector<BasicBlock*>::const_iterator BI = PredBlocks.begin(),
- BE = PredBlocks.end(); BI != BE; ++BI) {
- if (DT.dominates(FI, *BI)) {
- BlockDominatesAny = true;
+
+ // Now update dominance frontiers which either used to contain NewBBSucc
+ // or which now need to include NewBB.
+
+ // Collect the set of blocks which dominate a predecessor of NewBB or
+ // NewSuccBB and which don't dominate both. This is an initial
+ // approximation of the blocks whose dominance frontiers will need updates.
+ SmallVector<DomTreeNode *, 16> AllPredDoms;
+
+ // Compute the block which dominates both NewBBSucc and NewBB. This is
+ // the immediate dominator of NewBBSucc unless NewBB dominates NewBBSucc.
+ // The code below which climbs dominator trees will stop at this point,
+ // because from this point up, dominance frontiers are unaffected.
+ DomTreeNode *DominatesBoth = 0;
+ if (NewBBSuccNode) {
+ DominatesBoth = NewBBSuccNode->getIDom();
+ if (DominatesBoth == NewBBNode)
+ DominatesBoth = NewBBNode->getIDom();
+ }
+
+ // Collect the set of all blocks which dominate a predecessor of NewBB.
+ SmallPtrSet<DomTreeNode *, 8> NewBBPredDoms;
+ for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB); PI != E; ++PI)
+ for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
+ if (DTN == DominatesBoth)
break;
- }
+ if (!NewBBPredDoms.insert(DTN))
+ break;
+ AllPredDoms.push_back(DTN);
}
-
- if (!BlockDominatesAny)
- continue;
-
- // If NewBBSucc should not stay in our dominator frontier, remove it.
- // We remove it unless there is a predecessor of NewBBSucc that we
- // dominate, but we don't strictly dominate NewBBSucc.
- bool ShouldRemove = true;
- if ((BasicBlock*)FI == NewBBSucc || !DT.dominates(FI, NewBBSucc)) {
- // Okay, we know that PredDom does not strictly dominate NewBBSucc.
- // Check to see if it dominates any predecessors of NewBBSucc.
- for (pred_iterator PI = pred_begin(NewBBSucc),
- E = pred_end(NewBBSucc); PI != E; ++PI)
- if (DT.dominates(FI, *PI)) {
- ShouldRemove = false;
- break;
- }
+
+ // Collect the set of all blocks which dominate a predecessor of NewSuccBB.
+ SmallPtrSet<DomTreeNode *, 8> NewBBSuccPredDoms;
+ for (pred_iterator PI = pred_begin(NewBBSucc),
+ E = pred_end(NewBBSucc); PI != E; ++PI)
+ for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
+ if (DTN == DominatesBoth)
+ break;
+ if (!NewBBSuccPredDoms.insert(DTN))
+ break;
+ if (!NewBBPredDoms.count(DTN))
+ AllPredDoms.push_back(DTN);
}
-
- if (ShouldRemove)
+
+ // Visit all relevant dominance frontiers and make any needed updates.
+ for (SmallVectorImpl<DomTreeNode *>::const_iterator I = AllPredDoms.begin(),
+ E = AllPredDoms.end(); I != E; ++I) {
+ DomTreeNode *DTN = *I;
+ iterator DFI = find((*I)->getBlock());
+
+ // Only consider nodes that have NewBBSucc in their dominator frontier.
+ if (DFI == end() || !DFI->second.count(NewBBSucc)) continue;
+
+ // If the block dominates a predecessor of NewBB but does not properly
+ // dominate NewBB itself, add NewBB to its dominance frontier.
+ if (NewBBPredDoms.count(DTN) &&
+ !DT.properlyDominates(DTN, NewBBNode))
+ addToFrontier(DFI, NewBB);
+
+ // If the block does not dominate a predecessor of NewBBSucc or
+ // properly dominates NewBBSucc itself, remove NewBBSucc from its
+ // dominance frontier.
+ if (!NewBBSuccPredDoms.count(DTN) ||
+ DT.properlyDominates(DTN, NewBBSuccNode))
removeFromFrontier(DFI, NewBBSucc);
- addToFrontier(DFI, NewBB);
}
}
return *Result;
}
-void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {
+void DominanceFrontierBase::print(raw_ostream &OS, const Module* ) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
- o << " DomFrontier for BB";
+ OS << " DomFrontier for BB ";
if (I->first)
- WriteAsOperand(o, I->first, false);
+ WriteAsOperand(OS, I->first, false);
else
- o << " <<exit node>>";
- o << " is:\t" << I->second << "\n";
+ OS << " <<exit node>>";
+ OS << " is:\t";
+
+ const std::set<BasicBlock*> &BBs = I->second;
+
+ for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
+ I != E; ++I) {
+ OS << ' ';
+ if (*I)
+ WriteAsOperand(OS, *I, false);
+ else
+ OS << "<<exit node>>";
+ }
+ OS << "\n";
}
}
-void DominanceFrontierBase::dump() {
- print (llvm::cerr);
+void DominanceFrontierBase::dump() const {
+ print(dbgs());
}
+
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