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//===- Dominators.cpp - Dominator Calculation -----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements simple dominator construction algorithms for finding
// forward dominators. Postdominators are available in libanalysis, but are not
// included in libvmcore, because it's not needed. Forward dominators are
// needed to support the Verifier pass.
//
//===----------------------------------------------------------------------===//
#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/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/DominatorInternals.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Instructions.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CommandLine.h"
#include <algorithm>
using namespace llvm;
// 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
//===----------------------------------------------------------------------===//
//
// Provide public access to DominatorTree information. Implementation details
// can be found in DominatorInternals.h.
//
//===----------------------------------------------------------------------===//
TEMPLATE_INSTANTIATION(class llvm::DomTreeNodeBase<BasicBlock>);
TEMPLATE_INSTANTIATION(class llvm::DominatorTreeBase<BasicBlock>);
char DominatorTree::ID = 0;
INITIALIZE_PASS(DominatorTree, "domtree",
"Dominator Tree Construction", true, true)
bool DominatorTree::runOnFunction(Function &F) {
DT->recalculate(F);
return false;
}
void DominatorTree::verifyAnalysis() const {
if (!VerifyDomInfo) return;
Function &F = *getRoot()->getParent();
DominatorTree OtherDT;
OtherDT.getBase().recalculate(F);
if (compare(OtherDT)) {
errs() << "DominatorTree is not up to date!\nComputed:\n";
print(errs());
errs() << "\nActual:\n";
OtherDT.print(errs());
abort();
}
}
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();
// 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();
if (BBA != BBB) return dominates(BBA, BBB);
// It is not possible to determine dominance between two PHI nodes
// based on their ordering.
if (isa<PHINode>(A) && isa<PHINode>(B))
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;
}
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