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107 lines
3.5 KiB
C++
107 lines
3.5 KiB
C++
//===- Dominators.cpp - Dominator Calculation -----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements simple dominator construction algorithms for finding
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// forward dominators. Postdominators are available in libanalysis, but are not
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// included in libvmcore, because it's not needed. Forward dominators are
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// needed to support the Verifier pass.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Analysis/DominatorInternals.h"
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#include "llvm/Assembly/Writer.h"
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#include "llvm/Instructions.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Support/CommandLine.h"
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#include <algorithm>
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using namespace llvm;
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// Always verify dominfo if expensive checking is enabled.
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#ifdef XDEBUG
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static bool VerifyDomInfo = true;
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#else
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static bool VerifyDomInfo = false;
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#endif
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static cl::opt<bool,true>
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VerifyDomInfoX("verify-dom-info", cl::location(VerifyDomInfo),
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cl::desc("Verify dominator info (time consuming)"));
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//===----------------------------------------------------------------------===//
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// DominatorTree Implementation
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//===----------------------------------------------------------------------===//
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//
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// Provide public access to DominatorTree information. Implementation details
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// can be found in DominatorInternals.h.
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//
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//===----------------------------------------------------------------------===//
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TEMPLATE_INSTANTIATION(class llvm::DomTreeNodeBase<BasicBlock>);
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TEMPLATE_INSTANTIATION(class llvm::DominatorTreeBase<BasicBlock>);
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char DominatorTree::ID = 0;
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INITIALIZE_PASS(DominatorTree, "domtree",
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"Dominator Tree Construction", true, true)
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bool DominatorTree::runOnFunction(Function &F) {
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DT->recalculate(F);
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return false;
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}
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void DominatorTree::verifyAnalysis() const {
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if (!VerifyDomInfo) return;
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Function &F = *getRoot()->getParent();
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DominatorTree OtherDT;
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OtherDT.getBase().recalculate(F);
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if (compare(OtherDT)) {
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errs() << "DominatorTree is not up to date!\nComputed:\n";
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print(errs());
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errs() << "\nActual:\n";
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OtherDT.print(errs());
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abort();
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}
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}
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void DominatorTree::print(raw_ostream &OS, const Module *) const {
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DT->print(OS);
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}
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// dominates - Return true if A dominates a use in B. This performs the
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// special checks necessary if A and B are in the same basic block.
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bool DominatorTree::dominates(const Instruction *A, const Instruction *B) const{
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const BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
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// If A is an invoke instruction, its value is only available in this normal
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// successor block.
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if (const InvokeInst *II = dyn_cast<InvokeInst>(A))
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BBA = II->getNormalDest();
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if (BBA != BBB) return dominates(BBA, BBB);
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// It is not possible to determine dominance between two PHI nodes
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// based on their ordering.
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if (isa<PHINode>(A) && isa<PHINode>(B))
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return false;
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// Loop through the basic block until we find A or B.
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BasicBlock::const_iterator I = BBA->begin();
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for (; &*I != A && &*I != B; ++I)
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/*empty*/;
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return &*I == A;
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}
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