diff options
| -rw-r--r-- | include/llvm/Analysis/Dominators.h | 4 | ||||
| -rw-r--r-- | lib/VMCore/Dominators.cpp | 23 |
2 files changed, 27 insertions, 0 deletions
diff --git a/include/llvm/Analysis/Dominators.h b/include/llvm/Analysis/Dominators.h index f98db6f13d..d1fc5eb05a 100644 --- a/include/llvm/Analysis/Dominators.h +++ b/include/llvm/Analysis/Dominators.h @@ -219,6 +219,10 @@ protected: return dominates(getNode(A), getNode(B)); } + // dominates - Return true if A dominates B. This performs the + // special checks necessary if A and B are in the same basic block. + bool dominates(Instruction *A, Instruction *B); + //===--------------------------------------------------------------------===// // API to update (Post)DominatorTree information based on modifications to // the CFG... diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp index 9bfbbec9b9..fc5d6a63ca 100644 --- a/lib/VMCore/Dominators.cpp +++ b/lib/VMCore/Dominators.cpp @@ -324,6 +324,29 @@ void DominatorTreeBase::updateDFSNumbers() DFSInfoValid = true; } +// dominates - Return true if A dominates B. THis performs the +// special checks necessary if A and B are in the same basic block. +bool DominatorTreeBase::dominates(Instruction *A, Instruction *B) { + BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); + 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::iterator I = BBA->begin(); + for (; &*I != A && &*I != B; ++I) /*empty*/; + + if(!IsPostDominators) { + // A dominates B if it is found first in the basic block. + return &*I == A; + } else { + // A post-dominates B if B is found first in the basic block. + return &*I == B; + } +} // DominatorTreeBase::reset - Free all of the tree node memory. // |