Add instruction level dominates(A,B) interface.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37504 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-06-07 23:52:40 +00:00
parent 27af5c414b
commit e029b2c369
2 changed files with 27 additions and 0 deletions

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@ -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...

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@ -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.
//