Changes in directory llvm/lib/VMCore:
Dominators.cpp updated: 1.117 -> 1.118
---
Log message:
Move code to update dominator information after basic block is split
from LoopSimplify.cpp to Dominator.cpp
---
Diffs of the changes: (+184 -0)
Dominators.cpp | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 184 insertions(+)
Index: llvm/lib/VMCore/Dominators.cpp
diff -u llvm/lib/VMCore/Dominators.cpp:1.117
llvm/lib/VMCore/Dominators.cpp:1.118
--- llvm/lib/VMCore/Dominators.cpp:1.117 Tue Jun 12 12:50:25 2007
+++ llvm/lib/VMCore/Dominators.cpp Thu Jun 21 12:23:45 2007
@@ -63,6 +63,89 @@
static RegisterPass<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
+// NewBB is split and now it has one successor. Update dominator tree to
+// reflect this change.
+void DominatorTree::splitBlock(BasicBlock *NewBB) {
+
+ 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);
+
+ assert(!PredBlocks.empty() && "No predblocks??");
+
+ // The newly inserted basic block will dominate existing basic blocks iff the
+ // PredBlocks dominate all of the non-pred blocks. If all predblocks
dominate
+ // the non-pred blocks, then they all must be the same block!
+ //
+ bool NewBBDominatesNewBBSucc = true;
+ {
+ BasicBlock *OnePred = PredBlocks[0];
+ unsigned i = 1, e = PredBlocks.size();
+ for (i = 1; !isReachableFromEntry(OnePred); ++i) {
+ assert(i != e && "Didn't find reachable pred?");
+ OnePred = PredBlocks[i];
+ }
+
+ for (; i != e; ++i)
+ if (PredBlocks[i] != OnePred && isReachableFromEntry(OnePred)){
+ NewBBDominatesNewBBSucc = false;
+ break;
+ }
+
+ if (NewBBDominatesNewBBSucc)
+ for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
+ PI != E; ++PI)
+ if (*PI != NewBB && !dominates(NewBBSucc, *PI)) {
+ NewBBDominatesNewBBSucc = false;
+ break;
+ }
+ }
+
+ // The other scenario where the new block can dominate its successors are
when
+ // all predecessors of NewBBSucc that are not NewBB are dominated by
NewBBSucc
+ // already.
+ if (!NewBBDominatesNewBBSucc) {
+ NewBBDominatesNewBBSucc = true;
+ for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
+ PI != E; ++PI)
+ if (*PI != NewBB && !dominates(NewBBSucc, *PI)) {
+ NewBBDominatesNewBBSucc = false;
+ break;
+ }
+ }
+
+
+ // Find NewBB's immediate dominator and create new dominator tree node for
NewBB.
+ BasicBlock *NewBBIDom = 0;
+ unsigned i = 0;
+ for (i = 0; i < PredBlocks.size(); ++i)
+ if (isReachableFromEntry(PredBlocks[i])) {
+ NewBBIDom = PredBlocks[i];
+ break;
+ }
+ assert(i != PredBlocks.size() && "No reachable preds?");
+ for (i = i + 1; i < PredBlocks.size(); ++i) {
+ if (isReachableFromEntry(PredBlocks[i]))
+ NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
+ }
+ assert(NewBBIDom && "No immediate dominator found??");
+
+ // Create the new dominator tree node... and set the idom of NewBB.
+ DomTreeNode *NewBBNode = addNewBlock(NewBB, NewBBIDom);
+
+ // If NewBB strictly dominates other blocks, then it is now the immediate
+ // dominator of NewBBSucc. Update the dominator tree as appropriate.
+ if (NewBBDominatesNewBBSucc) {
+ DomTreeNode *NewBBSuccNode = getNode(NewBBSucc);
+ changeImmediateDominator(NewBBSuccNode, NewBBNode);
+ }
+}
+
unsigned DominatorTree::DFSPass(BasicBlock *V, InfoRec &VInfo,
unsigned N) {
// This is more understandable as a recursive algorithm, but we can't use the
@@ -520,6 +603,107 @@
static RegisterPass<DominanceFrontier>
G("domfrontier", "Dominance Frontier Construction", true);
+// NewBB is split and now it has one successor. Update dominace frontier to
+// reflect this change.
+void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
+
+ 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);
+
+ assert(!PredBlocks.empty() && "No predblocks??");
+
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ bool NewBBDominatesNewBBSucc = true;
+ if (!DT.dominates(NewBB, NewBBSucc))
+ NewBBDominatesNewBBSucc = false;
+
+ // 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
+ // a predecessor of.
+ if (NewBBDominatesNewBBSucc) {
+ DominanceFrontier::iterator DFI = find(PredBlocks[0]);
+ if (DFI != end()) {
+ DominanceFrontier::DomSetType Set = DFI->second;
+ // Filter out stuff in Set that we do not dominate a predecessor of.
+ for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
+ E = Set.end(); SetI != E;) {
+ bool DominatesPred = false;
+ for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
+ PI != E; ++PI)
+ if (DT.dominates(NewBB, *PI))
+ DominatesPred = true;
+ if (!DominatesPred)
+ Set.erase(SetI++);
+ else
+ ++SetI;
+ }
+
+ addBasicBlock(NewBB, Set);
+ }
+
+ } else {
+ // DF(NewBB) is {NewBBSucc} because NewBB does not strictly dominate
+ // NewBBSucc, but it does dominate itself (and there is an edge (NewBB ->
+ // NewBBSucc)). NewBBSucc is the single successor of NewBB.
+ DominanceFrontier::DomSetType NewDFSet;
+ 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 dominators of NewBBSucc
+ if (!DFI->second.count(NewBBSucc)) continue;
+
+ 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;
+ break;
+ }
+ }
+
+ if (BlockDominatesAny) {
+ // 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;
+ }
+
+ if (ShouldRemove)
+ removeFromFrontier(DFI, NewBBSucc);
+ addToFrontier(DFI, NewBB);
+
+ break;
+ }
+ }
+ }
+}
+
namespace {
class DFCalculateWorkObject {
public:
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