/// If not then a load from this mbb may not be safe to hoist.
bool IsGuaranteedToExecute(MachineBasicBlock *BB);
- /// HoistRegion - Walk the specified region of the CFG (defined by all
- /// blocks dominated by the specified block, and that are in the current
- /// loop) in depth first order w.r.t the DominatorTree. This allows us to
- /// visit definitions before uses, allowing us to hoist a loop body in one
- /// pass without iteration.
+ void EnterScope(MachineBasicBlock *MBB);
+
+ void ExitScope(MachineBasicBlock *MBB);
+
+ /// ExitScopeIfDone - Destroy scope for the MBB that corresponds to given
+ /// dominator tree node if its a leaf or all of its children are done. Walk
+ /// up the dominator tree to destroy ancestors which are now done.
+ void ExitScopeIfDone(MachineDomTreeNode *Node,
+ DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren,
+ DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> &ParentMap);
+
+ /// HoistOutOfLoop - Walk the specified loop in the CFG (defined by all
+ /// blocks dominated by the specified header block, and that are in the
+ /// current loop) in depth first order w.r.t the DominatorTree. This allows
+ /// us to visit definitions before uses, allowing us to hoist a loop body in
+ /// one pass without iteration.
///
- void HoistRegion(MachineDomTreeNode *N, bool IsHeader = false);
+ void HoistOutOfLoop(MachineDomTreeNode *LoopHeaderNode);
+ void HoistRegion(MachineDomTreeNode *N, bool IsHeader);
/// getRegisterClassIDAndCost - For a given MI, register, and the operand
/// index, return the ID and cost of its representative register class by
// being hoisted.
MachineDomTreeNode *N = DT->getNode(CurLoop->getHeader());
FirstInLoop = true;
- HoistRegion(N, true);
+ HoistOutOfLoop(N);
CSEMap.clear();
}
}
return true;
}
-/// HoistRegion - Walk the specified region of the CFG (defined by all blocks
-/// dominated by the specified block, and that are in the current loop) in depth
-/// first order w.r.t the DominatorTree. This allows us to visit definitions
-/// before uses, allowing us to hoist a loop body in one pass without iteration.
-///
-void MachineLICM::HoistRegion(MachineDomTreeNode *N, bool IsHeader) {
- assert(N != 0 && "Null dominator tree node?");
- MachineBasicBlock *BB = N->getBlock();
+void MachineLICM::EnterScope(MachineBasicBlock *MBB) {
+ DEBUG(dbgs() << "Entering: " << MBB->getName() << '\n');
- // If the header of the loop containing this basic block is a landing pad,
- // then don't try to hoist instructions out of this loop.
- const MachineLoop *ML = MLI->getLoopFor(BB);
- if (ML && ML->getHeader()->isLandingPad()) return;
+ // Remember livein register pressure.
+ BackTrace.push_back(RegPressure);
+}
- // If this subregion is not in the top level loop at all, exit.
- if (!CurLoop->contains(BB)) return;
+void MachineLICM::ExitScope(MachineBasicBlock *MBB) {
+ DEBUG(dbgs() << "Exiting: " << MBB->getName() << '\n');
+ BackTrace.pop_back();
+}
- MachineBasicBlock *Preheader = getCurPreheader();
- if (!Preheader)
+/// ExitScopeIfDone - Destroy scope for the MBB that corresponds to the given
+/// dominator tree node if its a leaf or all of its children are done. Walk
+/// up the dominator tree to destroy ancestors which are now done.
+void MachineLICM::ExitScopeIfDone(MachineDomTreeNode *Node,
+ DenseMap<MachineDomTreeNode*, unsigned> &OpenChildren,
+ DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> &ParentMap) {
+ if (OpenChildren[Node])
return;
- if (IsHeader) {
+ // Pop scope.
+ ExitScope(Node->getBlock());
+
+ // Now traverse upwards to pop ancestors whose offsprings are all done.
+ while (MachineDomTreeNode *Parent = ParentMap[Node]) {
+ unsigned Left = --OpenChildren[Parent];
+ if (Left != 0)
+ break;
+ ExitScope(Parent->getBlock());
+ Node = Parent;
+ }
+}
+
+/// HoistOutOfLoop - Walk the specified loop in the CFG (defined by all
+/// blocks dominated by the specified header block, and that are in the
+/// current loop) in depth first order w.r.t the DominatorTree. This allows
+/// us to visit definitions before uses, allowing us to hoist a loop body in
+/// one pass without iteration.
+///
+void MachineLICM::HoistOutOfLoop(MachineDomTreeNode *HeaderN) {
+ SmallVector<MachineDomTreeNode*, 32> Scopes;
+ SmallVector<MachineDomTreeNode*, 8> WorkList;
+ DenseMap<MachineDomTreeNode*, MachineDomTreeNode*> ParentMap;
+ DenseMap<MachineDomTreeNode*, unsigned> OpenChildren;
+
+ // Perform a DFS walk to determine the order of visit.
+ WorkList.push_back(HeaderN);
+ do {
+ MachineDomTreeNode *Node = WorkList.pop_back_val();
+ assert(Node != 0 && "Null dominator tree node?");
+ MachineBasicBlock *BB = Node->getBlock();
+
+ // If the header of the loop containing this basic block is a landing pad,
+ // then don't try to hoist instructions out of this loop.
+ const MachineLoop *ML = MLI->getLoopFor(BB);
+ if (ML && ML->getHeader()->isLandingPad())
+ continue;
+
+ // If this subregion is not in the top level loop at all, exit.
+ if (!CurLoop->contains(BB))
+ continue;
+
+ Scopes.push_back(Node);
+ const std::vector<MachineDomTreeNode*> &Children = Node->getChildren();
+ unsigned NumChildren = Children.size();
+
+ // Don't hoist things out of a large switch statement. This often causes
+ // code to be hoisted that wasn't going to be executed, and increases
+ // register pressure in a situation where it's likely to matter.
+ if (BB->succ_size() >= 25)
+ NumChildren = 0;
+
+ OpenChildren[Node] = NumChildren;
+ // Add children in reverse order as then the next popped worklist node is
+ // the first child of this node. This means we ultimately traverse the
+ // DOM tree in exactly the same order as if we'd recursed.
+ for (int i = (int)NumChildren-1; i >= 0; --i) {
+ MachineDomTreeNode *Child = Children[i];
+ ParentMap[Child] = Node;
+ WorkList.push_back(Child);
+ }
+ } while (!WorkList.empty());
+
+ if (Scopes.size() != 0) {
+ MachineBasicBlock *Preheader = getCurPreheader();
+ if (!Preheader)
+ return;
+
// Compute registers which are livein into the loop headers.
RegSeen.clear();
BackTrace.clear();
InitRegPressure(Preheader);
}
- // Remember livein register pressure.
- BackTrace.push_back(RegPressure);
+ // Now perform LICM.
+ for (unsigned i = 0, e = Scopes.size(); i != e; ++i) {
+ MachineDomTreeNode *Node = Scopes[i];
+ MachineBasicBlock *MBB = Node->getBlock();
- SpeculationState = SpeculateUnknown;
- for (MachineBasicBlock::iterator
- MII = BB->begin(), E = BB->end(); MII != E; ) {
- MachineBasicBlock::iterator NextMII = MII; ++NextMII;
- MachineInstr *MI = &*MII;
- if (!Hoist(MI, Preheader))
- UpdateRegPressure(MI);
- MII = NextMII;
- }
+ MachineBasicBlock *Preheader = getCurPreheader();
+ if (!Preheader)
+ continue;
- // Don't hoist things out of a large switch statement. This often causes
- // code to be hoisted that wasn't going to be executed, and increases
- // register pressure in a situation where it's likely to matter.
- if (BB->succ_size() < 25) {
- const std::vector<MachineDomTreeNode*> &Children = N->getChildren();
- for (unsigned I = 0, E = Children.size(); I != E; ++I)
- HoistRegion(Children[I]);
- }
+ EnterScope(MBB);
- BackTrace.pop_back();
+ // Process the block
+ SpeculationState = SpeculateUnknown;
+ for (MachineBasicBlock::iterator
+ MII = MBB->begin(), E = MBB->end(); MII != E; ) {
+ MachineBasicBlock::iterator NextMII = MII; ++NextMII;
+ MachineInstr *MI = &*MII;
+ if (!Hoist(MI, Preheader))
+ UpdateRegPressure(MI);
+ MII = NextMII;
+ }
+
+ // If it's a leaf node, it's done. Traverse upwards to pop ancestors.
+ ExitScopeIfDone(Node, OpenChildren, ParentMap);
+ }
}
static bool isOperandKill(const MachineOperand &MO, MachineRegisterInfo *MRI) {
unsigned &RCId, unsigned &RCCost) const {
const TargetRegisterClass *RC = MRI->getRegClass(Reg);
EVT VT = *RC->vt_begin();
- if (VT == MVT::untyped) {
+ if (VT == MVT::Untyped) {
RCId = RC->getID();
RCCost = 1;
} else {
/// isLoadFromGOTOrConstantPool - Return true if this machine instruction
/// loads from global offset table or constant pool.
static bool isLoadFromGOTOrConstantPool(MachineInstr &MI) {
- assert (MI.getDesc().mayLoad() && "Expected MI that loads!");
+ assert (MI.mayLoad() && "Expected MI that loads!");
for (MachineInstr::mmo_iterator I = MI.memoperands_begin(),
E = MI.memoperands_end(); I != E; ++I) {
if (const Value *V = (*I)->getValue()) {
// from constant memory are not safe to speculate all the time, for example
// indexed load from a jump table.
// Stores and side effects are already checked by isSafeToMove.
- if (I.getDesc().mayLoad() && !isLoadFromGOTOrConstantPool(I) &&
+ if (I.mayLoad() && !isLoadFromGOTOrConstantPool(I) &&
!IsGuaranteedToExecute(I.getParent()))
return false;
/// IsCheapInstruction - Return true if the instruction is marked "cheap" or
/// the operand latency between its def and a use is one or less.
bool MachineLICM::IsCheapInstruction(MachineInstr &MI) const {
- if (MI.getDesc().isAsCheapAsAMove() || MI.isCopyLike())
+ if (MI.isAsCheapAsAMove() || MI.isCopyLike())
return true;
if (!InstrItins || InstrItins->isEmpty())
return false;
continue;
unsigned RCId = CI->first;
+ unsigned Limit = RegLimit[RCId];
+ int Cost = CI->second;
for (unsigned i = BackTrace.size(); i != 0; --i) {
SmallVector<unsigned, 8> &RP = BackTrace[i-1];
- if (RP[RCId] + CI->second >= RegLimit[RCId])
+ if (RP[RCId] + Cost >= Limit)
return true;
}
}
MachineInstr *MachineLICM::ExtractHoistableLoad(MachineInstr *MI) {
// Don't unfold simple loads.
- if (MI->getDesc().canFoldAsLoad())
+ if (MI->canFoldAsLoad())
return 0;
// If not, we may be able to unfold a load and hoist that.
assert(NewMIs.size() == 2 &&
"Unfolded a load into multiple instructions!");
MachineBasicBlock *MBB = MI->getParent();
- MBB->insert(MI, NewMIs[0]);
- MBB->insert(MI, NewMIs[1]);
+ MachineBasicBlock::iterator Pos = MI;
+ MBB->insert(Pos, NewMIs[0]);
+ MBB->insert(Pos, NewMIs[1]);
// If unfolding produced a load that wasn't loop-invariant or profitable to
// hoist, discard the new instructions and bail.
if (!IsLoopInvariantInst(*NewMIs[0]) || !IsProfitableToHoist(*NewMIs[0])) {
projects / oota-llvm.git / blobdiff