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Another step of stronger PHI elimination down.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43684 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -21,6 +21,7 @@
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#define DEBUG_TYPE "strongphielim"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/LiveVariables.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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@ -44,6 +45,8 @@ namespace {
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addPreserved<LiveVariables>();
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AU.addPreservedID(PHIEliminationID);
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AU.addRequired<MachineDominatorTree>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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@ -54,10 +57,35 @@ namespace {
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}
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private:
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struct DomForestNode {
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private:
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std::vector<DomForestNode*> children;
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MachineInstr* instr;
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void addChild(DomForestNode* DFN) { children.push_back(DFN); }
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public:
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typedef std::vector<DomForestNode*>::iterator iterator;
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DomForestNode(MachineInstr* MI, DomForestNode* parent) : instr(MI) {
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if (parent)
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parent->addChild(this);
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}
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MachineInstr* getInstr() { return instr; }
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DomForestNode::iterator begin() { return children.begin(); }
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DomForestNode::iterator end() { return children.end(); }
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};
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DenseMap<MachineBasicBlock*, unsigned> preorder;
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DenseMap<MachineBasicBlock*, unsigned> maxpreorder;
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void computeDFS(MachineFunction& MF);
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std::vector<DomForestNode*>
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computeDomForest(SmallPtrSet<MachineInstr*, 8>& instrs);
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};
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char StrongPHIElimination::ID = 0;
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@ -110,3 +138,63 @@ void StrongPHIElimination::computeDFS(MachineFunction& MF) {
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}
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}
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}
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class PreorderSorter {
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private:
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DenseMap<MachineBasicBlock*, unsigned>& preorder;
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public:
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PreorderSorter(DenseMap<MachineBasicBlock*, unsigned>& p) : preorder(p) { }
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bool operator()(MachineInstr* A, MachineInstr* B) {
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if (A == B)
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return false;
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if (preorder[A->getParent()] < preorder[B->getParent()])
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return true;
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else if (preorder[A->getParent()] > preorder[B->getParent()])
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return false;
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if (A->getOpcode() == TargetInstrInfo::PHI &&
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B->getOpcode() == TargetInstrInfo::PHI)
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return A < B;
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MachineInstr* begin = A->getParent()->begin();
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return std::distance(begin, A) < std::distance(begin, B);
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}
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};
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std::vector<StrongPHIElimination::DomForestNode*>
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StrongPHIElimination::computeDomForest(SmallPtrSet<MachineInstr*, 8>& instrs) {
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DomForestNode* VirtualRoot = new DomForestNode(0, 0);
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maxpreorder.insert(std::make_pair((MachineBasicBlock*)0, ~0UL));
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std::vector<MachineInstr*> worklist;
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worklist.reserve(instrs.size());
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for (SmallPtrSet<MachineInstr*, 8>::iterator I = instrs.begin(),
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E = instrs.end(); I != E; ++I)
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worklist.push_back(*I);
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PreorderSorter PS(preorder);
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std::sort(worklist.begin(), worklist.end(), PS);
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DomForestNode* CurrentParent = VirtualRoot;
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std::vector<DomForestNode*> stack;
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stack.push_back(VirtualRoot);
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for (std::vector<MachineInstr*>::iterator I = worklist.begin(),
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E = worklist.end(); I != E; ++I) {
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while (preorder[(*I)->getParent()] >
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maxpreorder[CurrentParent->getInstr()->getParent()]) {
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stack.pop_back();
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CurrentParent = stack.back();
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}
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DomForestNode* child = new DomForestNode(*I, CurrentParent);
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stack.push_back(child);
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CurrentParent = child;
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}
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std::vector<DomForestNode*> ret;
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ret.insert(ret.end(), VirtualRoot->begin(), VirtualRoot->end());
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return ret;
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}
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