diff options
| -rw-r--r-- | lib/CodeGen/LiveRangeCalc.cpp | 94 | ||||
| -rw-r--r-- | lib/CodeGen/LiveRangeCalc.h | 29 |
2 files changed, 76 insertions, 47 deletions
diff --git a/lib/CodeGen/LiveRangeCalc.cpp b/lib/CodeGen/LiveRangeCalc.cpp index c3ff4f1b6d..dede490d91 100644 --- a/lib/CodeGen/LiveRangeCalc.cpp +++ b/lib/CodeGen/LiveRangeCalc.cpp @@ -18,10 +18,11 @@ using namespace llvm; -void LiveRangeCalc::reset(const MachineFunction *MF, +void LiveRangeCalc::reset(const MachineFunction *mf, SlotIndexes *SI, MachineDominatorTree *MDT, VNInfo::Allocator *VNIA) { + MF = mf; MRI = &MF->getRegInfo(); Indexes = SI; DomTree = MDT; @@ -104,28 +105,28 @@ void LiveRangeCalc::extendToUses(LiveInterval *LI, unsigned Reg) { // Transfer information from the LiveIn vector to the live ranges. -void LiveRangeCalc::updateLiveIns(VNInfo *OverrideVNI) { +void LiveRangeCalc::updateLiveIns() { + LiveRangeUpdater Updater; for (SmallVectorImpl<LiveInBlock>::iterator I = LiveIn.begin(), E = LiveIn.end(); I != E; ++I) { if (!I->DomNode) continue; MachineBasicBlock *MBB = I->DomNode->getBlock(); - - VNInfo *VNI = OverrideVNI ? OverrideVNI : I->Value; - assert(VNI && "No live-in value found"); - + assert(I->Value && "No live-in value found"); SlotIndex Start, End; tie(Start, End) = Indexes->getMBBRange(MBB); if (I->Kill.isValid()) - I->LI->addRange(LiveRange(Start, I->Kill, VNI)); + // Value is killed inside this block. + End = I->Kill; else { - I->LI->addRange(LiveRange(Start, End, VNI)); - // The value is live-through, update LiveOut as well. Defer the Domtree - // lookup until it is needed. + // The value is live-through, update LiveOut as well. + // Defer the Domtree lookup until it is needed. assert(Seen.test(MBB->getNumber())); - LiveOut[MBB] = LiveOutPair(VNI, (MachineDomTreeNode *)0); + LiveOut[MBB] = LiveOutPair(I->Value, (MachineDomTreeNode *)0); } + Updater.setDest(I->LI); + Updater.add(Start, End, I->Value); } LiveIn.clear(); } @@ -150,13 +151,11 @@ void LiveRangeCalc::extend(LiveInterval *LI, // multiple values, and we may need to create even more phi-defs to preserve // VNInfo SSA form. Perform a search for all predecessor blocks where we // know the dominating VNInfo. - VNInfo *VNI = findReachingDefs(LI, KillMBB, Kill, PhysReg); + if (findReachingDefs(LI, KillMBB, Kill, PhysReg)) + return; // When there were multiple different values, we may need new PHIs. - if (!VNI) - updateSSA(); - - updateLiveIns(VNI); + calculateValues(); } @@ -167,16 +166,18 @@ void LiveRangeCalc::calculateValues() { assert(Indexes && "Missing SlotIndexes"); assert(DomTree && "Missing dominator tree"); updateSSA(); - updateLiveIns(0); + updateLiveIns(); } -VNInfo *LiveRangeCalc::findReachingDefs(LiveInterval *LI, - MachineBasicBlock *KillMBB, - SlotIndex Kill, - unsigned PhysReg) { - // Blocks where LI should be live-in. - SmallVector<MachineBasicBlock*, 16> WorkList(1, KillMBB); +bool LiveRangeCalc::findReachingDefs(LiveInterval *LI, + MachineBasicBlock *KillMBB, + SlotIndex Kill, + unsigned PhysReg) { + unsigned KillMBBNum = KillMBB->getNumber(); + + // Block numbers where LI should be live-in. + SmallVector<unsigned, 16> WorkList(1, KillMBBNum); // Remember if we have seen more than one value. bool UniqueVNI = true; @@ -184,7 +185,7 @@ VNInfo *LiveRangeCalc::findReachingDefs(LiveInterval *LI, // Using Seen as a visited set, perform a BFS for all reaching defs. for (unsigned i = 0; i != WorkList.size(); ++i) { - MachineBasicBlock *MBB = WorkList[i]; + MachineBasicBlock *MBB = MF->getBlockNumbered(WorkList[i]); #ifndef NDEBUG if (MBB->pred_empty()) { @@ -231,25 +232,50 @@ VNInfo *LiveRangeCalc::findReachingDefs(LiveInterval *LI, // No, we need a live-in value for Pred as well if (Pred != KillMBB) - WorkList.push_back(Pred); + WorkList.push_back(Pred->getNumber()); else // Loopback to KillMBB, so value is really live through. Kill = SlotIndex(); } } - // Transfer WorkList to LiveInBlocks in reverse order. - // This ordering works best with updateSSA(). LiveIn.clear(); - LiveIn.reserve(WorkList.size()); - while(!WorkList.empty()) - addLiveInBlock(LI, DomTree->getNode(WorkList.pop_back_val())); - // The kill block may not be live-through. - assert(LiveIn.back().DomNode->getBlock() == KillMBB); - LiveIn.back().Kill = Kill; + // Both updateSSA() and LiveRangeUpdater benefit from ordered blocks, but + // neither require it. Skip the sorting overhead for small updates. + if (WorkList.size() > 4) + array_pod_sort(WorkList.begin(), WorkList.end()); + + // If a unique reaching def was found, blit in the live ranges immediately. + if (UniqueVNI) { + LiveRangeUpdater Updater(LI); + for (SmallVectorImpl<unsigned>::const_iterator + I = WorkList.begin(), E = WorkList.end(); I != E; ++I) { + SlotIndex Start, End; + tie(Start, End) = Indexes->getMBBRange(*I); + // Trim the live range in KillMBB. + if (*I == KillMBBNum && Kill.isValid()) + End = Kill; + else + LiveOut[MF->getBlockNumbered(*I)] = + LiveOutPair(TheVNI, (MachineDomTreeNode *)0); + Updater.add(Start, End, TheVNI); + } + return true; + } + + // Multiple values were found, so transfer the work list to the LiveIn array + // where UpdateSSA will use it as a work list. + LiveIn.reserve(WorkList.size()); + for (SmallVectorImpl<unsigned>::const_iterator + I = WorkList.begin(), E = WorkList.end(); I != E; ++I) { + MachineBasicBlock *MBB = MF->getBlockNumbered(*I); + addLiveInBlock(LI, DomTree->getNode(MBB)); + if (MBB == KillMBB) + LiveIn.back().Kill = Kill; + } - return UniqueVNI ? TheVNI : 0; + return false; } diff --git a/lib/CodeGen/LiveRangeCalc.h b/lib/CodeGen/LiveRangeCalc.h index 909829b228..57cab7b342 100644 --- a/lib/CodeGen/LiveRangeCalc.h +++ b/lib/CodeGen/LiveRangeCalc.h @@ -34,6 +34,7 @@ template <class NodeT> class DomTreeNodeBase; typedef DomTreeNodeBase<MachineBasicBlock> MachineDomTreeNode; class LiveRangeCalc { + const MachineFunction *MF; const MachineRegisterInfo *MRI; SlotIndexes *Indexes; MachineDominatorTree *DomTree; @@ -100,17 +101,20 @@ class LiveRangeCalc { /// used to add entries directly. SmallVector<LiveInBlock, 16> LiveIn; - /// findReachingDefs - Assuming that LI is live-in to KillMBB and killed at - /// Kill, search for values that can reach KillMBB. All blocks that need LI - /// to be live-in are added to LiveIn. If a unique reaching def is found, - /// its value is returned, if Kill is jointly dominated by multiple values, - /// NULL is returned. + /// Assuming that LI is live-in to KillMBB and killed at Kill, find the set + /// of defs that can reach it. + /// + /// If only one def can reach Kill, all paths from the def to kill are added + /// to LI, and the function returns true. + /// + /// If multiple values can reach Kill, the blocks that need LI to be live in + /// are added to the LiveIn array, and the function returns false. /// /// PhysReg, when set, is used to verify live-in lists on basic blocks. - VNInfo *findReachingDefs(LiveInterval *LI, - MachineBasicBlock *KillMBB, - SlotIndex Kill, - unsigned PhysReg); + bool findReachingDefs(LiveInterval *LI, + MachineBasicBlock *KillMBB, + SlotIndex Kill, + unsigned PhysReg); /// updateSSA - Compute the values that will be live in to all requested /// blocks in LiveIn. Create PHI-def values as required to preserve SSA form. @@ -119,12 +123,11 @@ class LiveRangeCalc { /// blocks. No values are read from the live ranges. void updateSSA(); - /// updateLiveIns - Add liveness as specified in the LiveIn vector, using VNI - /// as a wildcard value for LiveIn entries without a value. - void updateLiveIns(VNInfo *VNI); + /// Add liveness as specified in the LiveIn vector. + void updateLiveIns(); public: - LiveRangeCalc() : MRI(0), Indexes(0), DomTree(0), Alloc(0) {} + LiveRangeCalc() : MF(0), MRI(0), Indexes(0), DomTree(0), Alloc(0) {} //===--------------------------------------------------------------------===// // High-level interface. |