1 //===-- LiveStackAnalysis.cpp - Live Stack Slot Analysis ------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the live stack slot analysis pass. It is analogous to 11 // live interval analysis except it's analyzing liveness of stack slots rather 12 // than registers. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/CodeGen/LiveStackAnalysis.h" 17 #include "llvm/ADT/Statistic.h" 18 #include "llvm/CodeGen/LiveIntervalAnalysis.h" 19 #include "llvm/CodeGen/Passes.h" 20 #include "llvm/Support/Debug.h" 21 #include "llvm/Support/raw_ostream.h" 22 #include "llvm/Target/TargetRegisterInfo.h" 23 #include "llvm/Target/TargetSubtargetInfo.h" 24 #include <limits> 25 using namespace llvm; 26 27 #define DEBUG_TYPE "livestacks" 28 29 char LiveStacks::ID = 0; 30 INITIALIZE_PASS_BEGIN(LiveStacks, "livestacks", 31 "Live Stack Slot Analysis", false, false) 32 INITIALIZE_PASS_DEPENDENCY(SlotIndexes) 33 INITIALIZE_PASS_END(LiveStacks, "livestacks", 34 "Live Stack Slot Analysis", false, false) 35 36 char &llvm::LiveStacksID = LiveStacks::ID; 37 38 void LiveStacks::getAnalysisUsage(AnalysisUsage &AU) const { 39 AU.setPreservesAll(); 40 AU.addPreserved<SlotIndexes>(); 41 AU.addRequiredTransitive<SlotIndexes>(); 42 MachineFunctionPass::getAnalysisUsage(AU); 43 } 44 45 void LiveStacks::releaseMemory() { 46 // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd. 47 VNInfoAllocator.Reset(); 48 S2IMap.clear(); 49 S2RCMap.clear(); 50 } 51 52 bool LiveStacks::runOnMachineFunction(MachineFunction &MF) { 53 TRI = MF.getSubtarget().getRegisterInfo(); 54 // FIXME: No analysis is being done right now. We are relying on the 55 // register allocators to provide the information. 56 return false; 57 } 58 59 LiveInterval & 60 LiveStacks::getOrCreateInterval(int Slot, const TargetRegisterClass *RC) { 61 assert(Slot >= 0 && "Spill slot indice must be >= 0"); 62 SS2IntervalMap::iterator I = S2IMap.find(Slot); 63 if (I == S2IMap.end()) { 64 I = S2IMap.emplace(std::piecewise_construct, std::forward_as_tuple(Slot), 65 std::forward_as_tuple( 66 TargetRegisterInfo::index2StackSlot(Slot), 0.0F)) 67 .first; 68 S2RCMap.insert(std::make_pair(Slot, RC)); 69 } else { 70 // Use the largest common subclass register class. 71 const TargetRegisterClass *OldRC = S2RCMap[Slot]; 72 S2RCMap[Slot] = TRI->getCommonSubClass(OldRC, RC); 73 } 74 return I->second; 75 } 76 77 /// print - Implement the dump method. 78 void LiveStacks::print(raw_ostream &OS, const Module*) const { 79 80 OS << "********** INTERVALS **********\n"; 81 for (const_iterator I = begin(), E = end(); I != E; ++I) { 82 I->second.print(OS); 83 int Slot = I->first; 84 const TargetRegisterClass *RC = getIntervalRegClass(Slot); 85 if (RC) 86 OS << " [" << TRI->getRegClassName(RC) << "]\n"; 87 else 88 OS << " [Unknown]\n"; 89 } 90 } 91