1 //===-- StackMapLivenessAnalysis.cpp - StackMap live Out 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 StackMap Liveness analysis pass. The pass calculates 11 // the liveness for each basic block in a function and attaches the register 12 // live-out information to a stackmap or patchpoint intrinsic if present. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/ADT/Statistic.h" 17 #include "llvm/CodeGen/MachineFrameInfo.h" 18 #include "llvm/CodeGen/MachineFunction.h" 19 #include "llvm/CodeGen/MachineFunctionAnalysis.h" 20 #include "llvm/CodeGen/Passes.h" 21 #include "llvm/CodeGen/StackMapLivenessAnalysis.h" 22 #include "llvm/Support/CommandLine.h" 23 #include "llvm/Support/Debug.h" 24 25 26 using namespace llvm; 27 28 #define DEBUG_TYPE "stackmaps" 29 30 namespace llvm { 31 cl::opt<bool> EnableStackMapLiveness("enable-stackmap-liveness", 32 cl::Hidden, cl::desc("Enable StackMap Liveness Analysis Pass")); 33 cl::opt<bool> EnablePatchPointLiveness("enable-patchpoint-liveness", 34 cl::Hidden, cl::desc("Enable PatchPoint Liveness Analysis Pass")); 35 } 36 37 STATISTIC(NumStackMapFuncVisited, "Number of functions visited"); 38 STATISTIC(NumStackMapFuncSkipped, "Number of functions skipped"); 39 STATISTIC(NumBBsVisited, "Number of basic blocks visited"); 40 STATISTIC(NumBBsHaveNoStackmap, "Number of basic blocks with no stackmap"); 41 STATISTIC(NumStackMaps, "Number of StackMaps visited"); 42 43 char StackMapLiveness::ID = 0; 44 char &llvm::StackMapLivenessID = StackMapLiveness::ID; 45 INITIALIZE_PASS(StackMapLiveness, "stackmap-liveness", 46 "StackMap Liveness Analysis", false, false) 47 48 /// Default construct and initialize the pass. 49 StackMapLiveness::StackMapLiveness() : MachineFunctionPass(ID) { 50 initializeStackMapLivenessPass(*PassRegistry::getPassRegistry()); 51 } 52 53 /// Tell the pass manager which passes we depend on and what information we 54 /// preserve. 55 void StackMapLiveness::getAnalysisUsage(AnalysisUsage &AU) const { 56 // We preserve all information. 57 AU.setPreservesAll(); 58 AU.setPreservesCFG(); 59 // Default dependencie for all MachineFunction passes. 60 AU.addRequired<MachineFunctionAnalysis>(); 61 } 62 63 /// Calculate the liveness information for the given machine function. 64 bool StackMapLiveness::runOnMachineFunction(MachineFunction &_MF) { 65 DEBUG(dbgs() << "********** COMPUTING STACKMAP LIVENESS: " 66 << _MF.getName() << " **********\n"); 67 MF = &_MF; 68 TRI = MF->getTarget().getRegisterInfo(); 69 ++NumStackMapFuncVisited; 70 71 // Skip this function if there are no stackmaps or patchpoints to process. 72 if (!((MF->getFrameInfo()->hasStackMap() && EnableStackMapLiveness) || 73 (MF->getFrameInfo()->hasPatchPoint() && EnablePatchPointLiveness))) { 74 ++NumStackMapFuncSkipped; 75 return false; 76 } 77 return calculateLiveness(); 78 } 79 80 /// Performs the actual liveness calculation for the function. 81 bool StackMapLiveness::calculateLiveness() { 82 bool HasChanged = false; 83 // For all basic blocks in the function. 84 for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end(); 85 MBBI != MBBE; ++MBBI) { 86 DEBUG(dbgs() << "****** BB " << MBBI->getName() << " ******\n"); 87 LiveRegs.init(TRI); 88 LiveRegs.addLiveOuts(MBBI); 89 bool HasStackMap = false; 90 // Reverse iterate over all instructions and add the current live register 91 // set to an instruction if we encounter a stackmap or patchpoint 92 // instruction. 93 for (MachineBasicBlock::reverse_iterator I = MBBI->rbegin(), 94 E = MBBI->rend(); I != E; ++I) { 95 int Opc = I->getOpcode(); 96 if ((EnableStackMapLiveness && (Opc == TargetOpcode::STACKMAP)) || 97 (EnablePatchPointLiveness && (Opc == TargetOpcode::PATCHPOINT))) { 98 addLiveOutSetToMI(*I); 99 HasChanged = true; 100 HasStackMap = true; 101 ++NumStackMaps; 102 } 103 DEBUG(dbgs() << " " << LiveRegs << " " << *I); 104 LiveRegs.stepBackward(*I); 105 } 106 ++NumBBsVisited; 107 if (!HasStackMap) 108 ++NumBBsHaveNoStackmap; 109 } 110 return HasChanged; 111 } 112 113 /// Add the current register live set to the instruction. 114 void StackMapLiveness::addLiveOutSetToMI(MachineInstr &MI) { 115 uint32_t *Mask = createRegisterMask(); 116 MachineOperand MO = MachineOperand::CreateRegLiveOut(Mask); 117 MI.addOperand(*MF, MO); 118 } 119 120 /// Create a register mask and initialize it with the registers from the 121 /// register live set. 122 uint32_t *StackMapLiveness::createRegisterMask() const { 123 // The mask is owned and cleaned up by the Machine Function. 124 uint32_t *Mask = MF->allocateRegisterMask(TRI->getNumRegs()); 125 for (LivePhysRegs::const_iterator RI = LiveRegs.begin(), RE = LiveRegs.end(); 126 RI != RE; ++RI) 127 Mask[*RI / 32] |= 1U << (*RI % 32); 128 return Mask; 129 } 130