1 //===---------- PPCTLSDynamicCall.cpp - TLS Dynamic Call Fixup ------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This pass expands ADDItls{ld,gd}LADDR[32] machine instructions into 10 // separate ADDItls[gd]L[32] and GETtlsADDR[32] instructions, both of 11 // which define GPR3. A copy is added from GPR3 to the target virtual 12 // register of the original instruction. The GETtlsADDR[32] is really 13 // a call instruction, so its target register is constrained to be GPR3. 14 // This is not true of ADDItls[gd]L[32], but there is a legacy linker 15 // optimization bug that requires the target register of the addi of 16 // a local- or general-dynamic TLS access sequence to be GPR3. 17 // 18 // This is done in a late pass so that TLS variable accesses can be 19 // fully commoned by MachineCSE. 20 // 21 //===----------------------------------------------------------------------===// 22 23 #include "PPC.h" 24 #include "PPCInstrBuilder.h" 25 #include "PPCInstrInfo.h" 26 #include "PPCTargetMachine.h" 27 #include "llvm/CodeGen/LiveIntervals.h" 28 #include "llvm/CodeGen/MachineFunctionPass.h" 29 #include "llvm/CodeGen/MachineInstrBuilder.h" 30 #include "llvm/InitializePasses.h" 31 #include "llvm/Support/Debug.h" 32 #include "llvm/Support/raw_ostream.h" 33 34 using namespace llvm; 35 36 #define DEBUG_TYPE "ppc-tls-dynamic-call" 37 38 namespace { 39 struct PPCTLSDynamicCall : public MachineFunctionPass { 40 static char ID; 41 PPCTLSDynamicCall() : MachineFunctionPass(ID) { 42 initializePPCTLSDynamicCallPass(*PassRegistry::getPassRegistry()); 43 } 44 45 const PPCInstrInfo *TII; 46 LiveIntervals *LIS; 47 48 protected: 49 bool processBlock(MachineBasicBlock &MBB) { 50 bool Changed = false; 51 bool NeedFence = true; 52 bool Is64Bit = MBB.getParent()->getSubtarget<PPCSubtarget>().isPPC64(); 53 54 for (MachineBasicBlock::iterator I = MBB.begin(), IE = MBB.end(); 55 I != IE;) { 56 MachineInstr &MI = *I; 57 58 if (MI.getOpcode() != PPC::ADDItlsgdLADDR && 59 MI.getOpcode() != PPC::ADDItlsldLADDR && 60 MI.getOpcode() != PPC::ADDItlsgdLADDR32 && 61 MI.getOpcode() != PPC::ADDItlsldLADDR32) { 62 63 // Although we create ADJCALLSTACKDOWN and ADJCALLSTACKUP 64 // as scheduling fences, we skip creating fences if we already 65 // have existing ADJCALLSTACKDOWN/UP to avoid nesting, 66 // which causes verification error with -verify-machineinstrs. 67 if (MI.getOpcode() == PPC::ADJCALLSTACKDOWN) 68 NeedFence = false; 69 else if (MI.getOpcode() == PPC::ADJCALLSTACKUP) 70 NeedFence = true; 71 72 ++I; 73 continue; 74 } 75 76 LLVM_DEBUG(dbgs() << "TLS Dynamic Call Fixup:\n " << MI); 77 78 Register OutReg = MI.getOperand(0).getReg(); 79 Register InReg = MI.getOperand(1).getReg(); 80 DebugLoc DL = MI.getDebugLoc(); 81 Register GPR3 = Is64Bit ? PPC::X3 : PPC::R3; 82 unsigned Opc1, Opc2; 83 const Register OrigRegs[] = {OutReg, InReg, GPR3}; 84 85 switch (MI.getOpcode()) { 86 default: 87 llvm_unreachable("Opcode inconsistency error"); 88 case PPC::ADDItlsgdLADDR: 89 Opc1 = PPC::ADDItlsgdL; 90 Opc2 = PPC::GETtlsADDR; 91 break; 92 case PPC::ADDItlsldLADDR: 93 Opc1 = PPC::ADDItlsldL; 94 Opc2 = PPC::GETtlsldADDR; 95 break; 96 case PPC::ADDItlsgdLADDR32: 97 Opc1 = PPC::ADDItlsgdL32; 98 Opc2 = PPC::GETtlsADDR32; 99 break; 100 case PPC::ADDItlsldLADDR32: 101 Opc1 = PPC::ADDItlsldL32; 102 Opc2 = PPC::GETtlsldADDR32; 103 break; 104 } 105 106 // We create ADJCALLSTACKUP and ADJCALLSTACKDOWN around _tls_get_addr 107 // as scheduling fence to avoid it is scheduled before 108 // mflr in the prologue and the address in LR is clobbered (PR25839). 109 // We don't really need to save data to the stack - the clobbered 110 // registers are already saved when the SDNode (e.g. PPCaddiTlsgdLAddr) 111 // gets translated to the pseudo instruction (e.g. ADDItlsgdLADDR). 112 if (NeedFence) 113 BuildMI(MBB, I, DL, TII->get(PPC::ADJCALLSTACKDOWN)).addImm(0) 114 .addImm(0); 115 116 // Expand into two ops built prior to the existing instruction. 117 MachineInstr *Addi = BuildMI(MBB, I, DL, TII->get(Opc1), GPR3) 118 .addReg(InReg); 119 Addi->addOperand(MI.getOperand(2)); 120 121 // The ADDItls* instruction is the first instruction in the 122 // repair range. 123 MachineBasicBlock::iterator First = I; 124 --First; 125 126 MachineInstr *Call = (BuildMI(MBB, I, DL, TII->get(Opc2), GPR3) 127 .addReg(GPR3)); 128 Call->addOperand(MI.getOperand(3)); 129 130 if (NeedFence) 131 BuildMI(MBB, I, DL, TII->get(PPC::ADJCALLSTACKUP)).addImm(0).addImm(0); 132 133 BuildMI(MBB, I, DL, TII->get(TargetOpcode::COPY), OutReg) 134 .addReg(GPR3); 135 136 // The COPY is the last instruction in the repair range. 137 MachineBasicBlock::iterator Last = I; 138 --Last; 139 140 // Move past the original instruction and remove it. 141 ++I; 142 MI.removeFromParent(); 143 144 // Repair the live intervals. 145 LIS->repairIntervalsInRange(&MBB, First, Last, OrigRegs); 146 Changed = true; 147 } 148 149 return Changed; 150 } 151 152 public: 153 bool runOnMachineFunction(MachineFunction &MF) override { 154 TII = MF.getSubtarget<PPCSubtarget>().getInstrInfo(); 155 LIS = &getAnalysis<LiveIntervals>(); 156 157 bool Changed = false; 158 159 for (MachineFunction::iterator I = MF.begin(); I != MF.end();) { 160 MachineBasicBlock &B = *I++; 161 if (processBlock(B)) 162 Changed = true; 163 } 164 165 return Changed; 166 } 167 168 void getAnalysisUsage(AnalysisUsage &AU) const override { 169 AU.addRequired<LiveIntervals>(); 170 AU.addPreserved<LiveIntervals>(); 171 AU.addRequired<SlotIndexes>(); 172 AU.addPreserved<SlotIndexes>(); 173 MachineFunctionPass::getAnalysisUsage(AU); 174 } 175 }; 176 } 177 178 INITIALIZE_PASS_BEGIN(PPCTLSDynamicCall, DEBUG_TYPE, 179 "PowerPC TLS Dynamic Call Fixup", false, false) 180 INITIALIZE_PASS_DEPENDENCY(LiveIntervals) 181 INITIALIZE_PASS_DEPENDENCY(SlotIndexes) 182 INITIALIZE_PASS_END(PPCTLSDynamicCall, DEBUG_TYPE, 183 "PowerPC TLS Dynamic Call Fixup", false, false) 184 185 char PPCTLSDynamicCall::ID = 0; 186 FunctionPass* 187 llvm::createPPCTLSDynamicCallPass() { return new PPCTLSDynamicCall(); } 188