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