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
34using namespace llvm;
35
36#define DEBUG_TYPE "ppc-tls-dynamic-call"
37
38namespace llvm {
39  void initializePPCTLSDynamicCallPass(PassRegistry&);
40}
41
42namespace {
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
52protected:
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; ++I) {
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          continue;
66
67        DEBUG(dbgs() << "TLS Dynamic Call Fixup:\n    " << *MI;);
68
69        unsigned OutReg = MI->getOperand(0).getReg();
70        unsigned InReg  = MI->getOperand(1).getReg();
71        DebugLoc DL = MI->getDebugLoc();
72        unsigned GPR3 = Is64Bit ? PPC::X3 : PPC::R3;
73        unsigned Opc1, Opc2;
74        SmallVector<unsigned, 4> OrigRegs;
75        OrigRegs.push_back(OutReg);
76        OrigRegs.push_back(InReg);
77        OrigRegs.push_back(GPR3);
78
79        switch (MI->getOpcode()) {
80        default:
81          llvm_unreachable("Opcode inconsistency error");
82        case PPC::ADDItlsgdLADDR:
83          Opc1 = PPC::ADDItlsgdL;
84          Opc2 = PPC::GETtlsADDR;
85          break;
86        case PPC::ADDItlsldLADDR:
87          Opc1 = PPC::ADDItlsldL;
88          Opc2 = PPC::GETtlsldADDR;
89          break;
90        case PPC::ADDItlsgdLADDR32:
91          Opc1 = PPC::ADDItlsgdL32;
92          Opc2 = PPC::GETtlsADDR32;
93          break;
94        case PPC::ADDItlsldLADDR32:
95          Opc1 = PPC::ADDItlsldL32;
96          Opc2 = PPC::GETtlsldADDR32;
97          break;
98        }
99
100        // Expand into two ops built prior to the existing instruction.
101        MachineInstr *Addi = BuildMI(MBB, I, DL, TII->get(Opc1), GPR3)
102          .addReg(InReg);
103        Addi->addOperand(MI->getOperand(2));
104
105        // The ADDItls* instruction is the first instruction in the
106        // repair range.
107        MachineBasicBlock::iterator First = I;
108        --First;
109
110        MachineInstr *Call = (BuildMI(MBB, I, DL, TII->get(Opc2), GPR3)
111                              .addReg(GPR3));
112        Call->addOperand(MI->getOperand(3));
113
114        BuildMI(MBB, I, DL, TII->get(TargetOpcode::COPY), OutReg)
115          .addReg(GPR3);
116
117        // The COPY is the last instruction in the repair range.
118        MachineBasicBlock::iterator Last = I;
119        --Last;
120
121        // Move past the original instruction and remove it.
122        ++I;
123        MI->removeFromParent();
124
125        // Repair the live intervals.
126        LIS->repairIntervalsInRange(&MBB, First, Last, OrigRegs);
127        Changed = true;
128      }
129
130      return Changed;
131    }
132
133public:
134    bool runOnMachineFunction(MachineFunction &MF) override {
135      TII = MF.getSubtarget<PPCSubtarget>().getInstrInfo();
136      LIS = &getAnalysis<LiveIntervals>();
137
138      bool Changed = false;
139
140      for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
141        MachineBasicBlock &B = *I++;
142        if (processBlock(B))
143          Changed = true;
144      }
145
146      return Changed;
147    }
148
149    void getAnalysisUsage(AnalysisUsage &AU) const override {
150      AU.addRequired<LiveIntervals>();
151      AU.addPreserved<LiveIntervals>();
152      AU.addRequired<SlotIndexes>();
153      AU.addPreserved<SlotIndexes>();
154      MachineFunctionPass::getAnalysisUsage(AU);
155    }
156  };
157}
158
159INITIALIZE_PASS_BEGIN(PPCTLSDynamicCall, DEBUG_TYPE,
160                      "PowerPC TLS Dynamic Call Fixup", false, false)
161INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
162INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
163INITIALIZE_PASS_END(PPCTLSDynamicCall, DEBUG_TYPE,
164                    "PowerPC TLS Dynamic Call Fixup", false, false)
165
166char PPCTLSDynamicCall::ID = 0;
167FunctionPass*
168llvm::createPPCTLSDynamicCallPass() { return new PPCTLSDynamicCall(); }
169