Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/Target/SystemZ/SystemZLDCleanup.cpp
Line
Count
Source (jump to first uncovered line)
1
//===-- SystemZLDCleanup.cpp - Clean up local-dynamic TLS accesses --------===//
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 combines multiple accesses to local-dynamic TLS variables so that
10
// the TLS base address for the module is only fetched once per execution path
11
// through the function.
12
//
13
//===----------------------------------------------------------------------===//
14
15
#include "SystemZMachineFunctionInfo.h"
16
#include "SystemZTargetMachine.h"
17
#include "llvm/CodeGen/MachineDominators.h"
18
#include "llvm/CodeGen/MachineFunctionPass.h"
19
#include "llvm/CodeGen/MachineInstrBuilder.h"
20
#include "llvm/CodeGen/MachineRegisterInfo.h"
21
#include "llvm/CodeGen/TargetInstrInfo.h"
22
#include "llvm/CodeGen/TargetRegisterInfo.h"
23
#include "llvm/Target/TargetMachine.h"
24
25
using namespace llvm;
26
27
namespace {
28
29
class SystemZLDCleanup : public MachineFunctionPass {
30
public:
31
  static char ID;
32
  SystemZLDCleanup(const SystemZTargetMachine &tm)
33
1.00k
    : MachineFunctionPass(ID), TII(nullptr), MF(nullptr) {}
34
35
8.09k
  StringRef getPassName() const override {
36
8.09k
    return "SystemZ Local Dynamic TLS Access Clean-up";
37
8.09k
  }
38
39
  bool runOnMachineFunction(MachineFunction &MF) override;
40
  void getAnalysisUsage(AnalysisUsage &AU) const override;
41
42
private:
43
  bool VisitNode(MachineDomTreeNode *Node, unsigned TLSBaseAddrReg);
44
  MachineInstr *ReplaceTLSCall(MachineInstr *I, unsigned TLSBaseAddrReg);
45
  MachineInstr *SetRegister(MachineInstr *I, unsigned *TLSBaseAddrReg);
46
47
  const SystemZInstrInfo *TII;
48
  MachineFunction *MF;
49
};
50
51
char SystemZLDCleanup::ID = 0;
52
53
} // end anonymous namespace
54
55
1.00k
FunctionPass *llvm::createSystemZLDCleanupPass(SystemZTargetMachine &TM) {
56
1.00k
  return new SystemZLDCleanup(TM);
57
1.00k
}
58
59
986
void SystemZLDCleanup::getAnalysisUsage(AnalysisUsage &AU) const {
60
986
  AU.setPreservesCFG();
61
986
  AU.addRequired<MachineDominatorTree>();
62
986
  MachineFunctionPass::getAnalysisUsage(AU);
63
986
}
64
65
8.09k
bool SystemZLDCleanup::runOnMachineFunction(MachineFunction &F) {
66
8.09k
  if (skipFunction(F.getFunction()))
67
0
    return false;
68
8.09k
69
8.09k
  TII = static_cast<const SystemZInstrInfo *>(F.getSubtarget().getInstrInfo());
70
8.09k
  MF = &F;
71
8.09k
72
8.09k
  SystemZMachineFunctionInfo* MFI = F.getInfo<SystemZMachineFunctionInfo>();
73
8.09k
  if (MFI->getNumLocalDynamicTLSAccesses() < 2) {
74
8.09k
    // No point folding accesses if there isn't at least two.
75
8.09k
    return false;
76
8.09k
  }
77
1
78
1
  MachineDominatorTree *DT = &getAnalysis<MachineDominatorTree>();
79
1
  return VisitNode(DT->getRootNode(), 0);
80
1
}
81
82
// Visit the dominator subtree rooted at Node in pre-order.
83
// If TLSBaseAddrReg is non-null, then use that to replace any
84
// TLS_LDCALL instructions. Otherwise, create the register
85
// when the first such instruction is seen, and then use it
86
// as we encounter more instructions.
87
bool SystemZLDCleanup::VisitNode(MachineDomTreeNode *Node,
88
1
                                 unsigned TLSBaseAddrReg) {
89
1
  MachineBasicBlock *BB = Node->getBlock();
90
1
  bool Changed = false;
91
1
92
1
  // Traverse the current block.
93
26
  for (auto I = BB->begin(), E = BB->end(); I != E; 
++I25
) {
94
25
    switch (I->getOpcode()) {
95
25
      case SystemZ::TLS_LDCALL:
96
2
        if (TLSBaseAddrReg)
97
1
          I = ReplaceTLSCall(&*I, TLSBaseAddrReg);
98
1
        else
99
1
          I = SetRegister(&*I, &TLSBaseAddrReg);
100
2
        Changed = true;
101
2
        break;
102
25
      default:
103
23
        break;
104
25
    }
105
25
  }
106
1
107
1
  // Visit the children of this block in the dominator tree.
108
1
  for (auto I = Node->begin(), E = Node->end(); I != E; 
++I0
)
109
0
    Changed |= VisitNode(*I, TLSBaseAddrReg);
110
1
111
1
  return Changed;
112
1
}
113
114
// Replace the TLS_LDCALL instruction I with a copy from TLSBaseAddrReg,
115
// returning the new instruction.
116
MachineInstr *SystemZLDCleanup::ReplaceTLSCall(MachineInstr *I,
117
1
                                               unsigned TLSBaseAddrReg) {
118
1
  // Insert a Copy from TLSBaseAddrReg to R2.
119
1
  MachineInstr *Copy = BuildMI(*I->getParent(), I, I->getDebugLoc(),
120
1
                               TII->get(TargetOpcode::COPY), SystemZ::R2D)
121
1
                               .addReg(TLSBaseAddrReg);
122
1
123
1
  // Erase the TLS_LDCALL instruction.
124
1
  I->eraseFromParent();
125
1
126
1
  return Copy;
127
1
}
128
129
// Create a virtual register in *TLSBaseAddrReg, and populate it by
130
// inserting a copy instruction after I. Returns the new instruction.
131
MachineInstr *SystemZLDCleanup::SetRegister(MachineInstr *I,
132
1
                                            unsigned *TLSBaseAddrReg) {
133
1
  // Create a virtual register for the TLS base address.
134
1
  MachineRegisterInfo &RegInfo = MF->getRegInfo();
135
1
  *TLSBaseAddrReg = RegInfo.createVirtualRegister(&SystemZ::GR64BitRegClass);
136
1
137
1
  // Insert a copy from R2 to TLSBaseAddrReg.
138
1
  MachineInstr *Next = I->getNextNode();
139
1
  MachineInstr *Copy = BuildMI(*I->getParent(), Next, I->getDebugLoc(),
140
1
                               TII->get(TargetOpcode::COPY), *TLSBaseAddrReg)
141
1
                               .addReg(SystemZ::R2D);
142
1
143
1
  return Copy;
144
1
}
145