1//===- THMToARMStub.cpp ---------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "THMToARMStub.h"
11#include "ARMLDBackend.h"
12
13#include <llvm/Support/ELF.h>
14#include <mcld/LD/ResolveInfo.h>
15#include <mcld/LD/LDSymbol.h>
16#include <mcld/Fragment/Relocation.h>
17
18using namespace mcld;
19
20//===----------------------------------------------------------------------===//
21// THMToARMStub
22//===----------------------------------------------------------------------===//
23const uint32_t THMToARMStub::PIC_TEMPLATE[] = {
24  0x46c04778, // bx    pc ... nop
25  0xe59fc000, // ldr   ip, [pc, #0]
26  0xe08cf00f, // add   pc, ip, pc
27  0x0         // dcd   R_ARM_REL32(X)
28};
29
30const uint32_t THMToARMStub::TEMPLATE[] = {
31  0x46c04778, // bx    pc ... nop
32  0xe51ff004, // ldr   pc, [pc, #-4]
33  0x0         // dcd   R_ARM_ABS32(X)
34};
35
36THMToARMStub::THMToARMStub(bool pIsOutputPIC)
37 : Stub(), m_Name("T2A_prototype"), m_pData(NULL), m_Size(0x0)
38{
39  if (pIsOutputPIC) {
40    m_pData = PIC_TEMPLATE;
41    m_Size = sizeof(PIC_TEMPLATE);
42    addFixup(12u, -4, llvm::ELF::R_ARM_REL32);
43  }
44  else {
45    m_pData = TEMPLATE;
46    m_Size = sizeof(TEMPLATE);
47    addFixup(8u, 0x0, llvm::ELF::R_ARM_ABS32);
48  }
49}
50
51/// for doClone
52THMToARMStub::THMToARMStub(const uint32_t* pData,
53                           size_t pSize,
54                           const_fixup_iterator pBegin,
55                           const_fixup_iterator pEnd)
56 : Stub(), m_Name("T2A_veneer"), m_pData(pData), m_Size(pSize)
57{
58  for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
59    addFixup(**it);
60}
61
62THMToARMStub::~THMToARMStub()
63{
64}
65
66bool THMToARMStub::isMyDuty(const class Relocation& pReloc,
67                            uint64_t pSource,
68                            uint64_t pTargetSymValue) const
69{
70  bool result = false;
71  // Check if the branch target is ARM
72  if ((pTargetSymValue & 0x1) == 0x0) {
73    switch (pReloc.type()) {
74      case llvm::ELF::R_ARM_THM_CALL: {
75        // FIXME: Assuming blx is available (i.e., target is armv5 or above!)
76        // then, we do not need a stub unless the branch target is too far.
77        uint64_t dest = pTargetSymValue + pReloc.addend() + 4u;
78        int64_t branch_offset = static_cast<int64_t>(dest) - pSource;
79        if ((branch_offset > ARMGNULDBackend::THM_MAX_FWD_BRANCH_OFFSET) ||
80            (branch_offset < ARMGNULDBackend::THM_MAX_BWD_BRANCH_OFFSET))
81          result = true;
82        break;
83      }
84      case llvm::ELF::R_ARM_THM_JUMP24: {
85        // always need a stub to switch mode
86        result = true;
87        break;
88      }
89      default:
90        break;
91    }
92  }
93  return result;
94}
95
96const std::string& THMToARMStub::name() const
97{
98  return m_Name;
99}
100
101const uint8_t* THMToARMStub::getContent() const
102{
103  return reinterpret_cast<const uint8_t*>(m_pData);
104}
105
106size_t THMToARMStub::size() const
107{
108  return m_Size;
109}
110
111size_t THMToARMStub::alignment() const
112{
113  return 4u;
114}
115
116// for T bit of this stub
117uint64_t THMToARMStub::initSymValue() const
118{
119  return 0x1;
120}
121
122Stub* THMToARMStub::doClone()
123{
124  return new THMToARMStub(m_pData, m_Size, fixup_begin(), fixup_end());
125}
126
127