1 //===- BranchIslandFactory.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 #include "mcld/LD/BranchIslandFactory.h"
10
11 #include "mcld/Fragment/Fragment.h"
12 #include "mcld/LD/LDSection.h"
13 #include "mcld/LD/SectionData.h"
14 #include "mcld/Module.h"
15
16 namespace mcld {
17
18 //===----------------------------------------------------------------------===//
19 // BranchIslandFactory
20 //===----------------------------------------------------------------------===//
21
22 /// ctor
23 /// @param pMaxFwdBranchRange - the max forward branch range of the target
24 /// @param pMaxBwdBranchRange - the max backward branch range of the target
25 /// @param pMaxIslandSize - the predefined value for the max size of a island
BranchIslandFactory(int64_t pMaxFwdBranchRange,int64_t pMaxBwdBranchRange,size_t pMaxIslandSize)26 BranchIslandFactory::BranchIslandFactory(int64_t pMaxFwdBranchRange,
27 int64_t pMaxBwdBranchRange,
28 size_t pMaxIslandSize)
29 : GCFactory<BranchIsland, 0>(1u), // magic number
30 m_MaxFwdBranchRange(pMaxFwdBranchRange - pMaxIslandSize),
31 m_MaxBwdBranchRange(pMaxBwdBranchRange + pMaxIslandSize),
32 m_MaxIslandSize(pMaxIslandSize) {
33 }
34
~BranchIslandFactory()35 BranchIslandFactory::~BranchIslandFactory() {
36 }
37
38 /// group - group fragments and create islands when needed
39 /// @param pSectionData - the SectionData holds fragments need to be grouped
group(Module & pModule)40 void BranchIslandFactory::group(Module& pModule) {
41 /* FIXME: Currently only support relaxing .text section! */
42 LDSection* text = pModule.getSection(".text");
43 if (text != NULL && text->hasSectionData()) {
44 SectionData& sd = *text->getSectionData();
45 uint64_t group_end = m_MaxFwdBranchRange;
46 for (SectionData::iterator it = sd.begin(), ie = sd.end(); it != ie; ++it) {
47 if ((*it).getOffset() + (*it).size() > group_end) {
48 Fragment* frag = (*it).getPrevNode();
49 while (frag != NULL && frag->getKind() == Fragment::Alignment) {
50 frag = frag->getPrevNode();
51 }
52 if (frag != NULL) {
53 produce(*frag);
54 group_end = (*it).getOffset() + m_MaxFwdBranchRange;
55 }
56 }
57 }
58 if (getIslands(sd.back()).first == NULL)
59 produce(sd.back());
60 }
61 }
62
63 /// produce - produce a island for the given fragment
64 /// @param pFragment - the fragment needs a branch island
produce(Fragment & pFragment)65 BranchIsland* BranchIslandFactory::produce(Fragment& pFragment) {
66 BranchIsland* island = allocate();
67 new (island) BranchIsland(pFragment, // entry fragment to the island
68 m_MaxIslandSize, // the max size of the island
69 size() - 1u); // index in the island factory
70 return island;
71 }
72
73 /// getIsland - find fwd and bwd islands for the fragment
74 /// @param pFragment - the fragment needs a branch island
getIslands(const Fragment & pFragment)75 std::pair<BranchIsland*, BranchIsland*> BranchIslandFactory::getIslands(
76 const Fragment& pFragment) {
77 BranchIsland* fwd = NULL;
78 BranchIsland* bwd = NULL;
79 for (iterator it = begin(), ie = end(), prev = ie; it != ie;
80 prev = it, ++it) {
81 if ((pFragment.getOffset() < (*it).offset()) &&
82 ((pFragment.getOffset() + m_MaxFwdBranchRange) >= (*it).offset())) {
83 fwd = &*it;
84
85 if (prev != ie) {
86 int64_t bwd_off = (int64_t)pFragment.getOffset() + m_MaxBwdBranchRange;
87 if ((pFragment.getOffset() > (*prev).offset()) &&
88 (bwd_off <= (int64_t)(*prev).offset())) {
89 bwd = &*prev;
90 }
91 }
92 break;
93 }
94 }
95 return std::make_pair(fwd, bwd);
96 }
97
98 } // namespace mcld
99