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 #include <mcld/Fragment/Fragment.h>
11 #include <mcld/LD/LDSection.h>
12 #include <mcld/LD/SectionData.h>
13 #include <mcld/Module.h>
14
15 using namespace mcld;
16
17 //===----------------------------------------------------------------------===//
18 // BranchIslandFactory
19 //===----------------------------------------------------------------------===//
20
21 /// ctor
22 /// @param pMaxFwdBranchRange - the max forward branch range of the target
23 /// @param pMaxBwdBranchRange - the max backward branch range of the target
24 /// @param pMaxIslandSize - the predefined value for the max size of a island
BranchIslandFactory(int64_t pMaxFwdBranchRange,int64_t pMaxBwdBranchRange,size_t pMaxIslandSize)25 BranchIslandFactory::BranchIslandFactory(int64_t pMaxFwdBranchRange,
26 int64_t pMaxBwdBranchRange,
27 size_t pMaxIslandSize)
28 : GCFactory<BranchIsland, 0>(1u), // magic number
29 m_MaxFwdBranchRange(pMaxFwdBranchRange - pMaxIslandSize),
30 m_MaxBwdBranchRange(pMaxBwdBranchRange + pMaxIslandSize),
31 m_MaxIslandSize(pMaxIslandSize)
32 {
33 }
34
~BranchIslandFactory()35 BranchIslandFactory::~BranchIslandFactory()
36 {
37 }
38
39 /// group - group fragments and create islands when needed
40 /// @param pSectionData - the SectionData holds fragments need to be grouped
group(Module & pModule)41 void BranchIslandFactory::group(Module& pModule)
42 {
43 /* FIXME: Currently only support relaxing .text section! */
44 LDSection* text = pModule.getSection(".text");
45 if (text != NULL && text->hasSectionData()) {
46 SectionData& sd = *text->getSectionData();
47 uint64_t group_end = m_MaxFwdBranchRange;
48 for (SectionData::iterator it = sd.begin(), ie = sd.end(); it != ie; ++it) {
49 if ((*it).getOffset() + (*it).size() > group_end) {
50 Fragment* frag = (*it).getPrevNode();
51 while (frag != NULL && frag->getKind() == Fragment::Alignment) {
52 frag = frag->getPrevNode();
53 }
54 if (frag != NULL) {
55 produce(*frag);
56 group_end = (*it).getOffset() + m_MaxFwdBranchRange;
57 }
58 }
59 }
60 if (getIslands(sd.back()).first == NULL)
61 produce(sd.back());
62 }
63 }
64
65 /// produce - produce a island for the given fragment
66 /// @param pFragment - the fragment needs a branch island
produce(Fragment & pFragment)67 BranchIsland* BranchIslandFactory::produce(Fragment& pFragment)
68 {
69 BranchIsland *island = allocate();
70 new (island) BranchIsland(pFragment, // entry fragment to the island
71 m_MaxIslandSize, // the max size of the island
72 size() - 1u); // index in the island factory
73 return island;
74 }
75
76 /// getIsland - find fwd and bwd islands for the fragment
77 /// @param pFragment - the fragment needs a branch island
78 std::pair<BranchIsland*, BranchIsland*>
getIslands(const Fragment & pFragment)79 BranchIslandFactory::getIslands(const Fragment& pFragment)
80 {
81 BranchIsland* fwd = NULL;
82 BranchIsland* bwd = NULL;
83 for (iterator it = begin(), ie = end(), prev = ie; it != ie;
84 prev = it, ++it) {
85 if ((pFragment.getOffset() < (*it).offset()) &&
86 ((pFragment.getOffset() + m_MaxFwdBranchRange) >= (*it).offset())) {
87
88 fwd = &*it;
89
90 if (prev != ie) {
91 int64_t bwd_off = (int64_t)pFragment.getOffset() + m_MaxBwdBranchRange;
92 if ((pFragment.getOffset() > (*prev).offset()) &&
93 (bwd_off <= (int64_t) (*prev).offset())) {
94 bwd = &*prev;
95 }
96 }
97 break;
98 }
99 }
100 return std::make_pair(fwd, bwd);
101 }
102