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//===- BranchIslandFactory.cpp --------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <mcld/LD/BranchIslandFactory.h>
#include <mcld/Fragment/Fragment.h>
#include <mcld/LD/LDSection.h>
#include <mcld/LD/SectionData.h>
#include <mcld/Module.h>
using namespace mcld;
//===----------------------------------------------------------------------===//
// BranchIslandFactory
//===----------------------------------------------------------------------===//
/// ctor
/// @param pMaxBranchRange - the max branch range of the target backend
/// @param pMaxIslandSize - a predifned value (1KB here) to decide the max
/// size of the island
BranchIslandFactory::BranchIslandFactory(uint64_t pMaxBranchRange,
uint64_t pMaxIslandSize)
: GCFactory<BranchIsland, 0>(1u), // magic number
m_MaxBranchRange(pMaxBranchRange - pMaxIslandSize),
m_MaxIslandSize(pMaxIslandSize)
{
}
BranchIslandFactory::~BranchIslandFactory()
{
}
/// group - group fragments and create islands when needed
/// @param pSectionData - the SectionData holds fragments need to be grouped
void BranchIslandFactory::group(Module& pModule)
{
/* Currently only support relaxing .text section! */
LDSection* text = pModule.getSection(".text");
if (text != NULL && text->hasSectionData()) {
SectionData& sd = *text->getSectionData();
uint64_t group_end = m_MaxBranchRange - m_MaxIslandSize;
for (SectionData::iterator it = sd.begin(), ie = sd.end(); it != ie; ++it) {
if ((*it).getOffset() + (*it).size() > group_end) {
Fragment* frag = (*it).getPrevNode();
while (frag != NULL && frag->getKind() == Fragment::Alignment) {
frag = frag->getPrevNode();
}
if (frag != NULL) {
produce(*frag);
group_end = (*it).getOffset() + m_MaxBranchRange - m_MaxIslandSize;
}
}
}
if (find(sd.back()) == NULL)
produce(sd.back());
}
}
/// produce - produce a island for the given fragment
/// @param pFragment - the fragment needs a branch island
BranchIsland* BranchIslandFactory::produce(Fragment& pFragment)
{
BranchIsland *island = allocate();
new (island) BranchIsland(pFragment, // entry fragment to the island
m_MaxIslandSize, // the max size of the island
size() - 1u); // index in the island factory
return island;
}
/// find - find a island for the given fragment
/// @param pFragment - the fragment needs a branch isladn
BranchIsland* BranchIslandFactory::find(const Fragment& pFragment)
{
// Currently we always find the island in a forward direction.
// TODO: If we can search backward, then we may reduce the number of stubs.
for (iterator it = begin(), ie = end(); it != ie; ++it) {
if ((pFragment.getOffset() < (*it).offset()) &&
((pFragment.getOffset() + m_MaxBranchRange) >= (*it).offset()))
return &(*it);
}
return NULL;
}
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