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//===- StaticResolver.cpp -------------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <mcld/LD/StaticResolver.h>
#include <mcld/LD/LDSymbol.h>
#include <mcld/Support/MsgHandling.h>
using namespace mcld;
//==========================
// StaticResolver
StaticResolver::~StaticResolver()
{
}
bool StaticResolver::resolve(ResolveInfo& __restrict__ pOld,
const ResolveInfo& __restrict__ pNew,
bool &pOverride, LDSymbol::ValueType pValue) const
{
/* The state table itself.
* The first index is a link_row and the second index is a bfd_link_hash_type.
*
* Cs -> all rest kind of common (d_C, wd_C)
* Is -> all kind of indirect
*/
static const enum LinkAction link_action[LAST_ORD][LAST_ORD] =
{
/* new\old U w_U d_U wd_U D w_D d_D wd_D C w_C, Cs, Is */
/* U */ {NOACT, UND, UND, UND, NOACT, NOACT, DUND, DUND, NOACT, NOACT, NOACT, REFC },
/* w_U */ {NOACT, NOACT, NOACT, WEAK, NOACT, NOACT, DUNDW, DUNDW, NOACT, NOACT, NOACT, REFC },
/* d_U */ {NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, REFC },
/* wd_U */ {NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, REFC },
/* D */ {DEF, DEF, DEF, DEF, MDEF, DEF, DEF, DEF, CDEF, CDEF, CDEF, MDEF },
/* w_D */ {DEFW, DEFW, DEFW, DEFW, NOACT, NOACT, DEFW, DEFW, NOACT, NOACT, NOACT, NOACT},
/* d_D */ {MDEFD, MDEFD, DEFD, DEFD, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, MDEF },
/* wd_D */ {MDEFWD, MDEFWD, DEFWD, DEFWD, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT},
/* C */ {COM, COM, COM, COM, CREF, COM, COM, COM, MBIG, COM, BIG, REFC },
/* w_C */ {COM, COM, COM, COM, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, NOACT, REFC },
/* Cs */ {COM, COM, COM, COM, NOACT, NOACT, NOACT, NOACT, MBIG, MBIG, MBIG, REFC },
/* Is */ {IND, IND, IND, IND, MDEF, IND, IND, IND, CIND, CIND, CIND, MIND }
};
// Special cases:
// * when a dynamic defined symbol meets a dynamic weak defined symbol, act
// noting.
// * when a undefined symbol meets a dynamic defined symbol, override by
// dynamic defined first, then recover back to undefined symbol later.
// * when a dynamic defined symbol meets a undefined symbol or a weak
// undefined symbol, do not override, instead of marking.
// * When a undefined symbol meets a dynamic defined symbol or a weak
// undefined symbol meets a dynamic defined symbol, should override.
// * When a common symbol meets a weak common symbol, adjust the size of
// common symbol (ref: Google gold linker: resolve.cc)
unsigned int row = getOrdinate(pNew);
unsigned int col = getOrdinate(pOld);
bool cycle = false;
pOverride = false;
ResolveInfo* old = &pOld;
LinkAction action;
do {
cycle = false;
action = link_action[row][col];
switch(action) {
case FAIL: { /* abort. */
fatal(diag::fail_sym_resolution)
<< __FILE__ << __LINE__
<< "mclinker@googlegroups.com";
return false;
}
case NOACT: { /* no action. */
pOverride = false;
old->overrideVisibility(pNew);
break;
}
case UND: /* override by symbol undefined symbol. */
case WEAK: /* override by symbol weak undefined. */
case DEF: /* override by symbol defined. */
case DEFW: /* override by symbol weak defined. */
case DEFD: /* override by symbol dynamic defined. */
case DEFWD: /* override by symbol dynamic weak defined. */
case COM: { /* override by symbol common defined. */
pOverride = true;
old->override(pNew);
break;
}
case MDEFD: /* mark symbol dynamic defined. */
case MDEFWD: { /* mark symbol dynamic weak defined. */
uint32_t binding = old->binding();
old->override(pNew);
old->setBinding(binding);
ignore(diag::mark_dynamic_defined) << old->name();
pOverride = true;
break;
}
case DUND:
case DUNDW: {
old->overrideVisibility(pNew);
old->setDynamic();
pOverride = false;
break;
}
case CREF: { /* Possibly warn about common reference to defined symbol. */
// A common symbol does not override a definition.
ignore(diag::comm_refer_to_define) << old->name();
pOverride = false;
break;
}
case CDEF: { /* redefine existing common symbol. */
// We've seen a common symbol and now we see a definition. The
// definition overrides.
//
// NOTE: m_Mesg uses 'name' instead of `name' for being compatible to GNU ld.
ignore(diag::redefine_common) << old->name();
old->override(pNew);
pOverride = true;
break;
}
case BIG: { /* override by symbol common using largest size. */
if (old->size() < pNew.size())
old->setSize(pNew.size());
old->overrideAttributes(pNew);
old->overrideVisibility(pNew);
pOverride = true;
break;
}
case MBIG: { /* mark common symbol by larger size. */
if (old->size() < pNew.size())
old->setSize(pNew.size());
old->overrideVisibility(pNew);
pOverride = false;
break;
}
case CIND: { /* mark indirect symbol from existing common symbol. */
ignore(diag::indirect_refer_to_common) << old->name();
}
/* Fall through */
case IND: { /* override by indirect symbol. */
if (NULL == pNew.link()) {
fatal(diag::indirect_refer_to_inexist) << pNew.name();
break;
}
/** Should detect the loop of indirect symbol during file reading **/
// if (pNew.link()->isIndirect() && pNew.link()->link() == &pNew) {
// m_Mesg = "indirect symbol `"+pNew.name()+"' to `"+pNew.link()->name()+"' is a loop.";
// return Resolver::Abort;
//}
// change the old symbol to the indirect symbol
old->setLink(pNew.link());
pOverride = true;
break;
}
case MIND: { /* multiple indirect symbols. */
// it is OK if they both point to the same symbol
if (old->link() == pNew.link()) {
pOverride = false;
break;
}
}
/* Fall through */
case MDEF: { /* multiple definition error. */
if (pOld.isDefine() && pNew.isDefine() &&
pOld.isAbsolute() && pNew.isAbsolute() &&
(pOld.desc() == pNew.desc() || pOld.desc() == ResolveInfo::NoType ||
pNew.desc() == ResolveInfo::NoType)) {
if (pOld.outSymbol()->value() == pValue) {
pOverride = true;
old->override(pNew);
break;
} else {
error(diag::multiple_absolute_definitions) << pNew.name()
<< pOld.outSymbol()->value() << pValue;
break;
}
}
error(diag::multiple_definitions) << pNew.name();
break;
}
case REFC: { /* Mark indirect symbol referenced and then CYCLE. */
if (NULL == old->link()) {
fatal(diag::indirect_refer_to_inexist) << old->name();
break;
}
old = old->link();
col = getOrdinate(*old);
cycle = true;
break;
}
default: {
error(diag::undefined_situation) << action << old->name() << pNew.name();
return false;
}
} // end of the big switch (action)
} while(cycle);
return true;
}
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