bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
const MCFixup &Fixup, const MCFragment *DF,
MCValue &Target, uint64_t &Value) const {
++stats::EvaluateFixup;
if (!Fixup.getValue()->EvaluateAsRelocatable(Target, &Layout))
report_fatal_error("expected relocatable expression");
// FIXME: How do non-scattered symbols work in ELF? I presume the linker
// doesn't support small relocations, but then under what criteria does the
// assembler allow symbol differences?
Value = Target.getConstant();
bool IsPCRel = Emitter.getFixupKindInfo(
Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel;
bool IsResolved = true;
if (const MCSymbolRefExpr *A = Target.getSymA()) {
if (A->getSymbol().isDefined())
Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
else
IsResolved = false;
}
if (const MCSymbolRefExpr *B = Target.getSymB()) {
if (B->getSymbol().isDefined())
Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
else
IsResolved = false;
}
// If we are using scattered symbols, determine whether this value is actually
// resolved; scattering may cause atoms to move.
if (IsResolved && getBackend().hasScatteredSymbols()) {
if (getBackend().hasReliableSymbolDifference()) {
// If this is a PCrel relocation, find the base atom (identified by its
// symbol) that the fixup value is relative to.
const MCSymbolData *BaseSymbol = 0;
if (IsPCRel) {
BaseSymbol = DF->getAtom();
if (!BaseSymbol)
IsResolved = false;
}
if (IsResolved)
IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
BaseSymbol);
} else {
const MCSection *BaseSection = 0;
if (IsPCRel)
BaseSection = &DF->getParent()->getSection();
IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
BaseSection);
}
}
if (IsPCRel)
Value -= Layout.getFragmentAddress(DF) + Fixup.getOffset();
return IsResolved;
}
