- if (Target.isAbsolute()) { // constant
- // SymbolNum of 0 indicates the absolute section.
- Type = macho::RIT_X86_64_Unsigned;
- Index = 0;
-
- // FIXME: I believe this is broken, I don't think the linker can
- // understand it. I think it would require a local relocation, but I'm not
- // sure if that would work either. The official way to get an absolute
- // PCrel relocation is to use an absolute symbol (which we don't support
- // yet).
- if (IsPCRel) {
- IsExtern = 1;
- Type = macho::RIT_X86_64_Branch;
- }
- } else if (Target.getSymB()) { // A - B + constant
- const MCSymbol *A = &Target.getSymA()->getSymbol();
- MCSymbolData &A_SD = Asm.getSymbolData(*A);
- const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
-
- const MCSymbol *B = &Target.getSymB()->getSymbol();
- MCSymbolData &B_SD = Asm.getSymbolData(*B);
- const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
-
- // Neither symbol can be modified.
- if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
- Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported relocation of modified symbol");
-
- // We don't support PCrel relocations of differences. Darwin 'as' doesn't
- // implement most of these correctly.
- if (IsPCRel)
- report_fatal_error("unsupported pc-relative relocation of difference");
-
- // The support for the situation where one or both of the symbols would
- // require a local relocation is handled just like if the symbols were
- // external. This is certainly used in the case of debug sections where
- // the section has only temporary symbols and thus the symbols don't have
- // base symbols. This is encoded using the section ordinal and
- // non-extern relocation entries.
-
- // Darwin 'as' doesn't emit correct relocations for this (it ends up with
- // a single SIGNED relocation); reject it for now. Except the case where
- // both symbols don't have a base, equal but both NULL.
- if (A_Base == B_Base && A_Base)
- report_fatal_error("unsupported relocation with identical base");
-
- assert((A_Base == NULL) == (B_Base == NULL));
- assert(A_SD.getFragment()->getParent() ==
- B_SD.getFragment()->getParent());
-
- Value += Layout.getSymbolOffset(&A_SD) -
- (A_Base == NULL ? 0 : Layout.getSymbolOffset(A_Base));
- Value -= Layout.getSymbolOffset(&B_SD) -
- (B_Base == NULL ? 0 : Layout.getSymbolOffset(B_Base));
-
- if (A_Base) {
- Index = A_Base->getIndex();
- IsExtern = 1;
- }
- else {
- Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
- IsExtern = 0;
- }
- Type = macho::RIT_X86_64_Unsigned;
-
- macho::RelocationEntry MRE;
- MRE.Word0 = FixupOffset;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (IsExtern << 27) |
- (Type << 28));
- Relocations[Fragment->getParent()].push_back(MRE);
-
- if (B_Base) {
- Index = B_Base->getIndex();
- IsExtern = 1;
- }
- else {
- Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
- IsExtern = 0;
- }
- Type = macho::RIT_X86_64_Subtractor;
- } else {
- const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
- MCSymbolData &SD = Asm.getSymbolData(*Symbol);
- const MCSymbolData *Base = Asm.getAtom(&SD);
-
- // Relocations inside debug sections always use local relocations when
- // possible. This seems to be done because the debugger doesn't fully
- // understand x86_64 relocation entries, and expects to find values that
- // have already been fixed up.
- if (Symbol->isInSection()) {
- const MCSectionMachO &Section = static_cast<const MCSectionMachO&>(
- Fragment->getParent()->getSection());
- if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG))
- Base = 0;
- }