- MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
- if (IsPCRel) {
- if (IsRIPRel) {
- if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
- // x86_64 distinguishes movq foo@GOTPCREL so that the linker can
- // rewrite the movq to an leaq at link time if the symbol ends up in
- // the same linkage unit.
- if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load)
- Type = macho::RIT_X86_64_GOTLoad;
- else
- Type = macho::RIT_X86_64_GOT;
- } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
- Type = macho::RIT_X86_64_TLV;
- } else if (Modifier != MCSymbolRefExpr::VK_None) {
- report_fatal_error("unsupported symbol modifier in relocation");
- } else {
- Type = macho::RIT_X86_64_Signed;
-
- // The Darwin x86_64 relocation format has a problem where it cannot
- // encode an address (L<foo> + <constant>) which is outside the atom
- // containing L<foo>. Generally, this shouldn't occur but it does
- // happen when we have a RIPrel instruction with data following the
- // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel
- // adjustment Darwin x86_64 uses, the offset is still negative and
- // the linker has no way to recognize this.
- //
- // To work around this, Darwin uses several special relocation types
- // to indicate the offsets. However, the specification or
- // implementation of these seems to also be incomplete; they should
- // adjust the addend as well based on the actual encoded instruction
- // (the additional bias), but instead appear to just look at the
- // final offset.
- switch (-(Target.getConstant() + (1LL << Log2Size))) {
- case 1: Type = macho::RIT_X86_64_Signed1; break;
- case 2: Type = macho::RIT_X86_64_Signed2; break;
- case 4: Type = macho::RIT_X86_64_Signed4; break;
- }
- }
- } else {
- if (Modifier != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported symbol modifier in branch "
- "relocation");
-
- Type = macho::RIT_X86_64_Branch;
- }
- } else {
- if (Modifier == MCSymbolRefExpr::VK_GOT) {
- Type = macho::RIT_X86_64_GOT;
- } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
- // GOTPCREL is allowed as a modifier on non-PCrel instructions, in
- // which case all we do is set the PCrel bit in the relocation entry;
- // this is used with exception handling, for example. The source is
- // required to include any necessary offset directly.
- Type = macho::RIT_X86_64_GOT;
- IsPCRel = 1;
- } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
- report_fatal_error("TLVP symbol modifier should have been rip-rel");
- } else if (Modifier != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported symbol modifier in relocation");
- else
- Type = macho::RIT_X86_64_Unsigned;
- }
- }
-
- // x86_64 always writes custom values into the fixups.
- FixedValue = Value;
-
- // struct relocation_info (8 bytes)
- macho::RelocationEntry MRE;
- MRE.Word0 = FixupOffset;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (IsExtern << 27) |
- (Type << 28));
- Relocations[Fragment->getParent()].push_back(MRE);
- }
-
- void RecordScatteredRelocation(const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup, MCValue Target,
- unsigned Log2Size,
- uint64_t &FixedValue) {
- uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
- unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
- unsigned Type = macho::RIT_Vanilla;
-
- // See <reloc.h>.
- const MCSymbol *A = &Target.getSymA()->getSymbol();
- MCSymbolData *A_SD = &Asm.getSymbolData(*A);
-
- if (!A_SD->getFragment())
- report_fatal_error("symbol '" + A->getName() +
- "' can not be undefined in a subtraction expression");
-
- uint32_t Value = getSymbolAddress(A_SD, Layout);
- uint64_t SecAddr = getSectionAddress(A_SD->getFragment()->getParent());
- FixedValue += SecAddr;
- uint32_t Value2 = 0;
-
- if (const MCSymbolRefExpr *B = Target.getSymB()) {
- MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
-
- if (!B_SD->getFragment())
- report_fatal_error("symbol '" + B->getSymbol().getName() +
- "' can not be undefined in a subtraction expression");
-
- // Select the appropriate difference relocation type.
- //
- // Note that there is no longer any semantic difference between these two
- // relocation types from the linkers point of view, this is done solely
- // for pedantic compatibility with 'as'.
- Type = A_SD->isExternal() ? (unsigned)macho::RIT_Difference :
- (unsigned)macho::RIT_Generic_LocalDifference;
- Value2 = getSymbolAddress(B_SD, Layout);
- FixedValue -= getSectionAddress(B_SD->getFragment()->getParent());
- }
-
- // Relocations are written out in reverse order, so the PAIR comes first.
- if (Type == macho::RIT_Difference ||
- Type == macho::RIT_Generic_LocalDifference) {
- macho::RelocationEntry MRE;
- MRE.Word0 = ((0 << 0) |
- (macho::RIT_Pair << 24) |
- (Log2Size << 28) |
- (IsPCRel << 30) |
- macho::RF_Scattered);
- MRE.Word1 = Value2;
- Relocations[Fragment->getParent()].push_back(MRE);
- }