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[AArch64][MachO] Encode @AUTH to ARM64_RELOC_AUTHENTICATED_POINTER.
This adds MachO support for emission of authenticated pointer relocations. We already support AArch64AuthMCExpr, to represent assembly expressions such as: .quad <symbol>@AUTH(<key>, <discriminator> [, addr]) For example: .quad _g3@AUTH(ib, 1234, addr) These @AUTH expressions lower to a new kind of MachO relocation: ARM64_RELOC_AUTHENTICATED_POINTER (11) The relocation points to the referenced symbol. The other data, describing the signing scheme and original addend (only 32 bits instead of 64), is encoded into the addend (in the relocated location): |63|62|61-51|50-49| 48 |47 - 32|31 - 0| | 1| 0| 0 | key | addr | discriminator | addend |
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‎llvm/docs/PointerAuth.md

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@@ -374,6 +374,19 @@ For example:
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.quad _sym@AUTH(ia,12,addr)
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```
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#### MachO Object File Representation
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At the object file level, authenticated relocations are represented using the
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``ARM64_RELOC_AUTHENTICATED_POINTER`` relocation kind (with value ``11``).
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The pointer authentication information is encoded into the addend as follows:
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```
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| 63 | 62 | 61-51 | 50-49 | 48 | 47 - 32 | 31 - 0 |
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| -- | -- | ----- | ----- | ------ | --------------- | -------- |
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| 1 | 0 | 0 | key | addr | discriminator | addend |
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```
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#### ELF Object File Representation
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At the object file level, authenticated relocations are represented

‎llvm/lib/Object/MachOObjectFile.cpp

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@@ -2341,7 +2341,7 @@ void MachOObjectFile::getRelocationTypeName(
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"ARM64_RELOC_PAGEOFF12", "ARM64_RELOC_GOT_LOAD_PAGE21",
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"ARM64_RELOC_GOT_LOAD_PAGEOFF12", "ARM64_RELOC_POINTER_TO_GOT",
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"ARM64_RELOC_TLVP_LOAD_PAGE21", "ARM64_RELOC_TLVP_LOAD_PAGEOFF12",
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"ARM64_RELOC_ADDEND"
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"ARM64_RELOC_ADDEND", "ARM64_RELOC_AUTHENTICATED_POINTER"
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};
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if (RType >= std::size(Table))

‎llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp

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@@ -7,6 +7,7 @@
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/AArch64FixupKinds.h"
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#include "MCTargetDesc/AArch64MCExpr.h"
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#include "MCTargetDesc/AArch64MCTargetDesc.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/BinaryFormat/MachO.h"
@@ -394,6 +395,46 @@ void AArch64MachObjectWriter::recordRelocation(
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Value = 0;
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}
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if (Target.getRefKind() == AArch64MCExpr::VK_AUTH ||
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Target.getRefKind() == AArch64MCExpr::VK_AUTHADDR) {
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auto *Expr = cast<AArch64AuthMCExpr>(Fixup.getValue());
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assert(Type == MachO::ARM64_RELOC_UNSIGNED);
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if (IsPCRel) {
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Asm.getContext().reportError(Fixup.getLoc(),
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"invalid PC relative auth relocation");
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return;
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}
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if (Log2Size != 3) {
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Asm.getContext().reportError(
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Fixup.getLoc(), "invalid auth relocation size, must be 8 bytes");
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return;
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}
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if (Target.getSymB()) {
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Asm.getContext().reportError(
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Fixup.getLoc(),
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"invalid auth relocation, can't reference two symbols");
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return;
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}
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uint16_t Discriminator = Expr->getDiscriminator();
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AArch64PACKey::ID Key = Expr->getKey();
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if (!isInt<32>(Value)) {
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Asm.getContext().reportError(Fixup.getLoc(),
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"addend too big for relocation");
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return;
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}
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Type = MachO::ARM64_RELOC_AUTHENTICATED_POINTER;
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Value = (uint32_t(Value)) | (uint64_t(Discriminator) << 32) |
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(uint64_t(Expr->hasAddressDiversity()) << 48) |
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(uint64_t(Key) << 49) | (1ULL << 63);
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}
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// If there's any addend left to handle, encode it in the instruction.
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FixedValue = Value;
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‎llvm/test/MC/AArch64/arm64e-authenticated-pointer-reloc.s

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// RUN: llvm-mc -triple=arm64-apple-darwin < %s | \
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// RUN: FileCheck %s --check-prefix=ASM
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// RUN: llvm-mc -triple=arm64-apple-darwin -filetype=obj < %s | \
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// RUN: llvm-readobj --expand-relocs --sections \
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// RUN: --section-relocations --section-data - | \
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// RUN: FileCheck %s --check-prefix=RELOC
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// RELOC: Sections [
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// RELOC-LABEL: Section {
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// RELOC-LABEL: Section {
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// RELOC-NEXT: Index: 1
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// RELOC-NEXT: Name: __const (5F 5F 63 6F 6E 73 74 00 00 00 00 00 00 00 00 00)
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// RELOC-NEXT: Segment: __DATA (5F 5F 44 41 54 41 00 00 00 00 00 00 00 00 00 00)
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.section __DATA,__const
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.p2align 3
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// RELOC-LABEL: Relocations [
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x70
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g 7
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x60
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g 6
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x50
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g5
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x40
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g4
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x30
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g3
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x20
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g2
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x10
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g1
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// RELOC-NEXT: }
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// RELOC-NEXT: Relocation {
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// RELOC-NEXT: Offset: 0x0
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// RELOC-NEXT: PCRel: 0
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// RELOC-NEXT: Length: 3
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// RELOC-NEXT: Type: ARM64_RELOC_AUTHENTICATED_POINTER (11)
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// RELOC-NEXT: Symbol: _g0
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// RELOC-NEXT: }
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// RELOC-NEXT: ]
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// RELOC-NEXT: SectionData (
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// RELOC-NEXT: 0000: 00000000 2A000080
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// ASM: .quad _g0@AUTH(ia,42)
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.quad _g0@AUTH(ia,42)
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.quad 0
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// RELOC-NEXT: 0010: 00000000 00000280
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// ASM: .quad _g1@AUTH(ib,0)
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.quad _g1@AUTH(ib,0)
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.quad 0
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// RELOC-NEXT: 0020: 00000000 05000580
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// ASM: .quad _g2@AUTH(da,5,addr)
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.quad _g2@AUTH(da,5,addr)
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.quad 0
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// RELOC-NEXT: 0030: 00000000 FFFF0780
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// ASM: .quad _g3@AUTH(db,65535,addr)
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.quad _g3@AUTH(db,0xffff,addr)
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.quad 0
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// RELOC-NEXT: 0040: 07000000 00000080
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// ASM: .quad (_g4+7)@AUTH(ia,0)
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.quad (_g4 + 7)@AUTH(ia,0)
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.quad 0
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// RELOC-NEXT: 0050: FDFFFFFF 00DE0280
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// ASM: .quad (_g5-3)@AUTH(ib,56832)
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.quad (_g5 - 3)@AUTH(ib,0xde00)
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.quad 0
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// RELOC-NEXT: 0060: 00000000 FF000780
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// ASM: .quad "_g 6"@AUTH(db,255,addr)
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.quad "_g 6"@AUTH(db,0xff,addr)
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.quad 0
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// RELOC-NEXT: 0070: 07000000 10000080
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// ASM: .quad ("_g 7"+7)@AUTH(ia,16)
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.quad ("_g 7" + 7)@AUTH(ia,16)
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.quad 0

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