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ahmedbougacha
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[PAC][AArch64] Lower ptrauth constants in data (#94240)
Lower global references to ptrauth constants into `@AUTH` `MCExpr`'s. The logic is common for MachO and ELF - test both. --------- Co-authored-by: Ahmed Bougacha <[email protected]>
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‎llvm/include/llvm/CodeGen/AsmPrinter.h

+5
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,7 @@ class BasicBlock;
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class BlockAddress;
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class Constant;
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class ConstantArray;
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class ConstantPtrAuth;
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class DataLayout;
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class DIE;
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class DIEAbbrev;
@@ -585,6 +586,10 @@ class AsmPrinter : public MachineFunctionPass {
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emitGlobalConstant(DL, CV);
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}
587588

589+
virtual const MCExpr *lowerConstantPtrAuth(const ConstantPtrAuth &CPA) {
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report_fatal_error("ptrauth constant lowering not implemented");
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}
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/// Return true if the basic block has exactly one predecessor and the control
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/// transfer mechanism between the predecessor and this block is a
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/// fall-through.

‎llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

+3
Original file line numberDiff line numberDiff line change
@@ -3181,6 +3181,9 @@ const MCExpr *AsmPrinter::lowerConstant(const Constant *CV) {
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
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return MCConstantExpr::create(CI->getZExtValue(), Ctx);
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3184+
if (const ConstantPtrAuth *CPA = dyn_cast<ConstantPtrAuth>(CV))
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return lowerConstantPtrAuth(*CPA);
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if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
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return MCSymbolRefExpr::create(getSymbol(GV), Ctx);
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‎llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

+48
Original file line numberDiff line numberDiff line change
@@ -90,6 +90,8 @@ class AArch64AsmPrinter : public AsmPrinter {
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return MCInstLowering.lowerOperand(MO, MCOp);
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}
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const MCExpr *lowerConstantPtrAuth(const ConstantPtrAuth &CPA) override;
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void emitStartOfAsmFile(Module &M) override;
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void emitJumpTableInfo() override;
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std::tuple<const MCSymbol *, uint64_t, const MCSymbol *,
@@ -1575,6 +1577,52 @@ void AArch64AsmPrinter::emitPtrauthBranch(const MachineInstr *MI) {
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assert(STI->getInstrInfo()->getInstSizeInBytes(*MI) >= InstsEmitted * 4);
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}
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const MCExpr *
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AArch64AsmPrinter::lowerConstantPtrAuth(const ConstantPtrAuth &CPA) {
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MCContext &Ctx = OutContext;
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// Figure out the base symbol and the addend, if any.
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APInt Offset(64, 0);
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const Value *BaseGV = CPA.getPointer()->stripAndAccumulateConstantOffsets(
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getDataLayout(), Offset, /*AllowNonInbounds=*/true);
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auto *BaseGVB = dyn_cast<GlobalValue>(BaseGV);
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// If we can't understand the referenced ConstantExpr, there's nothing
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// else we can do: emit an error.
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if (!BaseGVB) {
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BaseGV->getContext().emitError(
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"cannot resolve target base/addend of ptrauth constant");
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return nullptr;
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}
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// If there is an addend, turn that into the appropriate MCExpr.
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const MCExpr *Sym = MCSymbolRefExpr::create(getSymbol(BaseGVB), Ctx);
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if (Offset.sgt(0))
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Sym = MCBinaryExpr::createAdd(
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Sym, MCConstantExpr::create(Offset.getSExtValue(), Ctx), Ctx);
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else if (Offset.slt(0))
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Sym = MCBinaryExpr::createSub(
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Sym, MCConstantExpr::create((-Offset).getSExtValue(), Ctx), Ctx);
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uint64_t KeyID = CPA.getKey()->getZExtValue();
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// We later rely on valid KeyID value in AArch64PACKeyIDToString call from
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// AArch64AuthMCExpr::printImpl, so fail fast.
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if (KeyID > AArch64PACKey::LAST)
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report_fatal_error("AArch64 PAC Key ID '" + Twine(KeyID) +
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"' out of range [0, " +
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Twine((unsigned)AArch64PACKey::LAST) + "]");
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uint64_t Disc = CPA.getDiscriminator()->getZExtValue();
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if (!isUInt<16>(Disc))
1618+
report_fatal_error("AArch64 PAC Discriminator '" + Twine(Disc) +
1619+
"' out of range [0, 0xFFFF]");
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// Finally build the complete @AUTH expr.
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return AArch64AuthMCExpr::create(Sym, Disc, AArch64PACKey::ID(KeyID),
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CPA.hasAddressDiscriminator(), Ctx);
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}
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// Simple pseudo-instructions have their lowering (with expansion to real
15791627
// instructions) auto-generated.
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#include "AArch64GenMCPseudoLowering.inc"

‎llvm/test/CodeGen/AArch64/ptrauth-reloc.ll

+176
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,176 @@
1+
; RUN: rm -rf %t && split-file %s %t && cd %t
2+
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;--- ok.ll
4+
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; RUN: llc < ok.ll -mtriple arm64e-apple-darwin \
6+
; RUN: | FileCheck %s --check-prefix=CHECK-MACHO
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; RUN: llc < ok.ll -mtriple aarch64-elf -mattr=+pauth \
8+
; RUN: | FileCheck %s --check-prefix=CHECK-ELF
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; RUN: llc < ok.ll -mtriple arm64e-apple-darwin \
11+
; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 \
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; RUN: | FileCheck %s --check-prefix=CHECK-MACHO
13+
; RUN: llc < ok.ll -mtriple aarch64-elf -mattr=+pauth \
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; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 \
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; RUN: | FileCheck %s --check-prefix=CHECK-ELF
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@g = external global i32
18+
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@g_weak = extern_weak global i32
20+
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@g_strong_def = constant i32 42
22+
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; CHECK-ELF-LABEL: .globl g.ref.ia.0
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; CHECK-ELF-NEXT: .p2align 4
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; CHECK-ELF-NEXT: g.ref.ia.0:
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; CHECK-ELF-NEXT: .xword 5
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; CHECK-ELF-NEXT: .xword g@AUTH(ia,0)
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; CHECK-ELF-NEXT: .xword 6
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; CHECK-MACHO-LABEL: .section __DATA,__const
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; CHECK-MACHO-NEXT: .globl _g.ref.ia.0
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; CHECK-MACHO-NEXT: .p2align 4
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; CHECK-MACHO-NEXT: _g.ref.ia.0:
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; CHECK-MACHO-NEXT: .quad 5
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; CHECK-MACHO-NEXT: .quad _g@AUTH(ia,0)
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; CHECK-MACHO-NEXT: .quad 6
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@g.ref.ia.0 = constant { i64, ptr, i64 } { i64 5, ptr ptrauth (ptr @g, i32 0), i64 6 }
39+
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; CHECK-ELF-LABEL: .globl g.ref.ia.42
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; CHECK-ELF-NEXT: .p2align 3
42+
; CHECK-ELF-NEXT: g.ref.ia.42:
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; CHECK-ELF-NEXT: .xword g@AUTH(ia,42)
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; CHECK-MACHO-LABEL: .globl _g.ref.ia.42
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g.ref.ia.42:
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; CHECK-MACHO-NEXT: .quad _g@AUTH(ia,42)
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@g.ref.ia.42 = constant ptr ptrauth (ptr @g, i32 0, i64 42)
51+
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; CHECK-ELF-LABEL: .globl g.ref.ib.0
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; CHECK-ELF-NEXT: .p2align 4
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; CHECK-ELF-NEXT: g.ref.ib.0:
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; CHECK-ELF-NEXT: .xword 5
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; CHECK-ELF-NEXT: .xword g@AUTH(ib,0)
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; CHECK-ELF-NEXT: .xword 6
58+
59+
; CHECK-MACHO-LABEL: .globl _g.ref.ib.0
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; CHECK-MACHO-NEXT: .p2align 4
61+
; CHECK-MACHO-NEXT: _g.ref.ib.0:
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; CHECK-MACHO-NEXT: .quad 5
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; CHECK-MACHO-NEXT: .quad _g@AUTH(ib,0)
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; CHECK-MACHO-NEXT: .quad 6
65+
66+
@g.ref.ib.0 = constant { i64, ptr, i64 } { i64 5, ptr ptrauth (ptr @g, i32 1, i64 0), i64 6 }
67+
68+
; CHECK-ELF-LABEL: .globl g.ref.da.42.addr
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; CHECK-ELF-NEXT: .p2align 3
70+
; CHECK-ELF-NEXT: g.ref.da.42.addr:
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; CHECK-ELF-NEXT: .xword g@AUTH(da,42,addr)
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; CHECK-MACHO-LABEL: .globl _g.ref.da.42.addr
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g.ref.da.42.addr:
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; CHECK-MACHO-NEXT: .quad _g@AUTH(da,42,addr)
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@g.ref.da.42.addr = constant ptr ptrauth (ptr @g, i32 2, i64 42, ptr @g.ref.da.42.addr)
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; CHECK-ELF-LABEL: .globl g.offset.ref.da.0
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; CHECK-ELF-NEXT: .p2align 3
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; CHECK-ELF-NEXT: g.offset.ref.da.0:
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; CHECK-ELF-NEXT: .xword (g+16)@AUTH(da,0)
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; CHECK-MACHO-LABEL: .globl _g.offset.ref.da.0
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g.offset.ref.da.0:
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; CHECK-MACHO-NEXT: .quad (_g+16)@AUTH(da,0)
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@g.offset.ref.da.0 = constant ptr ptrauth (i8* getelementptr (i8, ptr @g, i64 16), i32 2)
91+
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; CHECK-ELF-LABEL: .globl g.big_offset.ref.da.0
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; CHECK-ELF-NEXT: .p2align 3
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; CHECK-ELF-NEXT: g.big_offset.ref.da.0:
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; CHECK-ELF-NEXT: .xword (g+2147549185)@AUTH(da,0)
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; CHECK-MACHO-LABEL: .globl _g.big_offset.ref.da.0
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g.big_offset.ref.da.0:
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; CHECK-MACHO-NEXT: .quad (_g+2147549185)@AUTH(da,0)
101+
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@g.big_offset.ref.da.0 = constant ptr ptrauth (i8* getelementptr (i8, ptr @g, i64 add (i64 2147483648, i64 65537)), i32 2)
103+
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; CHECK-ELF-LABEL: .globl g.weird_ref.da.0
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; CHECK-ELF-NEXT: .p2align 3
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; CHECK-ELF-NEXT: g.weird_ref.da.0:
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; CHECK-ELF-NEXT: .xword (g+16)@AUTH(da,0)
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; CHECK-MACHO-LABEL: .globl _g.weird_ref.da.0
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g.weird_ref.da.0:
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; CHECK-MACHO-NEXT: .quad (_g+16)@AUTH(da,0)
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@g.weird_ref.da.0 = constant i64 ptrtoint (ptr inttoptr (i64 ptrtoint (ptr ptrauth (i8* getelementptr (i8, ptr @g, i64 16), i32 2) to i64) to ptr) to i64)
115+
116+
; CHECK-ELF-LABEL: .globl g_weak.ref.ia.42
117+
; CHECK-ELF-NEXT: .p2align 3
118+
; CHECK-ELF-NEXT: g_weak.ref.ia.42:
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; CHECK-ELF-NEXT: .xword g_weak@AUTH(ia,42)
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; CHECK-MACHO-LABEL: .globl _g_weak.ref.ia.42
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; CHECK-MACHO-NEXT: .p2align 3
123+
; CHECK-MACHO-NEXT: _g_weak.ref.ia.42:
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; CHECK-MACHO-NEXT: .quad _g_weak@AUTH(ia,42)
125+
126+
@g_weak.ref.ia.42 = constant ptr ptrauth (ptr @g_weak, i32 0, i64 42)
127+
128+
; CHECK-ELF-LABEL: .globl g_strong_def.ref.da.0
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; CHECK-ELF-NEXT: .p2align 3
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; CHECK-ELF-NEXT: g_strong_def.ref.da.0:
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; CHECK-ELF-NEXT: .xword g_strong_def@AUTH(da,0)
132+
133+
; CHECK-MACHO-LABEL: .globl _g_strong_def.ref.da.0
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; CHECK-MACHO-NEXT: .p2align 3
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; CHECK-MACHO-NEXT: _g_strong_def.ref.da.0:
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; CHECK-MACHO-NEXT: .quad _g_strong_def@AUTH(da,0)
137+
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@g_strong_def.ref.da.0 = constant ptr ptrauth (ptr @g_strong_def, i32 2)
139+
140+
;--- err-key.ll
141+
142+
; RUN: not --crash llc < err-key.ll -mtriple arm64e-apple-darwin 2>&1 \
143+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-KEY
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; RUN: not --crash llc < err-key.ll -mtriple aarch64-elf -mattr=+pauth 2>&1 \
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; RUN: | FileCheck %s --check-prefix=CHECK-ERR-KEY
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; RUN: not --crash llc < err-key.ll -mtriple arm64e-apple-darwin \
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; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 2>&1 \
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; RUN: | FileCheck %s --check-prefix=CHECK-ERR-KEY
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; RUN: not --crash llc < err-key.ll -mtriple aarch64-elf -mattr=+pauth \
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; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 2>&1 \
152+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-KEY
153+
154+
; CHECK-ERR-KEY: LLVM ERROR: AArch64 PAC Key ID '4' out of range [0, 3]
155+
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@g = external global i32
157+
@g.ref.4.0 = constant ptr ptrauth (ptr @g, i32 4, i64 0)
158+
159+
;--- err-disc.ll
160+
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; RUN: not --crash llc < err-disc.ll -mtriple arm64e-apple-darwin 2>&1 \
162+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-DISC
163+
; RUN: not --crash llc < err-disc.ll -mtriple aarch64-elf -mattr=+pauth 2>&1 \
164+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-DISC
165+
166+
; RUN: not --crash llc < err-disc.ll -mtriple arm64e-apple-darwin \
167+
; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 2>&1 \
168+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-DISC
169+
; RUN: not --crash llc < err-disc.ll -mtriple aarch64-elf -mattr=+pauth \
170+
; RUN: -global-isel -verify-machineinstrs -global-isel-abort=1 2>&1 \
171+
; RUN: | FileCheck %s --check-prefix=CHECK-ERR-DISC
172+
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; CHECK-ERR-DISC: LLVM ERROR: AArch64 PAC Discriminator '65536' out of range [0, 0xFFFF]
174+
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@g = external global i32
176+
@g.ref.ia.65536 = constant ptr ptrauth (ptr @g, i32 0, i64 65536)

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