Re-land "[AArch64] Codegen support for FEAT_PAuthLR" (#75947)

This reverts commit 9f0f5587426a4ff24b240018cf8bf3acc3c566ae.

Fix expensive checks failure by properly marking register def for ADR.

21 files changed, 752 insertions, 25 deletions

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 152d9f65f86d..21abc346cf17 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -456,6 +456,7 @@ ENUM_LANGOPT(SignReturnAddressScope, SignReturnAddressScopeKind, 2, SignReturnAd
 ENUM_LANGOPT(SignReturnAddressKey, SignReturnAddressKeyKind, 1, SignReturnAddressKeyKind::AKey,
              "Key used for return address signing")
 LANGOPT(BranchTargetEnforcement, 1, 0, "Branch-target enforcement enabled")
+LANGOPT(BranchProtectionPAuthLR, 1, 0, "Use PC as a diversifier using PAuthLR NOP instructions.")
 
 LANGOPT(SpeculativeLoadHardening, 1, 0, "Speculative load hardening enabled")
 
diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
index aa0f5023104a..ac3c324c6c29 100644
--- a/clang/include/clang/Basic/TargetInfo.h
+++ b/clang/include/clang/Basic/TargetInfo.h
@@ -1372,6 +1372,7 @@ public:
     LangOptions::SignReturnAddressKeyKind SignKey =
         LangOptions::SignReturnAddressKeyKind::AKey;
     bool BranchTargetEnforcement = false;
+    bool BranchProtectionPAuthLR = false;
   };
 
   /// Determine if the Architecture in this TargetInfo supports branch
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 9678165bfd98..2b93ddf03349 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -7000,6 +7000,8 @@ def msign_return_address_key_EQ : Joined<["-"], "msign-return-address-key=">,
     Values<"a_key,b_key">;
 def mbranch_target_enforce : Flag<["-"], "mbranch-target-enforce">,
   MarshallingInfoFlag<LangOpts<"BranchTargetEnforcement">>;
+def mbranch_protection_pauth_lr : Flag<["-"], "mbranch-protection-pauth-lr">,
+  MarshallingInfoFlag<LangOpts<"BranchProtectionPAuthLR">>;
 def fno_dllexport_inlines : Flag<["-"], "fno-dllexport-inlines">,
   MarshallingInfoNegativeFlag<LangOpts<"DllExportInlines">>;
 def cfguard_no_checks : Flag<["-"], "cfguard-no-checks">,
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index def16c032c86..3ee39133fcee 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -225,6 +225,7 @@ bool AArch64TargetInfo::validateBranchProtection(StringRef Spec, StringRef,
     BPI.SignKey = LangOptions::SignReturnAddressKeyKind::BKey;
 
   BPI.BranchTargetEnforcement = PBP.BranchTargetEnforcement;
+  BPI.BranchProtectionPAuthLR = PBP.BranchProtectionPAuthLR;
   return true;
 }
 
diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
index ce7e4d4639ce..6e1842fc64e5 100644
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -419,6 +419,7 @@ bool ARMTargetInfo::validateBranchProtection(StringRef Spec, StringRef Arch,
   BPI.SignKey = LangOptions::SignReturnAddressKeyKind::AKey;
 
   BPI.BranchTargetEnforcement = PBP.BranchTargetEnforcement;
+  BPI.BranchProtectionPAuthLR = PBP.BranchProtectionPAuthLR;
   return true;
 }
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index b2e173d0d694..d78f2594a237 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1106,6 +1106,9 @@ void CodeGenModule::Release() {
     if (LangOpts.BranchTargetEnforcement)
       getModule().addModuleFlag(llvm::Module::Min, "branch-target-enforcement",
                                 1);
+    if (LangOpts.BranchProtectionPAuthLR)
+      getModule().addModuleFlag(llvm::Module::Min, "branch-protection-pauth-lr",
+                                1);
     if (LangOpts.hasSignReturnAddress())
       getModule().addModuleFlag(llvm::Module::Min, "sign-return-address", 1);
     if (LangOpts.isSignReturnAddressScopeAll())
diff --git a/clang/lib/CodeGen/Targets/AArch64.cpp b/clang/lib/CodeGen/Targets/AArch64.cpp
index be5145daa00b..7102d190fe00 100644
--- a/clang/lib/CodeGen/Targets/AArch64.cpp
+++ b/clang/lib/CodeGen/Targets/AArch64.cpp
@@ -136,6 +136,8 @@ public:
 
     Fn->addFnAttr("branch-target-enforcement",
                   BPI.BranchTargetEnforcement ? "true" : "false");
+    Fn->addFnAttr("branch-protection-pauth-lr",
+                  BPI.BranchProtectionPAuthLR ? "true" : "false");
   }
 
   bool isScalarizableAsmOperand(CodeGen::CodeGenFunction &CGF,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index de9fd5eaa1e0..4783affd3220 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1497,7 +1497,7 @@ static void CollectARMPACBTIOptions(const ToolChain &TC, const ArgList &Args,
         << Triple.getArchName();
 
   StringRef Scope, Key;
-  bool IndirectBranches;
+  bool IndirectBranches, BranchProtectionPAuthLR;
 
   if (A->getOption().matches(options::OPT_msign_return_address_EQ)) {
     Scope = A->getValue();
@@ -1506,6 +1506,7 @@ static void CollectARMPACBTIOptions(const ToolChain &TC, const ArgList &Args,
           << A->getSpelling() << Scope;
     Key = "a_key";
     IndirectBranches = false;
+    BranchProtectionPAuthLR = false;
   } else {
     StringRef DiagMsg;
     llvm::ARM::ParsedBranchProtection PBP;
@@ -1517,6 +1518,7 @@ static void CollectARMPACBTIOptions(const ToolChain &TC, const ArgList &Args,
           << "b-key" << A->getAsString(Args);
     Scope = PBP.Scope;
     Key = PBP.Key;
+    BranchProtectionPAuthLR = PBP.BranchProtectionPAuthLR;
     IndirectBranches = PBP.BranchTargetEnforcement;
   }
 
@@ -1525,6 +1527,9 @@ static void CollectARMPACBTIOptions(const ToolChain &TC, const ArgList &Args,
   if (!Scope.equals("none"))
     CmdArgs.push_back(
         Args.MakeArgString(Twine("-msign-return-address-key=") + Key));
+  if (BranchProtectionPAuthLR)
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine("-mbranch-protection-pauth-lr")));
   if (IndirectBranches)
     CmdArgs.push_back("-mbranch-target-enforce");
 }
diff --git a/clang/test/CodeGen/aarch64-branch-protection-attr.c b/clang/test/CodeGen/aarch64-branch-protection-attr.c
index 3c2714e2feda..8ab3e17ade42 100644
--- a/clang/test/CodeGen/aarch64-branch-protection-attr.c
+++ b/clang/test/CodeGen/aarch64-branch-protection-attr.c
@@ -46,6 +46,24 @@ __attribute__ ((target("branch-protection=pac-ret+leaf+bti")))
 void btileaf() {}
 // CHECK: define{{.*}} void @btileaf() #[[#BTIPACLEAF:]]
 
+
+__attribute__ ((target("branch-protection=pac-ret+pc")))
+void pauthlr() {}
+// CHECK: define{{.*}} void @pauthlr()  #[[#PAUTHLR:]]
+
+__attribute__ ((target("branch-protection=pac-ret+pc+b-key")))
+void pauthlr_bkey() {}
+// CHECK: define{{.*}} void @pauthlr_bkey()  #[[#PAUTHLR_BKEY:]]
+
+__attribute__ ((target("branch-protection=pac-ret+pc+leaf")))
+void pauthlr_leaf() {}
+// CHECK: define{{.*}} void @pauthlr_leaf()  #[[#PAUTHLR_LEAF:]]
+
+__attribute__ ((target("branch-protection=pac-ret+pc+bti")))
+void pauthlr_bti() {}
+// CHECK: define{{.*}} void @pauthlr_bti()  #[[#PAUTHLR_BTI:]]
+
+
 // CHECK-DAG: attributes #[[#NONE]] = { {{.*}} "branch-target-enforcement"="false" {{.*}} "sign-return-address"="none"
 
 // CHECK-DAG: attributes #[[#STD]] = { {{.*}} "branch-target-enforcement"="true" {{.*}} "sign-return-address"="non-leaf" "sign-return-address-key"="a_key"
@@ -61,3 +79,13 @@ void btileaf() {}
 // CHECK-DAG: attributes #[[#PACBKEYLEAF]] = { {{.*}} "branch-target-enforcement"="false" {{.*}}"sign-return-address"="all" "sign-return-address-key"="b_key"
 
 // CHECK-DAG: attributes #[[#BTIPACLEAF]] = { {{.*}}"branch-target-enforcement"="true" {{.*}} "sign-return-address"="all" "sign-return-address-key"="a_key"
+
+
+// CHECK-DAG: attributes #[[#PAUTHLR]] = { {{.*}}"branch-protection-pauth-lr"="true" {{.*}}"branch-target-enforcement"="false" {{.*}}"sign-return-address"="non-leaf" "sign-return-address-key"="a_key"
+
+// CHECK-DAG: attributes #[[#PAUTHLR_BKEY]] = { {{.*}}"branch-protection-pauth-lr"="true" {{.*}}"branch-target-enforcement"="false" {{.*}}"sign-return-address"="non-leaf" "sign-return-address-key"="b_key"
+
+// CHECK-DAG: attributes #[[#PAUTHLR_LEAF]] = { {{.*}}"branch-protection-pauth-lr"="true" {{.*}}"branch-target-enforcement"="false" {{.*}}"sign-return-address"="all" "sign-return-address-key"="a_key"
+
+// CHECK-DAG: attributes #[[#PAUTHLR_BTI]] = { {{.*}}"branch-protection-pauth-lr"="true" {{.*}}"branch-target-enforcement"="true" {{.*}}"sign-return-address"="non-leaf" "sign-return-address-key"="a_key"
+
diff --git a/clang/test/Driver/aarch64-pauth-lr.c b/clang/test/Driver/aarch64-pauth-lr.c
new file mode 100644
index 000000000000..2e1b530fc989
--- /dev/null
+++ b/clang/test/Driver/aarch64-pauth-lr.c
@@ -0,0 +1,23 @@
+// Check the -cc1 flags for the various forms of -mbranch-protection=pac-ret+pc.
+
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc                  2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+b-key            2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-B-KEY
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+leaf             2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-LEAF
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+bti              2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-BTI
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+leaf+b-key+bti   2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-LEAF-B-KEY-BTI
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc                  -march=armv9.5-a 2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+b-key            -march=armv9.5-a 2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-B-KEY
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+leaf             -march=armv9.5-a 2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-LEAF
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+bti              -march=armv9.5-a 2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-BTI
+// RUN: %clang -target aarch64-arm-none-eabi -c %s -### -mbranch-protection=pac-ret+pc+leaf+b-key+bti   -march=armv9.5-a 2>&1 |  FileCheck %s --check-prefixes=PAUTH-LR-LEAF-B-KEY-BTI
+
+// PAUTH-LR: "-msign-return-address=non-leaf" "-msign-return-address-key=a_key" "-mbranch-protection-pauth-lr"
+// PAUTH-LR-B-KEY: "-msign-return-address=non-leaf" "-msign-return-address-key=b_key" "-mbranch-protection-pauth-lr"
+// PAUTH-LR-LEAF: "-msign-return-address=all" "-msign-return-address-key=a_key" "-mbranch-protection-pauth-lr"
+// PAUTH-LR-BTI: "-msign-return-address=non-leaf" "-msign-return-address-key=a_key" "-mbranch-protection-pauth-lr"
+// PAUTH-LR-LEAF-B-KEY-BTI: "-msign-return-address=all" "-msign-return-address-key=b_key" "-mbranch-protection-pauth-lr" "-mbranch-target-enforce"
+
+// NOT-PAUTH-LR: "-mbranch-target-enforce"
+// NOT-PAUTH-LR-B-KEY: "-mbranch-target-enforce"
+// NOT-PAUTH-LR-LEAF: "-mbranch-target-enforce"
+// NOT-PAUTH-LR-BTI: "-mbranch-target-enforce"
diff --git a/clang/test/Driver/aarch64-v95a.c b/clang/test/Driver/aarch64-v95a.c
index 366cade86a9f..6fac62e8b389 100644
--- a/clang/test/Driver/aarch64-v95a.c
+++ b/clang/test/Driver/aarch64-v95a.c
@@ -1,3 +1,5 @@
+// ===== Base v9.5a architecture =====
+
 // RUN: %clang -target aarch64 -march=armv9.5a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A %s
 // RUN: %clang -target aarch64 -march=armv9.5-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A %s
 // RUN: %clang -target aarch64 -mlittle-endian -march=armv9.5a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A %s
@@ -5,6 +7,7 @@
 // RUN: %clang -target aarch64_be -mlittle-endian -march=armv9.5a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A %s
 // RUN: %clang -target aarch64_be -mlittle-endian -march=armv9.5-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A %s
 // GENERICV95A: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+neon" "-target-feature" "+v9.5a"
+
 // RUN: %clang -target aarch64_be -march=armv9.5a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A-BE %s
 // RUN: %clang -target aarch64_be -march=armv9.5-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A-BE %s
 // RUN: %clang -target aarch64 -mbig-endian -march=armv9.5a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV95A-BE %s
@@ -18,3 +21,7 @@
 // RUN: %clang -target aarch64 -march=armv9.5a+cpa -### -c %s 2>&1 | FileCheck -check-prefix=V95A-CPA %s
 // RUN: %clang -target aarch64 -march=armv9.5-a+cpa -### -c %s 2>&1 | FileCheck -check-prefix=V95A-CPA %s
 // V95A-CPA: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+neon" "-target-feature" "+v9.5a" "-target-feature" "+cpa"
+
+// RUN: %clang -target aarch64 -march=armv9.5a+pauth-lr -### -c %s 2>&1 | FileCheck -check-prefix=V95A-PAUTHLR %s
+// RUN: %clang -target aarch64 -march=armv9.5-a+pauth-lr -### -c %s 2>&1 | FileCheck -check-prefix=V95A-PAUTHLR %s
+// V95A-PAUTHLR: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+neon" "-target-feature" "+v9.5a" "-target-feature" "+pauth-lr"
diff --git a/llvm/include/llvm/TargetParser/AArch64TargetParser.h b/llvm/include/llvm/TargetParser/AArch64TargetParser.h
index f0b35790133f..6c7410a8b8f7 100644
--- a/llvm/include/llvm/TargetParser/AArch64TargetParser.h
+++ b/llvm/include/llvm/TargetParser/AArch64TargetParser.h
@@ -174,6 +174,7 @@ enum ArchExtKind : unsigned {
   AEK_SMEF8F32 =      70, // FEAT_SME_F8F32
   AEK_SMEFA64 =       71, // FEAT_SME_FA64
   AEK_CPA =           72, // FEAT_CPA
+  AEK_PAUTHLR =       73, // FEAT_PAuth_LR
   AEK_NUM_EXTENSIONS
 };
 using ExtensionBitset = Bitset<AEK_NUM_EXTENSIONS>;
@@ -297,6 +298,7 @@ inline constexpr ExtensionInfo Extensions[] = {
     {"sme-f8f32", AArch64::AEK_SMEF8F32, "+sme-f8f32", "-sme-f8f32", FEAT_INIT, "+sme2,+fp8", 0},
     {"sme-fa64",  AArch64::AEK_SMEFA64,  "+sme-fa64", "-sme-fa64",  FEAT_INIT, "", 0},
     {"cpa", AArch64::AEK_CPA, "+cpa", "-cpa", FEAT_INIT, "", 0},
+    {"pauth-lr", AArch64::AEK_PAUTHLR, "+pauth-lr", "-pauth-lr", FEAT_INIT, "", 0},
     // Special cases
     {"none", AArch64::AEK_NONE, {}, {}, FEAT_INIT, "", ExtensionInfo::MaxFMVPriority},
 };
diff --git a/llvm/include/llvm/TargetParser/ARMTargetParserCommon.h b/llvm/include/llvm/TargetParser/ARMTargetParserCommon.h
index e3d9ffc1d4db..1e4187c6fb11 100644
--- a/llvm/include/llvm/TargetParser/ARMTargetParserCommon.h
+++ b/llvm/include/llvm/TargetParser/ARMTargetParserCommon.h
@@ -41,6 +41,7 @@ struct ParsedBranchProtection {
   StringRef Scope;
   StringRef Key;
   bool BranchTargetEnforcement;
+  bool BranchProtectionPAuthLR;
 };
 
 bool parseBranchProtection(StringRef Spec, ParsedBranchProtection &PBP,
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 175f6ef49c3b..6d85e1fb5fbf 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -8802,12 +8802,23 @@ AArch64InstrInfo::getOutliningTypeImpl(MachineBasicBlock::iterator &MIT,
   // Don't outline anything used for return address signing. The outlined
   // function will get signed later if needed
   switch (MI.getOpcode()) {
+  case AArch64::PACM:
   case AArch64::PACIASP:
   case AArch64::PACIBSP:
+  case AArch64::PACIASPPC:
+  case AArch64::PACIBSPPC:
   case AArch64::AUTIASP:
   case AArch64::AUTIBSP:
+  case AArch64::AUTIASPPCi:
+  case AArch64::AUTIASPPCr:
+  case AArch64::AUTIBSPPCi:
+  case AArch64::AUTIBSPPCr:
   case AArch64::RETAA:
   case AArch64::RETAB:
+  case AArch64::RETAASPPCi:
+  case AArch64::RETAASPPCr:
+  case AArch64::RETABSPPCi:
+  case AArch64::RETABSPPCr:
   case AArch64::EMITBKEY:
   case AArch64::PAUTH_PROLOGUE:
   case AArch64::PAUTH_EPILOGUE:
diff --git a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
index 9da59ef2a806..1a8c71888a85 100644
--- a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.cpp
@@ -93,16 +93,24 @@ AArch64FunctionInfo::AArch64FunctionInfo(const Function &F,
   // TODO: skip functions that have no instrumented allocas for optimization
   IsMTETagged = F.hasFnAttribute(Attribute::SanitizeMemTag);
 
-  if (!F.hasFnAttribute("branch-target-enforcement")) {
-    if (const auto *BTE = mdconst::extract_or_null<ConstantInt>(
-            F.getParent()->getModuleFlag("branch-target-enforcement")))
-      BranchTargetEnforcement = BTE->getZExtValue();
-  } else {
-    const StringRef BTIEnable =
-        F.getFnAttribute("branch-target-enforcement").getValueAsString();
-    assert(BTIEnable == "true" || BTIEnable == "false");
-    BranchTargetEnforcement = BTIEnable == "true";
-  }
+  // BTI/PAuthLR may be set either on the function or the module. Set Bool from
+  // either the function attribute or module attribute, depending on what is
+  // set.
+  // Note: the module attributed is numeric (0 or 1) but the function attribute
+  // is stringy ("true" or "false").
+  auto TryFnThenModule = [&](StringRef AttrName, bool &Bool) {
+    if (F.hasFnAttribute(AttrName)) {
+      const StringRef V = F.getFnAttribute(AttrName).getValueAsString();
+      assert(V.equals_insensitive("true") || V.equals_insensitive("false"));
+      Bool = V.equals_insensitive("true");
+    } else if (const auto *ModVal = mdconst::extract_or_null<ConstantInt>(
+                   F.getParent()->getModuleFlag(AttrName))) {
+      Bool = ModVal->getZExtValue();
+    }
+  };
+
+  TryFnThenModule("branch-target-enforcement", BranchTargetEnforcement);
+  TryFnThenModule("branch-protection-pauth-lr", BranchProtectionPAuthLR);
 
   // The default stack probe size is 4096 if the function has no
   // stack-probe-size attribute. This is a safe default because it is the
diff --git a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
index 219f83cfd32e..cd4a18bfbc23 100644
--- a/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64MachineFunctionInfo.h
@@ -22,6 +22,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/IR/Function.h"
 #include "llvm/MC/MCLinkerOptimizationHint.h"
+#include "llvm/MC/MCSymbol.h"
 #include <cassert>
 #include <optional>
 
@@ -164,10 +165,21 @@ class AArch64FunctionInfo final : public MachineFunctionInfo {
   /// SignWithBKey modifies the default PAC-RET mode to signing with the B key.
   bool SignWithBKey = false;
 
+  /// SigningInstrOffset captures the offset of the PAC-RET signing instruction
+  /// within the prologue, so it can be re-used for authentication in the
+  /// epilogue when using PC as a second salt (FEAT_PAuth_LR)
+  MCSymbol *SignInstrLabel = nullptr;
+
   /// BranchTargetEnforcement enables placing BTI instructions at potential
   /// indirect branch destinations.
   bool BranchTargetEnforcement = false;
 
+  /// Indicates that SP signing should be diversified with PC as-per PAuthLR.
+  /// This is set by -mbranch-protection and will emit NOP instructions unless
+  /// the subtarget feature +pauthlr is also used (in which case non-NOP
+  /// instructions are emitted).
+  bool BranchProtectionPAuthLR = false;
+
   /// Whether this function has an extended frame record [Ctx, FP, LR]. If so,
   /// bit 60 of the in-memory FP will be 1 to enable other tools to detect the
   /// extended record.
@@ -436,10 +448,16 @@ public:
   bool needsShadowCallStackPrologueEpilogue(MachineFunction &MF) const;
 
   bool shouldSignWithBKey() const { return SignWithBKey; }
+
+  MCSymbol *getSigningInstrLabel() const { return SignInstrLabel; }
+  void setSigningInstrLabel(MCSymbol *Label) { SignInstrLabel = Label; }
+
   bool isMTETagged() const { return IsMTETagged; }
 
   bool branchTargetEnforcement() const { return BranchTargetEnforcement; }
 
+  bool branchProtectionPAuthLR() const { return BranchProtectionPAuthLR; }
+
   void setHasSwiftAsyncContext(bool HasContext) {
     HasSwiftAsyncContext = HasContext;
   }
diff --git a/llvm/lib/Target/AArch64/AArch64PointerAuth.cpp b/llvm/lib/Target/AArch64/AArch64PointerAuth.cpp
index 7576d2a899d1..7509afaeb5fe 100644
--- a/llvm/lib/Target/AArch64/AArch64PointerAuth.cpp
+++ b/llvm/lib/Target/AArch64/AArch64PointerAuth.cpp
@@ -60,11 +60,35 @@ FunctionPass *llvm::createAArch64PointerAuthPass() {
 
 char AArch64PointerAuth::ID = 0;
 
+// Where PAuthLR support is not known at compile time, it is supported using
+// PACM. PACM is in the hint space so has no effect when PAuthLR is not
+// supported by the hardware, but will alter the behaviour of PACI*SP, AUTI*SP
+// and RETAA/RETAB if the hardware supports PAuthLR.
+static void BuildPACM(const AArch64Subtarget &Subtarget, MachineBasicBlock &MBB,
+                      MachineBasicBlock::iterator MBBI, DebugLoc DL,
+                      MachineInstr::MIFlag Flags, MCSymbol *PACSym = nullptr) {
+  const TargetInstrInfo *TII = Subtarget.getInstrInfo();
+  auto &MFnI = *MBB.getParent()->getInfo<AArch64FunctionInfo>();
+
+  // ADR X16,<address_of_PACIASP>
+  if (PACSym) {
+    assert(Flags == MachineInstr::FrameDestroy);
+    BuildMI(MBB, MBBI, DL, TII->get(AArch64::ADR))
+        .addReg(AArch64::X16, RegState::Define)
+        .addSym(PACSym);
+  }
+
+  // Only emit PACM if -mbranch-protection has +pc and the target does not
+  // have feature +pauth-lr.
+  if (MFnI.branchProtectionPAuthLR() && !Subtarget.hasPAuthLR())
+    BuildMI(MBB, MBBI, DL, TII->get(AArch64::PACM)).setMIFlag(Flags);
+}
+
 void AArch64PointerAuth::signLR(MachineFunction &MF,
                                 MachineBasicBlock::iterator MBBI) const {
-  const AArch64FunctionInfo *MFnI = MF.getInfo<AArch64FunctionInfo>();
-  bool UseBKey = MFnI->shouldSignWithBKey();
-  bool EmitCFI = MFnI->needsDwarfUnwindInfo(MF);
+  auto &MFnI = *MF.getInfo<AArch64FunctionInfo>();
+  bool UseBKey = MFnI.shouldSignWithBKey();
+  bool EmitCFI = MFnI.needsDwarfUnwindInfo(MF);
   bool NeedsWinCFI = MF.hasWinCFI();
 
   MachineBasicBlock &MBB = *MBBI->getParent();
@@ -77,11 +101,29 @@ void AArch64PointerAuth::signLR(MachineFunction &MF,
         .setMIFlag(MachineInstr::FrameSetup);
   }
 
+  // PAuthLR authentication instructions need to know the value of PC at the
+  // point of signing (PACI*).
+  if (MFnI.branchProtectionPAuthLR()) {
+    MCSymbol *PACSym = MF.getMMI().getContext().createTempSymbol();
+    MFnI.setSigningInstrLabel(PACSym);
+  }
+
   // No SEH opcode for this one; it doesn't materialize into an
   // instruction on Windows.
-  BuildMI(MBB, MBBI, DL,
-          TII->get(UseBKey ? AArch64::PACIBSP : AArch64::PACIASP))
-      .setMIFlag(MachineInstr::FrameSetup);
+  if (MFnI.branchProtectionPAuthLR() && Subtarget->hasPAuthLR()) {
+    BuildMI(MBB, MBBI, DL,
+            TII->get(MFnI.shouldSignWithBKey() ? AArch64::PACIBSPPC
+                                               : AArch64::PACIASPPC))
+        .setMIFlag(MachineInstr::FrameSetup)
+        ->setPreInstrSymbol(MF, MFnI.getSigningInstrLabel());
+  } else {
+    BuildPACM(*Subtarget, MBB, MBBI, DL, MachineInstr::FrameSetup);
+    BuildMI(MBB, MBBI, DL,
+            TII->get(MFnI.shouldSignWithBKey() ? AArch64::PACIBSP
+                                               : AArch64::PACIASP))
+        .setMIFlag(MachineInstr::FrameSetup)
+        ->setPreInstrSymbol(MF, MFnI.getSigningInstrLabel());
+  }
 
   if (EmitCFI) {
     unsigned CFIIndex =
@@ -118,15 +160,37 @@ void AArch64PointerAuth::authenticateLR(
   // DW_CFA_AARCH64_negate_ra_state can't be emitted.
   bool TerminatorIsCombinable =
       TI != MBB.end() && TI->getOpcode() == AArch64::RET;
+  MCSymbol *PACSym = MFnI->getSigningInstrLabel();
+
   if (Subtarget->hasPAuth() && TerminatorIsCombinable && !NeedsWinCFI &&
       !MF.getFunction().hasFnAttribute(Attribute::ShadowCallStack)) {
-    unsigned CombinedRetOpcode = UseBKey ? AArch64::RETAB : AArch64::RETAA;
-    BuildMI(MBB, TI, DL, TII->get(CombinedRetOpcode)).copyImplicitOps(*TI);
+    if (MFnI->branchProtectionPAuthLR() && Subtarget->hasPAuthLR()) {
+      assert(PACSym && "No PAC instruction to refer to");
+      BuildMI(MBB, TI, DL,
+              TII->get(UseBKey ? AArch64::RETABSPPCi : AArch64::RETAASPPCi))
+          .addSym(PACSym)
+          .copyImplicitOps(*MBBI)
+          .setMIFlag(MachineInstr::FrameDestroy);
+    } else {
+      BuildPACM(*Subtarget, MBB, TI, DL, MachineInstr::FrameDestroy, PACSym);
+      BuildMI(MBB, TI, DL, TII->get(UseBKey ? AArch64::RETAB : AArch64::RETAA))
+          .copyImplicitOps(*MBBI)
+          .setMIFlag(MachineInstr::FrameDestroy);
+    }
     MBB.erase(TI);
   } else {
-    unsigned AutOpcode = UseBKey ? AArch64::AUTIBSP : AArch64::AUTIASP;
-    BuildMI(MBB, MBBI, DL, TII->get(AutOpcode))
-        .setMIFlag(MachineInstr::FrameDestroy);
+    if (MFnI->branchProtectionPAuthLR() && Subtarget->hasPAuthLR()) {
+      assert(PACSym && "No PAC instruction to refer to");
+      BuildMI(MBB, MBBI, DL,
+              TII->get(UseBKey ? AArch64::AUTIBSPPCi : AArch64::AUTIASPPCi))
+          .addSym(PACSym)
+          .setMIFlag(MachineInstr::FrameDestroy);
+    } else {
+      BuildPACM(*Subtarget, MBB, MBBI, DL, MachineInstr::FrameDestroy, PACSym);
+      BuildMI(MBB, MBBI, DL,
+              TII->get(UseBKey ? AArch64::AUTIBSP : AArch64::AUTIASP))
+          .setMIFlag(MachineInstr::FrameDestroy);
+    }
 
     if (EmitAsyncCFI) {
       unsigned CFIIndex =
diff --git a/llvm/lib/TargetParser/ARMTargetParserCommon.cpp b/llvm/lib/TargetParser/ARMTargetParserCommon.cpp
index 10b80cad4347..6d3a59d532fd 100644
--- a/llvm/lib/TargetParser/ARMTargetParserCommon.cpp
+++ b/llvm/lib/TargetParser/ARMTargetParserCommon.cpp
@@ -134,13 +134,13 @@ ARM::EndianKind ARM::parseArchEndian(StringRef Arch) {
 }
 
 // Parse a branch protection specification, which has the form
-//   standard | none | [bti,pac-ret[+b-key,+leaf]*]
+//   standard | none | [bti,pac-ret[+b-key,+leaf,+pc]*]
 // Returns true on success, with individual elements of the specification
 // returned in `PBP`. Returns false in error, with `Err` containing
 // an erroneous part of the spec.
 bool ARM::parseBranchProtection(StringRef Spec, ParsedBranchProtection &PBP,
                                 StringRef &Err) {
-  PBP = {"none", "a_key", false};
+  PBP = {"none", "a_key", false, false};
   if (Spec == "none")
     return true; // defaults are ok
 
@@ -166,6 +166,8 @@ bool ARM::parseBranchProtection(StringRef Spec, ParsedBranchProtection &PBP,
           PBP.Scope = "all";
         else if (PACOpt == "b-key")
           PBP.Key = "b_key";
+        else if (PACOpt == "pc")
+          PBP.BranchProtectionPAuthLR = true;
         else
           break;
       }
diff --git a/llvm/test/CodeGen/AArch64/sign-return-address-pauth-lr.ll b/llvm/test/CodeGen/AArch64/sign-return-address-pauth-lr.ll
new file mode 100644
index 000000000000..a78fa853d99d
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/sign-return-address-pauth-lr.ll
@@ -0,0 +1,542 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+
+; PauthLR is controlled via a combination of -mbranch-protection and +pauth-lr.
+; -mbranch-protection=+pc enables branch protection. If the feature +pauth-lr
+; is available (v9.5a onwards) then non-NOP instructions are used; otherwise
+; NOP instructions are used.
+
+; There are 6 cases to cover:
+
+; feature \ -mbranch-protection= |    none    | pac-ret |   pac-ret+pc
+; ------------------------------------------------------------------------
+; without +pauth-lr              | no codegen | old pac |     NOP pauth-lr
+;    with +pauth-lr              | no codegen | old pac | non-NOP pauth-lr
+
+; sign-return-address.ll tests combinations of -mbranch-protection=none/pac-ret
+; and whether +pauth-lr is present or not.
+
+; sign-return-address-pauth-lr.ll is identical, with the addition of this module
+; attribute, which enables -mbranch-protection=pac-ret+pc, and therefore tests
+; the remaining parameter combinations in the table:
+!llvm.module.flags = !{!1}
+!1 = !{i32 1, !"branch-protection-pauth-lr", i32 1}
+
+; RUN: llc -mtriple=aarch64              < %s | FileCheck --check-prefixes=CHECK,COMPAT %s
+; RUN: llc -mtriple=aarch64 -mattr=v8.3a < %s | FileCheck --check-prefixes=CHECK,V83A %s
+; RUN: llc -mtriple=aarch64 -mattr=v9a -mattr=pauth-lr < %s | FileCheck --check-prefixes=PAUTHLR %s
+
+define i32 @leaf(i32 %x) {
+; CHECK-LABEL: leaf:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+;
+; PAUTHLR-LABEL: leaf:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    ret
+  ret i32 %x
+}
+
+define i32 @leaf_sign_none(i32 %x) "sign-return-address"="none"  {
+; CHECK-LABEL: leaf_sign_none:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+;
+; PAUTHLR-LABEL: leaf_sign_none:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    ret
+  ret i32 %x
+}
+
+define i32 @leaf_sign_non_leaf(i32 %x) "sign-return-address"="non-leaf"  {
+; CHECK-LABEL: leaf_sign_non_leaf:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+;
+; PAUTHLR-LABEL: leaf_sign_non_leaf:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    ret
+  ret i32 %x
+}
+
+define i32 @leaf_sign_all(i32 %x) "sign-return-address"="all" {
+; COMPAT-LABEL: leaf_sign_all:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp0:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    adr x16, .Ltmp0
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_sign_all:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp0:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    adr x16, .Ltmp0
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: leaf_sign_all:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp0:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retaasppc .Ltmp0
+  ret i32 %x
+}
+
+define i64 @leaf_clobbers_lr(i64 %x) "sign-return-address"="non-leaf"  {
+; COMPAT-LABEL: leaf_clobbers_lr:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp1:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; COMPAT-NEXT:    .cfi_def_cfa_offset 16
+; COMPAT-NEXT:    .cfi_offset w30, -16
+; COMPAT-NEXT:    //APP
+; COMPAT-NEXT:    mov x30, x0
+; COMPAT-NEXT:    //NO_APP
+; COMPAT-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; COMPAT-NEXT:    adr x16, .Ltmp1
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_clobbers_lr:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp1:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; V83A-NEXT:    .cfi_def_cfa_offset 16
+; V83A-NEXT:    .cfi_offset w30, -16
+; V83A-NEXT:    //APP
+; V83A-NEXT:    mov x30, x0
+; V83A-NEXT:    //NO_APP
+; V83A-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; V83A-NEXT:    adr x16, .Ltmp1
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: leaf_clobbers_lr:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp1:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; PAUTHLR-NEXT:    .cfi_def_cfa_offset 16
+; PAUTHLR-NEXT:    .cfi_offset w30, -16
+; PAUTHLR-NEXT:    //APP
+; PAUTHLR-NEXT:    mov x30, x0
+; PAUTHLR-NEXT:    //NO_APP
+; PAUTHLR-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; PAUTHLR-NEXT:    retaasppc .Ltmp1
+  call void asm sideeffect "mov x30, $0", "r,~{lr}"(i64 %x) #1
+  ret i64 %x
+}
+
+declare i32 @foo(i32)
+
+define i32 @non_leaf_sign_all(i32 %x) "sign-return-address"="all" {
+; COMPAT-LABEL: non_leaf_sign_all:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp2:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; COMPAT-NEXT:    .cfi_def_cfa_offset 16
+; COMPAT-NEXT:    .cfi_offset w30, -16
+; COMPAT-NEXT:    bl foo
+; COMPAT-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; COMPAT-NEXT:    adr x16, .Ltmp2
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: non_leaf_sign_all:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp2:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; V83A-NEXT:    .cfi_def_cfa_offset 16
+; V83A-NEXT:    .cfi_offset w30, -16
+; V83A-NEXT:    bl foo
+; V83A-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; V83A-NEXT:    adr x16, .Ltmp2
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: non_leaf_sign_all:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp2:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; PAUTHLR-NEXT:    .cfi_def_cfa_offset 16
+; PAUTHLR-NEXT:    .cfi_offset w30, -16
+; PAUTHLR-NEXT:    bl foo
+; PAUTHLR-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; PAUTHLR-NEXT:    retaasppc .Ltmp2
+  %call = call i32 @foo(i32 %x)
+  ret i32 %call
+}
+
+define i32 @non_leaf_sign_non_leaf(i32 %x) "sign-return-address"="non-leaf"  {
+; COMPAT-LABEL: non_leaf_sign_non_leaf:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp3:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; COMPAT-NEXT:    .cfi_def_cfa_offset 16
+; COMPAT-NEXT:    .cfi_offset w30, -16
+; COMPAT-NEXT:    bl foo
+; COMPAT-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; COMPAT-NEXT:    adr x16, .Ltmp3
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: non_leaf_sign_non_leaf:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp3:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; V83A-NEXT:    .cfi_def_cfa_offset 16
+; V83A-NEXT:    .cfi_offset w30, -16
+; V83A-NEXT:    bl foo
+; V83A-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; V83A-NEXT:    adr x16, .Ltmp3
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: non_leaf_sign_non_leaf:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp3:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; PAUTHLR-NEXT:    .cfi_def_cfa_offset 16
+; PAUTHLR-NEXT:    .cfi_offset w30, -16
+; PAUTHLR-NEXT:    bl foo
+; PAUTHLR-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; PAUTHLR-NEXT:    retaasppc .Ltmp3
+  %call = call i32 @foo(i32 %x)
+  ret i32 %call
+}
+
+; Should not use the RETAA instruction.
+define i32 @non_leaf_scs(i32 %x) "sign-return-address"="non-leaf" shadowcallstack "target-features"="+v8.3a,+reserve-x18"  {
+; CHECK-LABEL: non_leaf_scs:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    str x30, [x18], #8
+; CHECK-NEXT:    .cfi_escape 0x16, 0x12, 0x02, 0x82, 0x78 //
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:  .Ltmp4:
+; CHECK-NEXT:    paciasp
+; CHECK-NEXT:    .cfi_negate_ra_state
+; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    .cfi_offset w30, -16
+; CHECK-NEXT:    bl foo
+; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; CHECK-NEXT:    adr x16, .Ltmp4
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:    autiasp
+; CHECK-NEXT:    ldr x30, [x18, #-8]!
+; CHECK-NEXT:    ret
+;
+; PAUTHLR-LABEL: non_leaf_scs:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    str x30, [x18], #8
+; PAUTHLR-NEXT:    .cfi_escape 0x16, 0x12, 0x02, 0x82, 0x78 //
+; PAUTHLR-NEXT:  .Ltmp4:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; PAUTHLR-NEXT:    .cfi_def_cfa_offset 16
+; PAUTHLR-NEXT:    .cfi_offset w30, -16
+; PAUTHLR-NEXT:    bl foo
+; PAUTHLR-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; PAUTHLR-NEXT:    autiasppc .Ltmp4
+; PAUTHLR-NEXT:    ldr x30, [x18, #-8]!
+; PAUTHLR-NEXT:    ret
+  %call = call i32 @foo(i32 %x)
+  ret i32 %call
+}
+
+define i32 @leaf_sign_all_v83(i32 %x) "sign-return-address"="all" "target-features"="+v8.3a" {
+; CHECK-LABEL: leaf_sign_all_v83:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:  .Ltmp5:
+; CHECK-NEXT:    paciasp
+; CHECK-NEXT:    .cfi_negate_ra_state
+; CHECK-NEXT:    adr x16, .Ltmp5
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:    retaa
+;
+; PAUTHLR-LABEL: leaf_sign_all_v83:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp5:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retaasppc .Ltmp5
+  ret i32 %x
+}
+
+declare fastcc i64 @bar(i64)
+
+define fastcc void @spill_lr_and_tail_call(i64 %x) "sign-return-address"="all" {
+; COMPAT-LABEL: spill_lr_and_tail_call:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp6:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; COMPAT-NEXT:    .cfi_def_cfa_offset 16
+; COMPAT-NEXT:    .cfi_offset w30, -16
+; COMPAT-NEXT:    //APP
+; COMPAT-NEXT:    mov x30, x0
+; COMPAT-NEXT:    //NO_APP
+; COMPAT-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; COMPAT-NEXT:    adr x16, .Ltmp6
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    b bar
+;
+; V83A-LABEL: spill_lr_and_tail_call:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp6:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; V83A-NEXT:    .cfi_def_cfa_offset 16
+; V83A-NEXT:    .cfi_offset w30, -16
+; V83A-NEXT:    //APP
+; V83A-NEXT:    mov x30, x0
+; V83A-NEXT:    //NO_APP
+; V83A-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; V83A-NEXT:    adr x16, .Ltmp6
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    autiasp
+; V83A-NEXT:    b bar
+;
+; PAUTHLR-LABEL: spill_lr_and_tail_call:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp6:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; PAUTHLR-NEXT:    .cfi_def_cfa_offset 16
+; PAUTHLR-NEXT:    .cfi_offset w30, -16
+; PAUTHLR-NEXT:    //APP
+; PAUTHLR-NEXT:    mov x30, x0
+; PAUTHLR-NEXT:    //NO_APP
+; PAUTHLR-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; PAUTHLR-NEXT:    autiasppc .Ltmp6
+; PAUTHLR-NEXT:    b bar
+  call void asm sideeffect "mov x30, $0", "r,~{lr}"(i64 %x) #1
+  tail call fastcc i64 @bar(i64 %x)
+  ret void
+}
+
+define i32 @leaf_sign_all_a_key(i32 %x) "sign-return-address"="all" "sign-return-address-key"="a_key" {
+; COMPAT-LABEL: leaf_sign_all_a_key:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp7:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    adr x16, .Ltmp7
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_sign_all_a_key:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp7:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    adr x16, .Ltmp7
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: leaf_sign_all_a_key:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:  .Ltmp7:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retaasppc .Ltmp7
+  ret i32 %x
+}
+
+define i32 @leaf_sign_all_b_key(i32 %x) "sign-return-address"="all" "sign-return-address-key"="b_key" {
+; COMPAT-LABEL: leaf_sign_all_b_key:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    .cfi_b_key_frame
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp8:
+; COMPAT-NEXT:    hint #27
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    adr x16, .Ltmp8
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #31
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_sign_all_b_key:
+; V83A:       // %bb.0:
+; V83A-NEXT:    .cfi_b_key_frame
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp8:
+; V83A-NEXT:    pacibsp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    adr x16, .Ltmp8
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retab
+;
+; PAUTHLR-LABEL: leaf_sign_all_b_key:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    .cfi_b_key_frame
+; PAUTHLR-NEXT:  .Ltmp8:
+; PAUTHLR-NEXT:    pacibsppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retabsppc .Ltmp8
+  ret i32 %x
+}
+
+define i32 @leaf_sign_all_v83_b_key(i32 %x) "sign-return-address"="all" "target-features"="+v8.3a" "sign-return-address-key"="b_key" {
+; CHECK-LABEL: leaf_sign_all_v83_b_key:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    .cfi_b_key_frame
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:  .Ltmp9:
+; CHECK-NEXT:    pacibsp
+; CHECK-NEXT:    .cfi_negate_ra_state
+; CHECK-NEXT:    adr x16, .Ltmp9
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:    retab
+;
+; PAUTHLR-LABEL: leaf_sign_all_v83_b_key:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    .cfi_b_key_frame
+; PAUTHLR-NEXT:  .Ltmp9:
+; PAUTHLR-NEXT:    pacibsppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retabsppc .Ltmp9
+  ret i32 %x
+}
+
+; Note that BTI instruction is not needed before PACIASP.
+define i32 @leaf_sign_all_a_key_bti(i32 %x) "sign-return-address"="all" "sign-return-address-key"="a_key" "branch-target-enforcement"="true"{
+; COMPAT-LABEL: leaf_sign_all_a_key_bti:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #34
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp10:
+; COMPAT-NEXT:    hint #25
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    adr x16, .Ltmp10
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #29
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_sign_all_a_key_bti:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #34
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp10:
+; V83A-NEXT:    paciasp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    adr x16, .Ltmp10
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retaa
+;
+; PAUTHLR-LABEL: leaf_sign_all_a_key_bti:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    bti c
+; PAUTHLR-NEXT:  .Ltmp10:
+; PAUTHLR-NEXT:    paciasppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retaasppc .Ltmp10
+  ret i32 %x
+}
+
+; Note that BTI instruction is not needed before PACIBSP.
+define i32 @leaf_sign_all_b_key_bti(i32 %x) "sign-return-address"="all" "sign-return-address-key"="b_key" "branch-target-enforcement"="true"{
+; COMPAT-LABEL: leaf_sign_all_b_key_bti:
+; COMPAT:       // %bb.0:
+; COMPAT-NEXT:    hint #34
+; COMPAT-NEXT:    .cfi_b_key_frame
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:  .Ltmp11:
+; COMPAT-NEXT:    hint #27
+; COMPAT-NEXT:    .cfi_negate_ra_state
+; COMPAT-NEXT:    adr x16, .Ltmp11
+; COMPAT-NEXT:    hint #39
+; COMPAT-NEXT:    hint #31
+; COMPAT-NEXT:    ret
+;
+; V83A-LABEL: leaf_sign_all_b_key_bti:
+; V83A:       // %bb.0:
+; V83A-NEXT:    hint #34
+; V83A-NEXT:    .cfi_b_key_frame
+; V83A-NEXT:    hint #39
+; V83A-NEXT:  .Ltmp11:
+; V83A-NEXT:    pacibsp
+; V83A-NEXT:    .cfi_negate_ra_state
+; V83A-NEXT:    adr x16, .Ltmp11
+; V83A-NEXT:    hint #39
+; V83A-NEXT:    retab
+;
+; PAUTHLR-LABEL: leaf_sign_all_b_key_bti:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    bti c
+; PAUTHLR-NEXT:    .cfi_b_key_frame
+; PAUTHLR-NEXT:  .Ltmp11:
+; PAUTHLR-NEXT:    pacibsppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retabsppc .Ltmp11
+  ret i32 %x
+}
+
+; Note that BTI instruction is not needed before PACIBSP.
+define i32 @leaf_sign_all_v83_b_key_bti(i32 %x) "sign-return-address"="all" "target-features"="+v8.3a" "sign-return-address-key"="b_key" "branch-target-enforcement"="true" {
+; CHECK-LABEL: leaf_sign_all_v83_b_key_bti:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    hint #34
+; CHECK-NEXT:    .cfi_b_key_frame
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:  .Ltmp12:
+; CHECK-NEXT:    pacibsp
+; CHECK-NEXT:    .cfi_negate_ra_state
+; CHECK-NEXT:    adr x16, .Ltmp12
+; CHECK-NEXT:    hint #39
+; CHECK-NEXT:    retab
+;
+; PAUTHLR-LABEL: leaf_sign_all_v83_b_key_bti:
+; PAUTHLR:       // %bb.0:
+; PAUTHLR-NEXT:    bti c
+; PAUTHLR-NEXT:    .cfi_b_key_frame
+; PAUTHLR-NEXT:  .Ltmp12:
+; PAUTHLR-NEXT:    pacibsppc
+; PAUTHLR-NEXT:    .cfi_negate_ra_state
+; PAUTHLR-NEXT:    retabsppc .Ltmp12
+  ret i32 %x
+}
diff --git a/llvm/test/CodeGen/AArch64/sign-return-address.ll b/llvm/test/CodeGen/AArch64/sign-return-address.ll
index 5680915c7f41..1481d4beb50d 100644
--- a/llvm/test/CodeGen/AArch64/sign-return-address.ll
+++ b/llvm/test/CodeGen/AArch64/sign-return-address.ll
@@ -2,6 +2,9 @@
 ; RUN: llc -mtriple=aarch64              < %s | FileCheck --check-prefixes=CHECK,COMPAT %s
 ; RUN: llc -mtriple=aarch64 -mattr=v8.3a < %s | FileCheck --check-prefixes=CHECK,V83A %s
 
+; v9.5-A is not expected to change codegen without -mbranch-protection=+pc, so reuse V83A.
+; RUN: llc -mtriple=aarch64 -mattr=v9.5a < %s | FileCheck --check-prefixes=CHECK,V83A %s
+
 define i32 @leaf(i32 %x) {
 ; CHECK-LABEL: leaf:
 ; CHECK:       // %bb.0:
diff --git a/llvm/unittests/TargetParser/TargetParserTest.cpp b/llvm/unittests/TargetParser/TargetParserTest.cpp
index 30e60ad92b68..866176ab0983 100644
--- a/llvm/unittests/TargetParser/TargetParserTest.cpp
+++ b/llvm/unittests/TargetParser/TargetParserTest.cpp
@@ -1812,7 +1812,8 @@ TEST(TargetParserTest, AArch64ExtensionFeatures) {
       AArch64::AEK_SSVE_FP8DOT4, AArch64::AEK_LUT,
       AArch64::AEK_SME_LUTv2,    AArch64::AEK_SMEF8F16,
       AArch64::AEK_SMEF8F32,     AArch64::AEK_SMEFA64,
-      AArch64::AEK_CPA};
+      AArch64::AEK_CPA,          AArch64::AEK_PAUTHLR,
+  };
 
   std::vector<StringRef> Features;
 
@@ -1899,6 +1900,7 @@ TEST(TargetParserTest, AArch64ExtensionFeatures) {
   EXPECT_TRUE(llvm::is_contained(Features, "+sme-f8f32"));
   EXPECT_TRUE(llvm::is_contained(Features, "+sme-fa64"));
   EXPECT_TRUE(llvm::is_contained(Features, "+cpa"));
+  EXPECT_TRUE(llvm::is_contained(Features, "+pauth-lr"));
 
   // Assuming we listed every extension above, this should produce the same
   // result. (note that AEK_NONE doesn't have a name so it won't be in the