[llvm-branch-commits] [clang] [clang] Define ptrauth_sign_constant builtin. (PR #93904)

Ahmed Bougacha via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Thu May 30 17:35:12 PDT 2024


https://github.com/ahmedbougacha created https://github.com/llvm/llvm-project/pull/93904

This is a constant-expression equivalent to __builtin_ptrauth_sign, allowing its usage in global initializers, but requiring constant pointers and discriminators.

>From 1a23a99f23714ba6a83b354e3b9afd056b263a02 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed at bougacha.org>
Date: Thu, 30 May 2024 17:33:04 -0700
Subject: [PATCH] [clang] Define ptrauth_sign_constant builtin.

This is constant-expression equivalent to __builtin_ptrauth_sign,
allowing its usage in global initializers, but requiring constant
pointers and discriminators.

Co-Authored-By: John McCall <rjmccall at apple.com>
---
 clang/include/clang/Basic/Builtins.td         |   6 +
 .../clang/Basic/DiagnosticSemaKinds.td        |   7 +
 clang/include/clang/CodeGen/CodeGenABITypes.h |   6 +
 clang/lib/AST/ExprConstant.cpp                |   1 +
 clang/lib/CodeGen/CGBuiltin.cpp               |   3 +
 clang/lib/CodeGen/CGExprConstant.cpp          |  62 +++++++++
 clang/lib/CodeGen/CGPointerAuth.cpp           |  77 +++++++++++
 clang/lib/CodeGen/CMakeLists.txt              |   1 +
 clang/lib/CodeGen/CodeGenModule.h             |   5 +
 clang/lib/Headers/ptrauth.h                   |  25 ++++
 clang/lib/Sema/SemaChecking.cpp               | 128 ++++++++++++++++--
 .../CodeGen/ptrauth-intrinsic-sign-constant.c |  20 +++
 clang/test/Sema/ptrauth-intrinsics-macro.c    |   4 +
 clang/test/Sema/ptrauth.c                     |  29 ++++
 14 files changed, 360 insertions(+), 14 deletions(-)
 create mode 100644 clang/lib/CodeGen/CGPointerAuth.cpp
 create mode 100644 clang/test/CodeGen/ptrauth-intrinsic-sign-constant.c

diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index 836697632a3bc..557b70172fc08 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -4393,6 +4393,12 @@ def PtrauthSignUnauthenticated : Builtin {
   let Prototype = "void*(void*,int,void*)";
 }
 
+def PtrauthSignConstant : Builtin {
+  let Spellings = ["__builtin_ptrauth_sign_constant"];
+  let Attributes = [CustomTypeChecking, NoThrow, Const, Constexpr];
+  let Prototype = "void*(void*,int,void*)";
+}
+
 def PtrauthSignGenericData : Builtin {
   let Spellings = ["__builtin_ptrauth_sign_generic_data"];
   let Attributes = [CustomTypeChecking, NoThrow, Const];
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 64add46248c69..753e775ce0968 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -922,6 +922,13 @@ def err_ptrauth_value_bad_type :
   Error<"%select{signed value|extra discriminator|blended pointer|blended "
         "integer}0 must have %select{pointer|integer|pointer or integer}1 "
         "type; type here is %2">;
+def err_ptrauth_bad_constant_pointer :
+  Error<"argument to ptrauth_sign_constant must refer to a global variable "
+        "or function">;
+def err_ptrauth_bad_constant_discriminator :
+  Error<"discriminator argument to ptrauth_sign_constant must be a constant "
+        "integer, the address of the global variable where the result "
+        "will be stored, or a blend of the two">;
 def warn_ptrauth_sign_null_pointer :
   Warning<"signing a null pointer will yield a non-null pointer">,
   InGroup<PtrAuthNullPointers>;
diff --git a/clang/include/clang/CodeGen/CodeGenABITypes.h b/clang/include/clang/CodeGen/CodeGenABITypes.h
index fda0855dc8683..8c62d8597ecbe 100644
--- a/clang/include/clang/CodeGen/CodeGenABITypes.h
+++ b/clang/include/clang/CodeGen/CodeGenABITypes.h
@@ -104,6 +104,12 @@ llvm::Type *convertTypeForMemory(CodeGenModule &CGM, QualType T);
 unsigned getLLVMFieldNumber(CodeGenModule &CGM,
                             const RecordDecl *RD, const FieldDecl *FD);
 
+/// Return a signed constant pointer.
+llvm::Constant *getConstantSignedPointer(CodeGenModule &CGM,
+                                         llvm::Constant *pointer,
+                                         unsigned key,
+                                         llvm::Constant *storageAddress,
+                                         llvm::Constant *otherDiscriminator);
 /// Given the language and code-generation options that Clang was configured
 /// with, set the default LLVM IR attributes for a function definition.
 /// The attributes set here are mostly global target-configuration and
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index eafecfb5fe5b1..b1cb3c323074b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2042,6 +2042,7 @@ static bool IsNoOpCall(const CallExpr *E) {
   unsigned Builtin = E->getBuiltinCallee();
   return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
           Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
+          Builtin == Builtin::BI__builtin_ptrauth_sign_constant ||
           Builtin == Builtin::BI__builtin_function_start);
 }
 
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index a3c6510503324..b2e3b6fa64284 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -5273,6 +5273,9 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__iso_volatile_store64:
     return RValue::get(EmitISOVolatileStore(*this, E));
 
+  case Builtin::BI__builtin_ptrauth_sign_constant:
+    return RValue::get(ConstantEmitter(*this).emitAbstract(E, E->getType()));
+
   case Builtin::BI__builtin_ptrauth_auth:
   case Builtin::BI__builtin_ptrauth_auth_and_resign:
   case Builtin::BI__builtin_ptrauth_blend_discriminator:
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index 4eb65b34a89f5..de9380c0e63be 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1856,6 +1856,12 @@ class ConstantLValueEmitter : public ConstStmtVisitor<ConstantLValueEmitter,
   ConstantLValue VisitMaterializeTemporaryExpr(
                                          const MaterializeTemporaryExpr *E);
 
+  ConstantLValue emitPointerAuthSignConstant(const CallExpr *E);
+  llvm::Constant *emitPointerAuthPointer(const Expr *E);
+  unsigned emitPointerAuthKey(const Expr *E);
+  std::pair<llvm::Constant*, llvm::Constant*>
+  emitPointerAuthDiscriminator(const Expr *E);
+
   bool hasNonZeroOffset() const {
     return !Value.getLValueOffset().isZero();
   }
@@ -2048,6 +2054,10 @@ ConstantLValueEmitter::VisitCallExpr(const CallExpr *E) {
   if (builtin == Builtin::BI__builtin_function_start)
     return CGM.GetFunctionStart(
         E->getArg(0)->getAsBuiltinConstantDeclRef(CGM.getContext()));
+
+  if (builtin == Builtin::BI__builtin_ptrauth_sign_constant)
+    return emitPointerAuthSignConstant(E);
+
   if (builtin != Builtin::BI__builtin___CFStringMakeConstantString &&
       builtin != Builtin::BI__builtin___NSStringMakeConstantString)
     return nullptr;
@@ -2061,6 +2071,58 @@ ConstantLValueEmitter::VisitCallExpr(const CallExpr *E) {
   }
 }
 
+ConstantLValue
+ConstantLValueEmitter::emitPointerAuthSignConstant(const CallExpr *E) {
+  auto unsignedPointer = emitPointerAuthPointer(E->getArg(0));
+  auto key = emitPointerAuthKey(E->getArg(1));
+  llvm::Constant *storageAddress;
+  llvm::Constant *otherDiscriminator;
+  std::tie(storageAddress, otherDiscriminator) =
+    emitPointerAuthDiscriminator(E->getArg(2));
+
+  auto signedPointer =
+    CGM.getConstantSignedPointer(unsignedPointer, key, storageAddress,
+                                 otherDiscriminator);
+  return signedPointer;
+}
+
+llvm::Constant *ConstantLValueEmitter::emitPointerAuthPointer(const Expr *E) {
+  Expr::EvalResult result;
+  bool succeeded = E->EvaluateAsRValue(result, CGM.getContext());
+  assert(succeeded); (void) succeeded;
+
+  // The assertions here are all checked by Sema.
+  assert(result.Val.isLValue());
+  return ConstantEmitter(CGM, Emitter.CGF)
+           .emitAbstract(E->getExprLoc(), result.Val, E->getType());
+}
+
+unsigned ConstantLValueEmitter::emitPointerAuthKey(const Expr *E) {
+  return E->EvaluateKnownConstInt(CGM.getContext()).getZExtValue();
+}
+
+std::pair<llvm::Constant*, llvm::Constant*>
+ConstantLValueEmitter::emitPointerAuthDiscriminator(const Expr *E) {
+  E = E->IgnoreParens();
+
+  if (auto call = dyn_cast<CallExpr>(E)) {
+    if (call->getBuiltinCallee() ==
+          Builtin::BI__builtin_ptrauth_blend_discriminator) {
+      auto pointer = ConstantEmitter(CGM).emitAbstract(call->getArg(0),
+                                            call->getArg(0)->getType());
+      auto extra = ConstantEmitter(CGM).emitAbstract(call->getArg(1),
+                                            call->getArg(1)->getType());
+      return { pointer, extra };
+    }
+  }
+
+  auto result = ConstantEmitter(CGM).emitAbstract(E, E->getType());
+  if (result->getType()->isPointerTy())
+    return { result, nullptr };
+  else
+    return { nullptr, result };
+}
+
 ConstantLValue
 ConstantLValueEmitter::VisitBlockExpr(const BlockExpr *E) {
   StringRef functionName;
diff --git a/clang/lib/CodeGen/CGPointerAuth.cpp b/clang/lib/CodeGen/CGPointerAuth.cpp
new file mode 100644
index 0000000000000..756c00aa42c8c
--- /dev/null
+++ b/clang/lib/CodeGen/CGPointerAuth.cpp
@@ -0,0 +1,77 @@
+//===--- CGPointerAuth.cpp - IR generation for pointer authentication -----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains common routines relating to the emission of
+// pointer authentication operations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGCXXABI.h"
+#include "CGCall.h"
+#include "CodeGenFunction.h"
+#include "CodeGenModule.h"
+#include "clang/AST/Attr.h"
+#include "clang/Basic/PointerAuthOptions.h"
+#include "clang/CodeGen/CodeGenABITypes.h"
+#include "clang/CodeGen/ConstantInitBuilder.h"
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/IR/ValueMap.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include <vector>
+
+using namespace clang;
+using namespace CodeGen;
+
+/// Build a signed-pointer "ptrauth" constant.
+static llvm::ConstantPtrAuth *
+buildConstantAddress(CodeGenModule &CGM, llvm::Constant *pointer, unsigned key,
+                     llvm::Constant *storageAddress,
+                     llvm::Constant *otherDiscriminator) {
+  llvm::Constant *addressDiscriminator = nullptr;
+  if (storageAddress) {
+    addressDiscriminator = storageAddress;
+    assert(storageAddress->getType() == CGM.UnqualPtrTy);
+  } else {
+    addressDiscriminator = llvm::Constant::getNullValue(CGM.UnqualPtrTy);
+  }
+
+  llvm::ConstantInt *integerDiscriminator = nullptr;
+  if (otherDiscriminator) {
+    assert(otherDiscriminator->getType() == CGM.Int64Ty);
+    integerDiscriminator = cast<llvm::ConstantInt>(otherDiscriminator);
+  } else {
+    integerDiscriminator = llvm::ConstantInt::get(CGM.Int64Ty, 0);
+  }
+
+  return llvm::ConstantPtrAuth::get(
+    pointer, llvm::ConstantInt::get(CGM.Int32Ty, key), integerDiscriminator,
+    addressDiscriminator);
+}
+
+llvm::Constant *
+CodeGenModule::getConstantSignedPointer(llvm::Constant *pointer,
+                                        unsigned key,
+                                        llvm::Constant *storageAddress,
+                                        llvm::Constant *otherDiscriminator) {
+  // Unique based on the underlying value, not a signing of it.
+  auto stripped = pointer->stripPointerCasts();
+
+  // Build the constant.
+  return buildConstantAddress(*this, stripped, key, storageAddress,
+                              otherDiscriminator);
+}
+
+llvm::Constant *
+CodeGen::getConstantSignedPointer(CodeGenModule &CGM,
+                                  llvm::Constant *pointer, unsigned key,
+                                  llvm::Constant *storageAddress,
+                                  llvm::Constant *otherDiscriminator) {
+  return CGM.getConstantSignedPointer(pointer, key, storageAddress,
+                                      otherDiscriminator);
+}
diff --git a/clang/lib/CodeGen/CMakeLists.txt b/clang/lib/CodeGen/CMakeLists.txt
index 7a933d0ed0d0d..8dd9d8b54c25f 100644
--- a/clang/lib/CodeGen/CMakeLists.txt
+++ b/clang/lib/CodeGen/CMakeLists.txt
@@ -89,6 +89,7 @@ add_clang_library(clangCodeGen
   CGOpenCLRuntime.cpp
   CGOpenMPRuntime.cpp
   CGOpenMPRuntimeGPU.cpp
+  CGPointerAuth.cpp
   CGRecordLayoutBuilder.cpp
   CGStmt.cpp
   CGStmtOpenMP.cpp
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 0f68418130ead..194ac180171e0 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -938,6 +938,11 @@ class CodeGenModule : public CodeGenTypeCache {
   // Return the function body address of the given function.
   llvm::Constant *GetFunctionStart(const ValueDecl *Decl);
 
+  llvm::Constant *getConstantSignedPointer(llvm::Constant *pointer,
+                                           unsigned key,
+                                           llvm::Constant *storageAddress,
+                                           llvm::Constant *extraDiscrim);
+
   // Return whether RTTI information should be emitted for this target.
   bool shouldEmitRTTI(bool ForEH = false) {
     return (ForEH || getLangOpts().RTTI) && !getLangOpts().CUDAIsDevice &&
diff --git a/clang/lib/Headers/ptrauth.h b/clang/lib/Headers/ptrauth.h
index 3e58af1802084..069bd6ad03b03 100644
--- a/clang/lib/Headers/ptrauth.h
+++ b/clang/lib/Headers/ptrauth.h
@@ -78,12 +78,30 @@ typedef __UINTPTR_TYPE__ ptrauth_generic_signature_t;
    On arm64e, the integer must fall within the range of a uint16_t;
    other bits may be ignored.
 
+   For the purposes of ptrauth_sign_constant, the result of calling
+   this function is considered a constant expression if the arguments
+   are constant.  Some restrictions may be imposed on the pointer.
+
    The first argument must be an expression of pointer type.
    The second argument must be an expression of integer type.
    The result will have type uintptr_t. */
 #define ptrauth_blend_discriminator(__pointer, __integer)                      \
   __builtin_ptrauth_blend_discriminator(__pointer, __integer)
 
+/* Add a signature to the given pointer value using a specific key,
+   using the given extra data as a salt to the signing process.
+
+   The value must be a constant expression of pointer type.
+   The key must be a constant expression of type ptrauth_key.
+   The extra data must be a constant expression of pointer or integer type;
+   if an integer, it will be coerced to ptrauth_extra_data_t.
+   The result will have the same type as the original value.
+
+   This is a constant expression if the extra data is an integer or
+   null pointer constant. */
+#define ptrauth_sign_constant(__value, __key, __data)                          \
+  __builtin_ptrauth_sign_constant(__value, __key, __data)
+
 /* Add a signature to the given pointer value using a specific key,
    using the given extra data as a salt to the signing process.
 
@@ -183,6 +201,13 @@ typedef __UINTPTR_TYPE__ ptrauth_generic_signature_t;
     ((ptrauth_extra_data_t)0);                                                 \
   })
 
+#define ptrauth_sign_constant(__value, __key, __data)                          \
+  ({                                                                           \
+    (void)__key;                                                               \
+    (void)__data;                                                              \
+    __value;                                                                   \
+  })
+
 #define ptrauth_sign_unauthenticated(__value, __key, __data)                   \
   ({                                                                           \
     (void)__key;                                                               \
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index f6012ef4b3601..52eba53cd2053 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -2030,8 +2030,26 @@ bool Sema::checkConstantPointerAuthKey(Expr *Arg, unsigned &Result) {
   return false;
 }
 
+static std::pair<const ValueDecl *, CharUnits>
+findConstantBaseAndOffset(Sema &S, Expr *E) {
+  // Must evaluate as a pointer.
+  Expr::EvalResult result;
+  if (!E->EvaluateAsRValue(result, S.Context) ||
+      !result.Val.isLValue())
+    return std::make_pair(nullptr, CharUnits());
+
+  // Base must be a declaration and can't be weakly imported.
+  auto baseDecl =
+    result.Val.getLValueBase().dyn_cast<const ValueDecl *>();
+  if (!baseDecl || baseDecl->hasAttr<WeakRefAttr>())
+    return std::make_pair(nullptr, CharUnits());
+
+  return std::make_pair(baseDecl, result.Val.getLValueOffset());
+}
+
 static bool checkPointerAuthValue(Sema &S, Expr *&Arg,
-                                  PointerAuthOpKind OpKind) {
+                                  PointerAuthOpKind OpKind,
+                                  bool RequireConstant = false) {
   if (Arg->hasPlaceholderType()) {
     ExprResult R = S.CheckPlaceholderExpr(Arg);
     if (R.isInvalid())
@@ -2074,16 +2092,91 @@ static bool checkPointerAuthValue(Sema &S, Expr *&Arg,
   if (convertArgumentToType(S, Arg, ExpectedTy))
     return true;
 
-  // Warn about null pointers for non-generic sign and auth operations.
-  if ((OpKind == PAO_Sign || OpKind == PAO_Auth) &&
-      Arg->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNull)) {
-    S.Diag(Arg->getExprLoc(), OpKind == PAO_Sign
-                                  ? diag::warn_ptrauth_sign_null_pointer
-                                  : diag::warn_ptrauth_auth_null_pointer)
-        << Arg->getSourceRange();
+  if (!RequireConstant) {
+    // Warn about null pointers for non-generic sign and auth operations.
+    if ((OpKind == PAO_Sign || OpKind == PAO_Auth) &&
+        Arg->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNull)) {
+      S.Diag(Arg->getExprLoc(), OpKind == PAO_Sign
+                                    ? diag::warn_ptrauth_sign_null_pointer
+                                    : diag::warn_ptrauth_auth_null_pointer)
+          << Arg->getSourceRange();
+    }
+
+    return false;
   }
 
-  return false;
+  // Perform special checking on the arguments to ptrauth_sign_constant.
+
+  // The main argument.
+  if (OpKind == PAO_Sign) {
+    // Require the value we're signing to have a special form.
+    auto result = findConstantBaseAndOffset(S, Arg);
+    bool invalid;
+
+    // Must be rooted in a declaration reference.
+    if (!result.first) {
+      invalid = true;
+
+    // If it's a function declaration, we can't have an offset.
+    } else if (isa<FunctionDecl>(result.first)) {
+      invalid = !result.second.isZero();
+
+    // Otherwise we're fine.
+    } else {
+      invalid = false;
+    }
+
+    if (invalid) {
+      S.Diag(Arg->getExprLoc(), diag::err_ptrauth_bad_constant_pointer);
+    }
+    return invalid;
+  }
+
+  // The discriminator argument.
+  assert(OpKind == PAO_Discriminator);
+
+  // Must be a pointer or integer or blend thereof.
+  Expr *pointer = nullptr;
+  Expr *integer = nullptr;
+  if (auto call = dyn_cast<CallExpr>(Arg->IgnoreParens())) {
+    if (call->getBuiltinCallee() ==
+          Builtin::BI__builtin_ptrauth_blend_discriminator) {
+      pointer = call->getArg(0);
+      integer = call->getArg(1);
+    }
+  }
+  if (!pointer && !integer) {
+    if (Arg->getType()->isPointerType())
+      pointer = Arg;
+    else
+      integer = Arg;
+  }
+
+  // Check the pointer.
+  bool invalid = false;
+  if (pointer) {
+    assert(pointer->getType()->isPointerType());
+
+    // TODO: if we're initializing a global, check that the address is
+    // somehow related to what we're initializing.  This probably will
+    // never really be feasible and we'll have to catch it at link-time.
+    auto result = findConstantBaseAndOffset(S, pointer);
+    if (!result.first || !isa<VarDecl>(result.first)) {
+      invalid = true;
+    }
+  }
+
+  // Check the integer.
+  if (integer) {
+    assert(integer->getType()->isIntegerType());
+    if (!integer->isEvaluatable(S.Context))
+      invalid = true;
+  }
+
+  if (invalid) {
+    S.Diag(Arg->getExprLoc(), diag::err_ptrauth_bad_constant_discriminator);
+  }
+  return invalid;
 }
 
 static ExprResult PointerAuthStrip(Sema &S, CallExpr *Call) {
@@ -2126,14 +2219,16 @@ static ExprResult PointerAuthSignGenericData(Sema &S, CallExpr *Call) {
 }
 
 static ExprResult PointerAuthSignOrAuth(Sema &S, CallExpr *Call,
-                                        PointerAuthOpKind OpKind) {
+                                        PointerAuthOpKind OpKind,
+                                        bool RequireConstant) {
   if (S.checkArgCount(Call, 3))
     return ExprError();
   if (checkPointerAuthEnabled(S, Call))
     return ExprError();
-  if (checkPointerAuthValue(S, Call->getArgs()[0], OpKind) ||
+  if (checkPointerAuthValue(S, Call->getArgs()[0], OpKind, RequireConstant) ||
       checkPointerAuthKey(S, Call->getArgs()[1]) ||
-      checkPointerAuthValue(S, Call->getArgs()[2], PAO_Discriminator))
+      checkPointerAuthValue(S, Call->getArgs()[2], PAO_Discriminator,
+                            RequireConstant))
     return ExprError();
 
   Call->setType(Call->getArgs()[0]->getType());
@@ -2932,10 +3027,15 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     return PointerAuthStrip(*this, TheCall);
   case Builtin::BI__builtin_ptrauth_blend_discriminator:
     return PointerAuthBlendDiscriminator(*this, TheCall);
+  case Builtin::BI__builtin_ptrauth_sign_constant:
+    return PointerAuthSignOrAuth(*this, TheCall, PAO_Sign,
+                                 /*constant*/ true);
   case Builtin::BI__builtin_ptrauth_sign_unauthenticated:
-    return PointerAuthSignOrAuth(*this, TheCall, PAO_Sign);
+    return PointerAuthSignOrAuth(*this, TheCall, PAO_Sign,
+                                 /*constant*/ false);
   case Builtin::BI__builtin_ptrauth_auth:
-    return PointerAuthSignOrAuth(*this, TheCall, PAO_Auth);
+    return PointerAuthSignOrAuth(*this, TheCall, PAO_Auth,
+                                 /*constant*/ false);
   case Builtin::BI__builtin_ptrauth_sign_generic_data:
     return PointerAuthSignGenericData(*this, TheCall);
   case Builtin::BI__builtin_ptrauth_auth_and_resign:
diff --git a/clang/test/CodeGen/ptrauth-intrinsic-sign-constant.c b/clang/test/CodeGen/ptrauth-intrinsic-sign-constant.c
new file mode 100644
index 0000000000000..3915834812990
--- /dev/null
+++ b/clang/test/CodeGen/ptrauth-intrinsic-sign-constant.c
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-intrinsics -emit-llvm %s  -o - | FileCheck %s
+
+extern int external;
+
+// CHECK: @ptr1 = global ptr ptrauth (ptr @external, i32 0, i64 26)
+void *ptr1 = __builtin_ptrauth_sign_constant(&external, 0, 26);
+
+// CHECK: @ptr2 = global ptr ptrauth (ptr @external, i32 2, i64 26, ptr @ptr2)
+void *ptr2 = __builtin_ptrauth_sign_constant(&external, 2, __builtin_ptrauth_blend_discriminator(&ptr2, 26));
+
+// CHECK: @ptr3 = global ptr null
+void *ptr3;
+
+void test_sign_constant_code() {
+// CHECK-LABEL: define void @test_sign_constant_code()
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    store ptr ptrauth (ptr @external, i32 2, i64 1234), ptr @ptr3, align 8
+// CHECK-NEXT:    ret void
+  ptr3 = __builtin_ptrauth_sign_constant(&external, 2, 1234);
+}
diff --git a/clang/test/Sema/ptrauth-intrinsics-macro.c b/clang/test/Sema/ptrauth-intrinsics-macro.c
index 540f2846b7ce1..f76f677315dd3 100644
--- a/clang/test/Sema/ptrauth-intrinsics-macro.c
+++ b/clang/test/Sema/ptrauth-intrinsics-macro.c
@@ -37,3 +37,7 @@ void test_string_discriminator(int *dp) {
   ptrauth_extra_data_t t0 = ptrauth_string_discriminator("string");
   (void)t0;
 }
+
+void test_sign_constant(int *dp) {
+  dp = ptrauth_sign_constant(&dv, VALID_DATA_KEY, 0);
+}
diff --git a/clang/test/Sema/ptrauth.c b/clang/test/Sema/ptrauth.c
index 3ad3d70c24e41..06ce1a4193691 100644
--- a/clang/test/Sema/ptrauth.c
+++ b/clang/test/Sema/ptrauth.c
@@ -47,6 +47,35 @@ void test_blend_discriminator(int *dp, int (*fp)(int), int value) {
   float *mismatch = __builtin_ptrauth_blend_discriminator(dp, value); // expected-error {{incompatible integer to pointer conversion initializing 'float *' with an expression of type}}
 }
 
+void test_sign_constant(int *dp, int (*fp)(int)) {
+  __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY); // expected-error {{too few arguments}}
+  __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY, &dv, &dv); // expected-error {{too many arguments}}
+
+  __builtin_ptrauth_sign_constant(mismatched_type, VALID_DATA_KEY, 0); // expected-error {{signed value must have pointer type; type here is 'struct A'}}
+  __builtin_ptrauth_sign_constant(&dv, mismatched_type, 0); // expected-error {{passing 'struct A' to parameter of incompatible type 'int'}}
+  __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY, mismatched_type); // expected-error {{extra discriminator must have pointer or integer type; type here is 'struct A'}}
+
+  (void) __builtin_ptrauth_sign_constant(NULL, VALID_DATA_KEY, &dv); // expected-error {{argument to ptrauth_sign_constant must refer to a global variable or function}}
+
+  int *dr = __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY, 0);
+  dr = __builtin_ptrauth_sign_constant(&dv, INVALID_KEY, 0); // expected-error {{does not identify a valid pointer authentication key for the current target}}
+
+  dr = __builtin_ptrauth_sign_constant(dp, VALID_DATA_KEY, 0); // expected-error {{argument to ptrauth_sign_constant must refer to a global variable or function}}
+  dr = __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY, dp); // expected-error {{discriminator argument to ptrauth_sign_constant must be a constant integer, the address of the global variable where the result will be stored, or a blend of the two}}
+
+  int (*fr)(int) = __builtin_ptrauth_sign_constant(&fv, VALID_CODE_KEY, 0);
+  fr = __builtin_ptrauth_sign_constant(&fv, INVALID_KEY, 0); // expected-error {{does not identify a valid pointer authentication key for the current target}}
+
+  fr = __builtin_ptrauth_sign_constant(fp, VALID_DATA_KEY, 0); // expected-error {{argument to ptrauth_sign_constant must refer to a global variable or function}}
+  fr = __builtin_ptrauth_sign_constant(&fv, VALID_DATA_KEY, dp); // expected-error {{discriminator argument to ptrauth_sign_constant must be a constant integer, the address of the global variable where the result will be stored, or a blend of the two}}
+
+  fr = __builtin_ptrauth_sign_constant(&fv, VALID_DATA_KEY, __builtin_ptrauth_blend_discriminator(&fr, 0)); // expected-error {{discriminator argument to ptrauth_sign_constant must be a constant integer, the address of the global variable where the result will be stored, or a blend of the two}}
+  fr = __builtin_ptrauth_sign_constant(&fv, VALID_DATA_KEY, __builtin_ptrauth_blend_discriminator(&dv, *dp)); // expected-error {{discriminator argument to ptrauth_sign_constant must be a constant integer, the address of the global variable where the result will be stored, or a blend of the two}}
+  fr = __builtin_ptrauth_sign_constant(&fv, VALID_DATA_KEY, __builtin_ptrauth_blend_discriminator(&dv, 0));
+
+  float *mismatch = __builtin_ptrauth_sign_constant(&dv, VALID_DATA_KEY, 0); // expected-warning {{incompatible pointer types initializing 'float *' with an expression of type 'int *'}}
+}
+
 void test_sign_unauthenticated(int *dp, int (*fp)(int)) {
   __builtin_ptrauth_sign_unauthenticated(dp, VALID_DATA_KEY); // expected-error {{too few arguments}}
   __builtin_ptrauth_sign_unauthenticated(dp, VALID_DATA_KEY, dp, dp); // expected-error {{too many arguments}}



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