[C API] Support new ptrauth constant type (#93909)

This is a new constant type that was added to the C++ API in
0edc97f. This adds the ability to
create instances of this constant and get its values to the C API.

Author: Benjins

llvm/docs/ReleaseNotes.rst

@@ -320,6 +320,14 @@ They are described in detail in the `debug info migration guide <https://llvm.or
   * ``LLVMGEPGetNoWrapFlags``
   * ``LLVMGEPSetNoWrapFlags``
 
+* Added the following functions for creating and accessing data for ConstantPtrAuth constants:
+
+  * ``LLVMConstantPtrAuth``
+  * ``LLVMGetConstantPtrAuthPointer``
+  * ``LLVMGetConstantPtrAuthKey``
+  * ``LLVMGetConstantPtrAuthDiscriminator``
+  * ``LLVMGetConstantPtrAuthAddrDiscriminator``
+
 Changes to the CodeGen infrastructure
 -------------------------------------
 

llvm/include/llvm-c/Core.h

@@ -286,6 +286,7 @@ typedef enum {
   LLVMInstructionValueKind,
   LLVMPoisonValueValueKind,
   LLVMConstantTargetNoneValueKind,
+  LLVMConstantPtrAuthValueKind,
 } LLVMValueKind;
 
 typedef enum {
@@ -1666,6 +1667,35 @@ LLVMTypeRef LLVMScalableVectorType(LLVMTypeRef ElementType,
  */
 unsigned LLVMGetVectorSize(LLVMTypeRef VectorTy);
 
+/**
+ * Get the pointer value for the associated ConstantPtrAuth constant.
+ *
+ * @see llvm::ConstantPtrAuth::getPointer
+ */
+LLVMValueRef LLVMGetConstantPtrAuthPointer(LLVMValueRef PtrAuth);
+
+/**
+ * Get the key value for the associated ConstantPtrAuth constant.
+ *
+ * @see llvm::ConstantPtrAuth::getKey
+ */
+LLVMValueRef LLVMGetConstantPtrAuthKey(LLVMValueRef PtrAuth);
+
+/**
+ * Get the discriminator value for the associated ConstantPtrAuth constant.
+ *
+ * @see llvm::ConstantPtrAuth::getDiscriminator
+ */
+LLVMValueRef LLVMGetConstantPtrAuthDiscriminator(LLVMValueRef PtrAuth);
+
+/**
+ * Get the address discriminator value for the associated ConstantPtrAuth
+ * constant.
+ *
+ * @see llvm::ConstantPtrAuth::getAddrDiscriminator
+ */
+LLVMValueRef LLVMGetConstantPtrAuthAddrDiscriminator(LLVMValueRef PtrAuth);
+
 /**
  * @}
  */
@@ -1789,6 +1819,10 @@ unsigned LLVMGetTargetExtTypeIntParam(LLVMTypeRef TargetExtTy, unsigned Idx);
  * @{
  */
 
+// Currently, clang-format tries to format the LLVM_FOR_EACH_VALUE_SUBCLASS
+// macro in a progressively-indented fashion, which is not desired
+// clang-format off
+
 #define LLVM_FOR_EACH_VALUE_SUBCLASS(macro) \
   macro(Argument)                           \
   macro(BasicBlock)                         \
@@ -1808,6 +1842,7 @@ unsigned LLVMGetTargetExtTypeIntParam(LLVMTypeRef TargetExtTy, unsigned Idx);
       macro(ConstantStruct)                 \
       macro(ConstantTokenNone)              \
       macro(ConstantVector)                 \
+      macro(ConstantPtrAuth)                \
       macro(GlobalValue)                    \
         macro(GlobalAlias)                  \
         macro(GlobalObject)                 \
@@ -1879,6 +1914,8 @@ unsigned LLVMGetTargetExtTypeIntParam(LLVMTypeRef TargetExtTy, unsigned Idx);
       macro(AtomicRMWInst)                  \
       macro(FenceInst)
 
+// clang-format on
+
 /**
  * @defgroup LLVMCCoreValueGeneral General APIs
  *
@@ -2372,6 +2409,14 @@ LLVM_ATTRIBUTE_C_DEPRECATED(
  */
 LLVMValueRef LLVMConstVector(LLVMValueRef *ScalarConstantVals, unsigned Size);
 
+/**
+ * Create a ConstantPtrAuth constant with the given values.
+ *
+ * @see llvm::ConstantPtrAuth::get()
+ */
+LLVMValueRef LLVMConstantPtrAuth(LLVMValueRef Ptr, LLVMValueRef Key,
+                                 LLVMValueRef Disc, LLVMValueRef AddrDisc);
+
 /**
  * @}
  */

llvm/include/llvm/IR/Value.def

@@ -81,7 +81,7 @@ HANDLE_CONSTANT(BlockAddress)
 HANDLE_CONSTANT(ConstantExpr)
 HANDLE_CONSTANT_EXCLUDE_LLVM_C_API(DSOLocalEquivalent)
 HANDLE_CONSTANT_EXCLUDE_LLVM_C_API(NoCFIValue)
-HANDLE_CONSTANT_EXCLUDE_LLVM_C_API(ConstantPtrAuth)
+HANDLE_CONSTANT(ConstantPtrAuth)
 
 // ConstantAggregate.
 HANDLE_CONSTANT(ConstantArray)

llvm/lib/IR/Core.cpp

@@ -917,6 +917,22 @@ unsigned LLVMGetVectorSize(LLVMTypeRef VectorTy) {
   return unwrap<VectorType>(VectorTy)->getElementCount().getKnownMinValue();
 }
 
+LLVMValueRef LLVMGetConstantPtrAuthPointer(LLVMValueRef PtrAuth) {
+  return wrap(unwrap<ConstantPtrAuth>(PtrAuth)->getPointer());
+}
+
+LLVMValueRef LLVMGetConstantPtrAuthKey(LLVMValueRef PtrAuth) {
+  return wrap(unwrap<ConstantPtrAuth>(PtrAuth)->getKey());
+}
+
+LLVMValueRef LLVMGetConstantPtrAuthDiscriminator(LLVMValueRef PtrAuth) {
+  return wrap(unwrap<ConstantPtrAuth>(PtrAuth)->getDiscriminator());
+}
+
+LLVMValueRef LLVMGetConstantPtrAuthAddrDiscriminator(LLVMValueRef PtrAuth) {
+  return wrap(unwrap<ConstantPtrAuth>(PtrAuth)->getAddrDiscriminator());
+}
+
 /*--.. Operations on other types ...........................................--*/
 
 LLVMTypeRef LLVMPointerTypeInContext(LLVMContextRef C, unsigned AddressSpace) {
@@ -1663,6 +1679,13 @@ LLVMValueRef LLVMConstVector(LLVMValueRef *ScalarConstantVals, unsigned Size) {
       ArrayRef(unwrap<Constant>(ScalarConstantVals, Size), Size)));
 }
 
+LLVMValueRef LLVMConstantPtrAuth(LLVMValueRef Ptr, LLVMValueRef Key,
+                                 LLVMValueRef Disc, LLVMValueRef AddrDisc) {
+  return wrap(ConstantPtrAuth::get(
+      unwrap<Constant>(Ptr), unwrap<ConstantInt>(Key),
+      unwrap<ConstantInt>(Disc), unwrap<Constant>(AddrDisc)));
+}
+
 /*-- Opcode mapping */
 
 static LLVMOpcode map_to_llvmopcode(int opcode)

llvm/test/Bindings/llvm-c/echo.ll

@@ -37,6 +37,11 @@ module asm "classical GAS"
 
 @ifunc = ifunc i32 (i32), ptr @ifunc_resolver
 
+@ptrauth_addr_disc = global i32 0
+@ptrauth_data = global i32 0
+@ptrauth_ptr_01 = global ptr ptrauth (ptr @ptrauth_data, i32 77, i64 1001, ptr @ptrauth_addr_disc)
+@ptrauth_ptr_02 = global ptr ptrauth (ptr @ptrauth_data, i32 11, i64 99, ptr null)
+
 define ptr @ifunc_resolver() {
 entry:
   ret ptr null

llvm/tools/llvm-c-test/echo.cpp

@@ -391,6 +391,16 @@ static LLVMValueRef clone_constant_impl(LLVMValueRef Cst, LLVMModuleRef M) {
     return LLVMConstVector(Elts.data(), EltCount);
   }
 
+  if (LLVMIsAConstantPtrAuth(Cst)) {
+    LLVMValueRef Ptr = clone_constant(LLVMGetConstantPtrAuthPointer(Cst), M);
+    LLVMValueRef Key = clone_constant(LLVMGetConstantPtrAuthKey(Cst), M);
+    LLVMValueRef Disc =
+        clone_constant(LLVMGetConstantPtrAuthDiscriminator(Cst), M);
+    LLVMValueRef AddrDisc =
+        clone_constant(LLVMGetConstantPtrAuthAddrDiscriminator(Cst), M);
+    return LLVMConstantPtrAuth(Ptr, Key, Disc, AddrDisc);
+  }
+
   // At this point, if it's not a constant expression, it's a kind of constant
   // which is not supported
   if (!LLVMIsAConstantExpr(Cst))