[clang] [PAC] Implement function pointer re-signing (PR #98847)

[Daniil Kovalev via cfe-commits]

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@@ -0,0 +1,77 @@
+// RUN: %clang_cc1 -fptrauth-function-pointer-type-discrimination -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm %s  -o - | FileCheck -check-prefix=CHECK -check-prefix=NOPCH %s
+// RUN: %clang_cc1 -fptrauth-function-pointer-type-discrimination -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-pch %s -o %t.ast
+// RUN: %clang_cc1 -fptrauth-function-pointer-type-discrimination -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -x ast -o - %t.ast | FileCheck -check-prefix=CHECK -check-prefix=PCH %s
+
+#define FNPTRKEY 0
+
+void (*fnptr)(void);
+long discriminator;
+
+extern void external_function(void);
+// CHECK: @fptr1 = global ptr ptrauth (ptr @external_function, i32 0, i64 18983)
+void (*fptr1)(void) = external_function;
+// CHECK: @fptr2 = global ptr ptrauth (ptr @external_function, i32 0, i64 18983)
+void (*fptr2)(void) = &external_function;
+
+// CHECK: @fptr3 = global ptr ptrauth (ptr @external_function, i32 2, i64 26)
+void (*fptr3)(void) = __builtin_ptrauth_sign_constant(&external_function, 2, 26);
+
+// CHECK: @fptr4 = global ptr ptrauth (ptr @external_function, i32 2, i64 26, ptr @fptr4)
+void (*fptr4)(void) = __builtin_ptrauth_sign_constant(&external_function, 2, __builtin_ptrauth_blend_discriminator(&fptr4, 26));
+
+// CHECK-LABEL: define void @test_call()
+void test_call() {
+  // CHECK:      [[T0:%.*]] = load ptr, ptr @fnptr,
+  // CHECK-NEXT: call void [[T0]]() [ "ptrauth"(i32 0, i64 18983) ]
+  fnptr();
+}
+
+// CHECK-LABEL: define void @test_direct_call()
+void test_direct_call() {
+  // CHECK: call void @test_call(){{$}}
+  test_call();
+}
+
+void abort();
+// CHECK-LABEL: define void @test_direct_builtin_call()
+void test_direct_builtin_call() {
+  // CHECK: call void @abort() {{#[0-9]+$}}
+  abort();
+}
+
+// CHECK-LABEL: define ptr @test_function_pointer()
+// CHECK:  ret ptr ptrauth (ptr @external_function, i32 0, i64 18983)
+void (*test_function_pointer())(void) {
+  return external_function;
+}
+
+struct InitiallyIncomplete;
+extern struct InitiallyIncomplete returns_initially_incomplete(void);
+// CHECK-LABEL: define void @use_while_incomplete()
+void use_while_incomplete() {
+  // NOPCH:      [[VAR:%.*]] = alloca ptr,
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kovdan01 wrote:

Do we need PCH and NOPCH here instead of just CHECK? The contents of the check lines looks identical for both cases. Since these are the only places where these prefixes are used, we can probably get rid of them in FileCheck invocations as well.

https://github.com/llvm/llvm-project/pull/98847