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

[Daniil Kovalev via llvm-branch-commits]

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@@ -2074,16 +2091,91 @@ 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 BaseOffsetPair = findConstantBaseAndOffset(S, Arg);
----------------
kovdan01 wrote:

Wouldn't this become easier to read if you use structured bindings declaration like this:

```suggestion
    auto [BaseDecl, Offset] = findConstantBaseAndOffset(S, Arg);
```

And below use `BaseDecl` instead of `BaseOffsetPair.first` and `Offset` instead of `BaseOffsetPair.second`? You do not use the pair itself, only its individual members, so just initializing them and having their names short and descriptive looks preferable to me.

Also applies to other usage of `findConstantBaseAndOffset` below.

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