[llvm-branch-commits] [Clang][Sema] Add __builtin_infer_alloc_token() declaration and semantic checks (PR #163638)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Marco Elver (melver)

<details>
<summary>Changes</summary>

Introduce the `__builtin_infer_alloc_token()` builtin declaration and
adds the necessary semantic checks in Sema.

---

This change is part of the following series:

1. https://github.com/llvm/llvm-project/pull/163632
2. https://github.com/llvm/llvm-project/pull/163633
3. https://github.com/llvm/llvm-project/pull/163634
4. https://github.com/llvm/llvm-project/pull/163635
5. https://github.com/llvm/llvm-project/pull/163636
6. https://github.com/llvm/llvm-project/pull/163638
7. https://github.com/llvm/llvm-project/pull/163639
8. https://github.com/llvm/llvm-project/pull/156842

---
Full diff: https://github.com/llvm/llvm-project/pull/163638.diff


3 Files Affected:

- (modified) clang/include/clang/Basic/Builtins.td (+7) 
- (modified) clang/lib/Sema/SemaChecking.cpp (+22) 
- (added) clang/test/SemaCXX/alloc-token.cpp (+12) 


``````````diff
diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index 792e2e07ec594..c21a048cf68c0 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -4727,6 +4727,13 @@ def PtrauthStringDiscriminator : Builtin {
   let Prototype = "size_t(char const*)";
 }
 
+// AllocToken builtins.
+def InferAllocToken : Builtin {
+  let Spellings = ["__builtin_infer_alloc_token"];
+  let Attributes = [NoThrow, Const, Pure, CustomTypeChecking, Constexpr, UnevaluatedArguments];
+  let Prototype = "size_t(...)";
+}
+
 // OpenCL v2.0 s6.13.16, s9.17.3.5 - Pipe functions.
 // We need the generic prototype, since the packet type could be anything.
 def ReadPipe : OCLPipeLangBuiltin {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 063db05665af1..953428e9e8f34 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1498,6 +1498,24 @@ static void builtinAllocaAddrSpace(Sema &S, CallExpr *TheCall) {
   TheCall->setType(S.Context.getPointerType(RT));
 }
 
+static bool checkBuiltinInferAllocToken(Sema &S, CallExpr *TheCall) {
+  if (S.checkArgCountAtLeast(TheCall, 1))
+    return true;
+
+  for (Expr *Arg : TheCall->arguments()) {
+    // If argument is dependent on a template parameter, we can't resolve now.
+    if (Arg->isTypeDependent() || Arg->isValueDependent())
+      continue;
+    // Reject void types.
+    QualType ArgTy = Arg->IgnoreParenImpCasts()->getType();
+    if (ArgTy->isVoidType())
+      return S.Diag(Arg->getBeginLoc(), diag::err_param_with_void_type);
+  }
+
+  TheCall->setType(S.Context.UnsignedLongLongTy);
+  return false;
+}
+
 namespace {
 enum PointerAuthOpKind {
   PAO_Strip,
@@ -2779,6 +2797,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
       builtinAllocaAddrSpace(*this, TheCall);
     }
     break;
+  case Builtin::BI__builtin_infer_alloc_token:
+    if (checkBuiltinInferAllocToken(*this, TheCall))
+      return ExprError();
+    break;
   case Builtin::BI__arithmetic_fence:
     if (BuiltinArithmeticFence(TheCall))
       return ExprError();
diff --git a/clang/test/SemaCXX/alloc-token.cpp b/clang/test/SemaCXX/alloc-token.cpp
new file mode 100644
index 0000000000000..5c490f2affda8
--- /dev/null
+++ b/clang/test/SemaCXX/alloc-token.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s -fexperimental-new-constant-interpreter
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++23 -fsyntax-only -verify %s -falloc-token-mode=typehash -DMODE_TYPEHASH
+
+#if !__has_builtin(__builtin_infer_alloc_token)
+#error "missing __builtin_infer_alloc_token"
+#endif
+
+void negative_tests() {
+  __builtin_infer_alloc_token(); // expected-error {{too few arguments to function call}}
+  __builtin_infer_alloc_token((void)0); // expected-error {{argument may not have 'void' type}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/163638