[Sema] Warn when alignof is used with __builtin_alloca_with_align
The second argument to __builtin_alloca_with_align is supposed to be in
bits, not bytes. Using alignof there would be indicative of a bug.
llvm-svn: 285609
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a4e3c5b..4d9ad78 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -3907,7 +3907,7 @@
return false;
}
-/// Handle __builtin_assume_aligned. This is declared
+/// Handle __builtin_alloca_with_align. This is declared
/// as (size_t, size_t) where the second size_t must be a power of 2 greater
/// than 8.
bool Sema::SemaBuiltinAllocaWithAlign(CallExpr *TheCall) {
@@ -3916,6 +3916,12 @@
// We can't check the value of a dependent argument.
if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
+ if (const auto *UE =
+ dyn_cast<UnaryExprOrTypeTraitExpr>(Arg->IgnoreParenImpCasts()))
+ if (UE->getKind() == UETT_AlignOf)
+ Diag(TheCall->getLocStart(), diag::warn_alloca_align_alignof)
+ << Arg->getSourceRange();
+
llvm::APSInt Result = Arg->EvaluateKnownConstInt(Context);
if (!Result.isPowerOf2())