Diagnose non-power-of-2 arguments to attribute aligned.

llvm-svn: 64700

clang/include/clang/Basic/DiagnosticSemaKinds.def

@@ -356,6 +356,8 @@ DIAG(err_as_qualified_auto_decl, ERROR,
      "automatic variable qualified with an address space")
 DIAG(err_attribute_annotate_no_string, ERROR,
      "argument to annotate attribute was not a string literal")
+DIAG(err_attribute_aligned_not_power_of_two, ERROR,
+     "requested alignment is not a power of 2")
 DIAG(warn_redeclaration_without_attribute_prev_attribute_ignored, WARNING,
   "'%0' redeclared without %1 attribute: previous %1 ignored")
 DIAG(warn_attribute_ignored, WARNING,

clang/lib/Sema/SemaDeclAttr.cpp

@@ -1218,6 +1218,12 @@ static void HandleAlignedAttr(Decl *d, const AttributeList &Attr, Sema &S) {
       << "aligned" << alignmentExpr->getSourceRange();
     return;
   }
+  if (!llvm::isPowerOf2_64(Alignment.getZExtValue())) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_aligned_not_power_of_two) 
+      << alignmentExpr->getSourceRange();
+    return;
+  }
+
   d->addAttr(new AlignedAttr(Alignment.getZExtValue() * 8));
 }
 

clang/test/Sema/attr-aligned.c

@@ -0,0 +1,3 @@
+// RUN: clang -fsyntax-only -verify %s
+
+int x __attribute__((aligned(3))); // expected-error {{requested alignment is not a power of 2}}