[flang-commits] [clang-tools-extra] [compiler-rt] [llvm] [clang] [flang] [clang] Add support for new loop attribute [[clang::code_align()]] (PR #70762)

[Erich Keane via flang-commits]

================
@@ -322,6 +322,61 @@ static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,
   return ::new (S.Context) UnlikelyAttr(S.Context, A);
 }
 
+CodeAlignAttr *Sema::BuildCodeAlignAttr(const AttributeCommonInfo &CI,
+                                        Expr *E) {
+  if (!E->isValueDependent()) {
+    llvm::APSInt ArgVal;
+    ExprResult Res = VerifyIntegerConstantExpression(E, &ArgVal);
+    if (Res.isInvalid())
+      return nullptr;
+    E = Res.get();
+
+    // This attribute requires an integer argument which is a constant power of
+    // two between 1 and 4096 inclusive.
+    if (ArgVal < CodeAlignAttr::MinimumAlignment ||
+        ArgVal > CodeAlignAttr::MaximumAlignment || !ArgVal.isPowerOf2()) {
+      if (std::optional<int64_t> Value = ArgVal.trySExtValue())
+        Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
+            << CI << CodeAlignAttr::MinimumAlignment
+            << CodeAlignAttr::MaximumAlignment << Value.value();
+      else
+        Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
+            << CI << CodeAlignAttr::MinimumAlignment
+            << CodeAlignAttr::MaximumAlignment << E;
+      return nullptr;
+    }
+  }
+  return new (Context) CodeAlignAttr(Context, CI, E);
+}
+
+static Attr *handleCodeAlignAttr(Sema &S, Stmt *St, const ParsedAttr &A) {
+
+  Expr *E = A.getArgAsExpr(0);
+  return S.BuildCodeAlignAttr(A, E);
+}
+
+// Emit duplicate error for [[clang::code_align()]] attribute.
+static void
+CheckForDuplicateCodeAlignAttrs(Sema &S,
+                                const SmallVectorImpl<const Attr *> &Attrs) {
+  auto FindFunc = [](const Attr *A) {
+    return isa<const CodeAlignAttr>(A);
+  };
+
+  const auto *FirstItr =
+    std::find_if(Attrs.begin(), Attrs.end(), FindFunc);
+
+  if (FirstItr == Attrs.end()) // no attributes found
+    return;
+
+  const auto *LastFoundItr = FirstItr;
+
+  while (Attrs.end() != (LastFoundItr = std::find_if(LastFoundItr + 1, Attrs.end(), FindFunc)))  {
+      S.Diag((*LastFoundItr)->getLocation(), diag::err_loop_attr_duplication) << *FirstItr;
----------------
erichkeane wrote:

Actually... this is a good point for discussion @AaronBallman : I'm now thinking perhaps we should only diagnose if we find a non-identical duplicate and diagnose it as a 'conflicting' loop attr.  WDYT?  Its a little tougher since we have to re-evaluate the expression each time, but would suppress overly noisy warnings (in cases where the two match).

https://github.com/llvm/llvm-project/pull/70762