[CIR] CountOf VLA with Array element type

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -2325,14 +2325,27 @@ mlir::Value ScalarExprEmitter::VisitUnaryExprOrTypeTraitExpr(
   const QualType typeToSize = e->getTypeOfArgument();
   const mlir::Location loc = cgf.getLoc(e->getSourceRange());
   if (auto kind = e->getKind();
-      kind == UETT_SizeOf || kind == UETT_DataSizeOf) {
-    if (cgf.getContext().getAsVariableArrayType(typeToSize)) {
-      cgf.getCIRGenModule().errorNYI(e->getSourceRange(),
-                                     "sizeof operator for VariableArrayType",
-                                     e->getStmtClassName());
-      return builder.getConstant(
-          loc, cir::IntAttr::get(cgf.cgm.uInt64Ty,
-                                 llvm::APSInt(llvm::APInt(64, 1), true)));
+      kind == UETT_SizeOf || kind == UETT_DataSizeOf || kind == UETT_CountOf) {
+    if (const VariableArrayType *vat =
+            cgf.getContext().getAsVariableArrayType(typeToSize)) {
+      // For _Countof, we only want to evaluate if the extent is actually
+      // variable as opposed to a multi-dimensional array whose extent is
+      // constant but whose element type is variable.
+      bool evaluateExtent = true;
+      if (kind == UETT_CountOf && vat->getElementType()->isArrayType()) {
+        evaluateExtent =
+            !vat->getSizeExpr()->isIntegerConstantExpr(cgf.getContext());
+      }
+
+      if (evaluateExtent) {
+        cgf.getCIRGenModule().errorNYI(
+            e->getSourceRange(),
+            "sizeof operator for VariableArrayType & evaluateExtent",
+            e->getStmtClassName());
+        return builder.getConstant(
+            loc, cir::IntAttr::get(cgf.cgm.uInt64Ty,
+                                   -llvm::APSInt(llvm::APInt(64, 1), true)));
+      }
     }
   } else if (e->getKind() == UETT_OpenMPRequiredSimdAlign) {
     cgf.getCIRGenModule().errorNYI(

clang/test/CIR/CodeGen/count-of.c

@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -std=c2y -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c2y -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -std=c2y -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+unsigned long vla_with_array_element_type() {
+  long size;
+#define int_arr int[5]
+  return _Countof(int_arr[size]);
+}
+
+// CIR: %[[RET_ADDR:.*]] = cir.alloca !u64i, !cir.ptr<!u64i>, ["__retval"]
+// CIR: %[[SIZE_ADDR:.*]] = cir.alloca !s64i, !cir.ptr<!s64i>, ["size"]
+// CIR: %[[CONST_5:.*]] = cir.const #cir.int<5> : !u64i
+// CIR: cir.store %[[CONST_5]], %[[RET_ADDR]] : !u64i, !cir.ptr<!u64i>
+// CIR: %[[RET_VAL:.*]] = cir.load %[[RET_ADDR]] : !cir.ptr<!u64i>, !u64i
+// CIR: cir.return %[[RET_VAL]] : !u64i
+
+// LLVM: %[[RET_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[SIZE_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: store i64 5, ptr %[[RET_ADDR]], align 8
+// LLVM: %[[RET_VAL:.*]] = load i64, ptr %[[RET_ADDR]], align 8
+// LLVM: ret i64 %[[RET_VAL]]
+
+// OGCG: %[[SIZE_ADDR:.*]] = alloca i64, align 8
+// OGCG: ret i64 5