[clang] [CIR] Add support for array constructors (PR #149142)

[Henrich Lauko via cfe-commits]

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@@ -311,6 +312,115 @@ void CIRGenFunction::emitInitializerForField(FieldDecl *field, LValue lhs,
   assert(!cir::MissingFeatures::requiresCleanups());
 }
 
+/// Emit a loop to call a particular constructor for each of several members
+/// of an array.
+///
+/// \param ctor the constructor to call for each element
+/// \param arrayType the type of the array to initialize
+/// \param arrayBegin an arrayType*
+/// \param zeroInitialize true if each element should be
+///   zero-initialized before it is constructed
+void CIRGenFunction::emitCXXAggrConstructorCall(
+    const CXXConstructorDecl *ctor, const clang::ArrayType *arrayType,
+    Address arrayBegin, const CXXConstructExpr *e, bool newPointerIsChecked,
+    bool zeroInitialize) {
+  QualType elementType;
+  mlir::Value numElements = emitArrayLength(arrayType, elementType, arrayBegin);
+  emitCXXAggrConstructorCall(ctor, numElements, arrayBegin, e,
+                             newPointerIsChecked, zeroInitialize);
+}
+
+/// Emit a loop to call a particular constructor for each of several members
+/// of an array.
+///
+/// \param ctor the constructor to call for each element
+/// \param numElements the number of elements in the array;
+///   may be zero
+/// \param arrayBase a T*, where T is the type constructed by ctor
+/// \param zeroInitialize true if each element should be
+///   zero-initialized before it is constructed
+void CIRGenFunction::emitCXXAggrConstructorCall(
+    const CXXConstructorDecl *ctor, mlir::Value numElements, Address arrayBase,
+    const CXXConstructExpr *e, bool newPointerIsChecked, bool zeroInitialize) {
+  // It's legal for numElements to be zero.  This can happen both
+  // dynamically, because x can be zero in 'new A[x]', and statically,
+  // because of GCC extensions that permit zero-length arrays.  There
+  // are probably legitimate places where we could assume that this
+  // doesn't happen, but it's not clear that it's worth it.
+
+  // Optimize for a constant count.
+  auto constantCount = dyn_cast<cir::ConstantOp>(numElements.getDefiningOp());
+  if (constantCount) {
+    auto constIntAttr = mlir::dyn_cast<cir::IntAttr>(constantCount.getValue());
+    // Just skip out if the constant count is zero.
+    if (constIntAttr && constIntAttr.getUInt() == 0)
+      return;
+    // Otherwise, emit the check.
+  } else {
+    cgm.errorNYI(e->getSourceRange(), "dynamic-length array expression");
+  }
+
+  auto arrayTy = mlir::dyn_cast<cir::ArrayType>(arrayBase.getElementType());
----------------
xlauko wrote:

Might be worth renaming `Address::getElementType()` to `Address::getPointeeType()` then?


https://github.com/llvm/llvm-project/pull/149142