[clang] [CIR] Add constant record ILE support (PR #155663)

[Andy Kaylor via cfe-commits]

================
@@ -21,20 +20,526 @@
 #include "clang/AST/APValue.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
+#include "clang/AST/CharUnits.h"
 #include "clang/AST/OperationKinds.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Basic/Builtins.h"
-#include "clang/Basic/Specifiers.h"
 #include "clang/CIR/Dialect/IR/CIRAttrs.h"
 #include "clang/CIR/Dialect/IR/CIRTypes.h"
+#include "clang/CIR/MissingFeatures.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/Sequence.h"
 #include "llvm/Support/ErrorHandling.h"
+#include <iterator>
 
 using namespace clang;
 using namespace clang::CIRGen;
 
+//===----------------------------------------------------------------------===//
+//                            ConstantAggregateBuilder
+//===----------------------------------------------------------------------===//
+
+namespace {
+class ConstExprEmitter;
+
+static mlir::TypedAttr computePadding(CIRGenModule &cgm, CharUnits size) {
+  mlir::Type eltTy = cgm.UCharTy;
+  clang::CharUnits::QuantityType arSize = size.getQuantity();
+  CIRGenBuilderTy &bld = cgm.getBuilder();
+  if (size > CharUnits::One()) {
+    SmallVector<mlir::Attribute, 4> elts(arSize, cir::ZeroAttr::get(eltTy));
+    return bld.getConstArray(mlir::ArrayAttr::get(bld.getContext(), elts),
+                             cir::ArrayType::get(eltTy, arSize));
+  }
+
+  return cir::ZeroAttr::get(eltTy);
+}
+
+static mlir::Attribute
+emitArrayConstant(CIRGenModule &cgm, mlir::Type desiredType,
+                  mlir::Type commonElementType, unsigned arrayBound,
+                  SmallVectorImpl<mlir::TypedAttr> &elements,
+                  mlir::TypedAttr filler);
+
+struct ConstantAggregateBuilderUtils {
+  CIRGenModule &cgm;
+  cir::CIRDataLayout dataLayout;
+
+  ConstantAggregateBuilderUtils(CIRGenModule &cgm)
+      : cgm(cgm), dataLayout{cgm.getModule()} {}
+
+  CharUnits getAlignment(const mlir::TypedAttr c) const {
+    return CharUnits::fromQuantity(
+        dataLayout.getAlignment(c.getType(), /*abiOrPref=*/true));
----------------
andykaylor wrote:

```suggestion
        dataLayout.getAlignment(c.getType(), /*useABIAlign=*/true));
```
`abiOrPref=true` has a real "if you come to a fork in the road, take it" quality to it. Fortunately, the actual parameter name has more clarity.

https://github.com/llvm/llvm-project/pull/155663