[clang] [clang] Lower _BitInt(129+) to a different type in LLVM IR (PR #91364)

[Mariya Podchishchaeva via cfe-commits]

================
@@ -610,8 +610,26 @@ bool ConstStructBuilder::AppendBytes(CharUnits FieldOffsetInChars,
 }
 
 bool ConstStructBuilder::AppendBitField(
-    const FieldDecl *Field, uint64_t FieldOffset, llvm::ConstantInt *CI,
+    const FieldDecl *Field, uint64_t FieldOffset, llvm::Constant *C,
     bool AllowOverwrite) {
+
+  llvm::ConstantInt *CI = nullptr;
+  if (!isa<llvm::ConstantInt>(C)) {
+    // Constants for long _BitInt types are split into individual bytes.
+    // Try to fold these back into an integer constant. If that doesn't work
+    // out, we We are trying to initialize a bitfield with a non-trivial
----------------
Fznamznon wrote:

```suggestion
    // out, then we are trying to initialize a bitfield with a non-trivial
```

https://github.com/llvm/llvm-project/pull/91364