[llvm] [AMDGPU] Update code object metadata for kernarg preload (PR #134666)

[Matt Arsenault via llvm-commits]

================
@@ -745,5 +782,51 @@ void MetadataStreamerMsgPackV6::emitVersion() {
   getRootMetadata("amdhsa.version") = Version;
 }
 
+void MetadataStreamerMsgPackV6::emitHiddenKernelArg(
+    const DataLayout &DL, Type *ArgTy, Align Alignment, StringRef ArgName,
+    unsigned &Offset, msgpack::ArrayDocNode Args,
+    KernArgPreload::HiddenArg HiddenArg, const AMDGPUFunctionArgInfo *ArgInfo) {
+  assert(ArgInfo && HiddenArg != KernArgPreload::END_HIDDEN_ARGS);
+
+  SmallString<32> PreloadStr;
+  const KernArgPreload::KernArgPreloadDescriptor *PreloadDesc =
+      ArgInfo->getHiddenArgPreloadDescriptor(HiddenArg);
+  if (PreloadDesc) {
+    const SmallVectorImpl<MCRegister> &Regs = PreloadDesc->Regs;
+    for (const auto &Reg : Regs) {
----------------
arsenm wrote:

```suggestion
    for (MCRegister Reg : Regs) {
```

https://github.com/llvm/llvm-project/pull/134666