[llvm] [llvm][DebugInfo] Add support for DW_OP_GNU_implicit_pointer (PR #142913)

[Chenguang Wang via llvm-commits]

wecing wrote:

Note that

```
llvm-project/lldb/source/Expression/DWARFExpression.cpp:134:11: error: enumeration value 'DW_OP_GNU_implicit_pointer' not handled in switch [-Werror,-Wswitch]
  134 |   switch (op) {
```

https://github.com/llvm/llvm-project/pull/142913