[llvm] [BPF] Handle nested wrapper structs in BPF map definition traversal (PR #144097)

[via llvm-commits]

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@@ -0,0 +1,606 @@
+; RUN: llc -mtriple=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK-SHORT %s
+; RUN: llc -mtriple=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+
+; Source code:
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eddyz87 wrote:

Could you please try to minimize your test case?
As far as I understand, the intended use case looks as follows in C:

```c
$ cat test_struct_dbg.c
struct foo { int i; };
struct bar { int j; };
struct key { struct foo *f; };
struct vak { struct bar *b; };

#define __uint(name, val) int (*name)[val]
#define __type(name, val) typeof(val) *name

struct {
        __uint(type, 1);
        __uint(max_entries, 1);
        __type(key, struct key);
        __type(value, struct val);
} map __attribute__((section(".maps")));
```

And it generates a much smaller amount of IR:

``` bash                                                                                                                                                                                                                 
$ clang -g -emit-llvm -S test_struct_dbg.c -o - | wc -l
47
```

https://github.com/llvm/llvm-project/pull/144097