| Issue |
151185
|
| Summary |
Inlined subroutine should own its call site entries, not the parent subprogram
|
| Labels |
debuginfo
|
| Assignees |
|
| Reporter |
jryans
|
When the following source is compiled...
```c
#include <stdio.h>
struct config_source {
FILE *file;
};
int config_file_fgetc(struct config_source *conf) {
return getc_unlocked(conf->file);
}
```
...`getc_unlocked` (from system headers) is inlined into `config_file_fgetc`, and a call site entry is added for a call to `__uflow` that happens inside `getc_unlocked`:
```
0x000001fa: DW_TAG_call_site
DW_AT_call_origin (0x00000201 "__uflow")
DW_AT_call_tail_call (true)
DW_AT_call_pc (0x000000000000000b)
```
With Clang, the call site entry is a child of the subprogram DIE for `config_file_fgetc`, while GCC adds the call site entry as a child of the inlined subroutine DIE for `getc_unlocked` (where the call occurs).
The DWARF 5 spec says (sec. 3.4.1):
> A call site is represented by a debugging information entry with the tag `DW_TAG_call_site`. The entry for a call site is owned by the innermost debugging information entry representing the scope within which the call is present in the source program.
The spec text suggests to me that the GCC interpretation is correct (call site entry inside inlined subroutine DIE where call occurred), and Clang / LLVM should be changed to match. The GCC approach also conveys slightly more information, since it is obvious who the caller is, whereas with Clang variant, it could be the subprogram or any inlined subroutine within it.
Example [available](https://godbolt.org/z/zxdhcn38e) on Compiler Explorer
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