Inline Functions (Debugging with ROCGDB)

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### 11.1 Inline Functions

Inlining is an optimization that inserts a copy of the function body directly at each call site, instead of jumping to a shared routine. ROCGDB displays inlined functions just like non-inlined functions. They appear in backtraces. You can view their arguments and local variables, step into them with `step`, skip them with `next`, and escape from them with `finish`. You can check whether a function was inlined by using the `info frame` command.

For ROCGDB to support inlined functions, the compiler must record information about inlining in the debug information — GCC using the DWARF 2 format does this, and several other compilers do also. ROCGDB only supports inlined functions when using DWARF 2. Versions of GCC before 4.1 do not emit two required attributes (‘`DW_AT_call_file`’ and ‘`DW_AT_call_line`’); ROCGDB does not display inlined function calls with earlier versions of GCC. It instead displays the arguments and local variables of inlined functions as local variables in the caller.

The body of an inlined function is directly included at its call site; unlike a non-inlined function, there are no instructions devoted to the call. ROCGDB still pretends that the call site and the start of the inlined function are different instructions. Stepping to the call site shows the call site, and then stepping again shows the first line of the inlined function, even though no additional instructions are executed.

This makes source-level debugging much clearer; you can see both the context of the call and then the effect of the call. Only stepping by a single instruction using `stepi` or `nexti` does not do this; single instruction steps always show the inlined body.

There are some ways that ROCGDB does not pretend that inlined function calls are the same as normal calls:

- Setting breakpoints at the call site of an inlined function may not work, because the call site does not contain any code. ROCGDB may incorrectly move the breakpoint to the next line of the enclosing function, after the call. This limitation will be removed in a future version of ROCGDB; until then, set a breakpoint on an earlier line or inside the inlined function instead.
- ROCGDB cannot locate the return value of inlined calls after using the `finish` command. This is a limitation of compiler-generated debugging information; after `finish`, you can step to the next line and print a variable where your program stored the return value.

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