[Bug tree-optimization/95565] New: [Feature request] add a flag to only instrument function entry.

[Bug tree-optimization/95565] New: [Feature request] add a flag to only instrument function entry.

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95565

            Bug ID: 95565
           Summary: [Feature request] add a flag to only instrument
                    function entry.
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hiraditya at msn dot com
  Target Milestone: ---

The flag -finstrument-functions instruments both entry and the exit of
function. There are many scenarios (like cheap profiling) only instrumenting
the function entry is sufficient. But gcc instruments exit as well contributing
to unwanted code size increase.

[Bug tree-optimization/95565] [Feature request] add a flag to only instrument function entry.

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95565

--- Comment #1 from AK <hiraditya at msn dot com> ---
I believe we need to conditionally disable the following code, but I'm not sure
of all the implications. If someone can implement it that'd be great.

```
gcc/gimplify.c   Around Line:14997

      x = builtin_decl_implicit (BUILT_IN_RETURN_ADDRESS);
      call = gimple_build_call (x, 1, integer_zero_node);
      tmp_var = create_tmp_var (ptr_type_node, "return_addr");
      gimple_call_set_lhs (call, tmp_var);
      gimplify_seq_add_stmt (&cleanup, call);
      x = builtin_decl_implicit (BUILT_IN_PROFILE_FUNC_EXIT);
      call = gimple_build_call (x, 2, this_fn_addr, tmp_var);
      gimplify_seq_add_stmt (&cleanup, call);
      tf = gimple_build_try (seq, cleanup, GIMPLE_TRY_FINALLY);


```

[Bug tree-optimization/95565] [Feature request] add a flag to only instrument function entry.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95565

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

[Bug tree-optimization/95565] [Feature request] add a flag to only instrument function entry.

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95565

--- Comment #2 from AK <hiraditya at msn dot com> ---
clang has `-finstrument-function-entry-bare` to this effect: 
https://reviews.llvm.org/D40276