[PATCH] D39331: Add flags to control the -finstrument-functions instrumentation calls to __cyg_profile functions

[Hans Wennborg via Phabricator via cfe-commits]

hans added inline comments.


================
Comment at: include/clang/Driver/Options.td:1032
+def fno_instrument_functions_inline : Flag<["-"], "fno-instrument-functions-inline">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"When using -finstrument-functions, insert the calls after inlining">;
 
----------------
rnk wrote:
> This actually describes GCC's behavior for `-finstrument-functions`. I suspect the current behavior is pretty useless for most people. I'd rather make the new behavior the default and add a flag to request the old behavior.
At least with the GCC I tried, they do insert the calls before inlining, and inline them:

```
$ echo 'static void f() {} void g() { f(); }' | gcc -x c -O3 -finstrument-functions -S -o - - | grep -A50 g:
g:
.LFB1:
        .cfi_startproc
        subq    $8, %rsp
        .cfi_def_cfa_offset 16
        movl    $g, %edi
        movq    8(%rsp), %rsi
        call    __cyg_profile_func_enter
        movq    8(%rsp), %rsi
        movl    $f, %edi
        call    __cyg_profile_func_enter
        movq    8(%rsp), %rsi
        movl    $f, %edi
        call    __cyg_profile_func_exit
        movq    8(%rsp), %rsi
        movl    $g, %edi
        addq    $8, %rsp
        .cfi_def_cfa_offset 8
        jmp     __cyg_profile_func_exit
        .cfi_endproc
```


https://reviews.llvm.org/D39331