Re: [PATCH v2 1/4] scripts/tracetool: Fix dtrace generation for macOS

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 7/17/20 11:35 AM, Roman Bolshakov wrote:
> dtrace USDT is fully supported since OS X 10.6. There are a few
> peculiarities compared to other dtrace flavors.
> 
> 1. It doesn't accept empty files.
> 2. It doesn't recognize bool type but accepts C99 _Bool.
> 3. It converts int8_t * in probe points to char * in
>    header files and introduces [-Wpointer-sign] warning.
> 
> Cc: Cameron Esfahani <dirty@apple.com>
> Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
> ---
>  scripts/tracetool/format/d.py | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/tracetool/format/d.py b/scripts/tracetool/format/d.py
> index 0afb5f3f47..353722f89c 100644
> --- a/scripts/tracetool/format/d.py
> +++ b/scripts/tracetool/format/d.py
> @@ -13,6 +13,7 @@ __email__      = "stefanha@redhat.com"
>  
>  
>  from tracetool import out
> +from sys import platform
>  
>  
>  # Reserved keywords from
> @@ -34,7 +35,8 @@ def generate(events, backend, group):
>  
>      # SystemTap's dtrace(1) warns about empty "provider qemu {}" but is happy
>      # with an empty file.  Avoid the warning.
> -    if not events:
> +    # But dtrace on macOS can't deal with empty files.
> +    if not events and platform != "darwin":

or?

>          return
>  
>      out('/* This file is autogenerated by tracetool, do not edit. */'
> @@ -44,6 +46,17 @@ def generate(events, backend, group):
>      for e in events:
>          args = []
>          for type_, name in e.args:
> +            if platform == "darwin":
> +                # macOS dtrace accepts only C99 _Bool

Why not do that for all platforms?

> +                if type_ == 'bool':
> +                    type_ = '_Bool'
> +                if type_ == 'bool *':
> +                    type_ = '_Bool *'
> +                # It converts int8_t * in probe points to char * in header
> +                # files and introduces [-Wpointer-sign] warning.
> +                # Avoid it by changing probe type to signed char * beforehand.
> +                if type_ == 'int8_t *':
> +                    type_ = 'signed char *'
>              if name in RESERVED_WORDS:
>                  name += '_'
>              args.append(type_ + ' ' + name)
>