Re: [dpdk-dev] [PATCH v6 9/9] build: generate version.map file for MingW on Windows

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

On Fri, 19 Jun 2020 00:15:46 +0300
talshn@mellanox.com wrote:

> From: Tal Shnaiderman <talshn@mellanox.com>
> 
> The MingW build for Windows has special cases where exported
> function contain additional prefix:
> 
> __emutls_v.per_lcore__*
> 
> To avoid adding those prefixed functions to the version.map file
> the map_to_def.py script was modified to create a map file for Mingw
> with the needed changed.

Thanks for working on this. Your solution is even simpler than we discussed,
see some comments inline.

> 
> The file name was changed to map_to_win.py
> 
> Signed-off-by: Tal Shnaiderman <talshn@mellanox.com>
> ---
>  buildtools/{map_to_def.py => map_to_win.py} | 21 ++++++++++++++++-----
>  buildtools/meson.build                      |  4 ++--
>  drivers/meson.build                         | 12 +++++++++---
>  lib/meson.build                             | 15 ++++++++++++---
>  4 files changed, 39 insertions(+), 13 deletions(-)
>  rename buildtools/{map_to_def.py => map_to_win.py} (51%)
> 
> diff --git a/buildtools/map_to_def.py b/buildtools/map_to_win.py
> similarity index 51%
> rename from buildtools/map_to_def.py
> rename to buildtools/map_to_win.py
> index 6775b54a9d..dfb0748159 100644
> --- a/buildtools/map_to_def.py
> +++ b/buildtools/map_to_win.py
> @@ -13,23 +13,34 @@ def is_function_line(ln):
>  
>  def main(args):
>      if not args[1].endswith('version.map') or \
> -            not args[2].endswith('exports.def'):
> +            not args[2].endswith('exports.def') and \
> +            not args[2].endswith('mingw.map'):
>          return 1
>  
>  # special case, allow override if an def file already exists alongside map file
> +# for mingw also replace per_lcore__* to __emutls_v.per_lcore__*
>      override_file = join(dirname(args[1]), basename(args[2]))
>      if exists(override_file):
>          with open(override_file) as f_in:
> -            functions = f_in.readlines()
> +            lines = f_in.readlines()
> +            if args[2].endswith('mingw.map'):
> +                lines = [l.replace('per_lcore__', '__emutls_v.per_lcore__') for l in lines]
> +            functions = lines

MinGW GCC linker doesn't fail on undefined symbols, so .map overrides will
never be needed (and we're going to get rid of overrides soon anyway).

>  
>  # generate def file from map file.
> -# This works taking indented lines only which end with a ";" and which don't
> +# For clang this works taking indented lines only which end with a ";" and which don't
>  # have a colon in them, i.e. the lines defining functions only.
> +# mingw keeps the original .map file but replaces per_lcore__* to __emutls_v.per_lcore__*
>      else:
>          with open(args[1]) as f_in:
> -            functions = [ln[:-2] + '\n' for ln in sorted(f_in.readlines())
> +            lines = f_in.readlines()
> +            if args[2].endswith('mingw.map'):
> +                lines = [l.replace('per_lcore__', '__emutls_v.per_lcore__') for l in lines]
> +                functions = lines
> +            else:
> +                functions = [ln[:-2] + '\n' for ln in sorted(lines)
>                           if is_function_line(ln)]
> -            functions = ["EXPORTS\n"] + functions
> +                functions = ["EXPORTS\n"] + functions

Considering the comment above, entire logic for mingw.map is the following:

if args[2].endswith('mingw.map'):
    with open(args[1]) as f_in, open(args[2], 'w') as f_out:
	f_out.writelines([...replace... for line in f_in.readlines()])
    return 0

Wouldn't it be cleaner to move it to the beginning of function or even to a
separate function dispatched by filename (or even script)? Motivation: soon
.def logic will become more complicated and Windows-dependent (to analyze
dumpbin.exe output), intertwining it with .map saves nothing and will impede.

-- 
Dmitry Kozlyuk