Re: [PATCH v1 5/6] Adjust DLL import/export implementation for AArch64

[Richard Sandiford <richard.sandiford@arm.com>]

Evgeny Karpov <Evgeny.Karpov@microsoft.com> writes:
> The DLL import/export mingw implementation, originally from ix86, requires
> minor adjustments to be compatible with AArch64.
>
> gcc/ChangeLog:
>
> 	* config/mingw/mingw32.h (defined): Use the correct DllMainCRTStartup
> 	entry function.
> 	* config/mingw/winnt-dll.cc (defined): Exclude ix86-related code.
> ---
>  gcc/config/mingw/mingw32.h    | 2 +-
>  gcc/config/mingw/winnt-dll.cc | 4 ++++
>  2 files changed, 5 insertions(+), 1 deletion(-)

Could we provide some abstractions here, rather than testing
CPU-specific macros directly?  E.g.:

>
> diff --git a/gcc/config/mingw/mingw32.h b/gcc/config/mingw/mingw32.h
> index 08f1b5f0696..efe777051b4 100644
> --- a/gcc/config/mingw/mingw32.h
> +++ b/gcc/config/mingw/mingw32.h
> @@ -79,7 +79,7 @@ along with GCC; see the file COPYING3.  If not see
>  #endif
>  
>  #undef SUB_LINK_ENTRY
> -#if TARGET_64BIT_DEFAULT
> +#if TARGET_64BIT_DEFAULT || defined (TARGET_AARCH64_MS_ABI)

it looks like this is equivalent to something like "HAVE_64BIT_POINTERS"
or something, which aarch64 could define to 1 and x86 could define
to TARGET_64BIT_DEFAULT.

The name is just a suggestion, based on not really knowing what the
macro selects.  Please use whatever makes most sense :)

>  #define SUB_LINK_ENTRY SUB_LINK_ENTRY64
>  #else
>  #define SUB_LINK_ENTRY SUB_LINK_ENTRY32
> diff --git a/gcc/config/mingw/winnt-dll.cc b/gcc/config/mingw/winnt-dll.cc
> index 349ade6f5c0..294361fab4c 100644
> --- a/gcc/config/mingw/winnt-dll.cc
> +++ b/gcc/config/mingw/winnt-dll.cc
> @@ -206,9 +206,13 @@ legitimize_pe_coff_symbol (rtx addr, bool inreg)
>  	}
>      }
>  
> +#if !defined (TARGET_AARCH64_MS_ABI)
> +
>    if (ix86_cmodel != CM_LARGE_PIC && ix86_cmodel != CM_MEDIUM_PIC)
>      return NULL_RTX;
>  
> +#endif
> +

Similarly here, it feels like there is a concept underlying this check.
Could we just use:

  if (!NEW_MACRO)
    return NULL_RTX;

with NEW_MACRO describing the underlying property that is common to
medium x86 PIC, large x86 PIC, and aarch64.

Thanks,
Richard

>    if (GET_CODE (addr) == SYMBOL_REF
>        && !is_imported_p (addr)
>        && SYMBOL_REF_EXTERNAL_P (addr)