introduce --enable-mingw-full32 to default to --large-address-aware

[JonY]

On 10/31/2018 10:39 PM, Alexandre Oliva wrote:
> On Oct 12, 2018, Alexandre Oliva <oliva@adacore.com> wrote:
> 
>> 	* config/i386/mingw32.h (LINK_SPEC_LARGE_ADDR_AWARE): Define,
>> 	based on MINGW_DEFAULT_LARGE_ADDR_AWARE.
>> 	(LINK_SPEC): Insert it.
>> 	* config/i386/mingw-264.h: Likewise.
>                             ^ s/2/w/, fixing...
> 
> Now, it occurred to me that it is possible for biarch64.h to be
> included, thus enabling 64-bit mode even by default, without including
> mingw-w64.h.  I had assumed in my patch that this was not supposed to
> happen, but configuring with --target=x86_64-mingw32 shows it does
> happen, and such a toolchain may (after my patch) pass
> --large-address-aware to the linker, even when linking -m64 binaries.
> 
> Is that target configuration really supposed to be different from
> x86_64-w64-mingw32 (or however else the w64 configuration is supposed to
> be spelled), or should x86_64-mingw32 also use mingw-w64.h so that
> they're equivalent?
> 
> It seems to me that we need a further patch like this:
> 
> diff --git a/gcc/config/i386/mingw32.h b/gcc/config/i386/mingw32.h
> index c9d8a7a31f30..848eb8430b30 100644
> --- a/gcc/config/i386/mingw32.h
> +++ b/gcc/config/i386/mingw32.h
> @@ -114,11 +114,17 @@ along with GCC; see the file COPYING3.  If not see
>  #define SUBTARGET_EXTRA_SPECS						\
>    { "shared_libgcc_undefs", SHARED_LIBGCC_UNDEFS_SPEC }
>  
> -#if MINGW_DEFAULT_LARGE_ADDR_AWARE
> +#if ! MINGW_DEFAULT_LARGE_ADDR_AWARE
> +# define LINK_SPEC_LARGE_ADDR_AWARE ""
> +#elif ! TARGET_BI_ARCH
>  # define LINK_SPEC_LARGE_ADDR_AWARE \
>    "%{!shared:%{!mdll:--large-address-aware}}"
> +#elif TARGET_64BIT_DEFAULT
> +# define LINK_SPEC_LARGE_ADDR_AWARE \
> +  "%{!shared:%{!mdll:%{m32:--large-address-aware}}}"
>  #else
> -# define LINK_SPEC_LARGE_ADDR_AWARE ""
> +# define LINK_SPEC_LARGE_ADDR_AWARE \
> +  "%{!shared:%{!mdll:%{!m64:--large-address-aware}}}"
>  #endif
>  
>  #define LINK_SPEC "%{mwindows:--subsystem windows} \
> 
> But then, even this wouldn't necessarily do the right thing if e.g.
> biarchx32.h is in effect.  Is that even possible?
> 
> Or can we just leave mingw32.h as is, considering that (AFAIK) -m64 *is*
> --large-address-aware, it just has that enabled by default?
> 

Looks like it causes an error on 64bit:
/usr/libexec/gcc/x86_64-w64-mingw32/ld: unrecognized option
'--large-address-aware'

So it'll need to be excluded for x86_64.

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