Re: [PATCH v2 02/13] aarch64: The aarch64-w64-mingw32 target implements

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

Sorry for the slow reply.

Evgeny Karpov <Evgeny.Karpov@microsoft.com> writes:
> From: Zac Walker <zacwalker@microsoft.com>
> Date: Fri, 1 Mar 2024 01:45:13 +0100
> Subject: [PATCH v2 02/13] aarch64: The aarch64-w64-mingw32 target implements
>  the MS ABI
>
> Two ABIs for aarch64 have been defined for different platforms.
>
> gcc/ChangeLog:
>
> 	* config/aarch64/aarch64-opts.h (enum aarch64_calling_abi):
> 	Define two ABIs.
> ---
>  gcc/config/aarch64/aarch64-opts.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/gcc/config/aarch64/aarch64-opts.h b/gcc/config/aarch64/aarch64-opts.h
> index a05c0d3ded1..52c9e4596d6 100644
> --- a/gcc/config/aarch64/aarch64-opts.h
> +++ b/gcc/config/aarch64/aarch64-opts.h
> @@ -131,4 +131,11 @@ enum aarch64_early_ra_scope {
>    AARCH64_EARLY_RA_NONE
>  };
>  
> +/* Available call ABIs.  */
> +enum aarch64_calling_abi
> +{
> +  AARCH64_CALLING_ABI_EABI,
> +  AARCH64_CALLING_ABI_MS
> +};
> +
>  #endif

Thanks for removing the MS_ABI uses.  However, I'm still a bit uneasy
about this.  We already have a way of categorising ABIs (arm_pcs)
and it's not clear how this new enum would interact with it.  We also
have infrastructure for recording the arm_pcs for each call, including
in RTL insns.  Would we need to do the same for this classification?

It seems like the enum is currently unused.  At least, I was able
to build successfully with:

diff --git a/gcc/config/aarch64/aarch64-opts.h b/gcc/config/aarch64/aarch64-opts.h
index 52c9e4596d6..a05c0d3ded1 100644
--- a/gcc/config/aarch64/aarch64-opts.h
+++ b/gcc/config/aarch64/aarch64-opts.h
@@ -131,11 +131,4 @@ enum aarch64_early_ra_scope {
   AARCH64_EARLY_RA_NONE
 };
 
-/* Available call ABIs.  */
-enum aarch64_calling_abi
-{
-  AARCH64_CALLING_ABI_EABI,
-  AARCH64_CALLING_ABI_MS
-};
-
 #endif
diff --git a/gcc/config/aarch64/cygming.h b/gcc/config/aarch64/cygming.h
index 2f239c42a89..902539763bd 100644
--- a/gcc/config/aarch64/cygming.h
+++ b/gcc/config/aarch64/cygming.h
@@ -43,9 +43,6 @@ still needed for compilation.  */
 #define GENERAL_REGNO_P(N) 0
 #define SEH_MAX_FRAME_SIZE 0
 
-#undef DEFAULT_ABI
-#define DEFAULT_ABI AARCH64_CALLING_ABI_MS
-
 #undef TARGET_PECOFF
 #define TARGET_PECOFF 1
 
diff --git a/gcc/config/mingw/mingw32.h b/gcc/config/mingw/mingw32.h
index 040c3e1e521..08f1b5f0696 100644
--- a/gcc/config/mingw/mingw32.h
+++ b/gcc/config/mingw/mingw32.h
@@ -19,9 +19,7 @@ along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
 #undef DEFAULT_ABI
-#if defined (TARGET_AARCH64_MS_ABI)
-# define DEFAULT_ABI AARCH64_CALLING_ABI_MS
-#else
+#if !defined (TARGET_AARCH64_MS_ABI)
 # define DEFAULT_ABI MS_ABI
 #endif
 
Would you be happy with that for now?  We can then revisit this
later when the information is needed.

Thanks,
Richard