diff mbox series

x86: Honor preserve_none ABI for x86-64 MS calls

Message ID CAMe9rOrUyoDVm2_vpSA=G0ZNW-K_eYZ8vAEgd3qqphMEjzaTmg@mail.gmail.com
State New
Headers
Series x86: Honor preserve_none ABI for x86-64 MS calls |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_simplebootstrap_build--master-arm-bootstrap pending Patch applied
linaro-tcwg-bot/tcwg_simplebootstrap_build--master-aarch64-bootstrap pending Patch applied

Commit Message

H.J. Lu July 8, 2026, 6:01 a.m. UTC 
  In 64-bit mode, preserve_none attribute uses a different calling
convention.  Ignore MS ABI with preserve_none attribute to always
use the preserve_none calling convention with preserve_none
attribute.

gcc/

PR target/125297
* config/i386/i386.cc (ix86_function_arg_regno_p): Use
x86_64_preserve_none_int_parameter_registers for
TYPE_PRESERVE_NONE.
(ix86_function_type_abi): In 64-bit mode, ignore ms_abi
attribute with preserve_none attribute.
(x86_64_cumulative_ms_abi_p): New function.
(init_cumulative_args): Call x86_64_cumulative_ms_abi_p to
decide if MS_ABI is used.
(ix86_function_arg_advance): Likewise.
(ix86_function_arg): Likewise.

gcc/testsuite/

PR target/125297
* gcc.target/i386/preserve-none-31a.c: New test.
* gcc.target/i386/preserve-none-31b.c: Likewise.
* gcc.target/i386/preserve-none-32a.c: Likewise.
* gcc.target/i386/preserve-none-32b.c: Likewise.
* gcc.target/i386/preserve-none-33a.c: Likewise.
* gcc.target/i386/preserve-none-33b.c: Likewise.
* gcc.target/i386/preserve-none-34a.c: Likewise.
* gcc.target/i386/preserve-none-34b.c: Likewise.

Comments

Hongtao Liu July 8, 2026, 8:58 a.m. UTC | #1 
On Wed, Jul 8, 2026 at 2:03 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> In 64-bit mode, preserve_none attribute uses a different calling
> convention.  Ignore MS ABI with preserve_none attribute to always
> use the preserve_none calling convention with preserve_none
> attribute.
>

1) gcc/config/i386/i386.cc:4802 still uses cum->call_abi == MS_ABI for
incoming varargs. x86_64_cumulative_ms_abi_p should also be used
there?

4802  if (cum->call_abi == MS_ABI)
4803    setup_incoming_varargs_ms_64 (&next_cum);
4804  else
4805    setup_incoming_varargs_64 (&next_cum);
4806}

2) gcc/config/i386/i386.cc:3644 has the same raw MS ABI test in
ix86_pass_by_reference?

3634static bool
3635ix86_pass_by_reference (cumulative_args_t cum_v, const
function_arg_info &arg)
3636{
3637  CUMULATIVE_ARGS *cum = get_cumulative_args (cum_v);
3638
3639  if (TARGET_64BIT)
3640    {
3641      enum calling_abi call_abi = cum ? cum->call_abi : ix86_abi;
3642
3643      /* See Windows x64 Software Convention.  */
3644      if (call_abi == MS_ABI)
3645        {
3646          HOST_WIDE_INT msize = GET_MODE_SIZE (arg.mode);
3647

One question, under MS_ABI use 4 registers for parameter passing,
SYSV_ABI use 8, under preserve_none, should we also use 8 registers
for parameter passing for MS_ABI?
H.J. Lu July 9, 2026, 1:44 a.m. UTC | #2 
On Wed, Jul 8, 2026 at 4:37 PM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Wed, Jul 8, 2026 at 2:03 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > In 64-bit mode, preserve_none attribute uses a different calling
> > convention.  Ignore MS ABI with preserve_none attribute to always
> > use the preserve_none calling convention with preserve_none
> > attribute.
> >
>
> 1) gcc/config/i386/i386.cc:4802 still uses cum->call_abi == MS_ABI for
> incoming varargs. x86_64_cumulative_ms_abi_p should also be used
> there?
>
> 4802  if (cum->call_abi == MS_ABI)
> 4803    setup_incoming_varargs_ms_64 (&next_cum);
> 4804  else
> 4805    setup_incoming_varargs_64 (&next_cum);
> 4806}

Fixed in the v2 patch with tests

> 2) gcc/config/i386/i386.cc:3644 has the same raw MS ABI test in
> ix86_pass_by_reference?

Fixed in the v2 patch with tests.

> 3634static bool
> 3635ix86_pass_by_reference (cumulative_args_t cum_v, const
> function_arg_info &arg)
> 3636{
> 3637  CUMULATIVE_ARGS *cum = get_cumulative_args (cum_v);
> 3638
> 3639  if (TARGET_64BIT)
> 3640    {
> 3641      enum calling_abi call_abi = cum ? cum->call_abi : ix86_abi;
> 3642
> 3643      /* See Windows x64 Software Convention.  */
> 3644      if (call_abi == MS_ABI)
> 3645        {
> 3646          HOST_WIDE_INT msize = GET_MODE_SIZE (arg.mode);
> 3647
>
> One question, under MS_ABI use 4 registers for parameter passing,
> SYSV_ABI use 8, under preserve_none, should we also use 8 registers
> for parameter passing for MS_ABI?
>

It has 8 registers.   Tests show that
x86_64_preserve_none_int_parameter_registers
is used for functions with __attribute__ ((preserve_none, ms_abi)).

--
H.J.
diff mbox series

Patch

From 930551bb624e397594d2d59e1f82bfc86caebd22 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 13 May 2026 08:27:50 +0800
Subject: [PATCH] x86: Honor preserve_none ABI for x86-64 MS calls

In 64-bit mode, preserve_none attribute uses a different calling
convention.  Ignore MS ABI with preserve_none attribute to always
use the preserve_none calling convention with preserve_none
attribute.

gcc/

	PR target/125297
	* config/i386/i386.cc (ix86_function_arg_regno_p): Use
	x86_64_preserve_none_int_parameter_registers for
	TYPE_PRESERVE_NONE.
	(ix86_function_type_abi): In 64-bit mode, ignore ms_abi
	attribute with preserve_none attribute.
	(x86_64_cumulative_ms_abi_p): New function.
	(init_cumulative_args): Call x86_64_cumulative_ms_abi_p to
	decide if MS_ABI is used.
	(ix86_function_arg_advance): Likewise.
	(ix86_function_arg): Likewise.

gcc/testsuite/

	PR target/125297
	* gcc.target/i386/preserve-none-31a.c: New test.
	* gcc.target/i386/preserve-none-31b.c: Likewise.
	* gcc.target/i386/preserve-none-32a.c: Likewise.
	* gcc.target/i386/preserve-none-32b.c: Likewise.
	* gcc.target/i386/preserve-none-33a.c: Likewise.
	* gcc.target/i386/preserve-none-33b.c: Likewise.
	* gcc.target/i386/preserve-none-34a.c: Likewise.
	* gcc.target/i386/preserve-none-34b.c: Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 gcc/config/i386/i386.cc                       | 38 +++++++++++++------
 .../gcc.target/i386/preserve-none-31a.c       | 36 ++++++++++++++++++
 .../gcc.target/i386/preserve-none-31b.c       | 25 ++++++++++++
 .../gcc.target/i386/preserve-none-32a.c       | 29 ++++++++++++++
 .../gcc.target/i386/preserve-none-32b.c       | 18 +++++++++
 .../gcc.target/i386/preserve-none-33a.c       | 36 ++++++++++++++++++
 .../gcc.target/i386/preserve-none-33b.c       | 25 ++++++++++++
 .../gcc.target/i386/preserve-none-34a.c       | 29 ++++++++++++++
 .../gcc.target/i386/preserve-none-34b.c       | 18 +++++++++
 9 files changed, 243 insertions(+), 11 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-31a.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-31b.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-32a.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-32b.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-33a.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-33b.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-34a.c
 create mode 100644 gcc/testsuite/gcc.target/i386/preserve-none-34b.c

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 23f65ab401d..ff9428ddcff 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -1591,16 +1591,19 @@  ix86_function_arg_regno_p (int regno)
   if (call_abi == SYSV_ABI && regno == AX_REG)
     return true;
 
+  int regparm_max = X86_64_REGPARM_MAX;
   if (cfun
       && cfun->machine->call_saved_registers == TYPE_PRESERVE_NONE)
     parm_regs = x86_64_preserve_none_int_parameter_registers;
   else if (call_abi == MS_ABI)
-    parm_regs = x86_64_ms_abi_int_parameter_registers;
+    {
+      parm_regs = x86_64_ms_abi_int_parameter_registers;
+      regparm_max = X86_64_MS_REGPARM_MAX;
+    }
   else
     parm_regs = x86_64_int_parameter_registers;
 
-  for (i = 0; i < (call_abi == MS_ABI
-		   ? X86_64_MS_REGPARM_MAX : X86_64_REGPARM_MAX); i++)
+  for (i = 0; i < regparm_max; i++)
     if (regno == parm_regs[i])
       return true;
   return false;
@@ -1665,7 +1668,11 @@  ix86_function_type_abi (const_tree fntype)
 	  warned = 1;
 	}
 
-      abi = MS_ABI;
+      /* NB: preserve_none attribute overrides ms_abi in 64-bit mode.  */
+      if (!TARGET_64BIT
+	  || !lookup_attribute ("preserve_none",
+				TYPE_ATTRIBUTES (fntype)))
+	abi = MS_ABI;
     }
   else if (abi == MS_ABI
 	   && lookup_attribute ("sysv_abi", TYPE_ATTRIBUTES (fntype)))
@@ -1856,6 +1863,17 @@  ix86_init_pic_reg (void)
   commit_one_edge_insertion (entry_edge);
 }
 
+/* Return true if x86-64 CUM is MS_ABI.  */
+
+static bool
+x86_64_cumulative_ms_abi_p (CUMULATIVE_ARGS *cum)
+{
+  if (!cum)
+    return ix86_abi == MS_ABI;
+
+  return !cum->preserve_none_abi && cum->call_abi == MS_ABI;
+}
+
 /* Initialize a variable CUM of type CUMULATIVE_ARGS
    for a call to a function whose data type is FNTYPE.
    For a library call, FNTYPE is 0.  */
@@ -1910,9 +1928,9 @@  init_cumulative_args (CUMULATIVE_ARGS *cum,  /* Argument info to initialize */
   cum->nregs = ix86_regparm;
   if (TARGET_64BIT)
     {
-      cum->nregs = (cum->call_abi == SYSV_ABI
-                   ? X86_64_REGPARM_MAX
-                   : X86_64_MS_REGPARM_MAX);
+      cum->nregs = (x86_64_cumulative_ms_abi_p (cum)
+		    ? X86_64_MS_REGPARM_MAX
+		    : X86_64_REGPARM_MAX);
     }
   if (TARGET_SSE)
     {
@@ -3262,9 +3280,7 @@  ix86_function_arg_advance (cumulative_args_t cum_v,
 
   if (TARGET_64BIT)
     {
-      enum calling_abi call_abi = cum ? cum->call_abi : ix86_abi;
-
-      if (call_abi == MS_ABI)
+      if (x86_64_cumulative_ms_abi_p (cum))
 	nregs = function_arg_advance_ms_64 (cum, bytes, words);
       else
 	nregs = function_arg_advance_64 (cum, mode, arg.type, words,
@@ -3593,7 +3609,7 @@  ix86_function_arg (cumulative_args_t cum_v, const function_arg_info &arg)
 
   if (TARGET_64BIT)
     {
-      if (cum->call_abi == MS_ABI)
+      if (x86_64_cumulative_ms_abi_p (cum))
 	reg = function_arg_ms_64 (cum, mode, arg.mode, arg.named,
 				  arg.type, bytes);
       else
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-31a.c b/gcc/testsuite/gcc.target/i386/preserve-none-31a.c
new file mode 100644
index 00000000000..b24499cfb8f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-31a.c
@@ -0,0 +1,36 @@ 
+/* { dg-do compile { target { lp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.cfi_startproc', '.cfi_endproc').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.}  } } */
+
+/*
+**entry:
+**.LFB[0-9]+:
+**	.cfi_startproc
+**	subq	\$72, %rsp
+**...
+**	movl	%ecx, %r12d
+**	movl	%edx, %r13d
+**	movl	%r9d, %r15d
+**	movl	120\(%rsp\), %esi
+**	movl	112\(%rsp\), %edi
+**	movl	%r8d, %r14d
+**	xorl	%eax, %eax
+**	movl	\$-559038737, 48\(%rsp\)
+**	call	continuation
+**	addq	\$72, %rsp
+**...
+**	ret
+**	.cfi_endproc
+**...
+*/
+
+extern void continuation (int, int, int, int, int, int, ...)
+  __attribute__ ((preserve_none));
+
+__attribute__ ((no_callee_saved_registers))
+void
+entry (int arg1, int arg2, int arg3, int arg4, int arg5, int arg6)
+{
+  continuation (arg1, arg2, arg3, arg4, arg5, arg6, 0xdeadbeef);
+}
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-31b.c b/gcc/testsuite/gcc.target/i386/preserve-none-31b.c
new file mode 100644
index 00000000000..9b6ad95c36f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-31b.c
@@ -0,0 +1,25 @@ 
+/* { dg-do compile { target { llp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.seh_endprologue').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.} } } */
+
+/*
+**entry:
+**	subq	\$72, %rsp
+**	.seh_stackalloc	72
+**	.seh_endprologue
+**	xorl	%eax, %eax
+**	movl	120\(%rsp\), %esi
+**	movl	112\(%rsp\), %edi
+**	movl	%ecx, %r12d
+**	movl	%edx, %r13d
+**	movl	%r9d, %r15d
+**	movl	%r8d, %r14d
+**	movl	\$-559038737, 48\(%rsp\)
+**	call	continuation
+**	nop
+**	addq	\$72, %rsp
+**	ret
+*/
+
+#include "preserve-none-31a.c"
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-32a.c b/gcc/testsuite/gcc.target/i386/preserve-none-32a.c
new file mode 100644
index 00000000000..1928491a4f2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-32a.c
@@ -0,0 +1,29 @@ 
+/* { dg-do compile { target { lp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.cfi_startproc', '.cfi_endproc').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.}  } } */
+
+/*
+**entry:
+**.LFB[0-9]+:
+**	.cfi_startproc
+**	movl	56\(%rsp\), %esi
+**	movl	48\(%rsp\), %edi
+**	movl	%edx, %r12d
+**	movl	%r9d, %r14d
+**	movl	40\(%rsp\), %r15d
+**	movl	%r8d, %r13d
+**	jmp	continuation
+**	.cfi_endproc
+**...
+*/
+
+extern void continuation (double, int, int, int, int, int, int)
+  __attribute__ ((preserve_none));
+
+__attribute__ ((no_callee_saved_registers))
+void
+entry (double fp, int arg1, int arg2, int arg3, int arg4, int arg5, int arg6)
+{
+  continuation (fp, arg1, arg2, arg3, arg4, arg5, arg6);
+}
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-32b.c b/gcc/testsuite/gcc.target/i386/preserve-none-32b.c
new file mode 100644
index 00000000000..3de4322fef7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-32b.c
@@ -0,0 +1,18 @@ 
+/* { dg-do compile { target { llp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.seh_endprologue').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.} } } */
+
+/*
+**entry:
+**	.seh_endprologue
+**	movl	56\(%rsp\), %esi
+**	movl	48\(%rsp\), %edi
+**	movl	40\(%rsp\), %r15d
+**	movl	%edx, %r12d
+**	movl	%r9d, %r14d
+**	movl	%r8d, %r13d
+**	jmp	continuation
+*/
+
+#include "preserve-none-32a.c"
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-33a.c b/gcc/testsuite/gcc.target/i386/preserve-none-33a.c
new file mode 100644
index 00000000000..086df3681ec
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-33a.c
@@ -0,0 +1,36 @@ 
+/* { dg-do compile { target { lp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=sysv" } */
+/* Keep labels and directives ('.cfi_startproc', '.cfi_endproc').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.}  } } */
+
+/*
+**entry:
+**.LFB[0-9]+:
+**	.cfi_startproc
+**	subq	\$24, %rsp
+**...
+**	movl	%edi, %r12d
+**	movl	%esi, %r13d
+**	movl	%edx, %r14d
+**	movl	\$-559038737, \(%rsp\)
+**	movl	%ecx, %r15d
+**	movl	%r9d, %esi
+**	movl	%r8d, %edi
+**	xorl	%eax, %eax
+**	call	continuation
+**	addq	\$24, %rsp
+**...
+**	ret
+**	.cfi_endproc
+**...
+*/
+
+extern void continuation (int, int, int, int, int, int, ...)
+  __attribute__ ((preserve_none, ms_abi));
+
+__attribute__ ((no_callee_saved_registers))
+void
+entry (int arg1, int arg2, int arg3, int arg4, int arg5, int arg6)
+{
+  continuation (arg1, arg2, arg3, arg4, arg5, arg6, 0xdeadbeef);
+}
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-33b.c b/gcc/testsuite/gcc.target/i386/preserve-none-33b.c
new file mode 100644
index 00000000000..b82f790d645
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-33b.c
@@ -0,0 +1,25 @@ 
+/* { dg-do compile { target { llp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.seh_endprologue').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.} } } */
+
+/*
+**entry:
+**	subq	\$72, %rsp
+**	.seh_stackalloc	72
+**	.seh_endprologue
+**	xorl	%eax, %eax
+**	movl	120\(%rsp\), %esi
+**	movl	112\(%rsp\), %edi
+**	movl	%ecx, %r12d
+**	movl	%edx, %r13d
+**	movl	%r9d, %r15d
+**	movl	%r8d, %r14d
+**	movl	\$-559038737, 48\(%rsp\)
+**	call	continuation
+**	nop
+**	addq	\$72, %rsp
+**	ret
+*/
+
+#include "preserve-none-33a.c"
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-34a.c b/gcc/testsuite/gcc.target/i386/preserve-none-34a.c
new file mode 100644
index 00000000000..dbc36e9a21b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-34a.c
@@ -0,0 +1,29 @@ 
+/* { dg-do compile { target { lp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mtune=generic -mabi=sysv" } */
+/* Keep labels and directives ('.cfi_startproc', '.cfi_endproc').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.}  } } */
+
+/*
+**entry:
+**.LFB[0-9]+:
+**	.cfi_startproc
+**	movl	%edi, %r12d
+**	movl	%esi, %r13d
+**	movl	%edx, %r14d
+**	movl	%ecx, %r15d
+**	movl	%r9d, %esi
+**	movl	%r8d, %edi
+**	jmp	continuation
+**	.cfi_endproc
+**...
+*/
+
+extern void continuation (double, int, int, int, int, int, int)
+  __attribute__ ((preserve_none, ms_abi));
+
+__attribute__ ((no_callee_saved_registers))
+void
+entry (double fp, int arg1, int arg2, int arg3, int arg4, int arg5, int arg6)
+{
+  continuation (fp, arg1, arg2, arg3, arg4, arg5, arg6);
+}
diff --git a/gcc/testsuite/gcc.target/i386/preserve-none-34b.c b/gcc/testsuite/gcc.target/i386/preserve-none-34b.c
new file mode 100644
index 00000000000..75323ad7863
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/preserve-none-34b.c
@@ -0,0 +1,18 @@ 
+/* { dg-do compile { target { llp64 } } } */
+/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mno-push-args -fomit-frame-pointer -mtune=generic -mabi=ms" } */
+/* Keep labels and directives ('.seh_endprologue').  */
+/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" } {^\t?\.} } } */
+
+/*
+**entry:
+**	.seh_endprologue
+**	movl	56\(%rsp\), %esi
+**	movl	48\(%rsp\), %edi
+**	movl	40\(%rsp\), %r15d
+**	movl	%edx, %r12d
+**	movl	%r9d, %r14d
+**	movl	%r8d, %r13d
+**	jmp	continuation
+*/
+
+#include "preserve-none-34a.c"
-- 
2.55.0