Patchwork Adding target rdos to GCC

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Submitter Uros Bizjak
Date Jan. 6, 2013, 8:32 p.m.
Message ID <CAFULd4ad2fAQ3YhLVEWmuA8kBnrh6StkHPKWZndv10h3Ecm4GQ@mail.gmail.com>
Download mbox | patch
Permalink /patch/209800/
State New
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Comments

Uros Bizjak - Jan. 6, 2013, 8:32 p.m.
Hello!

> Updated patches with the suggestions below, except that the initial value is 0
> (which is not meaningful). I also added a setting in rdos target file to use r15
> for PIC instead of rbx.

*** gcc-4.8-20121230/gcc/config/i386/i386.c	Thu Dec 27 02:58:06 2012
--- gcc-work/gcc/config/i386/i386.c	Sun Jan  6 14:10:34 2013

+   if (ix86_section_threshold == 0)
+     ix86_section_threshold = DEFAULT_SECTION_THRESHOLD;

Please see attached patch on how to initialize an option.

*** gcc-4.8-20121230/gcc/config/i386/i386.h	Wed Dec 19 17:04:12 2012
--- gcc-work/gcc/config/i386/i386.h	Sun Jan  6 13:24:26 2013

+ #define TARGET_MEDIUM_PIC   0

You should just use TARGET_RDOS here (also, please see attached patch).

+ /* Default threshold for putting data in large sections with x86-64
+    medium memory model */
+ #define DEFAULT_SECTION_THRESHOLD 65536

Do not put this define in the middle of i386.h section that deals with
alignment...

*** gcc-4.8-20121230/gcc/config/i386/rdos.h	Thu Jan  1 01:00:00 1970
--- gcc-work/gcc/config/i386/rdos.h	Sun Jan  6 13:20:12 2013

+ #undef REAL_PIC_OFFSET_TABLE_REGNUM
+ #define REAL_PIC_OFFSET_TABLE_REGNUM  R15_REG

Is this header also used for 32bit target? You should not use REX
registers for 32bit targets.

+ #undef TARGET_MEDIUM_PIC
+ #define TARGET_MEDIUM_PIC           1

TARGET_RDOS

+ #define DEFAULT_SECTION_THRESHOLD    0x10

No hex numbers here. Also, you will need to #undef this first to
override the default in i386.h.

*** gcc-4.8-20121230/gcc/config.gcc	Thu Nov 22 00:33:40 2012
--- gcc-work/gcc/config.gcc	Fri Jan  4 21:08:46 2013

+ i[34567]86-*-rdos*)
+     tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h
newlib-stdint.h"
+     ;;

You forgot to include i386/rdos.h here (other headers too?). It is
needed at least for TARGET_EXECUTABLE_SUFFIX define.

Uros.
Leif Ekblad - Jan. 7, 2013, 10:13 p.m.
Hello Uros,

I tried to use your suggestion and use DEFAULT_SECTION_THRESHOLD
in i386.opt, however this doesn't work for me. It seems the default is 
always
65536 regardless of what I define in rdos.h. Therefore, I kept the design
as it was before.

Changing name to TARGET_RDOS seems reasonable, and this has been changed.
The location of the defines are also changed to the positions you proposed.

I added another include-file (rdos32.h) for the 32-bit target. Currently, 
the
32-bit target is supported with OpenWatcom. While I want to make sure
the header-files compile for both 32- and 64-bits, 32-bit support is not
my primary target right now. I just need a GCC that can build the 32-bit
version.

New change log:
* config/gthr.m4: Added rdos thread header.
* gcc/config/i386/i386.c: Provided a way to define a default setting for 
medium memory model and PIC using TARGET_RDOS define. Provided a way to 
define a default value for large-data-threshold.
* gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default value 
for large-data-threshold.
* gcc/config/i386/i386.md: Added r14 and r15 register names.
* gcc/config/i386/i386.opt: Changed initial value for large-data-threshold 
to 0 to allow detection of modification.
* gcc/config/i386/rdos.h: Added new file for 64-bit rdos target.
* gcc/config/i386/rdos32.h: Added new file for 32-bit rdos target.
* gcc/config.gcc: Added rdos targets

Leif Ekblad


----- Original Message ----- 
From: "Uros Bizjak" <ubizjak@gmail.com>
To: <gcc-patches@gcc.gnu.org>
Cc: "Leif Ekblad" <leif@rdos.net>; "H.J. Lu" <hjl.tools@gmail.com>
Sent: Sunday, January 06, 2013 9:32 PM
Subject: Re: [PATCH] Adding target rdos to GCC


> Hello!
>
>> Updated patches with the suggestions below, except that the initial value 
>> is 0
>> (which is not meaningful). I also added a setting in rdos target file to 
>> use r15
>> for PIC instead of rbx.
>
> *** gcc-4.8-20121230/gcc/config/i386/i386.c Thu Dec 27 02:58:06 2012
> --- gcc-work/gcc/config/i386/i386.c Sun Jan  6 14:10:34 2013
>
> +   if (ix86_section_threshold == 0)
> +     ix86_section_threshold = DEFAULT_SECTION_THRESHOLD;
>
> Please see attached patch on how to initialize an option.
>
> *** gcc-4.8-20121230/gcc/config/i386/i386.h Wed Dec 19 17:04:12 2012
> --- gcc-work/gcc/config/i386/i386.h Sun Jan  6 13:24:26 2013
>
> + #define TARGET_MEDIUM_PIC   0
>
> You should just use TARGET_RDOS here (also, please see attached patch).
>
> + /* Default threshold for putting data in large sections with x86-64
> +    medium memory model */
> + #define DEFAULT_SECTION_THRESHOLD 65536
>
> Do not put this define in the middle of i386.h section that deals with
> alignment...
>
> *** gcc-4.8-20121230/gcc/config/i386/rdos.h Thu Jan  1 01:00:00 1970
> --- gcc-work/gcc/config/i386/rdos.h Sun Jan  6 13:20:12 2013
>
> + #undef REAL_PIC_OFFSET_TABLE_REGNUM
> + #define REAL_PIC_OFFSET_TABLE_REGNUM  R15_REG
>
> Is this header also used for 32bit target? You should not use REX
> registers for 32bit targets.
>
> + #undef TARGET_MEDIUM_PIC
> + #define TARGET_MEDIUM_PIC           1
>
> TARGET_RDOS
>
> + #define DEFAULT_SECTION_THRESHOLD    0x10
>
> No hex numbers here. Also, you will need to #undef this first to
> override the default in i386.h.
>
> *** gcc-4.8-20121230/gcc/config.gcc Thu Nov 22 00:33:40 2012
> --- gcc-work/gcc/config.gcc Fri Jan  4 21:08:46 2013
>
> + i[34567]86-*-rdos*)
> +     tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h
> newlib-stdint.h"
> +     ;;
>
> You forgot to include i386/rdos.h here (other headers too?). It is
> needed at least for TARGET_EXECUTABLE_SUFFIX define.
>
> Uros.
>
Leif Ekblad - Jan. 8, 2013, 8:32 p.m.
After some new suggestions from Uros, I've made a new diff.

Change log:
* config/gthr.m4: Added rdos thread header.
* gcc/config/i386/i386.c: Provided a way to define a default setting for 
medium memory model and PIC using TARGET_RDOS define.
* gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default value 
for large-data-threshold.
* gcc/config/i386/i386.md: Added r14 and r15 register names.
* gcc/config/i386/i386.opt: Changed initial value for large-data-threshold 
to DEFAULT_LARGE_SECTION_THRESHOLD.
* gcc/config/i386/rdos.h: Common definitions for target rdos
* gcc/config/i386/rdos64.h: Specific definitions for 64-bit rdos target.
* gcc/config.gcc: Added rdos targets

Tested on target rdos and rdos32.

Leif Ekblad

----- Original Message ----- 
From: "Leif Ekblad" <leif@rdos.net>
To: "Uros Bizjak" <ubizjak@gmail.com>; <gcc-patches@gcc.gnu.org>
Cc: "H.J. Lu" <hjl.tools@gmail.com>
Sent: Monday, January 07, 2013 11:13 PM
Subject: Re: [PATCH] Adding target rdos to GCC


> Hello Uros,
>
> I tried to use your suggestion and use DEFAULT_SECTION_THRESHOLD
> in i386.opt, however this doesn't work for me. It seems the default is
> always
> 65536 regardless of what I define in rdos.h. Therefore, I kept the design
> as it was before.
>
> Changing name to TARGET_RDOS seems reasonable, and this has been changed.
> The location of the defines are also changed to the positions you 
> proposed.
>
> I added another include-file (rdos32.h) for the 32-bit target. Currently,
> the
> 32-bit target is supported with OpenWatcom. While I want to make sure
> the header-files compile for both 32- and 64-bits, 32-bit support is not
> my primary target right now. I just need a GCC that can build the 32-bit
> version.
>
> New change log:
> * config/gthr.m4: Added rdos thread header.
> * gcc/config/i386/i386.c: Provided a way to define a default setting for
> medium memory model and PIC using TARGET_RDOS define. Provided a way to
> define a default value for large-data-threshold.
> * gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default value
> for large-data-threshold.
> * gcc/config/i386/i386.md: Added r14 and r15 register names.
> * gcc/config/i386/i386.opt: Changed initial value for large-data-threshold
> to 0 to allow detection of modification.
> * gcc/config/i386/rdos.h: Added new file for 64-bit rdos target.
> * gcc/config/i386/rdos32.h: Added new file for 32-bit rdos target.
> * gcc/config.gcc: Added rdos targets
>
> Leif Ekblad
>
>
> ----- Original Message ----- 
> From: "Uros Bizjak" <ubizjak@gmail.com>
> To: <gcc-patches@gcc.gnu.org>
> Cc: "Leif Ekblad" <leif@rdos.net>; "H.J. Lu" <hjl.tools@gmail.com>
> Sent: Sunday, January 06, 2013 9:32 PM
> Subject: Re: [PATCH] Adding target rdos to GCC
>
>
>> Hello!
>>
>>> Updated patches with the suggestions below, except that the initial 
>>> value
>>> is 0
>>> (which is not meaningful). I also added a setting in rdos target file to
>>> use r15
>>> for PIC instead of rbx.
>>
>> *** gcc-4.8-20121230/gcc/config/i386/i386.c Thu Dec 27 02:58:06 2012
>> --- gcc-work/gcc/config/i386/i386.c Sun Jan  6 14:10:34 2013
>>
>> +   if (ix86_section_threshold == 0)
>> +     ix86_section_threshold = DEFAULT_SECTION_THRESHOLD;
>>
>> Please see attached patch on how to initialize an option.
>>
>> *** gcc-4.8-20121230/gcc/config/i386/i386.h Wed Dec 19 17:04:12 2012
>> --- gcc-work/gcc/config/i386/i386.h Sun Jan  6 13:24:26 2013
>>
>> + #define TARGET_MEDIUM_PIC   0
>>
>> You should just use TARGET_RDOS here (also, please see attached patch).
>>
>> + /* Default threshold for putting data in large sections with x86-64
>> +    medium memory model */
>> + #define DEFAULT_SECTION_THRESHOLD 65536
>>
>> Do not put this define in the middle of i386.h section that deals with
>> alignment...
>>
>> *** gcc-4.8-20121230/gcc/config/i386/rdos.h Thu Jan  1 01:00:00 1970
>> --- gcc-work/gcc/config/i386/rdos.h Sun Jan  6 13:20:12 2013
>>
>> + #undef REAL_PIC_OFFSET_TABLE_REGNUM
>> + #define REAL_PIC_OFFSET_TABLE_REGNUM  R15_REG
>>
>> Is this header also used for 32bit target? You should not use REX
>> registers for 32bit targets.
>>
>> + #undef TARGET_MEDIUM_PIC
>> + #define TARGET_MEDIUM_PIC           1
>>
>> TARGET_RDOS
>>
>> + #define DEFAULT_SECTION_THRESHOLD    0x10
>>
>> No hex numbers here. Also, you will need to #undef this first to
>> override the default in i386.h.
>>
>> *** gcc-4.8-20121230/gcc/config.gcc Thu Nov 22 00:33:40 2012
>> --- gcc-work/gcc/config.gcc Fri Jan  4 21:08:46 2013
>>
>> + i[34567]86-*-rdos*)
>> +     tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h
>> newlib-stdint.h"
>> +     ;;
>>
>> You forgot to include i386/rdos.h here (other headers too?). It is
>> needed at least for TARGET_EXECUTABLE_SUFFIX define.
>>
>> Uros.
>>
>
Uros Bizjak - Jan. 9, 2013, 6:58 a.m.
On Tue, Jan 8, 2013 at 9:32 PM, Leif Ekblad <leif@rdos.net> wrote:
> After some new suggestions from Uros, I've made a new diff.
>
>
> Change log:
> * config/gthr.m4: Added rdos thread header.
> * gcc/config/i386/i386.c: Provided a way to define a default setting for
> medium memory model and PIC using TARGET_RDOS define.
> * gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default value
> for large-data-threshold.
> * gcc/config/i386/i386.md: Added r14 and r15 register names.
> * gcc/config/i386/i386.opt: Changed initial value for large-data-threshold
> to DEFAULT_LARGE_SECTION_THRESHOLD.
> * gcc/config/i386/rdos.h: Common definitions for target rdos
> * gcc/config/i386/rdos64.h: Specific definitions for 64-bit rdos target.
> * gcc/config.gcc: Added rdos targets

Please use present tense in ChangeLog (see many other entries).

> Tested on target rdos and rdos32.

This is OK for mainline, but the patch needs explicit approval from
Release Managers at this stage.

Thanks,
Uros.
Richard Guenther - Jan. 9, 2013, 8:37 a.m.
On Wed, 9 Jan 2013, Uros Bizjak wrote:

> On Tue, Jan 8, 2013 at 9:32 PM, Leif Ekblad <leif@rdos.net> wrote:
> > After some new suggestions from Uros, I've made a new diff.
> >
> >
> > Change log:
> > * config/gthr.m4: Added rdos thread header.
> > * gcc/config/i386/i386.c: Provided a way to define a default setting for
> > medium memory model and PIC using TARGET_RDOS define.
> > * gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default value
> > for large-data-threshold.
> > * gcc/config/i386/i386.md: Added r14 and r15 register names.
> > * gcc/config/i386/i386.opt: Changed initial value for large-data-threshold
> > to DEFAULT_LARGE_SECTION_THRESHOLD.
> > * gcc/config/i386/rdos.h: Common definitions for target rdos
> > * gcc/config/i386/rdos64.h: Specific definitions for 64-bit rdos target.
> > * gcc/config.gcc: Added rdos targets
> 
> Please use present tense in ChangeLog (see many other entries).
> 
> > Tested on target rdos and rdos32.
> 
> This is OK for mainline, but the patch needs explicit approval from
> Release Managers at this stage.

Ok with me.

Richard.
Leif Ekblad - Jan. 28, 2013, 6:50 a.m.
If the patch is ok, could some maintainer add it to trunk?

Regards,
Leif Ekblad


----- Original Message ----- 
From: "Richard Biener" <rguenther@suse.de>
To: "Uros Bizjak" <ubizjak@gmail.com>
Cc: "Leif Ekblad" <leif@rdos.net>; <gcc-patches@gcc.gnu.org>; "H.J. Lu" 
<hjl.tools@gmail.com>; "Jakub Jelinek" <jakub@redhat.com>
Sent: Wednesday, January 09, 2013 9:37 AM
Subject: Re: [PATCH] Adding target rdos to GCC


> On Wed, 9 Jan 2013, Uros Bizjak wrote:
>
>> On Tue, Jan 8, 2013 at 9:32 PM, Leif Ekblad <leif@rdos.net> wrote:
>> > After some new suggestions from Uros, I've made a new diff.
>> >
>> >
>> > Change log:
>> > * config/gthr.m4: Added rdos thread header.
>> > * gcc/config/i386/i386.c: Provided a way to define a default setting 
>> > for
>> > medium memory model and PIC using TARGET_RDOS define.
>> > * gcc/config/i386/i386.h: Defined TARGET_RDOS macro. Defined default 
>> > value
>> > for large-data-threshold.
>> > * gcc/config/i386/i386.md: Added r14 and r15 register names.
>> > * gcc/config/i386/i386.opt: Changed initial value for 
>> > large-data-threshold
>> > to DEFAULT_LARGE_SECTION_THRESHOLD.
>> > * gcc/config/i386/rdos.h: Common definitions for target rdos
>> > * gcc/config/i386/rdos64.h: Specific definitions for 64-bit rdos 
>> > target.
>> > * gcc/config.gcc: Added rdos targets
>>
>> Please use present tense in ChangeLog (see many other entries).
>>
>> > Tested on target rdos and rdos32.
>>
>> This is OK for mainline, but the patch needs explicit approval from
>> Release Managers at this stage.
>
> Ok with me.
>
> Richard.
Uros Bizjak - Jan. 28, 2013, 7:23 a.m.
On Mon, Jan 28, 2013 at 7:50 AM, Leif Ekblad <leif@rdos.net> wrote:

> If the patch is ok, could some maintainer add it to trunk?

There is no gthr-rdos.h file in your patch:

*** gcc-4.8-20121230/config/gthr.m4	2012-10-15 15:10:30.000000000 +0200
--- gcc-work/config/gthr.m4	2013-01-07 10:14:04.620667900 +0100
***************
*** 21,26 ****
--- 21,27 ----
      tpf)	thread_header=config/s390/gthr-tpf.h ;;
      vxworks)	thread_header=config/gthr-vxworks.h ;;
      win32)	thread_header=config/i386/gthr-win32.h ;;
+     rdos)	thread_header=config/i386/gthr-rdos.h ;;

This file should be part of libgcc, so it needs its own ChangeLog.

Uros.
Leif Ekblad - Jan. 28, 2013, 7:57 p.m.
Uros,

That is intentional. The gthr-rdos.h file is part of libgcc. My intention 
was to first patch gcc, then update the patches for newlib, and finally 
libgcc. The gthr-rdos.h file would reference include-files part of newlib, 
so this is kind of circular. I also cannot define the thread model for RDOS 
unless I define this file.

I see a couple of possible solutions:
1. Keep as is. You cannot build libgcc at the current stage anyway, and the 
bootstrap must be built without threading
2. Add an empty gthr-rdos.h file until libgcc is done
3. Remove the threading-model for now, and add it with libgcc instead.

Regards,
Leif Ekblad



----- Original Message ----- 
From: "Uros Bizjak" <ubizjak@gmail.com>
To: "Leif Ekblad" <leif@rdos.net>
Cc: "Richard Biener" <rguenther@suse.de>; <gcc-patches@gcc.gnu.org>; "H.J. 
Lu" <hjl.tools@gmail.com>; "Jakub Jelinek" <jakub@redhat.com>
Sent: Monday, January 28, 2013 8:23 AM
Subject: Re: [PATCH] Adding target rdos to GCC


> On Mon, Jan 28, 2013 at 7:50 AM, Leif Ekblad <leif@rdos.net> wrote:
>
>> If the patch is ok, could some maintainer add it to trunk?
>
> There is no gthr-rdos.h file in your patch:
>
> *** gcc-4.8-20121230/config/gthr.m4 2012-10-15 15:10:30.000000000 +0200
> --- gcc-work/config/gthr.m4 2013-01-07 10:14:04.620667900 +0100
> ***************
> *** 21,26 ****
> --- 21,27 ----
>      tpf) thread_header=config/s390/gthr-tpf.h ;;
>      vxworks) thread_header=config/gthr-vxworks.h ;;
>      win32) thread_header=config/i386/gthr-win32.h ;;
> +     rdos) thread_header=config/i386/gthr-rdos.h ;;
>
> This file should be part of libgcc, so it needs its own ChangeLog.
>
> Uros.
Uros Bizjak - Jan. 28, 2013, 8:03 p.m.
On Mon, Jan 28, 2013 at 8:57 PM, Leif Ekblad <leif@rdos.net> wrote:

> That is intentional. The gthr-rdos.h file is part of libgcc. My intention
> was to first patch gcc, then update the patches for newlib, and finally
> libgcc. The gthr-rdos.h file would reference include-files part of newlib,
> so this is kind of circular. I also cannot define the thread model for RDOS
> unless I define this file.
>
> I see a couple of possible solutions:
> 1. Keep as is. You cannot build libgcc at the current stage anyway, and the
> bootstrap must be built without threading
> 2. Add an empty gthr-rdos.h file until libgcc is done
> 3. Remove the threading-model for now, and add it with libgcc instead.

I propose option 3.

Is it enough to remove gthr.m4 change from the patch in this case?

Uros.
Leif Ekblad - Jan. 28, 2013, 8:14 p.m.
----- Original Message ----- 
From: "Uros Bizjak" <ubizjak@gmail.com>
To: "Leif Ekblad" <leif@rdos.net>
Cc: "Richard Biener" <rguenther@suse.de>; <gcc-patches@gcc.gnu.org>; "H.J. 
Lu" <hjl.tools@gmail.com>; "Jakub Jelinek" <jakub@redhat.com>
Sent: Monday, January 28, 2013 9:03 PM
Subject: Re: [PATCH] Adding target rdos to GCC


> On Mon, Jan 28, 2013 at 8:57 PM, Leif Ekblad <leif@rdos.net> wrote:
>
>> That is intentional. The gthr-rdos.h file is part of libgcc. My intention
>> was to first patch gcc, then update the patches for newlib, and finally
>> libgcc. The gthr-rdos.h file would reference include-files part of 
>> newlib,
>> so this is kind of circular. I also cannot define the thread model for 
>> RDOS
>> unless I define this file.
>>
>> I see a couple of possible solutions:
>> 1. Keep as is. You cannot build libgcc at the current stage anyway, and 
>> the
>> bootstrap must be built without threading
>> 2. Add an empty gthr-rdos.h file until libgcc is done
>> 3. Remove the threading-model for now, and add it with libgcc instead.
>
> I propose option 3.
>
> Is it enough to remove gthr.m4 change from the patch in this case?
>
> Uros.

Yes, for all practical purposes. There is a reference to thread-file in 
config.gcc, when threading is enabled, which doesn't work for bootstrapping 
the compiler anyway.

Regards,
Leif Ekblad

Patch

Index: i386.c
===================================================================
--- i386.c	(revision 194945)
+++ i386.c	(working copy)
@@ -3239,6 +3239,8 @@ 
 	 DLL, and is essentially just as efficient as direct addressing.  */
       if (TARGET_64BIT && DEFAULT_ABI == MS_ABI)
 	ix86_cmodel = CM_SMALL_PIC, flag_pic = 1;
+      else if (TARGET_64BIT && TARGET_RDOS)
+	ix86_cmodel = CM_MEDIUM_PIC, flag_pic = 1;
       else if (TARGET_64BIT)
 	ix86_cmodel = flag_pic ? CM_SMALL_PIC : CM_SMALL;
       else
Index: i386.h
===================================================================
--- i386.h	(revision 194945)
+++ i386.h	(working copy)
@@ -519,6 +519,9 @@ 
 #define MACHOPIC_INDIRECT 0
 #define MACHOPIC_PURE 0
 
+/* For the RDOS  */
+#define TARGET_RDOS 0
+
 /* For the Windows 64-bit ABI.  */
 #define TARGET_64BIT_MS_ABI (TARGET_64BIT && ix86_cfun_abi () == MS_ABI)
 
@@ -2081,6 +2084,10 @@ 
    asm (SECTION_OP "\n\t"					\
 	"call " CRT_MKSTR(__USER_LABEL_PREFIX__) #FUNC "\n"	\
 	TEXT_SECTION_ASM_OP);
+
+/* Default threshold for putting data in large sections
+   with x86-64 medium memory model */
+#define DEFAULT_LARGE_SECTION_THRESHOLD 65536
 
 /* Which processor to tune code generation for.  */
 
Index: i386.opt
===================================================================
--- i386.opt	(revision 194945)
+++ i386.opt	(working copy)
@@ -141,7 +141,7 @@ 
 Branches are this expensive (1-5, arbitrary units)
 
 mlarge-data-threshold=
-Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(65536)
+Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(DEFAULT_LARGE_SECTION_THRESHOLD)
 Data greater than given threshold will go into .ldata section in x86-64 medium model
 
 mcmodel=