* LDBL_EQ_DBL Multilib Issues
@ 2023-09-26 14:42 Joel Sherrill
2023-09-26 22:39 ` Jeff Johnston
0 siblings, 1 reply; 3+ messages in thread
From: Joel Sherrill @ 2023-09-26 14:42 UTC (permalink / raw)
To: Newlib, Chris Johns, Gedare Bloom
[-- Attachment #1.1: Type: text/plain, Size: 701 bytes --]
Hi
I wondered when we reorganized LDBL_EQ_DBL logic if there wouldn't be a
multilib edge case. Chris encountered it.
Attached is a simple test program based on the autoconf probe in
configure.ac that can be preprocessed with different CPU/ABI flags. The
following shows that the default on m68k is not the same as for the 5282.
$ m68k-rtems6-gcc -O2 -E ldbl.c | less
$ m68k-rtems6-gcc -O2 -E -mcpu=5282 ldbl.c | less
Turns out the default flags end up with LDBL_EQ_DBL isn't defined but it
should be for -mcpu=5282 builds.
I don't know any mechanism to add header file variants in newlib by
multilib, so I we need to consider moving this to a dynamic check.
Any thoughts on where to move this?
[-- Attachment #2: ldbl.c --]
[-- Type: application/octet-stream, Size: 544 bytes --]
/* guts of test from newlib/configure.ac */
#include <float.h>
#if DBL_MANT_DIG == LDBL_MANT_DIG && LDBL_MIN_EXP == DBL_MIN_EXP && \
LDBL_MAX_EXP == DBL_MAX_EXP
#define _LDBL_EQ_DBL
#else
#error "LDBL != DBL"
#endif
/* just to get values */
int sDBL_MANT_DIG = DBL_MANT_DIG;
int sLDBL_MANT_DIG = LDBL_MANT_DIG;
int sLDBL_MIN_EXP = LDBL_MIN_EXP;
int sDBL_MIN_EXP = DBL_MIN_EXP;
int sLDBL_MAX_EXP = LDBL_MAX_EXP;
int sDBL_MAX_EXP = DBL_MAX_EXP;
const char *ldbl_eq_dbl =
#ifdef LDBL_EQ_DBL
"defined";
#else
"undefined";
#endif
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: LDBL_EQ_DBL Multilib Issues
2023-09-26 14:42 LDBL_EQ_DBL Multilib Issues Joel Sherrill
@ 2023-09-26 22:39 ` Jeff Johnston
2023-09-26 23:18 ` Joel Sherrill
0 siblings, 1 reply; 3+ messages in thread
From: Jeff Johnston @ 2023-09-26 22:39 UTC (permalink / raw)
To: joel; +Cc: Newlib, Chris Johns, Gedare Bloom
[-- Attachment #1: Type: text/plain, Size: 1084 bytes --]
Have you thought about adding a special case in sys/config.h which
when it has the appropriate conditions (platform plus compiler flag) will
define/redefine _LDBL_EQ_DBL?
It gets included as part of _ansi.h and after newlib.h.
-- Jeff J.
On Tue, Sep 26, 2023 at 10:43 AM Joel Sherrill <joel@rtems.org> wrote:
> Hi
>
> I wondered when we reorganized LDBL_EQ_DBL logic if there wouldn't be a
> multilib edge case. Chris encountered it.
>
> Attached is a simple test program based on the autoconf probe in
> configure.ac that can be preprocessed with different CPU/ABI flags. The
> following shows that the default on m68k is not the same as for the 5282.
>
> $ m68k-rtems6-gcc -O2 -E ldbl.c | less
>
> $ m68k-rtems6-gcc -O2 -E -mcpu=5282 ldbl.c | less
>
> Turns out the default flags end up with LDBL_EQ_DBL isn't defined but it
> should be for -mcpu=5282 builds.
>
> I don't know any mechanism to add header file variants in newlib by
> multilib, so I we need to consider moving this to a dynamic check.
>
> Any thoughts on where to move this?
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: LDBL_EQ_DBL Multilib Issues
2023-09-26 22:39 ` Jeff Johnston
@ 2023-09-26 23:18 ` Joel Sherrill
0 siblings, 0 replies; 3+ messages in thread
From: Joel Sherrill @ 2023-09-26 23:18 UTC (permalink / raw)
To: Jeff Johnston; +Cc: Newlib, Chris Johns, Gedare Bloom
[-- Attachment #1: Type: text/plain, Size: 1392 bytes --]
On Tue, Sep 26, 2023 at 5:40 PM Jeff Johnston <jjohnstn@redhat.com> wrote:
> Have you thought about adding a special case in sys/config.h which
> when it has the appropriate conditions (platform plus compiler flag) will
> define/redefine _LDBL_EQ_DBL?
>
> It gets included as part of _ansi.h and after newlib.h.
>
Thanks! You are confirming it needs to be decided at build time and giving
me the location to move it to.
I will try to get a patch out as soon as I can.
Thanks.
--joel
>
> -- Jeff J.
>
>
> On Tue, Sep 26, 2023 at 10:43 AM Joel Sherrill <joel@rtems.org> wrote:
>
>> Hi
>>
>> I wondered when we reorganized LDBL_EQ_DBL logic if there wouldn't be a
>> multilib edge case. Chris encountered it.
>>
>> Attached is a simple test program based on the autoconf probe in
>> configure.ac that can be preprocessed with different CPU/ABI flags. The
>> following shows that the default on m68k is not the same as for the 5282.
>>
>> $ m68k-rtems6-gcc -O2 -E ldbl.c | less
>>
>> $ m68k-rtems6-gcc -O2 -E -mcpu=5282 ldbl.c | less
>>
>> Turns out the default flags end up with LDBL_EQ_DBL isn't defined but it
>> should be for -mcpu=5282 builds.
>>
>> I don't know any mechanism to add header file variants in newlib by
>> multilib, so I we need to consider moving this to a dynamic check.
>>
>> Any thoughts on where to move this?
>>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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