Re: cpp /usr/include/threads.h fails; modfl segfaults

[Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>]

On 2020-08-31 01:35, Corinna Vinschen wrote:
> On Aug 30 14:39, Brian Inglis wrote:
>> On 2020-08-30 07:00, Corinna Vinschen wrote:
>>> On Aug 29 08:52, airplanemath via Cygwin wrote:
>>>> I have two reports.  A brief description of the system:
>>>> $ uname -a | sed "s/${HOSTNAME}/\${HOSTNAME}/g"
>>>> CYGWIN_NT-10.0 ${HOSTNAME} 3.1.7(0.340/5/3) 2020-08-22 17:48 x86_64 Cygwin
>> ...
>>>> $ cat test.c
>>>> #include <math.h>
>>>> #include <stdio.h>
>>>> #include <stdlib.h>
>>>>
>>>> int main(int argc, char *argv[]) {
>>>>   long double a, b, c;
>>>>   char *num_end = NULL;
>>>>   a = b = c = 0.0L;
>>>>   if (argc != 2) {
>>>>     fprintf(stderr, "Usage: %s NUMBER\n", argv[0]);
>>>>     exit(1);
>>>>   }
>>>>   a = strtold(argv[1], &num_end);
>>>>   b = modfl(a, &c);
>>>>   printf("%Lf %Lf %Lf\n", a, b, c);
>>>>   return 0;
>>>> }
>>>
>>> This is a bug in the assembler code taken from Mingw-w64.  The bug has
>>> been fixed upstream, so I just pulled in the upstream fixes.
>>
>> The 64 bit fix doesn't pop eax but *now* flags eax as clobbered, whereas the 32
>> bit fix both pops and *now* flags eax as clobbered, which it really doesn't need
>> to do. Is this inconsistent treatment correct?
> 
> You may be right that this is not necessary on i686, but it doesn't
> hurt either and I'd like to stick to the upstream code if possible.

The upstream patch changed only amd64/x86_64 code sequences for multiple modules
including modfl, and left i386/x86 untouched for those modules.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in IEC units and prefixes, physical quantities in SI.]