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?
diff --git a/winsup/cygwin/math/modfl.c b/winsup/cygwin/math/modfl.c
index af75a8b..ef1ab16 100644 (file)
--- a/winsup/cygwin/math/modfl.c
+++ b/winsup/cygwin/math/modfl.c
@@ -21,7 +21,7 @@ modfl (long double value, long double* iptr)
"fldcw (%%rsp)\n"
"frndint\n"
"fldcw 4(%%rsp)\n"
- "addq $8, %%rsp\n" : "=t" (int_part) : "0" (value)); /* round */
+ "addq $8, %%rsp\n" : "=t" (int_part) : "0" (value) : "eax"); /* round */
#elif defined(_X86_) || defined(__i386__)
asm ("push %%eax\n\tsubl $8, %%esp\n"
"fnstcw 4(%%esp)\n"
@@ -31,7 +31,7 @@ modfl (long double value, long double* iptr)
"fldcw (%%esp)\n"
"frndint\n"
"fldcw 4(%%esp)\n"
- "addl $8, %%esp\n\tpop %%eax\n" : "=t" (int_part) : "0" (value)); /* round
*/
+ "addl $8, %%esp\n\tpop %%eax\n" : "=t" (int_part) : "0" (value) : "eax");
/* round */
#else
int_part = truncl(value);
#endif
--
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.]
--
Problem reports: https://cygwin.com/problems.html
FAQ: https://cygwin.com/faq/
Documentation: https://cygwin.com/docs.html
Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
