https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64101
--- Comment #2 from niva at niisi dot msk.ru ---
Please explain why erf is marked as 'const' and
does not use ATTR_MATHFN_FPROUNDING_ERRNO?
ISO C does not say that erf may not set errno.
And POSIX directly requires that erf, erff, erfl
set errno=ERANGE in case of underflow.
Here is another example:
#include <stdio.h>
#include <errno.h>
#include <math.h>
extern double res;
int main ()
{
errno = 0;
res = erf (-1.2553634935946022721708238314E-308);
printf ("errno=%d, res=%g\n", errno, res);
return 0;
}
As a result of
mips64-none-elf-gcc -O1 -S tst2_erf.c -o tst2_erf.s
the following code is generated:
main:
...
addiu $sp,$sp,-40
sd $31,32($sp)
sw $0,%gp_rel(errno)($28)
jal erf
ldc1 $f12,%gp_rel($LC0)($28)
sdc1 $f0,%gp_rel(res)($28)
lui $4,%hi($LC1) # printf arg 0: format line
addiu $4,$4,%lo($LC1)
dmfc1 $6,$f0 # printf arg 2: res
jal printf
move $5,$0 #! printf arg 1: zero (must be errno)
move $2,$0
ld $31,32($sp)
j $31
addiu $sp,$sp,40
Zero ($0) is passed to printf instead of errno.
If -fno-builtin-printf is used the compiler generates
lw $5,%gp_rel(errno)($28)
instead of
move $5,$0
in the delay slot after "jal printf".
В Птн, 28/11/2014 в 13:24 +0000, rguenth at gcc dot gnu.org пишет:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64101
>
> Richard Biener <rguenth at gcc dot gnu.org> changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> Target| |x86_64-*-*, mips64-none-elf
> Status|UNCONFIRMED |NEW
> Last reconfirmed| |2014-11-28
> Ever confirmed|0 |1
>
> --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
> I think the issue is that you don't use the result of erf() and the function
> is marked as 'const' - thus does not use ATTR_MATHFN_FPROUNDING_ERRNO.
> If you make 'res' global then it will work.
>
