On 25.11.20 23:02, Maciej W. Rozycki wrote:
Well, it does not link, for the somewhat unsurprising reason of a missing
libgfortran runtime. I have modified the program with whatever little
Fortran skills I gained a while ago to get something that can be parseable
for a human being in the assembly form:
You could also try -fdump-tree-original or -fdump-parse-tree
which might be a bit more readable than assembler – at least
it avoids the problem of D-floating format.
real(8) :: h = HUGE(1.0)
real(8) :: e = EPSILON(1.0)
print *,h
print *,e
end
huge and epsilon are defined as:
huge(x) = (1 - b**(-p)) * b**(emax-1) * b
epsilon(x) = b**(1-p)
with
b = radix = REAL_MODE_FORMAT (mode)->b
p = digits = REAL_MODE_FORMAT (mode)->p
emax = max_exponent = REAL_MODE_FORMAT (mode)->emax
For C/C++, it is defined with
%s = FLT, DBL, LDBL + FLT%d%s with %d e.g. 128 and %s = "" or "X" if extended
as
__%s_MAX__ = builtin_define_with_hex_fp_value (... decimal_dig ...)
with
decimal_dig = 1 + fmt->p * log10_b
and
__%s_EPSILON__
as
if (fmt->pnan < fmt->p)
/* This is an IBM extended double format, so 1.0 + any double is
representable precisely. */
sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
else
sprintf (buf, "0x1p%d", 1 - fmt->p);
Tobias
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