Bruno Haible <[EMAIL PROTECTED]> writes:
> The code needed for isnan() needs to construct a NaN or Inf object. But
> doing so leads to a SIGFPE by default on Alpha systems. There's only one
> way to get IEEE compliant behaviour of elementary arithmetic operations on
> this platform: instruct the compiler to emit different (more expensive)
> floating-point instructions. This module implements it.
Is this also necessary on SH systems? The GCC manual has this in
the page specific to SH:
`-mieee'
Increase IEEE-compliance of floating-point code. At the moment,
this is equivalent to `-fno-finite-math-only'. When generating 16
bit SH opcodes, getting IEEE-conforming results for comparisons of
NANs / infinities incurs extra overhead in every floating point
comparison, therefore the default is set to `-ffinite-math-only'.
In GNU PSPP, I have a configure test that just checks whether the
compiler accepts -mieee and uses it if it is available. I wonder
whether this is an approach that is more likely to automatically
work as architectures appear.
Here's what PSPP is using:
dnl Check whether a C compiler option is accepted.
dnl If so, add it to CFLAGS.
dnl Example: PSPP_ENABLE_OPTION(-Wdeclaration-after-statement)
AC_DEFUN([PSPP_ENABLE_OPTION],
[
m4_define([pspp_cv_name], [pspp_cv_[]m4_translit([$1], [-], [_])])dnl
AC_CACHE_CHECK([whether $CC accepts $1], [pspp_cv_name],
[pspp_save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS $1"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,)], [pspp_cv_name[]=yes],
[pspp_cv_name[]=no])
CFLAGS="$pspp_save_CFLAGS"])
if test $pspp_cv_name = yes; then
CFLAGS="$CFLAGS $1"
fi
])
...
PSPP_ENABLE_OPTION(-mieee)
--
Only wimps use tape backup: _real_ men just upload their important stuff
on ftp, and let the rest of the world mirror it ;)
-- Linus Torvalds
