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[Bug other/63395] Cygwin vs Cygwin64 Floating Point Discrepancy
- From: "bernardwidynski at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sun, 28 Sep 2014 19:37:15 +0000
- Subject: [Bug other/63395] Cygwin vs Cygwin64 Floating Point Discrepancy
- Auto-submitted: auto-generated
- References: <bug-63395-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63395
--- Comment #11 from bernardwidynski at gmail dot com ---
Thanks for the information.
I looked at the .s assembly files.
32-bit Cygwin uses the "fmul" instruction.
64-bit Cygwin uses the "mulsd" instruction.
I tried -mpc64 on 32-bit Cygwin but got the same results.
On Sat, Sep 27, 2014 at 4:09 PM, mikpelinux at gmail dot com <
gcc-bugzilla@gcc.gnu.org> wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63395
>
> --- Comment #10 from Mikael Pettersson <mikpelinux at gmail dot com> ---
> I strongly suspect 32-bit Cygwin uses x87 by default, while 64-bit Cygwin
> probably uses SSE2 by default. These two FP implementations are very
> different, and it's not at all surprising to see different results from
> them.
>
> Try compiling with -mpc64 on 32-bit Cygwin.
>
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