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Re: get_condition and conditional move
- To: hjl at lucon dot org (H.J. Lu)
- Subject: Re: get_condition and conditional move
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Fri, 19 Jun 1998 21:07:35 -0600
- cc: amylaar at cygnus dot co dot uk (Joern Rennecke), egcs at cygnus dot com
- Reply-To: law at cygnus dot com
In message <m0ymAuj-00026AC@ocean.lucon.org>you write:
> > No, read again. This test applies only when flag_fast_math is zero.
> > Reversing a inequality comparison does not work correctly when handling NaNs.
Generally this is true. However, it is safe to reverse EQ and NE
comparisons, even for ieee floating point.
If some operand is a NaN, then EQ always evaluates to false and
NE will always evaluate to true.
See "can_reverse_comparison_p" in jump.c
jeff