1@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2@c 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
3@c This is part of the GCC manual.
4@c For copying conditions, see the file gcc.texi.
5
6@ignore
7@c man begin INCLUDE
8@include gcc-vers.texi

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5672
5673This option should never be turned on by any @option{-O} option since
5674it can result in incorrect output for programs which depend on
5675an exact implementation of IEEE or ISO rules/specifications for
5676math functions.
5677
5678The default is @option{-fmath-errno}.
5679
5680On Darwin systems, the math library never sets @code{errno}. There is therefore
5681no reason for the compiler to consider the possibility that it might,
5682and @option{-fno-math-errno} is the default.
5683
5684@item -funsafe-math-optimizations
5685@opindex funsafe-math-optimizations
5686Allow optimizations for floating-point arithmetic that (a) assume
5687that arguments and results are valid and (b) may violate IEEE or
5688ANSI standards. When used at link-time, it may include libraries

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9502
9503The option @option{-mno-fp-ret-in-387} causes such values to be returned
9504in ordinary CPU registers instead.
9505
9506@item -mno-fancy-math-387
9507@opindex mno-fancy-math-387
9508Some 387 emulators do not support the @code{sin}, @code{cos} and
9509@code{sqrt} instructions for the 387. Specify this option to avoid
9510generating those instructions. This option is the default on FreeBSD,
9511OpenBSD and NetBSD@. This option is overridden when @option{-march}
9512indicates that the target cpu will always have an FPU and so the
9513instruction will not need emulation. As of revision 2.6.1, these
9514instructions are not generated unless you also use the
9515@option{-funsafe-math-optimizations} switch.
9516
9517@item -malign-double
9518@itemx -mno-align-double

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