gcc/

[pf3gnuchains/gcc-fork.git] / gcc / doc / options.texi

diff --git a/gcc/doc/options.texi b/gcc/doc/options.texi
index 1c8f5d9..edab7a9 100644 (file)
--- a/gcc/doc/options.texi
+++ b/gcc/doc/options.texi
@@ -1,4 +1,4 @@
-@c Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+@c Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
 @c Free Software Foundation, Inc.
 @c This is part of the GCC manual.
 @c For copying conditions, see the file gcc.texi.
@@ -222,6 +222,13 @@ the option name with the leading ``-'' removed.  This chain action will
 propagate through the @code{Negative} property of the option to be
 turned off.
 
+As a consequence, if you have a group of mutually-exclusive
+options, their @code{Negative} properties should form a circular chain.
+For example, if options @option{-@var{a}}, @option{-@var{b}} and
+@option{-@var{c}} are mutually exclusive, their respective @code{Negative}
+properties should be @samp{Negative(@var{b})}, @samp{Negative(@var{c})}
+and @samp{Negative(@var{a})}.
+
 @item Joined
 @itemx Separate
 The option takes a mandatory argument.  @code{Joined} indicates
@@ -257,6 +264,11 @@ option handler.  @code{UInteger} should also be used on options like
 @code{-falign-loops}=@var{n} are supported to make sure the saved
 options are given a full integer.
 
+@item ToLower
+The option's argument should be converted to lowercase as part of
+putting it in canonical form, and before comparing with the strings
+indicated by any @code{Enum} property.
+
 @item NoDriverArg
 For an option marked @code{Separate}, the option only takes an
 argument in the compiler proper, not in the driver.  This is for
@@ -364,7 +376,8 @@ for later processing.
 @item Alias(@var{opt})
 @itemx Alias(@var{opt}, @var{arg})
 @itemx Alias(@var{opt}, @var{posarg}, @var{negarg})
-The option is an alias for @option{-@var{opt}}.  In the first form,
+The option is an alias for @option{-@var{opt}} (or the negative form
+of that option, depending on @code{NegativeAlias}).  In the first form,
 any argument passed to the alias is considered to be passed to
 @option{-@var{opt}}, and @option{-@var{opt}} is considered to be
 negated if the alias is used in negated form.  In the second form, the
@@ -387,6 +400,13 @@ not need to handle it and no @samp{OPT_} enumeration value is defined
 for it; only the canonical form of the option will be seen in those
 places.
 
+@item NegativeAlias
+For an option marked with @code{Alias(@var{opt})}, the option is
+considered to be an alias for the positive form of @option{-@var{opt}}
+if negated and for the negative form of @option{-@var{opt}} if not
+negated.  @code{NegativeAlias} may not be used with the forms of
+@code{Alias} taking more than one argument.
+
 @item Ignore
 This option is ignored apart from printing any warning specified using
 @code{Warn}.  The option will not be seen by specs and no @samp{OPT_}
@@ -436,4 +456,17 @@ the @option{--help} output.
 Build the @code{cl_target_option} structure to hold a copy of the
 option, add the functions @code{cl_target_option_save} and
 @code{cl_target_option_restore} to save and restore the options.
+
+@item SetByCombined
+The option may also be set by a combined option such as
+@option{-ffast-math}.  This causes the @code{gcc_options} struct to
+have a field @code{frontend_set_@var{name}}, where @code{@var{name}}
+is the name of the field holding the value of this option (without the
+leading @code{x_}).  This gives the front end a way to indicate that
+the value has been set explicitly and should not be changed by the
+combined option.  For example, some front ends use this to prevent
+@option{-ffast-math} and @option{-fno-fast-math} from changing the
+value of @option{-fmath-errno} for languages that do not use
+@code{errno}.
+
 @end table