The second field of an option record can specify any of the following properties. When an option takes an argument, it is enclosed in parentheses following the option property name. The parser that handles option files is quite simplistic, and will be tricked by any nested parentheses within the argument text itself; in this case, the entire option argument can be wrapped in curly braces within the parentheses to demarcate it, e.g.:
Condition({defined (USE_CYGWIN_LIBSTDCXX_WRAPPERS)})
CommonThe option is available for all languages and targets.
TargetThe option is available for all languages but is target-specific.
DriverThe option is handled by the compiler driver using code not shared with the compilers proper (cc1 etc.).
languageThe option is available when compiling for the given language.
It is possible to specify several different languages for the same
option. Each language must have been declared by an earlier
Language record. See Option file format.
RejectDriverThe option is only handled by the compilers proper (cc1 etc.) and should not be accepted by the driver.
RejectNegativeThe option does not have a “no-” form. All options beginning with “f”, “g”, “W” or “m” are assumed to have a “no-” form unless this property is used.
Negative(othername)The option will turn off another option othername, which is
the option name with the leading “-” removed. This chain action will
propagate through the Negative property of the option to be
turned off. The driver will prune options, removing those that are
turned off by some later option. This pruning is not done for options
with Joined or JoinedOrMissing properties, unless the
options have both the RejectNegative property and the Negative
property mentions itself.
As a consequence, if you have a group of mutually-exclusive
options, their Negative properties should form a circular chain.
For example, if options -a, -b and
-c are mutually exclusive, their respective Negative
properties should be ‘Negative(b)’, ‘Negative(c)’
and ‘Negative(a)’.
JoinedSeparateThe option takes a mandatory argument. Joined indicates
that the option and argument can be included in the same argv
entry (as with -mflush-func=name, for example).
Separate indicates that the option and argument can be
separate argv entries (as with -o). An option is
allowed to have both of these properties.
JoinedOrMissingThe option takes an optional argument. If the argument is given,
it will be part of the same argv entry as the option itself.
This property cannot be used alongside Joined or Separate.
MissingArgError(message)For an option marked Joined or Separate, the message
message will be used as an error message if the mandatory
argument is missing; for options without MissingArgError, a
generic error message is used. message should contain a single
‘%qs’ format, which will be used to format the name of the option
passed.
Args(n)For an option marked Separate, indicate that it takes n
arguments. The default is 1.
UIntegerThe option’s argument is a non-negative integer consisting of either
decimal or hexadecimal digits interpreted as int. Hexadecimal
integers may optionally start with the 0x or 0X prefix.
The option parser validates and converts the argument before passing
it to the relevant option handler. UInteger should also be used
with options like -falign-loops where both -falign-loops
and -falign-loops=n are supported to make sure the saved
options are given a full integer. Positive values of the argument in
excess of INT_MAX wrap around zero.
Host_Wide_IntThe option’s argument is a non-negative integer consisting of either
decimal or hexadecimal digits interpreted as the widest integer type
on the host. As with an UInteger argument, hexadecimal integers
may optionally start with the 0x or 0X prefix. The option
parser validates and converts the argument before passing it to
the relevant option handler. Host_Wide_Int should be used with
options that need to accept very large values. Positive values of
the argument in excess of HOST_WIDE_INT_M1U are assigned
HOST_WIDE_INT_M1U.
IntegerRange(n, m)The options’s arguments are integers of type int. The option’s
parser validates that the value of an option integer argument is within
the closed range [n, m].
ByteSizeA property applicable only to UInteger or Host_Wide_Int
arguments. The option’s integer argument is interpreted as if in infinite
precision using saturation arithmetic in the corresponding type. The argument
may be followed by a ‘byte-size’ suffix designating a multiple of bytes
such as kB and KiB for kilobyte and kibibyte, respectively,
MB and MiB for megabyte and mebibyte, GB and GiB
for gigabyte and gigibyte, and so on. ByteSize should be used for
with options that take a very large argument representing a size in bytes,
such as -Wlarger-than=.
ToLowerThe 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 Enum property.
NoDriverArgFor an option marked Separate, the option only takes an
argument in the compiler proper, not in the driver. This is for
compatibility with existing options that are used both directly and
via -Wp,; new options should not have this property.
Var(var)The state of this option should be stored in variable var
(actually a macro for global_options.x_var).
The way that the state is stored depends on the type of option:
Mask or InverseMask properties,
var is the integer variable that contains the mask.
UInteger property,
var is an integer variable that stores the value of the argument.
Enum property,
var is a variable (type given in the Type property of the
‘Enum’ record whose Name property has the same argument as
the Enum property of this option) that stores the value of the
argument.
Defer property, var is a pointer to
a VEC(cl_deferred_option,heap) that stores the option for later
processing. (var is declared with type void * and needs
to be cast to VEC(cl_deferred_option,heap) before use.)
The option-processing script will usually zero-initialize var.
You can modify this behavior using Init.
Var(var, set)The option controls an integer variable var and is active when
var equals set. The option parser will set var to
set when the positive form of the option is used and !set
when the “no-” form is used.
var is declared in the same way as for the single-argument form described above.
Init(value)The variable specified by the Var property should be statically
initialized to value. If more than one option using the same
variable specifies Init, all must specify the same initializer.
WarnRemovedThe option is removed and every usage of such option will result in a warning. We use it option backward compatibility.
Mask(name)The option is associated with a bit in the target_flags
variable (see Run-time Target Specification) and is active when that bit is set.
You may also specify Var to select a variable other than
target_flags.
The options-processing script will automatically allocate a unique bit
for the option. If the option is attached to ‘target_flags’ or Var
which is defined by TargetVariable, the script will set the macro
MASK_name to the appropriate bitmask. It will also declare a
TARGET_name, TARGET_name_P and
TARGET_name_OPTS_P: TARGET_name macros that has the
value 1 when the option is active and 0 otherwise, TARGET_name_P is
similar to TARGET_name but take an argument as ‘target_flags’
or TargetVariable, and TARGET_name_OPTS_P also similar to
TARGET_name but take an argument as gcc_options.
If you use Var to attach the option to a different variable which is not
defined by TargetVariable, the bitmask macro with be called
OPTION_MASK_name.
InverseMask(othername)InverseMask(othername, thisname)The option is the inverse of another option that has the
Mask(othername) property. If thisname is given,
the options-processing script will declare TARGET_thisname,
TARGET_name_P and TARGET_name_OPTS_P macros:
TARGET_thisname is 1 when the option is active and 0 otherwise,
TARGET_name_P is similar to TARGET_name but takes an
argument as ‘target_flags’, and TARGET_name_OPTS_P is also
similar to TARGET_name but takes an argument as gcc_options.
Enum(name)The option’s argument is a string from the set of strings associated with the corresponding ‘Enum’ record. The string is checked and converted to the integer specified in the corresponding ‘EnumValue’ record before being passed to option handlers.
EnumSetMust be used together with the Enum(name) property.
Corresponding ‘Enum’ record must use Set properties.
The option’s argument is either a string from the set like for
Enum(name), but with a slightly different behavior that
the whole Var isn’t overwritten, but only the bits in all the
enumeration values with the same set bitwise ored together.
Or option’s argument can be a comma separated list of strings where
each string is from a different Set(number).
EnumBitSetMust be used together with the Enum(name) property.
Similar to ‘EnumSet’, but corresponding ‘Enum’ record must
not use Set properties, each EnumValue should have
Value that is a power of 2, each value is treated as its own
set and its value as the set’s mask, so there are no mutually
exclusive arguments.
DeferThe option should be stored in a vector, specified with Var,
for later processing.
Alias(opt)Alias(opt, arg)Alias(opt, posarg, negarg)The option is an alias for -opt (or the negative form
of that option, depending on NegativeAlias). In the first form,
any argument passed to the alias is considered to be passed to
-opt, and -opt is considered to be
negated if the alias is used in negated form. In the second form, the
alias may not be negated or have an argument, and posarg is
considered to be passed as an argument to -opt. In the
third form, the alias may not have an argument, if the alias is used
in the positive form then posarg is considered to be passed to
-opt, and if the alias is used in the negative form
then negarg is considered to be passed to -opt.
Aliases should not specify Var or Mask or
UInteger. Aliases should normally specify the same languages
as the target of the alias; the flags on the target will be used to
determine any diagnostic for use of an option for the wrong language,
while those on the alias will be used to identify what command-line
text is the option and what text is any argument to that option.
When an Alias definition is used for an option, driver specs do
not need to handle it and no ‘OPT_’ enumeration value is defined
for it; only the canonical form of the option will be seen in those
places.
NegativeAliasFor an option marked with Alias(opt), the option is
considered to be an alias for the positive form of -opt
if negated and for the negative form of -opt if not
negated. NegativeAlias may not be used with the forms of
Alias taking more than one argument.
IgnoreThis option is ignored apart from printing any warning specified using
Warn. The option will not be seen by specs and no ‘OPT_’
enumeration value is defined for it.
SeparateAliasFor an option marked with Joined, Separate and
Alias, the option only acts as an alias when passed a separate
argument; with a joined argument it acts as a normal option, with an
‘OPT_’ enumeration value. This is for compatibility with the
Java -d option and should not be used for new options.
Warn(message)If this option is used, output the warning message.
message is a format string, either taking a single operand with
a ‘%qs’ format which is the option name, or not taking any
operands, which is passed to the ‘warning’ function. If an alias
is marked Warn, the target of the alias must not also be marked
Warn.
WarningThis is a warning option and should be shown as such in --help output. This flag does not currently affect anything other than --help.
OptimizationThis is an optimization option. It should be shown as such in
--help output, and any associated variable named using
Var should be saved and restored when the optimization level is
changed with optimize attributes.
PerFunctionThis is an option that can be overridden on a per-function basis.
Optimization implies PerFunction, but options that do not
affect executable code generation may use this flag instead, so that the
option is not taken into account in ways that might affect executable
code generation.
ParamThis is an option that is a parameter.
UndocumentedThe option is deliberately missing documentation and should not be included in the --help output.
Condition(cond)The option should only be accepted if preprocessor condition cond is true. Note that any C declarations associated with the option will be present even if cond is false; cond simply controls whether the option is accepted and whether it is printed in the --help output.
SaveBuild the cl_target_option structure to hold a copy of the
option, add the functions cl_target_option_save and
cl_target_option_restore to save and restore the options.
SetByCombinedThe option may also be set by a combined option such as
-ffast-math. This causes the gcc_options struct to
have a field frontend_set_name, where name
is the name of the field holding the value of this option (without the
leading 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
-ffast-math and -fno-fast-math from changing the
value of -fmath-errno for languages that do not use
errno.
EnabledBy(opt)EnabledBy(opt || opt2)EnabledBy(opt && opt2)If not explicitly set, the option is set to the value of
-opt; multiple options can be given, separated by
||. The third form using && specifies that the option is
only set if both opt and opt2 are set. The options opt
and opt2 must have the Common property; otherwise, use
LangEnabledBy.
LangEnabledBy(language, opt)LangEnabledBy(language, opt, posarg, negarg)When compiling for the given language, the option is set to the value
of -opt, if not explicitly set. opt can be also a list
of || separated options. In the second form, if
opt is used in the positive form then posarg is considered
to be passed to the option, and if opt is used in the negative
form then negarg is considered to be passed to the option. It
is possible to specify several different languages. Each
language must have been declared by an earlier Language
record. See Option file format.
NoDWARFRecordThe option is omitted from the producer string written by -grecord-gcc-switches.
PchIgnoreEven if this is a target option, this option will not be recorded / compared to determine if a precompiled header file matches.
CPP(var)The state of this option should be kept in sync with the preprocessor
option var. If this property is set, then properties Var
and Init must be set as well.
CppReason(CPP_W_Enum)This warning option corresponds to cpplib.h warning reason code
CPP_W_Enum. This should only be used for warning options of the
C-family front-ends.
UrlSuffix(url_suffix)Adjacent to each human-written .opt file in the source tree is
a corresponding file with a .opt.urls extension. These files
contain UrlSuffix directives giving the ending part of the URL
for the documentation of the option, such as:
Wabi-tag UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wabi-tag)
These URL suffixes are relative to DOCUMENTATION_ROOT_URL.
There files are generated from the .opt files and the generated
HTML documentation by regenerate-opt-urls.py, and should be
regenerated when adding new options, via manually invoking
make regenerate-opt-urls.
LangUrlSuffix_lang(url_suffix)In addition to UrlSuffix directives, regenerate-opt-urls.py
can generate language-specific URLs, such as:
LangUrlSuffix_D(gdc/Code-Generation.html#index-MMD)