компилятор C и C ++ проекта GNU (GNU project C and C++ compiler)
Параметры подробно (Options detail)
Linking
These options come into play when the compiler links object files
into an executable output file. They are meaningless if the
compiler is not doing a link step.
object-file-name
A file name that does not end in a special recognized suffix
is considered to name an object file or library. (Object
files are distinguished from libraries by the linker
according to the file contents.) If linking is done, these
object files are used as input to the linker.
-c
-S
-E If any of these options is used, then the linker is not run,
and object file names should not be used as arguments.
-flinker-output=type
This option controls the code generation of the link time
optimizer. By default the linker output is determined by the
linker plugin automatically. For debugging the compiler and
in the case of incremental linking to non-lto object file is
desired, it may be useful to control the type manually.
If type is exec the code generation is configured to produce
static binary. In this case -fpic and -fpie are both
disabled.
If type is dyn the code generation is configured to produce
shared library. In this case -fpic or -fPIC is preserved, but
not enabled automatically. This makes it possible to build
shared libraries without position independent code on
architectures this is possible, i.e. on x86.
If type is pie the code generation is configured to produce
-fpie executable. This result in similar optimizations as
exec except that -fpie is not disabled if specified at
compilation time.
If type is rel the compiler assumes that incremental linking
is done. The sections containing intermediate code for link-
time optimization are merged, pre-optimized, and output to
the resulting object file. In addition, if -ffat-lto-objects
is specified the binary code is produced for future non-lto
linking. The object file produced by incremental linking will
be smaller than a static library produced from the same
object files. At link-time the result of incremental linking
will also load faster to compiler than a static library
assuming that majority of objects in the library are used.
Finally nolto-rel configure compiler to for incremental
linking where code generation is forced, final binary is
produced and the intermediate code for later link-time
optimization is stripped. When multiple object files are
linked together the resulting code will be optimized better
than with link time optimizations disabled (for example, the
cross-module inlining will happen), most of benefits of whole
program optimizations are however lost.
During the incremental link (by -r) the linker plugin will
default to rel. With current interfaces to GNU Binutils it is
however not possible to link incrementally LTO objects and
non-LTO objects into a single mixed object file. In the case
any of object files in incremental link cannot be used for
link-time optimization the linker plugin will output warning
and use nolto-rel. To maintain the whole program optimization
it is recommended to link such objects into static library
instead. Alternatively it is possible to use H.J. Lu's
binutils with support for mixed objects.
-fuse-ld=bfd
Use the bfd linker instead of the default linker.
-fuse-ld=gold
Use the gold linker instead of the default linker.
-fuse-ld=lld
Use the LLVM lld linker instead of the default linker.
-llibrary
-l library
Search the library named library when linking. (The second
alternative with the library as a separate argument is only
for POSIX compliance and is not recommended.)
The -l option is passed directly to the linker by GCC. Refer
to your linker documentation for exact details. The general
description below applies to the GNU linker.
The linker searches a standard list of directories for the
library. The directories searched include several standard
system directories plus any that you specify with -L.
Static libraries are archives of object files, and have file
names like liblibrary.a. Some targets also support shared
libraries, which typically have names like liblibrary.so. If
both static and shared libraries are found, the linker gives
preference to linking with the shared library unless the
-static option is used.
It makes a difference where in the command you write this
option; the linker searches and processes libraries and
object files in the order they are specified. Thus, foo.o
-lz bar.o searches library z after file foo.o but before
bar.o. If bar.o refers to functions in z, those functions
may not be loaded.
-lobjc
You need this special case of the -l option in order to link
an Objective-C or Objective-C++ program.
-nostartfiles
Do not use the standard system startup files when linking.
The standard system libraries are used normally, unless
-nostdlib, -nolibc, or -nodefaultlibs is used.
-nodefaultlibs
Do not use the standard system libraries when linking. Only
the libraries you specify are passed to the linker, and
options specifying linkage of the system libraries, such as
-static-libgcc or -shared-libgcc, are ignored. The standard
startup files are used normally, unless -nostartfiles is
used.
The compiler may generate calls to "memcmp", "memset",
"memcpy" and "memmove". These entries are usually resolved
by entries in libc. These entry points should be supplied
through some other mechanism when this option is specified.
-nolibc
Do not use the C library or system libraries tightly coupled
with it when linking. Still link with the startup files,
libgcc or toolchain provided language support libraries such
as libgnat, libgfortran or libstdc++ unless options
preventing their inclusion are used as well. This typically
removes -lc from the link command line, as well as system
libraries that normally go with it and become meaningless
when absence of a C library is assumed, for example -lpthread
or -lm in some configurations. This is intended for bare-
board targets when there is indeed no C library available.
-nostdlib
Do not use the standard system startup files or libraries
when linking. No startup files and only the libraries you
specify are passed to the linker, and options specifying
linkage of the system libraries, such as -static-libgcc or
-shared-libgcc, are ignored.
The compiler may generate calls to "memcmp", "memset",
"memcpy" and "memmove". These entries are usually resolved
by entries in libc. These entry points should be supplied
through some other mechanism when this option is specified.
One of the standard libraries bypassed by -nostdlib and
-nodefaultlibs is libgcc.a, a library of internal subroutines
which GCC uses to overcome shortcomings of particular
machines, or special needs for some languages.
In most cases, you need libgcc.a even when you want to avoid
other standard libraries. In other words, when you specify
-nostdlib or -nodefaultlibs you should usually specify -lgcc
as well. This ensures that you have no unresolved references
to internal GCC library subroutines. (An example of such an
internal subroutine is "__main", used to ensure C++
constructors are called.)
-e entry
--entry=entry
Specify that the program entry point is entry. The argument
is interpreted by the linker; the GNU linker accepts either a
symbol name or an address.
-pie
Produce a dynamically linked position independent executable
on targets that support it. For predictable results, you
must also specify the same set of options used for
compilation (-fpie, -fPIE, or model suboptions) when you
specify this linker option.
-no-pie
Don't produce a dynamically linked position independent
executable.
-static-pie
Produce a static position independent executable on targets
that support it. A static position independent executable is
similar to a static executable, but can be loaded at any
address without a dynamic linker. For predictable results,
you must also specify the same set of options used for
compilation (-fpie, -fPIE, or model suboptions) when you
specify this linker option.
-pthread
Link with the POSIX threads library. This option is
supported on GNU/Linux targets, most other Unix derivatives,
and also on x86 Cygwin and MinGW targets. On some targets
this option also sets flags for the preprocessor, so it
should be used consistently for both compilation and linking.
-r Produce a relocatable object as output. This is also known
as partial linking.
-rdynamic
Pass the flag -export-dynamic to the ELF linker, on targets
that support it. This instructs the linker to add all
symbols, not only used ones, to the dynamic symbol table.
This option is needed for some uses of "dlopen" or to allow
obtaining backtraces from within a program.
-s Remove all symbol table and relocation information from the
executable.
-static
On systems that support dynamic linking, this overrides -pie
and prevents linking with the shared libraries. On other
systems, this option has no effect.
-shared
Produce a shared object which can then be linked with other
objects to form an executable. Not all systems support this
option. For predictable results, you must also specify the
same set of options used for compilation (-fpic, -fPIC, or
model suboptions) when you specify this linker option.[1]
-shared-libgcc
-static-libgcc
On systems that provide libgcc as a shared library, these
options force the use of either the shared or static version,
respectively. If no shared version of libgcc was built when
the compiler was configured, these options have no effect.
There are several situations in which an application should
use the shared libgcc instead of the static version. The
most common of these is when the application wishes to throw
and catch exceptions across different shared libraries. In
that case, each of the libraries as well as the application
itself should use the shared libgcc.
Therefore, the G++ driver automatically adds -shared-libgcc
whenever you build a shared library or a main executable,
because C++ programs typically use exceptions, so this is the
right thing to do.
If, instead, you use the GCC driver to create shared
libraries, you may find that they are not always linked with
the shared libgcc. If GCC finds, at its configuration time,
that you have a non-GNU linker or a GNU linker that does not
support option --eh-frame-hdr, it links the shared version of
libgcc into shared libraries by default. Otherwise, it takes
advantage of the linker and optimizes away the linking with
the shared version of libgcc, linking with the static version
of libgcc by default. This allows exceptions to propagate
through such shared libraries, without incurring relocation
costs at library load time.
However, if a library or main executable is supposed to throw
or catch exceptions, you must link it using the G++ driver,
or using the option -shared-libgcc, such that it is linked
with the shared libgcc.
-static-libasan
When the -fsanitize=address option is used to link a program,
the GCC driver automatically links against libasan. If
libasan is available as a shared library, and the -static
option is not used, then this links against the shared
version of libasan. The -static-libasan option directs the
GCC driver to link libasan statically, without necessarily
linking other libraries statically.
-static-libtsan
When the -fsanitize=thread option is used to link a program,
the GCC driver automatically links against libtsan. If
libtsan is available as a shared library, and the -static
option is not used, then this links against the shared
version of libtsan. The -static-libtsan option directs the
GCC driver to link libtsan statically, without necessarily
linking other libraries statically.
-static-liblsan
When the -fsanitize=leak option is used to link a program,
the GCC driver automatically links against liblsan. If
liblsan is available as a shared library, and the -static
option is not used, then this links against the shared
version of liblsan. The -static-liblsan option directs the
GCC driver to link liblsan statically, without necessarily
linking other libraries statically.
-static-libubsan
When the -fsanitize=undefined option is used to link a
program, the GCC driver automatically links against libubsan.
If libubsan is available as a shared library, and the -static
option is not used, then this links against the shared
version of libubsan. The -static-libubsan option directs the
GCC driver to link libubsan statically, without necessarily
linking other libraries statically.
-static-libstdc++
When the g++ program is used to link a C++ program, it
normally automatically links against libstdc++. If libstdc++
is available as a shared library, and the -static option is
not used, then this links against the shared version of
libstdc++. That is normally fine. However, it is sometimes
useful to freeze the version of libstdc++ used by the program
without going all the way to a fully static link. The
-static-libstdc++ option directs the g++ driver to link
libstdc++ statically, without necessarily linking other
libraries statically.
-symbolic
Bind references to global symbols when building a shared
object. Warn about any unresolved references (unless
overridden by the link editor option -Xlinker -z -Xlinker
defs). Only a few systems support this option.
-T script
Use script as the linker script. This option is supported by
most systems using the GNU linker. On some targets, such as
bare-board targets without an operating system, the -T option
may be required when linking to avoid references to undefined
symbols.
-Xlinker option
Pass option as an option to the linker. You can use this to
supply system-specific linker options that GCC does not
recognize.
If you want to pass an option that takes a separate argument,
you must use -Xlinker twice, once for the option and once for
the argument. For example, to pass -assert definitions, you
must write -Xlinker -assert -Xlinker definitions. It does
not work to write -Xlinker "-assert definitions", because
this passes the entire string as a single argument, which is
not what the linker expects.
When using the GNU linker, it is usually more convenient to
pass arguments to linker options using the option=value
syntax than as separate arguments. For example, you can
specify -Xlinker -Map=output.map rather than -Xlinker -Map
-Xlinker output.map. Other linkers may not support this
syntax for command-line options.
-Wl,option
Pass option as an option to the linker. If option contains
commas, it is split into multiple options at the commas. You
can use this syntax to pass an argument to the option. For
example, -Wl,-Map,output.map passes -Map output.map to the
linker. When using the GNU linker, you can also get the same
effect with -Wl,-Map=output.map.
-u symbol
Pretend the symbol symbol is undefined, to force linking of
library modules to define it. You can use -u multiple times
with different symbols to force loading of additional library
modules.
-z keyword
-z is passed directly on to the linker along with the keyword
keyword. See the section in the documentation of your linker
for permitted values and their meanings.
