gccgo command is a frontend to
supports many of the same options. See Option
Summary in Using the GNU Compiler Collection (GCC). This manual
only documents the options specific to
gccgo command may be used to compile Go source code into
an object file, link a collection of object files together, or do both
Go source code is compiled as packages. A package consists of one or
more Go source files. All the files in a single package must be
compiled together, by passing all the files as arguments to
gccgo. A single invocation of
gccgo may only
compile a single package.
One Go package may
import a different Go package. The imported
package must have already been compiled;
gccgo will read
the import data directly from the compiled package. When this package
is later linked, the compiled form of the package must be included in
the link command.
Go programs must generally be compiled with debugging information, and -g1 is the default as described below. Stripping a Go program will generally cause it to misbehave or fail.
Specify a directory to use when searching for an import package at compile time.
When linking, specify a library search directory, as with
Set the package path to use. This sets the value returned by the PkgPath method of reflect.Type objects. It is also used for the names of globally visible symbols. The argument to this option should normally be the string that will be used to import this package after it has been installed; in other words, a pathname within the directories specified by the -I option.
An alternative to -fgo-pkgpath. The argument will be combined with the package name from the source file to produce the package path. If -fgo-pkgpath is used, -fgo-prefix will be ignored.
Go permits a single program to include more than one package with the
same name in the
package clause in the source file, though
obviously the two packages must be imported using different pathnames.
In order for this to work with
-fgo-pkgpath or -fgo-prefix must be specified when
compiling a package.
Using either -fgo-pkgpath or -fgo-prefix disables
the special treatment of the
main package and permits that
package to be imported like any other.
A relative import is an import that starts with ./ or
../. If this option is used,
gccgo will use
dir as a prefix for the relative import when searching for it.
gccgo will warn about functions which have one or
more return parameters but lack an explicit
This warning may be disabled using
Add explicit checks for division by zero. In Go a division (or
modulos) by zero causes a panic. On Unix systems this is detected in
the runtime by catching the
SIGFPE signal. Some processors,
such as PowerPC, do not generate a SIGFPE on division by zero. Some
runtimes do not generate a signal that can be caught. On those
systems, this option may be used. Or the checks may be removed via
-fno-go-check-divide-zero. This option is currently on by
default, but in the future may be off by default on systems that do
not require it.
Add explicit checks for division overflow. For example, division
overflow occurs when computing
INT_MIN / -1. In Go this should
be wrapped, to produce
INT_MIN. Some processors, such as x86,
generate a trap on division overflow. On those systems, this option
may be used. Or the checks may be removed via
-fno-go-check-divide-overflow. This option is currently on
by default, but in the future may be off by default on systems that do
not require it.
Use escape analysis to allocate objects on the stack rather than the heap when possible. In the future this may be the default.
Output escape analysis debugging information. Larger values of n generate more information.
Write top-level named Go struct definitions to file as C code. This is used when compiling the runtime package.
Apply special rules for compiling the runtime package. Implicit memory allocation is forbidden. Some additional compiler directives are supported.
This is the standard
gcc option (see Debugging Options in Using the GNU Compiler Collection (GCC)). It
is mentioned here because by default
gccgo turns on
debugging information generation with the equivalent of the standard
option -g1. This is because Go programs require debugging
information to be available in order to get backtrace information. An
explicit -g0 may be used to disable the generation of
debugging information, in which case certain standard library
functions, such as
runtime.Callers, will not operate correctly.