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\input texinfo @c -*-texinfo-*-

\input texinfo @c -*-texinfo-*-

@setfilename gcj.info

@setfilename gcj.info

@settitle Guide to GNU gcj

@settitle Guide to GNU gcj

@c Merge the standard indexes into a single one.

@c Merge the standard indexes into a single one.

@syncodeindex fn cp

@syncodeindex fn cp

@syncodeindex vr cp

@syncodeindex vr cp

@syncodeindex ky cp

@syncodeindex ky cp

@syncodeindex pg cp

@syncodeindex pg cp

@syncodeindex tp cp

@syncodeindex tp cp

@include gcc-common.texi

@include gcc-common.texi

@c Note: When reading this manual you'll find lots of strange

@c Note: When reading this manual you'll find lots of strange

@c circumlocutions like ``compiler for the Java language''.

@c circumlocutions like ``compiler for the Java language''.

@c This is necessary due to Sun's restrictions on the use of

@c This is necessary due to Sun's restrictions on the use of

@c the word ``Java'.

@c the word ``Java'.

@c When this manual is copyrighted.

@c When this manual is copyrighted.

@set copyrights-gcj 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008

@set copyrights-gcj 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008

@copying

@copying

@c man begin COPYRIGHT

@c man begin COPYRIGHT

Copyright @copyright{} @value{copyrights-gcj} Free Software Foundation, Inc.

Copyright @copyright{} @value{copyrights-gcj} Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document

Permission is granted to copy, distribute and/or modify this document

under the terms of the GNU Free Documentation License, Version 1.2 or

under the terms of the GNU Free Documentation License, Version 1.2 or

any later version published by the Free Software Foundation; with no

any later version published by the Free Software Foundation; with no

Invariant Sections, the Front-Cover Texts being (a) (see below), and

Invariant Sections, the Front-Cover Texts being (a) (see below), and

with the Back-Cover Texts being (b) (see below).

with the Back-Cover Texts being (b) (see below).

A copy of the license is included in the

A copy of the license is included in the

@c man end

@c man end

section entitled ``GNU Free Documentation License''.

section entitled ``GNU Free Documentation License''.

@ignore

@ignore

@c man begin COPYRIGHT

@c man begin COPYRIGHT

man page gfdl(7).

man page gfdl(7).

@c man end

@c man end

@end ignore

@end ignore

@c man begin COPYRIGHT

@c man begin COPYRIGHT

(a) The FSF's Front-Cover Text is:

(a) The FSF's Front-Cover Text is:

     A GNU Manual

     A GNU Manual

(b) The FSF's Back-Cover Text is:

(b) The FSF's Back-Cover Text is:

     You have freedom to copy and modify this GNU Manual, like GNU

     You have freedom to copy and modify this GNU Manual, like GNU

     software.  Copies published by the Free Software Foundation raise

     software.  Copies published by the Free Software Foundation raise

     funds for GNU development.

     funds for GNU development.

@c man end

@c man end

@end copying

@end copying

@ifinfo

@ifinfo

@format

@format

@dircategory Software development

@dircategory Software development

@direntry

@direntry

* Gcj: (gcj).               Ahead-of-time compiler for the Java language

* Gcj: (gcj).               Ahead-of-time compiler for the Java language

@end direntry

@end direntry

@dircategory Individual utilities

@dircategory Individual utilities

@direntry

@direntry

* jcf-dump: (gcj)Invoking jcf-dump.

* jcf-dump: (gcj)Invoking jcf-dump.

                            Print information about Java class files

                            Print information about Java class files

* gij: (gcj)Invoking gij.   GNU interpreter for Java bytecode

* gij: (gcj)Invoking gij.   GNU interpreter for Java bytecode

* gcj-dbtool: (gcj)Invoking gcj-dbtool.

* gcj-dbtool: (gcj)Invoking gcj-dbtool.

                            Tool for manipulating class file databases.

                            Tool for manipulating class file databases.

* jv-convert: (gcj)Invoking jv-convert.

* jv-convert: (gcj)Invoking jv-convert.

                            Convert file from one encoding to another

                            Convert file from one encoding to another

* grmic: (gcj)Invoking grmic.

* grmic: (gcj)Invoking grmic.

                            Generate stubs for Remote Method Invocation.

                            Generate stubs for Remote Method Invocation.

* gc-analyze: (gcj)Invoking gc-analyze.

* gc-analyze: (gcj)Invoking gc-analyze.

                            Analyze Garbage Collector (GC) memory dumps.

                            Analyze Garbage Collector (GC) memory dumps.

* aot-compile: (gcj)Invoking aot-compile.

* aot-compile: (gcj)Invoking aot-compile.

                            Compile bytecode to native and generate databases.

                            Compile bytecode to native and generate databases.

* rebuild-gcj-db: (gcj)Invoking rebuild-gcj-db.

* rebuild-gcj-db: (gcj)Invoking rebuild-gcj-db.

                            Merge the per-solib databases made by aot-compile

                            Merge the per-solib databases made by aot-compile

                            into one system-wide database.

                            into one system-wide database.

@end direntry

@end direntry

@end format

@end format

@insertcopying

@insertcopying

@end ifinfo

@end ifinfo

@titlepage

@titlepage

@title GNU gcj

@title GNU gcj

@versionsubtitle

@versionsubtitle

@author Tom Tromey

@author Tom Tromey

@page

@page

@vskip 0pt plus 1filll

@vskip 0pt plus 1filll

Published by the Free Software Foundation @*

Published by the Free Software Foundation @*

51 Franklin Street, Fifth Floor@*

51 Franklin Street, Fifth Floor@*

Boston, MA 02110-1301, USA@*

Boston, MA 02110-1301, USA@*

@sp 1

@sp 1

@insertcopying

@insertcopying

@end titlepage

@end titlepage

@contents

@contents

@page

@page

@node Top

@node Top

@top Introduction

@top Introduction

This manual describes how to use @command{gcj}, the GNU compiler for the

This manual describes how to use @command{gcj}, the GNU compiler for the

Java programming language.  @command{gcj} can generate both @file{.class}

Java programming language.  @command{gcj} can generate both @file{.class}

files and object files, and it can read both Java source code and

files and object files, and it can read both Java source code and

@file{.class} files.

@file{.class} files.

@menu

@menu

* Copying::             The GNU General Public License

* Copying::             The GNU General Public License

* GNU Free Documentation License::

* GNU Free Documentation License::

                        How you can share and copy this manual

                        How you can share and copy this manual

* Invoking gcj::        Compiler options supported by @command{gcj}

* Invoking gcj::        Compiler options supported by @command{gcj}

* Compatibility::       Compatibility between gcj and other tools for Java

* Compatibility::       Compatibility between gcj and other tools for Java

* Invoking jcf-dump::   Print information about class files

* Invoking jcf-dump::   Print information about class files

* Invoking gij::        Interpreting Java bytecodes

* Invoking gij::        Interpreting Java bytecodes

* Invoking gcj-dbtool:: Tool for manipulating class file databases.

* Invoking gcj-dbtool:: Tool for manipulating class file databases.

* Invoking jv-convert:: Converting from one encoding to another

* Invoking jv-convert:: Converting from one encoding to another

* Invoking grmic::      Generate stubs for Remote Method Invocation.

* Invoking grmic::      Generate stubs for Remote Method Invocation.

* Invoking gc-analyze:: Analyze Garbage Collector (GC) memory dumps.

* Invoking gc-analyze:: Analyze Garbage Collector (GC) memory dumps.

* Invoking aot-compile:: Compile bytecode to native and generate databases.

* Invoking aot-compile:: Compile bytecode to native and generate databases.

* Invoking rebuild-gcj-db:: Merge the per-solib databases made by aot-compile

* Invoking rebuild-gcj-db:: Merge the per-solib databases made by aot-compile

                            into one system-wide database.

                            into one system-wide database.

* About CNI::           Description of the Compiled Native Interface

* About CNI::           Description of the Compiled Native Interface

* System properties::   Modifying runtime behavior of the libgcj library

* System properties::   Modifying runtime behavior of the libgcj library

* Resources::           Where to look for more information

* Resources::           Where to look for more information

* Index::               Index.

* Index::               Index.

@end menu

@end menu

@include gpl_v3.texi

@include gpl_v3.texi

@include fdl.texi

@include fdl.texi

@node Invoking gcj

@node Invoking gcj

@chapter Invoking gcj

@chapter Invoking gcj

@c man title gcj Ahead-of-time compiler for the Java language

@c man title gcj Ahead-of-time compiler for the Java language

@ignore

@ignore

@c man begin SYNOPSIS gcj

@c man begin SYNOPSIS gcj

gcj [@option{-I}@var{dir}@dots{}] [@option{-d} @var{dir}@dots{}]

gcj [@option{-I}@var{dir}@dots{}] [@option{-d} @var{dir}@dots{}]

    [@option{--CLASSPATH}=@var{path}] [@option{--classpath}=@var{path}]

    [@option{--CLASSPATH}=@var{path}] [@option{--classpath}=@var{path}]

    [@option{-f}@var{option}@dots{}] [@option{--encoding}=@var{name}]

    [@option{-f}@var{option}@dots{}] [@option{--encoding}=@var{name}]

    [@option{--main}=@var{classname}] [@option{-D}@var{name}[=@var{value}]@dots{}]

    [@option{--main}=@var{classname}] [@option{-D}@var{name}[=@var{value}]@dots{}]

    [@option{-C}] [@option{--resource} @var{resource-name}] [@option{-d} @var{directory}]

    [@option{-C}] [@option{--resource} @var{resource-name}] [@option{-d} @var{directory}]

    [@option{-W}@var{warn}@dots{}]

    [@option{-W}@var{warn}@dots{}]

    @var{sourcefile}@dots{}

    @var{sourcefile}@dots{}

@c man end

@c man end

@c man begin SEEALSO gcj

@c man begin SEEALSO gcj

gcc(1), gcjh(1), gjnih(1), gij(1), jcf-dump(1), gfdl(7),

gcc(1), gcjh(1), gjnih(1), gij(1), jcf-dump(1), gfdl(7),

and the Info entries for @file{gcj} and @file{gcc}.

and the Info entries for @file{gcj} and @file{gcc}.

@c man end

@c man end

@end ignore

@end ignore

@c man begin DESCRIPTION gcj

@c man begin DESCRIPTION gcj

As @command{gcj} is just another front end to @command{gcc}, it supports many

As @command{gcj} is just another front end to @command{gcc}, it supports many

of the same options as gcc.  @xref{Option Summary, , Option Summary,

of the same options as gcc.  @xref{Option Summary, , Option Summary,

gcc, Using the GNU Compiler Collection (GCC)}.  This manual only documents the

gcc, Using the GNU Compiler Collection (GCC)}.  This manual only documents the

options specific to @command{gcj}.

options specific to @command{gcj}.

@c man end

@c man end

@menu

@menu

* Input and output files::

* Input and output files::

* Input Options::               How gcj finds files

* Input Options::               How gcj finds files

* Encodings::                   Options controlling source file encoding

* Encodings::                   Options controlling source file encoding

* Warnings::                    Options controlling warnings specific to gcj

* Warnings::                    Options controlling warnings specific to gcj

* Linking::                     Options for making an executable

* Linking::                     Options for making an executable

* Code Generation::             Options controlling the output of gcj

* Code Generation::             Options controlling the output of gcj

* Configure-time Options::      Options you won't use

* Configure-time Options::      Options you won't use

@end menu

@end menu

@c man begin OPTIONS gcj

@c man begin OPTIONS gcj

@node Input and output files

@node Input and output files

@section Input and output files

@section Input and output files

A @command{gcj} command is like a @command{gcc} command, in that it

A @command{gcj} command is like a @command{gcc} command, in that it

consists of a number of options and file names.  The following kinds

consists of a number of options and file names.  The following kinds

of input file names are supported:

of input file names are supported:

@table @gcctabopt

@table @gcctabopt

@item @var{file}.java

@item @var{file}.java

Java source files.

Java source files.

@item @var{file}.class

@item @var{file}.class

Java bytecode files.

Java bytecode files.

@item @var{file}.zip

@item @var{file}.zip

@itemx @var{file}.jar

@itemx @var{file}.jar

An archive containing one or more @code{.class} files, all of

An archive containing one or more @code{.class} files, all of

which are compiled.  The archive may be compressed.  Files in

which are compiled.  The archive may be compressed.  Files in

an archive which don't end with @samp{.class} are treated as

an archive which don't end with @samp{.class} are treated as

resource files; they are compiled into the resulting object file

resource files; they are compiled into the resulting object file

as @samp{core:} URLs.

as @samp{core:} URLs.

@item @@@var{file}

@item @@@var{file}

A file containing a whitespace-separated list of input file names.

A file containing a whitespace-separated list of input file names.

(Currently, these must all be @code{.java} source files, but that

(Currently, these must all be @code{.java} source files, but that

may change.)

may change.)

Each named file is compiled, just as if it had been on the command line.

Each named file is compiled, just as if it had been on the command line.

@item @var{library}.a

@item @var{library}.a

@itemx @var{library}.so

@itemx @var{library}.so

@itemx -l@var{libname}

@itemx -l@var{libname}

Libraries to use when linking.  See the @command{gcc} manual.

Libraries to use when linking.  See the @command{gcc} manual.

@end table

@end table

You can specify more than one input file on the @command{gcj} command line,

You can specify more than one input file on the @command{gcj} command line,

in which case they will all be compiled.  If you specify a

in which case they will all be compiled.  If you specify a

@code{-o @var{FILENAME}}

@code{-o @var{FILENAME}}

option, all the input files will be compiled together, producing a

option, all the input files will be compiled together, producing a

single output file, named @var{FILENAME}.

single output file, named @var{FILENAME}.

This is allowed even when using @code{-S} or @code{-c},

This is allowed even when using @code{-S} or @code{-c},

but not when using @code{-C} or @code{--resource}.

but not when using @code{-C} or @code{--resource}.

(This is an extension beyond the what plain @command{gcc} allows.)

(This is an extension beyond the what plain @command{gcc} allows.)

(If more than one input file is specified, all must currently

(If more than one input file is specified, all must currently

be @code{.java} files, though we hope to fix this.)

be @code{.java} files, though we hope to fix this.)

@node Input Options

@node Input Options

@section Input Options

@section Input Options

@cindex class path

@cindex class path

@command{gcj} has options to control where it looks to find files it needs.

@command{gcj} has options to control where it looks to find files it needs.

For instance, @command{gcj} might need to load a class that is referenced

For instance, @command{gcj} might need to load a class that is referenced

by the file it has been asked to compile.  Like other compilers for the

by the file it has been asked to compile.  Like other compilers for the

Java language, @command{gcj} has a notion of a @dfn{class path}.  There are

Java language, @command{gcj} has a notion of a @dfn{class path}.  There are

several options and environment variables which can be used to

several options and environment variables which can be used to

manipulate the class path.  When @command{gcj} looks for a given class, it

manipulate the class path.  When @command{gcj} looks for a given class, it

searches the class path looking for matching @file{.class} or

searches the class path looking for matching @file{.class} or

@file{.java} file.  @command{gcj} comes with a built-in class path which

@file{.java} file.  @command{gcj} comes with a built-in class path which

points at the installed @file{libgcj.jar}, a file which contains all the

points at the installed @file{libgcj.jar}, a file which contains all the

standard classes.

standard classes.

In the text below, a directory or path component can refer either to an

In the text below, a directory or path component can refer either to an

actual directory on the filesystem, or to a @file{.zip} or @file{.jar}

actual directory on the filesystem, or to a @file{.zip} or @file{.jar}

file, which @command{gcj} will search as if it is a directory.

file, which @command{gcj} will search as if it is a directory.

@table @gcctabopt

@table @gcctabopt

@item -I@var{dir}

@item -I@var{dir}

All directories specified by @code{-I} are kept in order and prepended

All directories specified by @code{-I} are kept in order and prepended

to the class path constructed from all the other options.  Unless

to the class path constructed from all the other options.  Unless

compatibility with tools like @code{javac} is important, we recommend

compatibility with tools like @code{javac} is important, we recommend

always using @code{-I} instead of the other options for manipulating the

always using @code{-I} instead of the other options for manipulating the

class path.

class path.

@item --classpath=@var{path}

@item --classpath=@var{path}

This sets the class path to @var{path}, a colon-separated list of paths

This sets the class path to @var{path}, a colon-separated list of paths

(on Windows-based systems, a semicolon-separate list of paths).

(on Windows-based systems, a semicolon-separate list of paths).

This does not override the builtin (``boot'') search path.

This does not override the builtin (``boot'') search path.

@item --CLASSPATH=@var{path}

@item --CLASSPATH=@var{path}

Deprecated synonym for @code{--classpath}.

Deprecated synonym for @code{--classpath}.

@item --bootclasspath=@var{path}

@item --bootclasspath=@var{path}

Where to find the standard builtin classes, such as @code{java.lang.String}.

Where to find the standard builtin classes, such as @code{java.lang.String}.

@item --extdirs=@var{path}

@item --extdirs=@var{path}

For each directory in the @var{path}, place the contents of that

For each directory in the @var{path}, place the contents of that

directory at the end of the class path.

directory at the end of the class path.

@item CLASSPATH

@item CLASSPATH

This is an environment variable which holds a list of paths.

This is an environment variable which holds a list of paths.

@end table

@end table

The final class path is constructed like so:

The final class path is constructed like so:

@itemize @bullet

@itemize @bullet

@item

@item

First come all directories specified via @code{-I}.

First come all directories specified via @code{-I}.

@item

@item

If @option{--classpath} is specified, its value is appended.

If @option{--classpath} is specified, its value is appended.

Otherwise, if the @code{CLASSPATH} environment variable is specified,

Otherwise, if the @code{CLASSPATH} environment variable is specified,

then its value is appended.

then its value is appended.

Otherwise, the current directory (@code{"."}) is appended.

Otherwise, the current directory (@code{"."}) is appended.

@item

@item

If @code{--bootclasspath} was specified, append its value.

If @code{--bootclasspath} was specified, append its value.

Otherwise, append the built-in system directory, @file{libgcj.jar}.

Otherwise, append the built-in system directory, @file{libgcj.jar}.

@item

@item

Finally, if @code{--extdirs} was specified, append the contents of the

Finally, if @code{--extdirs} was specified, append the contents of the

specified directories at the end of the class path.  Otherwise, append

specified directories at the end of the class path.  Otherwise, append

the contents of the built-in extdirs at @code{$(prefix)/share/java/ext}.

the contents of the built-in extdirs at @code{$(prefix)/share/java/ext}.

@end itemize

@end itemize

The classfile built by @command{gcj} for the class @code{java.lang.Object}

The classfile built by @command{gcj} for the class @code{java.lang.Object}

(and placed in @code{libgcj.jar}) contains a special zero length

(and placed in @code{libgcj.jar}) contains a special zero length

attribute @code{gnu.gcj.gcj-compiled}. The compiler looks for this

attribute @code{gnu.gcj.gcj-compiled}. The compiler looks for this

attribute when loading @code{java.lang.Object} and will report an error

attribute when loading @code{java.lang.Object} and will report an error

if it isn't found, unless it compiles to bytecode (the option

if it isn't found, unless it compiles to bytecode (the option

@code{-fforce-classes-archive-check} can be used to override this

@code{-fforce-classes-archive-check} can be used to override this

behavior in this particular case.)

behavior in this particular case.)

@table @gcctabopt

@table @gcctabopt

@item -fforce-classes-archive-check

@item -fforce-classes-archive-check

This forces the compiler to always check for the special zero length

This forces the compiler to always check for the special zero length

attribute @code{gnu.gcj.gcj-compiled} in @code{java.lang.Object} and

attribute @code{gnu.gcj.gcj-compiled} in @code{java.lang.Object} and

issue an error if it isn't found.

issue an error if it isn't found.

@item -fsource=@var{VERSION}

@item -fsource=@var{VERSION}

This option is used to choose the source version accepted by

This option is used to choose the source version accepted by

@command{gcj}.  The default is @samp{1.5}.

@command{gcj}.  The default is @samp{1.5}.

@end table

@end table

@node Encodings

@node Encodings

@section Encodings

@section Encodings

The Java programming language uses Unicode throughout.  In an effort to

The Java programming language uses Unicode throughout.  In an effort to

integrate well with other locales, @command{gcj} allows @file{.java} files

integrate well with other locales, @command{gcj} allows @file{.java} files

to be written using almost any encoding.  @command{gcj} knows how to

to be written using almost any encoding.  @command{gcj} knows how to

convert these encodings into its internal encoding at compile time.

convert these encodings into its internal encoding at compile time.

You can use the @code{--encoding=@var{NAME}} option to specify an

You can use the @code{--encoding=@var{NAME}} option to specify an

encoding (of a particular character set) to use for source files.  If

encoding (of a particular character set) to use for source files.  If

this is not specified, the default encoding comes from your current

this is not specified, the default encoding comes from your current

locale.  If your host system has insufficient locale support, then

locale.  If your host system has insufficient locale support, then

@command{gcj} assumes the default encoding to be the @samp{UTF-8} encoding

@command{gcj} assumes the default encoding to be the @samp{UTF-8} encoding

of Unicode.

of Unicode.

To implement @code{--encoding}, @command{gcj} simply uses the host

To implement @code{--encoding}, @command{gcj} simply uses the host

platform's @code{iconv} conversion routine.  This means that in practice

platform's @code{iconv} conversion routine.  This means that in practice

@command{gcj} is limited by the capabilities of the host platform.

@command{gcj} is limited by the capabilities of the host platform.

The names allowed for the argument @code{--encoding} vary from platform

The names allowed for the argument @code{--encoding} vary from platform

to platform (since they are not standardized anywhere).  However,

to platform (since they are not standardized anywhere).  However,

@command{gcj} implements the encoding named @samp{UTF-8} internally, so if

@command{gcj} implements the encoding named @samp{UTF-8} internally, so if

you choose to use this for your source files you can be assured that it

you choose to use this for your source files you can be assured that it

will work on every host.

will work on every host.

@node Warnings

@node Warnings

@section Warnings

@section Warnings

@command{gcj} implements several warnings.  As with other generic

@command{gcj} implements several warnings.  As with other generic

@command{gcc} warnings, if an option of the form @code{-Wfoo} enables a

@command{gcc} warnings, if an option of the form @code{-Wfoo} enables a

warning, then @code{-Wno-foo} will disable it.  Here we've chosen to

warning, then @code{-Wno-foo} will disable it.  Here we've chosen to

document the form of the warning which will have an effect -- the

document the form of the warning which will have an effect -- the

default being the opposite of what is listed.

default being the opposite of what is listed.

@table @gcctabopt

@table @gcctabopt

@item -Wredundant-modifiers

@item -Wredundant-modifiers

With this flag, @command{gcj} will warn about redundant modifiers.  For

With this flag, @command{gcj} will warn about redundant modifiers.  For

instance, it will warn if an interface method is declared @code{public}.

instance, it will warn if an interface method is declared @code{public}.

@item -Wextraneous-semicolon

@item -Wextraneous-semicolon

This causes @command{gcj} to warn about empty statements.  Empty statements

This causes @command{gcj} to warn about empty statements.  Empty statements

have been deprecated.

have been deprecated.

@item -Wno-out-of-date

@item -Wno-out-of-date

This option will cause @command{gcj} not to warn when a source file is

This option will cause @command{gcj} not to warn when a source file is

newer than its matching class file.  By default @command{gcj} will warn

newer than its matching class file.  By default @command{gcj} will warn

about this.

about this.

@item -Wno-deprecated

@item -Wno-deprecated

Warn if a deprecated class, method, or field is referred to.

Warn if a deprecated class, method, or field is referred to.

@item -Wunused

@item -Wunused

This is the same as @command{gcc}'s @code{-Wunused}.

This is the same as @command{gcc}'s @code{-Wunused}.

@item -Wall

@item -Wall

This is the same as @code{-Wredundant-modifiers -Wextraneous-semicolon

This is the same as @code{-Wredundant-modifiers -Wextraneous-semicolon

-Wunused}.

-Wunused}.

@end table

@end table

@node Linking

@node Linking

@section Linking

@section Linking

To turn a Java application into an executable program,

To turn a Java application into an executable program,

you need to link it with the needed libraries, just as for C or C++.

you need to link it with the needed libraries, just as for C or C++.

The linker by default looks for a global function named @code{main}.

The linker by default looks for a global function named @code{main}.

Since Java does not have global functions, and a

Since Java does not have global functions, and a

collection of Java classes may have more than one class with a

collection of Java classes may have more than one class with a

@code{main} method, you need to let the linker know which of those

@code{main} method, you need to let the linker know which of those

@code{main} methods it should invoke when starting the application.

@code{main} methods it should invoke when starting the application.

You can do that in any of these ways:

You can do that in any of these ways:

@itemize @bullet

@itemize @bullet

@item

@item

Specify the class containing the desired @code{main} method

Specify the class containing the desired @code{main} method

when you link the application, using the @code{--main} flag,

when you link the application, using the @code{--main} flag,

described below.

described below.

@item

@item

Link the Java package(s) into a shared library (dll) rather than an

Link the Java package(s) into a shared library (dll) rather than an

executable.  Then invoke the application using the @code{gij} program,

executable.  Then invoke the application using the @code{gij} program,

making sure that @code{gij} can find the libraries it needs.

making sure that @code{gij} can find the libraries it needs.

@item

@item

Link the Java packages(s) with the flag @code{-lgij}, which links

Link the Java packages(s) with the flag @code{-lgij}, which links

in the @code{main} routine from the @code{gij} command.

in the @code{main} routine from the @code{gij} command.

This allows you to select the class whose @code{main} method you

This allows you to select the class whose @code{main} method you

want to run when you run the application.  You can also use

want to run when you run the application.  You can also use

other @code{gij} flags, such as @code{-D} flags to set properties.

other @code{gij} flags, such as @code{-D} flags to set properties.

Using the @code{-lgij} library (rather than the @code{gij} program

Using the @code{-lgij} library (rather than the @code{gij} program

of the previous mechanism) has some advantages: it is compatible with

of the previous mechanism) has some advantages: it is compatible with

static linking, and does not require configuring or installing libraries.

static linking, and does not require configuring or installing libraries.

@end itemize

@end itemize

These @code{gij} options relate to linking an executable:

These @code{gij} options relate to linking an executable:

@table @gcctabopt

@table @gcctabopt

@item --main=@var{CLASSNAME}

@item --main=@var{CLASSNAME}

This option is used when linking to specify the name of the class whose

This option is used when linking to specify the name of the class whose

@code{main} method should be invoked when the resulting executable is

@code{main} method should be invoked when the resulting executable is

run.

run.

@item -D@var{name}[=@var{value}]

@item -D@var{name}[=@var{value}]

This option can only be used with @code{--main}.  It defines a system

This option can only be used with @code{--main}.  It defines a system

property named @var{name} with value @var{value}.  If @var{value} is not

property named @var{name} with value @var{value}.  If @var{value} is not

specified then it defaults to the empty string.  These system properties

specified then it defaults to the empty string.  These system properties

are initialized at the program's startup and can be retrieved at runtime

are initialized at the program's startup and can be retrieved at runtime

using the @code{java.lang.System.getProperty} method.

using the @code{java.lang.System.getProperty} method.

@item -lgij

@item -lgij

Create an application whose command-line processing is that

Create an application whose command-line processing is that

of the @code{gij} command.

of the @code{gij} command.

This option is an alternative to using @code{--main}; you cannot use both.

This option is an alternative to using @code{--main}; you cannot use both.

@item -static-libgcj

@item -static-libgcj

This option causes linking to be done against a static version of the

This option causes linking to be done against a static version of the

libgcj runtime library.  This option is only available if

libgcj runtime library.  This option is only available if

corresponding linker support exists.

corresponding linker support exists.

@strong{Caution:} Static linking of libgcj may cause essential parts

@strong{Caution:} Static linking of libgcj may cause essential parts

of libgcj to be omitted.  Some parts of libgcj use reflection to load

of libgcj to be omitted.  Some parts of libgcj use reflection to load

classes at runtime.  Since the linker does not see these references at

classes at runtime.  Since the linker does not see these references at

link time, it can omit the referred to classes.  The result is usually

link time, it can omit the referred to classes.  The result is usually

(but not always) a @code{ClassNotFoundException} being thrown at

(but not always) a @code{ClassNotFoundException} being thrown at

runtime. Caution must be used when using this option.  For more

runtime. Caution must be used when using this option.  For more

details see:

details see:

@w{@uref{http://gcc.gnu.org/wiki/Statically%20linking%20libgcj}}

@w{@uref{http://gcc.gnu.org/wiki/Statically%20linking%20libgcj}}

@end table

@end table

@node Code Generation

@node Code Generation

@section Code Generation

@section Code Generation

In addition to the many @command{gcc} options controlling code generation,

In addition to the many @command{gcc} options controlling code generation,

@command{gcj} has several options specific to itself.

@command{gcj} has several options specific to itself.

@table @gcctabopt

@table @gcctabopt

@item -C

@item -C

This option is used to tell @command{gcj} to generate bytecode

This option is used to tell @command{gcj} to generate bytecode

(@file{.class} files) rather than object code.

(@file{.class} files) rather than object code.

@item --resource @var{resource-name}

@item --resource @var{resource-name}

This option is used to tell @command{gcj} to compile the contents of a

This option is used to tell @command{gcj} to compile the contents of a

given file to object code so it may be accessed at runtime with the core

given file to object code so it may be accessed at runtime with the core

protocol handler as @samp{core:/@var{resource-name}}.  Note that

protocol handler as @samp{core:/@var{resource-name}}.  Note that

@var{resource-name} is the name of the resource as found at runtime; for

@var{resource-name} is the name of the resource as found at runtime; for

instance, it could be used in a call to @code{ResourceBundle.getBundle}.

instance, it could be used in a call to @code{ResourceBundle.getBundle}.

The actual file name to be compiled this way must be specified

The actual file name to be compiled this way must be specified

separately.

separately.

@item -ftarget=@var{VERSION}

@item -ftarget=@var{VERSION}

This can be used with @option{-C} to choose the version of bytecode

This can be used with @option{-C} to choose the version of bytecode

emitted by @command{gcj}.  The default is @samp{1.5}.  When not

emitted by @command{gcj}.  The default is @samp{1.5}.  When not

generating bytecode, this option has no effect.

generating bytecode, this option has no effect.

@item -d @var{directory}

@item -d @var{directory}

When used with @code{-C}, this causes all generated @file{.class} files

When used with @code{-C}, this causes all generated @file{.class} files

to be put in the appropriate subdirectory of @var{directory}.  By

to be put in the appropriate subdirectory of @var{directory}.  By

default they will be put in subdirectories of the current working

default they will be put in subdirectories of the current working

directory.

directory.

@item -fno-bounds-check

@item -fno-bounds-check

By default, @command{gcj} generates code which checks the bounds of all

By default, @command{gcj} generates code which checks the bounds of all

array indexing operations.  With this option, these checks are omitted, which

array indexing operations.  With this option, these checks are omitted, which

can improve performance for code that uses arrays extensively.  Note that this

can improve performance for code that uses arrays extensively.  Note that this

can result in unpredictable behavior if the code in question actually does

can result in unpredictable behavior if the code in question actually does

violate array bounds constraints.  It is safe to use this option if you are

violate array bounds constraints.  It is safe to use this option if you are

sure that your code will never throw an @code{ArrayIndexOutOfBoundsException}.

sure that your code will never throw an @code{ArrayIndexOutOfBoundsException}.

@item -fno-store-check

@item -fno-store-check

Don't generate array store checks.  When storing objects into arrays, a runtime

Don't generate array store checks.  When storing objects into arrays, a runtime

check is normally generated in order to ensure that the object is assignment

check is normally generated in order to ensure that the object is assignment

compatible with the component type of the array (which may not be known

compatible with the component type of the array (which may not be known

at compile-time).  With this option, these checks are omitted.  This can

at compile-time).  With this option, these checks are omitted.  This can

improve performance for code which stores objects into arrays frequently.

improve performance for code which stores objects into arrays frequently.

It is safe to use this option if you are sure your code will never throw an

It is safe to use this option if you are sure your code will never throw an

@code{ArrayStoreException}.

@code{ArrayStoreException}.

@item -fjni

@item -fjni

With @command{gcj} there are two options for writing native methods: CNI

With @command{gcj} there are two options for writing native methods: CNI

and JNI@.  By default @command{gcj} assumes you are using CNI@.  If you are

and JNI@.  By default @command{gcj} assumes you are using CNI@.  If you are

compiling a class with native methods, and these methods are implemented

compiling a class with native methods, and these methods are implemented

using JNI, then you must use @code{-fjni}.  This option causes

using JNI, then you must use @code{-fjni}.  This option causes

@command{gcj} to generate stubs which will invoke the underlying JNI

@command{gcj} to generate stubs which will invoke the underlying JNI

methods.

methods.

@item -fno-assert

@item -fno-assert

Don't recognize the @code{assert} keyword.  This is for compatibility

Don't recognize the @code{assert} keyword.  This is for compatibility

with older versions of the language specification.

with older versions of the language specification.

@item -fno-optimize-static-class-initialization

@item -fno-optimize-static-class-initialization

When the optimization level is greater or equal to @code{-O2},

When the optimization level is greater or equal to @code{-O2},

@command{gcj} will try to optimize the way calls into the runtime are made

@command{gcj} will try to optimize the way calls into the runtime are made

to initialize static classes upon their first use (this optimization

to initialize static classes upon their first use (this optimization

isn't carried out if @code{-C} was specified.) When compiling to native

isn't carried out if @code{-C} was specified.) When compiling to native

code, @code{-fno-optimize-static-class-initialization} will turn this

code, @code{-fno-optimize-static-class-initialization} will turn this

optimization off, regardless of the optimization level in use.

optimization off, regardless of the optimization level in use.

@item --disable-assertions[=@var{class-or-package}]

@item --disable-assertions[=@var{class-or-package}]

Don't include code for checking assertions in the compiled code.

Don't include code for checking assertions in the compiled code.

If @code{=@var{class-or-package}} is missing disables assertion code

If @code{=@var{class-or-package}} is missing disables assertion code

generation for all classes, unless overridden by a more

generation for all classes, unless overridden by a more

specific @code{--enable-assertions} flag.

specific @code{--enable-assertions} flag.

If @var{class-or-package} is a class name, only disables generating

If @var{class-or-package} is a class name, only disables generating

assertion checks within the named class or its inner classes.

assertion checks within the named class or its inner classes.

If @var{class-or-package} is a package name, disables generating

If @var{class-or-package} is a package name, disables generating

assertion checks within the named package or a subpackage.

assertion checks within the named package or a subpackage.

By default, assertions are enabled when generating class files

By default, assertions are enabled when generating class files

or when not optimizing, and disabled when generating optimized binaries.

or when not optimizing, and disabled when generating optimized binaries.

@item --enable-assertions[=@var{class-or-package}]

@item --enable-assertions[=@var{class-or-package}]

Generates code to check assertions.  The option is perhaps misnamed,

Generates code to check assertions.  The option is perhaps misnamed,

as you still need to turn on assertion checking at run-time,

as you still need to turn on assertion checking at run-time,

and we don't support any easy way to do that.

and we don't support any easy way to do that.

So this flag isn't very useful yet, except to partially override

So this flag isn't very useful yet, except to partially override

@code{--disable-assertions}.

@code{--disable-assertions}.

@item -findirect-dispatch

@item -findirect-dispatch

@command{gcj} has a special binary compatibility ABI, which is enabled

@command{gcj} has a special binary compatibility ABI, which is enabled

by the @code{-findirect-dispatch} option.  In this mode, the code

by the @code{-findirect-dispatch} option.  In this mode, the code

generated by @command{gcj} honors the binary compatibility guarantees

generated by @command{gcj} honors the binary compatibility guarantees

in the Java Language Specification, and the resulting object files do

in the Java Language Specification, and the resulting object files do

not need to be directly linked against their dependencies.  Instead,

not need to be directly linked against their dependencies.  Instead,

all dependencies are looked up at runtime.  This allows free mixing of

all dependencies are looked up at runtime.  This allows free mixing of

interpreted and compiled code.

interpreted and compiled code.

Note that, at present, @code{-findirect-dispatch} can only be used

Note that, at present, @code{-findirect-dispatch} can only be used

when compiling @file{.class} files.  It will not work when compiling

when compiling @file{.class} files.  It will not work when compiling

from source.  CNI also does not yet work with the binary compatibility

from source.  CNI also does not yet work with the binary compatibility

ABI.  These restrictions will be lifted in some future release.

ABI.  These restrictions will be lifted in some future release.

However, if you compile CNI code with the standard ABI, you can call

However, if you compile CNI code with the standard ABI, you can call

it from code built with the binary compatibility ABI.

it from code built with the binary compatibility ABI.

@item -fbootstrap-classes

@item -fbootstrap-classes

This option can be use to tell @code{libgcj} that the compiled classes

This option can be use to tell @code{libgcj} that the compiled classes

should be loaded by the bootstrap loader, not the system class loader.

should be loaded by the bootstrap loader, not the system class loader.

By default, if you compile a class and link it into an executable, it

By default, if you compile a class and link it into an executable, it

will be treated as if it was loaded using the system class loader.

will be treated as if it was loaded using the system class loader.

This is convenient, as it means that things like

This is convenient, as it means that things like

@code{Class.forName()} will search @samp{CLASSPATH} to find the

@code{Class.forName()} will search @samp{CLASSPATH} to find the

desired class.

desired class.

@item -freduced-reflection

@item -freduced-reflection

This option causes the code generated by @command{gcj} to contain a

This option causes the code generated by @command{gcj} to contain a

reduced amount of the class meta-data used to support runtime

reduced amount of the class meta-data used to support runtime

reflection. The cost of this savings is the loss of

reflection. The cost of this savings is the loss of

the ability to use certain reflection capabilities of the standard

the ability to use certain reflection capabilities of the standard

Java runtime environment. When set all meta-data except for that

Java runtime environment. When set all meta-data except for that

which is needed to obtain correct runtime semantics is eliminated.

which is needed to obtain correct runtime semantics is eliminated.

For code that does not use reflection (i.e. serialization, RMI, CORBA

For code that does not use reflection (i.e. serialization, RMI, CORBA

or call methods in the @code{java.lang.reflect} package),

or call methods in the @code{java.lang.reflect} package),

@code{-freduced-reflection} will result in proper operation with a

@code{-freduced-reflection} will result in proper operation with a

savings in executable code size.

savings in executable code size.

JNI (@code{-fjni}) and the binary compatibility ABI

JNI (@code{-fjni}) and the binary compatibility ABI

(@code{-findirect-dispatch}) do not work properly without full

(@code{-findirect-dispatch}) do not work properly without full

reflection meta-data.  Because of this, it is an error to use these options

reflection meta-data.  Because of this, it is an error to use these options

with @code{-freduced-reflection}.

with @code{-freduced-reflection}.

@strong{Caution:} If there is no reflection meta-data, code that uses

@strong{Caution:} If there is no reflection meta-data, code that uses

a @code{SecurityManager} may not work properly.  Also calling

a @code{SecurityManager} may not work properly.  Also calling

@code{Class.forName()} may fail if the calling method has no

@code{Class.forName()} may fail if the calling method has no

reflection meta-data.

reflection meta-data.

@end table

@end table

@node Configure-time Options

@node Configure-time Options

@section Configure-time Options

@section Configure-time Options

Some @command{gcj} code generations options affect the resulting ABI, and

Some @command{gcj} code generations options affect the resulting ABI, and

so can only be meaningfully given when @code{libgcj}, the runtime

so can only be meaningfully given when @code{libgcj}, the runtime

package, is configured.  @code{libgcj} puts the appropriate options from

package, is configured.  @code{libgcj} puts the appropriate options from

this group into a @samp{spec} file which is read by @command{gcj}.  These

this group into a @samp{spec} file which is read by @command{gcj}.  These

options are listed here for completeness; if you are using @code{libgcj}

options are listed here for completeness; if you are using @code{libgcj}

then you won't want to touch these options.

then you won't want to touch these options.

@table @gcctabopt

@table @gcctabopt

@item -fuse-boehm-gc

@item -fuse-boehm-gc

This enables the use of the Boehm GC bitmap marking code.  In particular

This enables the use of the Boehm GC bitmap marking code.  In particular

this causes @command{gcj} to put an object marking descriptor into each

this causes @command{gcj} to put an object marking descriptor into each

vtable.

vtable.

@item -fhash-synchronization

@item -fhash-synchronization

By default, synchronization data (the data used for @code{synchronize},

By default, synchronization data (the data used for @code{synchronize},

@code{wait}, and @code{notify}) is pointed to by a word in each object.

@code{wait}, and @code{notify}) is pointed to by a word in each object.

With this option @command{gcj} assumes that this information is stored in a

With this option @command{gcj} assumes that this information is stored in a

hash table and not in the object itself.

hash table and not in the object itself.

@item -fuse-divide-subroutine

@item -fuse-divide-subroutine

On some systems, a library routine is called to perform integer

On some systems, a library routine is called to perform integer

division.  This is required to get exception handling correct when

division.  This is required to get exception handling correct when

dividing by zero.

dividing by zero.

@item -fcheck-references

@item -fcheck-references

On some systems it's necessary to insert inline checks whenever

On some systems it's necessary to insert inline checks whenever

accessing an object via a reference.  On other systems you won't need

accessing an object via a reference.  On other systems you won't need

this because null pointer accesses are caught automatically by the

this because null pointer accesses are caught automatically by the

processor.

processor.

@item -fuse-atomic-builtins

@item -fuse-atomic-builtins

On some systems, gcc can generate code for built-in atomic operations.

On some systems, gcc can generate code for built-in atomic operations.

Use this option to force gcj to use these builtins when compiling Java

Use this option to force gcj to use these builtins when compiling Java

code.  Where this capability is present it should be automatically

code.  Where this capability is present it should be automatically

detected, so you won't usually need to use this option.

detected, so you won't usually need to use this option.

@end table

@end table

@c man end

@c man end

@node Compatibility

@node Compatibility

@chapter Compatibility with the Java Platform

@chapter Compatibility with the Java Platform

As we believe it is important that the Java platform not be fragmented,

As we believe it is important that the Java platform not be fragmented,

@command{gcj} and @code{libgcj} try to conform to the relevant Java

@command{gcj} and @code{libgcj} try to conform to the relevant Java

specifications.  However, limited manpower and incomplete and unclear

specifications.  However, limited manpower and incomplete and unclear

documentation work against us.  So, there are caveats to using

documentation work against us.  So, there are caveats to using

@command{gcj}.

@command{gcj}.

@menu

@menu

* Limitations::

* Limitations::

* Extensions::

* Extensions::

@end menu

@end menu

@node Limitations

@node Limitations

@section Standard features not yet supported

@section Standard features not yet supported

This list of compatibility issues is by no means complete.

This list of compatibility issues is by no means complete.

@itemize @bullet

@itemize @bullet

@item

@item

@command{gcj} implements the JDK 1.2 language.  It supports inner classes

@command{gcj} implements the JDK 1.2 language.  It supports inner classes

and the new 1.4 @code{assert} keyword.  It does not yet support the Java 2

and the new 1.4 @code{assert} keyword.  It does not yet support the Java 2

@code{strictfp} keyword (it recognizes the keyword but ignores it).

@code{strictfp} keyword (it recognizes the keyword but ignores it).

@item

@item

@code{libgcj} is largely compatible with the JDK 1.2 libraries.

@code{libgcj} is largely compatible with the JDK 1.2 libraries.

However, @code{libgcj} is missing many packages, most notably

However, @code{libgcj} is missing many packages, most notably

@code{java.awt}.  There are also individual missing classes and methods.

@code{java.awt}.  There are also individual missing classes and methods.

We currently do not have a list showing differences between

We currently do not have a list showing differences between

@code{libgcj} and the Java 2 platform.

@code{libgcj} and the Java 2 platform.

@item

@item

Sometimes the @code{libgcj} implementation of a method or class differs

Sometimes the @code{libgcj} implementation of a method or class differs

from the JDK implementation.  This is not always a bug.  Still, if it

from the JDK implementation.  This is not always a bug.  Still, if it

affects you, it probably makes sense to report it so that we can discuss

affects you, it probably makes sense to report it so that we can discuss

the appropriate response.

the appropriate response.

@item

@item

@command{gcj} does not currently allow for piecemeal replacement of

@command{gcj} does not currently allow for piecemeal replacement of

components within @code{libgcj}. Unfortunately, programmers often want

components within @code{libgcj}. Unfortunately, programmers often want

to use newer versions of certain packages, such as those provided by

to use newer versions of certain packages, such as those provided by

the Apache Software Foundation's Jakarta project.  This has forced us

the Apache Software Foundation's Jakarta project.  This has forced us

to place the @code{org.w3c.dom} and @code{org.xml.sax} packages into

to place the @code{org.w3c.dom} and @code{org.xml.sax} packages into

their own libraries, separate from @code{libgcj}.  If you intend to

their own libraries, separate from @code{libgcj}.  If you intend to

use these classes, you must link them explicitly with

use these classes, you must link them explicitly with

@code{-l-org-w3c-dom} and @code{-l-org-xml-sax}.  Future versions of

@code{-l-org-w3c-dom} and @code{-l-org-xml-sax}.  Future versions of

@command{gcj} may not have this restriction.

@command{gcj} may not have this restriction.

@end itemize

@end itemize

@node Extensions

@node Extensions

@section Extra features unique to gcj

@section Extra features unique to gcj

The main feature of @command{gcj} is that it can compile programs written in

The main feature of @command{gcj} is that it can compile programs written in

the Java programming language to native code.  Most extensions that have been

the Java programming language to native code.  Most extensions that have been

added are to facilitate this functionality.

added are to facilitate this functionality.

@itemize @bullet

@itemize @bullet

@item

@item

@command{gcj} makes it easy and efficient to mix code written in Java and C++.

@command{gcj} makes it easy and efficient to mix code written in Java and C++.

@xref{About CNI}, for more info on how to use this in your programs.

@xref{About CNI}, for more info on how to use this in your programs.

@item

@item

When you compile your classes into a shared library using

When you compile your classes into a shared library using

@code{-findirect-dispatch} then add them to the system-wide

@code{-findirect-dispatch} then add them to the system-wide

classmap.db file using @code{gcj-dbtool}, they will be automatically

classmap.db file using @code{gcj-dbtool}, they will be automatically

loaded by the @code{libgcj} system classloader.  This is the new,

loaded by the @code{libgcj} system classloader.  This is the new,

preferred classname-to-library resolution mechanism.  @xref{Invoking

preferred classname-to-library resolution mechanism.  @xref{Invoking

gcj-dbtool}, for more information on using the classmap database.

gcj-dbtool}, for more information on using the classmap database.

@item

@item

The old classname-to-library lookup mechanism is still supported

The old classname-to-library lookup mechanism is still supported

through the @code{gnu.gcj.runtime.VMClassLoader.library_control}

through the @code{gnu.gcj.runtime.VMClassLoader.library_control}

property, but it is deprecated and will likely be removed in some

property, but it is deprecated and will likely be removed in some

future release.  When trying to load a class @code{gnu.pkg.SomeClass}

future release.  When trying to load a class @code{gnu.pkg.SomeClass}

the system classloader will first try to load the shared library

the system classloader will first try to load the shared library

@file{lib-gnu-pkg-SomeClass.so}, if that fails to load the class then

@file{lib-gnu-pkg-SomeClass.so}, if that fails to load the class then

it will try to load @file{lib-gnu-pkg.so} and finally when the class

it will try to load @file{lib-gnu-pkg.so} and finally when the class

is still not loaded it will try to load @file{lib-gnu.so}.  Note that

is still not loaded it will try to load @file{lib-gnu.so}.  Note that

all @samp{.}s will be transformed into @samp{-}s and that searching

all @samp{.}s will be transformed into @samp{-}s and that searching

for inner classes starts with their outermost outer class.  If the

for inner classes starts with their outermost outer class.  If the

class cannot be found this way the system classloader tries to use the

class cannot be found this way the system classloader tries to use the

@code{libgcj} bytecode interpreter to load the class from the standard

@code{libgcj} bytecode interpreter to load the class from the standard

classpath.  This process can be controlled to some degree via the

classpath.  This process can be controlled to some degree via the

@code{gnu.gcj.runtime.VMClassLoader.library_control} property;

@code{gnu.gcj.runtime.VMClassLoader.library_control} property;

@xref{libgcj Runtime Properties}.

@xref{libgcj Runtime Properties}.

@item

@item

@code{libgcj} includes a special @samp{gcjlib} URL type.  A URL of

@code{libgcj} includes a special @samp{gcjlib} URL type.  A URL of

this form is like a @code{jar} URL, and looks like

this form is like a @code{jar} URL, and looks like

@samp{gcjlib:/path/to/shared/library.so!/path/to/resource}.  An access

@samp{gcjlib:/path/to/shared/library.so!/path/to/resource}.  An access

to one of these URLs causes the shared library to be @code{dlopen()}d,

to one of these URLs causes the shared library to be @code{dlopen()}d,

and then the resource is looked for in that library.  These URLs are

and then the resource is looked for in that library.  These URLs are

most useful when used in conjunction with @code{java.net.URLClassLoader}.

most useful when used in conjunction with @code{java.net.URLClassLoader}.

Note that, due to implementation limitations, currently any such URL

Note that, due to implementation limitations, currently any such URL

can be accessed by only one class loader, and libraries are never

can be accessed by only one class loader, and libraries are never

unloaded.  This means some care must be exercised to make sure that

unloaded.  This means some care must be exercised to make sure that

a @code{gcjlib} URL is not accessed by more than one class loader at once.

a @code{gcjlib} URL is not accessed by more than one class loader at once.

In a future release this limitation will be lifted, and such

In a future release this limitation will be lifted, and such

libraries will be mapped privately.

libraries will be mapped privately.

@item

@item

A program compiled by @command{gcj} will examine the

A program compiled by @command{gcj} will examine the

@env{GCJ_PROPERTIES} environment variable and change its behavior in

@env{GCJ_PROPERTIES} environment variable and change its behavior in

some ways.  In particular @env{GCJ_PROPERTIES} holds a list of

some ways.  In particular @env{GCJ_PROPERTIES} holds a list of

assignments to global properties, such as would be set with the

assignments to global properties, such as would be set with the

@option{-D} option to @command{java}.  For instance,

@option{-D} option to @command{java}.  For instance,

@samp{java.compiler=gcj} is a valid (but currently meaningless)

@samp{java.compiler=gcj} is a valid (but currently meaningless)

setting.

setting.

@cindex GCJ_PROPERTIES

@cindex GCJ_PROPERTIES

@vindex GCJ_PROPERTIES

@vindex GCJ_PROPERTIES

@end itemize

@end itemize

@node Invoking jcf-dump

@node Invoking jcf-dump

@chapter Invoking jcf-dump

@chapter Invoking jcf-dump

@c man title jcf-dump print information about Java class files

@c man title jcf-dump print information about Java class files

@ignore

@ignore

@c man begin SYNOPSIS jcf-dump

@c man begin SYNOPSIS jcf-dump

jcf-dump [@option{-c}] [@option{--javap}]

jcf-dump [@option{-c}] [@option{--javap}]

    [@option{--classpath}=@var{path}] [@option{--CLASSPATH}=@var{path}]

    [@option{--classpath}=@var{path}] [@option{--CLASSPATH}=@var{path}]

    [@option{-I}@var{dir}@dots{}] [@option{-o} @var{file}]

    [@option{-I}@var{dir}@dots{}] [@option{-o} @var{file}]

    [@option{--version}] [@option{--help}] [@option{-v}] [@option{--verbose}]

    [@option{--version}] [@option{--help}] [@option{-v}] [@option{--verbose}]

    @var{classname}@dots{}

    @var{classname}@dots{}

@c man end

@c man end

@c man begin SEEALSO jcf-dump

@c man begin SEEALSO jcf-dump

gcc(1), gcj(1), gcjh(1), gij(1), jcf-dump(1), gfdl(7),

gcc(1), gcj(1), gcjh(1), gij(1), jcf-dump(1), gfdl(7),

and the Info entries for @file{gcj} and @file{gcc}.

and the Info entries for @file{gcj} and @file{gcc}.

@c man end

@c man end

@end ignore

@end ignore

@c man begin DESCRIPTION jcf-dump

@c man begin DESCRIPTION jcf-dump

This is a class file examiner, similar to @code{javap}.  It will print

This is a class file examiner, similar to @code{javap}.  It will print

information about a number of classes, which are specified by class name

information about a number of classes, which are specified by class name

or file name.

or file name.

@c man end

@c man end

@c man begin OPTIONS jcf-dump

@c man begin OPTIONS jcf-dump

@table @gcctabopt

@table @gcctabopt

@item -c

@item -c

Disassemble method bodies.  By default method bodies are not printed.

Disassemble method bodies.  By default method bodies are not printed.

@item --print-constants

@item --print-constants

Print the constant pool.  When printing a reference to a constant

Print the constant pool.  When printing a reference to a constant

also print its index in the constant pool.

also print its index in the constant pool.

@item --javap

@item --javap

Generate output in @code{javap} format.  The implementation of this

Generate output in @code{javap} format.  The implementation of this

feature is very incomplete.

feature is very incomplete.

@item --classpath=@var{path}

@item --classpath=@var{path}

@itemx --CLASSPATH=@var{path}

@itemx --CLASSPATH=@var{path}

@itemx -I@var{directory}

@itemx -I@var{directory}

@itemx -o @var{file}

@itemx -o @var{file}

These options as the same as the corresponding @command{gcj} options.

These options as the same as the corresponding @command{gcj} options.

@item --help

@item --help

Print help, then exit.

Print help, then exit.

@item --version

@item --version

Print version number, then exit.

Print version number, then exit.

@item -v, --verbose

@item -v, --verbose

Print extra information while running.

Print extra information while running.

Implies @code{--print-constants}.

Implies @code{--print-constants}.

@end table

@end table

@c man end

@c man end

@node Invoking gij

@node Invoking gij

@chapter Invoking gij

@chapter Invoking gij

@c man title gij GNU interpreter for Java bytecode

@c man title gij GNU interpreter for Java bytecode

@ignore

@ignore

@c man begin SYNOPSIS gij

@c man begin SYNOPSIS gij

gij [@option{OPTION}] @dots{} @var{JARFILE} [@var{ARGS}@dots{}]

gij [@option{OPTION}] @dots{} @var{JARFILE} [@var{ARGS}@dots{}]

gij [@option{-jar}] [@option{OPTION}] @dots{} @var{CLASS} [@var{ARGS}@dots{}]

gij [@option{-jar}] [@option{OPTION}] @dots{} @var{CLASS} [@var{ARGS}@dots{}]

  [@option{-cp} @var{path}] [@option{-classpath} @var{path}]

  [@option{-cp} @var{path}] [@option{-classpath} @var{path}]

  [@option{-D}@var{name}[=@var{value}]@dots{}]

  [@option{-D}@var{name}[=@var{value}]@dots{}]

  [@option{-ms=}@var{number}] [@option{-mx=}@var{number}]

  [@option{-ms=}@var{number}] [@option{-mx=}@var{number}]

  [@option{-X@var{argument}}] [@option{-verbose}] [@option{-verbose:class}]

  [@option{-X@var{argument}}] [@option{-verbose}] [@option{-verbose:class}]

  [@option{--showversion}] [@option{--version}] [@option{--help}][@option{-?}]

  [@option{--showversion}] [@option{--version}] [@option{--help}][@option{-?}]

@c man end

@c man end

@c man begin SEEALSO gij

@c man begin SEEALSO gij

gcc(1), gcj(1), gcjh(1), jcf-dump(1), gfdl(7),

gcc(1), gcj(1), gcjh(1), jcf-dump(1), gfdl(7),

and the Info entries for @file{gcj} and @file{gcc}.

and the Info entries for @file{gcj} and @file{gcc}.

@c man end

@c man end

@end ignore

@end ignore

@c man begin DESCRIPTION gij

@c man begin DESCRIPTION gij

@code{gij} is a Java bytecode interpreter included with @code{libgcj}.

@code{gij} is a Java bytecode interpreter included with @code{libgcj}.

@code{gij} is not available on every platform; porting it requires a

@code{gij} is not available on every platform; porting it requires a

small amount of assembly programming which has not been done for all the

small amount of assembly programming which has not been done for all the

targets supported by @command{gcj}.

targets supported by @command{gcj}.

The primary argument to @code{gij} is the name of a class or, with

The primary argument to @code{gij} is the name of a class or, with

@code{-jar}, a jar file.  Options before this argument are interpreted

@code{-jar}, a jar file.  Options before this argument are interpreted

by @code{gij}; remaining options are passed to the interpreted program.

by @code{gij}; remaining options are passed to the interpreted program.

If a class name is specified and this class does not have a @code{main}

If a class name is specified and this class does not have a @code{main}

method with the appropriate signature (a @code{static void} method with

method with the appropriate signature (a @code{static void} method with

a @code{String[]} as its sole argument), then @code{gij} will print an

a @code{String[]} as its sole argument), then @code{gij} will print an

error and exit.

error and exit.

If a jar file is specified then @code{gij} will use information in it to

If a jar file is specified then @code{gij} will use information in it to

determine which class' @code{main} method will be invoked.

determine which class' @code{main} method will be invoked.

@code{gij} will invoke the @code{main} method with all the remaining

@code{gij} will invoke the @code{main} method with all the remaining

command-line options.

command-line options.

Note that @code{gij} is not limited to interpreting code.  Because

Note that @code{gij} is not limited to interpreting code.  Because

@code{libgcj} includes a class loader which can dynamically load shared

@code{libgcj} includes a class loader which can dynamically load shared

objects, it is possible to give @code{gij} the name of a class which has

objects, it is possible to give @code{gij} the name of a class which has

been compiled and put into a shared library on the class path.

been compiled and put into a shared library on the class path.

@c man end

@c man end

@c man begin OPTIONS gij

@c man begin OPTIONS gij

@table @gcctabopt

@table @gcctabopt

@item -cp @var{path}

@item -cp @var{path}

@itemx -classpath @var{path}

@itemx -classpath @var{path}

Set the initial class path.  The class path is used for finding

Set the initial class path.  The class path is used for finding

class and resource files.  If specified, this option overrides the

class and resource files.  If specified, this option overrides the

@code{CLASSPATH} environment variable.  Note that this option is

@code{CLASSPATH} environment variable.  Note that this option is

ignored if @code{-jar} is used.

ignored if @code{-jar} is used.

@item -D@var{name}[=@var{value}]

@item -D@var{name}[=@var{value}]

This defines a system property named @var{name} with value @var{value}.

This defines a system property named @var{name} with value @var{value}.

If @var{value} is not specified then it defaults to the empty string.

If @var{value} is not specified then it defaults to the empty string.

These system properties are initialized at the program's startup and can

These system properties are initialized at the program's startup and can

be retrieved at runtime using the @code{java.lang.System.getProperty}

be retrieved at runtime using the @code{java.lang.System.getProperty}

method.

method.

@item -ms=@var{number}

@item -ms=@var{number}

Equivalent to @code{-Xms}.

Equivalent to @code{-Xms}.

@item -mx=@var{number}

@item -mx=@var{number}

Equivalent to @code{-Xmx}.

Equivalent to @code{-Xmx}.

@item -noverify

@item -noverify

Do not verify compliance of bytecode with the VM specification. In addition,

Do not verify compliance of bytecode with the VM specification. In addition,

this option disables type verification which is otherwise performed on BC-ABI

this option disables type verification which is otherwise performed on BC-ABI

compiled code.

compiled code.

@item -X

@item -X

@itemx -X@var{argument}

@itemx -X@var{argument}

Supplying @code{-X} by itself will cause @code{gij} to list all the

Supplying @code{-X} by itself will cause @code{gij} to list all the

supported @code{-X} options.  Currently these options are supported:

supported @code{-X} options.  Currently these options are supported:

@table @gcctabopt

@table @gcctabopt

@item -Xms@var{size}

@item -Xms@var{size}

Set the initial heap size.

Set the initial heap size.

@item -Xmx@var{size}

@item -Xmx@var{size}

Set the maximum heap size.

Set the maximum heap size.

@item -Xss@var{size}

@item -Xss@var{size}

Set the thread stack size.

Set the thread stack size.

@end table

@end table

Unrecognized @code{-X} options are ignored, for compatibility with

Unrecognized @code{-X} options are ignored, for compatibility with

other runtimes.

other runtimes.

@item -jar

@item -jar

This indicates that the name passed to @code{gij} should be interpreted

This indicates that the name passed to @code{gij} should be interpreted

as the name of a jar file, not a class.

as the name of a jar file, not a class.

@item --help

@item --help

@itemx -?

@itemx -?

Print help, then exit.

Print help, then exit.

@item --showversion

@item --showversion

Print version number and continue.

Print version number and continue.

@item --fullversion

@item --fullversion

Print detailed version information, then exit.

Print detailed version information, then exit.

@item --version

@item --version

Print version number, then exit.

Print version number, then exit.

@item -verbose

@item -verbose

@itemx -verbose:class

@itemx -verbose:class

Each time a class is initialized, print a short message on standard error.

Each time a class is initialized, print a short message on standard error.

@end table

@end table

@code{gij} also recognizes and ignores the following options, for

@code{gij} also recognizes and ignores the following options, for

compatibility with existing application launch scripts:

compatibility with existing application launch scripts:

@code{-client}, @code{-server}, @code{-hotspot}, @code{-jrockit},

@code{-client}, @code{-server}, @code{-hotspot}, @code{-jrockit},

@code{-agentlib}, @code{-agentpath}, @code{-debug}, @code{-d32},

@code{-agentlib}, @code{-agentpath}, @code{-debug}, @code{-d32},

@code{-d64}, @code{-javaagent}, @code{-noclassgc}, @code{-verify},

@code{-d64}, @code{-javaagent}, @code{-noclassgc}, @code{-verify},

and @code{-verifyremote}.

and @code{-verifyremote}.

@c man end

@c man end

@node Invoking gcj-dbtool

@node Invoking gcj-dbtool

@chapter Invoking gcj-dbtool.

@chapter Invoking gcj-dbtool.

@c man title gcj-dbtool Manipulate class file mapping databases for libgcj

@c man title gcj-dbtool Manipulate class file mapping databases for libgcj

@ignore

@ignore

@c man begin SYNOPSIS gcj-dbtool

@c man begin SYNOPSIS gcj-dbtool

gcj-dbtool @option{OPTION} @var{DBFILE} [@option{MORE}] @dots{}

gcj-dbtool @option{OPTION} @var{DBFILE} [@option{MORE}] @dots{}

gcj-dbtool [@option{-0}] [@option{-}] [@option{-n}] [@option{-a}] [@option{-f}]

gcj-dbtool [@option{-0}] [@option{-}] [@option{-n}] [@option{-a}] [@option{-f}]

  [@option{-t}] [@option{-l}] [@option{-p} [@var{LIBDIR}]]

  [@option{-t}] [@option{-l}] [@option{-p} [@var{LIBDIR}]]

  [@option{-v}] [@option{-m}] [@option{--version}] [@option{--help}]

  [@option{-v}] [@option{-m}] [@option{--version}] [@option{--help}]

@c man end

@c man end

@c man begin SEEALSO gcj-dbtool

@c man begin SEEALSO gcj-dbtool