Mercurial > hg > CbC > CbC_gcc
annotate gcc/doc/gcj.1 @ 63:b7f97abdc517 gcc-4.6-20100522
update gcc from gcc-4.5.0 to gcc-4.6
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 24 May 2010 12:47:05 +0900 |
| parents | 3bfb6c00c1e0 |
| children |
| rev | line source |
|---|---|
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| 132 .\" ======================================================================== | |
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| 134 .IX Title "GCJ 1" | |
|
47
3bfb6c00c1e0
update it from 4.4.2 to 4.4.3.
kent <kent@cr.ie.u-ryukyu.ac.jp>
parents:
19
diff
changeset
|
135 .TH GCJ 1 "2010-01-21" "gcc-4.4.3" "GNU" |
| 0 | 136 .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 137 .\" way too many mistakes in technical documents. | |
| 138 .if n .ad l | |
| 139 .nh | |
| 140 .SH "NAME" | |
| 141 gcj \- Ahead\-of\-time compiler for the Java language | |
| 142 .SH "SYNOPSIS" | |
| 143 .IX Header "SYNOPSIS" | |
| 144 gcj [\fB\-I\fR\fIdir\fR...] [\fB\-d\fR \fIdir\fR...] | |
| 145 [\fB\-\-CLASSPATH\fR=\fIpath\fR] [\fB\-\-classpath\fR=\fIpath\fR] | |
| 146 [\fB\-f\fR\fIoption\fR...] [\fB\-\-encoding\fR=\fIname\fR] | |
| 147 [\fB\-\-main\fR=\fIclassname\fR] [\fB\-D\fR\fIname\fR[=\fIvalue\fR]...] | |
| 148 [\fB\-C\fR] [\fB\-\-resource\fR \fIresource-name\fR] [\fB\-d\fR \fIdirectory\fR] | |
| 149 [\fB\-W\fR\fIwarn\fR...] | |
| 150 \fIsourcefile\fR... | |
| 151 .SH "DESCRIPTION" | |
| 152 .IX Header "DESCRIPTION" | |
| 153 As \fBgcj\fR is just another front end to \fBgcc\fR, it supports many | |
| 154 of the same options as gcc. This manual only documents the | |
| 155 options specific to \fBgcj\fR. | |
| 156 .SH "OPTIONS" | |
| 157 .IX Header "OPTIONS" | |
| 158 .Sh "Input and output files" | |
| 159 .IX Subsection "Input and output files" | |
| 160 A \fBgcj\fR command is like a \fBgcc\fR command, in that it | |
| 161 consists of a number of options and file names. The following kinds | |
| 162 of input file names are supported: | |
| 163 .IP "\fIfile\fR\fB.java\fR" 4 | |
| 164 .IX Item "file.java" | |
| 165 Java source files. | |
| 166 .IP "\fIfile\fR\fB.class\fR" 4 | |
| 167 .IX Item "file.class" | |
| 168 Java bytecode files. | |
| 169 .IP "\fIfile\fR\fB.zip\fR" 4 | |
| 170 .IX Item "file.zip" | |
| 171 .PD 0 | |
| 172 .IP "\fIfile\fR\fB.jar\fR" 4 | |
| 173 .IX Item "file.jar" | |
| 174 .PD | |
| 175 An archive containing one or more \f(CW\*(C`.class\*(C'\fR files, all of | |
| 176 which are compiled. The archive may be compressed. Files in | |
| 177 an archive which don't end with \fB.class\fR are treated as | |
| 178 resource files; they are compiled into the resulting object file | |
| 179 as \fBcore:\fR URLs. | |
| 180 .IP "\fB@\fR\fIfile\fR" 4 | |
| 181 .IX Item "@file" | |
| 182 A file containing a whitespace-separated list of input file names. | |
| 183 (Currently, these must all be \f(CW\*(C`.java\*(C'\fR source files, but that | |
| 184 may change.) | |
| 185 Each named file is compiled, just as if it had been on the command line. | |
| 186 .IP "\fIlibrary\fR\fB.a\fR" 4 | |
| 187 .IX Item "library.a" | |
| 188 .PD 0 | |
| 189 .IP "\fIlibrary\fR\fB.so\fR" 4 | |
| 190 .IX Item "library.so" | |
| 191 .IP "\fB\-l\fR\fIlibname\fR" 4 | |
| 192 .IX Item "-llibname" | |
| 193 .PD | |
| 194 Libraries to use when linking. See the \fBgcc\fR manual. | |
| 195 .PP | |
| 196 You can specify more than one input file on the \fBgcj\fR command line, | |
| 197 in which case they will all be compiled. If you specify a | |
| 198 \&\f(CW\*(C`\-o \f(CIFILENAME\f(CW\*(C'\fR | |
| 199 option, all the input files will be compiled together, producing a | |
| 200 single output file, named \fI\s-1FILENAME\s0\fR. | |
| 201 This is allowed even when using \f(CW\*(C`\-S\*(C'\fR or \f(CW\*(C`\-c\*(C'\fR, | |
| 202 but not when using \f(CW\*(C`\-C\*(C'\fR or \f(CW\*(C`\-\-resource\*(C'\fR. | |
| 203 (This is an extension beyond the what plain \fBgcc\fR allows.) | |
| 204 (If more than one input file is specified, all must currently | |
| 205 be \f(CW\*(C`.java\*(C'\fR files, though we hope to fix this.) | |
| 206 .Sh "Input Options" | |
| 207 .IX Subsection "Input Options" | |
| 208 \&\fBgcj\fR has options to control where it looks to find files it needs. | |
| 209 For instance, \fBgcj\fR might need to load a class that is referenced | |
| 210 by the file it has been asked to compile. Like other compilers for the | |
| 211 Java language, \fBgcj\fR has a notion of a \fIclass path\fR. There are | |
| 212 several options and environment variables which can be used to | |
| 213 manipulate the class path. When \fBgcj\fR looks for a given class, it | |
| 214 searches the class path looking for matching \fI.class\fR or | |
| 215 \&\fI.java\fR file. \fBgcj\fR comes with a built-in class path which | |
| 216 points at the installed \fIlibgcj.jar\fR, a file which contains all the | |
| 217 standard classes. | |
| 218 .PP | |
| 219 In the text below, a directory or path component can refer either to an | |
| 220 actual directory on the filesystem, or to a \fI.zip\fR or \fI.jar\fR | |
| 221 file, which \fBgcj\fR will search as if it is a directory. | |
| 222 .IP "\fB\-I\fR\fIdir\fR" 4 | |
| 223 .IX Item "-Idir" | |
| 224 All directories specified by \f(CW\*(C`\-I\*(C'\fR are kept in order and prepended | |
| 225 to the class path constructed from all the other options. Unless | |
| 226 compatibility with tools like \f(CW\*(C`javac\*(C'\fR is important, we recommend | |
| 227 always using \f(CW\*(C`\-I\*(C'\fR instead of the other options for manipulating the | |
| 228 class path. | |
| 229 .IP "\fB\-\-classpath=\fR\fIpath\fR" 4 | |
| 230 .IX Item "--classpath=path" | |
| 231 This sets the class path to \fIpath\fR, a colon-separated list of paths | |
| 232 (on Windows-based systems, a semicolon-separate list of paths). | |
| 233 This does not override the builtin (\*(L"boot\*(R") search path. | |
| 234 .IP "\fB\-\-CLASSPATH=\fR\fIpath\fR" 4 | |
| 235 .IX Item "--CLASSPATH=path" | |
| 236 Deprecated synonym for \f(CW\*(C`\-\-classpath\*(C'\fR. | |
| 237 .IP "\fB\-\-bootclasspath=\fR\fIpath\fR" 4 | |
| 238 .IX Item "--bootclasspath=path" | |
| 239 Where to find the standard builtin classes, such as \f(CW\*(C`java.lang.String\*(C'\fR. | |
| 240 .IP "\fB\-\-extdirs=\fR\fIpath\fR" 4 | |
| 241 .IX Item "--extdirs=path" | |
| 242 For each directory in the \fIpath\fR, place the contents of that | |
| 243 directory at the end of the class path. | |
| 244 .IP "\fB\s-1CLASSPATH\s0\fR" 4 | |
| 245 .IX Item "CLASSPATH" | |
| 246 This is an environment variable which holds a list of paths. | |
| 247 .PP | |
| 248 The final class path is constructed like so: | |
| 249 .IP "\(bu" 4 | |
| 250 First come all directories specified via \f(CW\*(C`\-I\*(C'\fR. | |
| 251 .IP "\(bu" 4 | |
| 252 If \fB\-\-classpath\fR is specified, its value is appended. | |
| 253 Otherwise, if the \f(CW\*(C`CLASSPATH\*(C'\fR environment variable is specified, | |
| 254 then its value is appended. | |
| 255 Otherwise, the current directory (\f(CW"."\fR) is appended. | |
| 256 .IP "\(bu" 4 | |
| 257 If \f(CW\*(C`\-\-bootclasspath\*(C'\fR was specified, append its value. | |
| 258 Otherwise, append the built-in system directory, \fIlibgcj.jar\fR. | |
| 259 .IP "\(bu" 4 | |
| 260 Finally, if \f(CW\*(C`\-\-extdirs\*(C'\fR was specified, append the contents of the | |
| 261 specified directories at the end of the class path. Otherwise, append | |
| 262 the contents of the built-in extdirs at \f(CW\*(C`$(prefix)/share/java/ext\*(C'\fR. | |
| 263 .PP | |
| 264 The classfile built by \fBgcj\fR for the class \f(CW\*(C`java.lang.Object\*(C'\fR | |
| 265 (and placed in \f(CW\*(C`libgcj.jar\*(C'\fR) contains a special zero length | |
| 266 attribute \f(CW\*(C`gnu.gcj.gcj\-compiled\*(C'\fR. The compiler looks for this | |
| 267 attribute when loading \f(CW\*(C`java.lang.Object\*(C'\fR and will report an error | |
| 268 if it isn't found, unless it compiles to bytecode (the option | |
| 269 \&\f(CW\*(C`\-fforce\-classes\-archive\-check\*(C'\fR can be used to override this | |
| 270 behavior in this particular case.) | |
| 271 .IP "\fB\-fforce\-classes\-archive\-check\fR" 4 | |
| 272 .IX Item "-fforce-classes-archive-check" | |
| 273 This forces the compiler to always check for the special zero length | |
| 274 attribute \f(CW\*(C`gnu.gcj.gcj\-compiled\*(C'\fR in \f(CW\*(C`java.lang.Object\*(C'\fR and | |
| 275 issue an error if it isn't found. | |
| 276 .IP "\fB\-fsource=\fR\fI\s-1VERSION\s0\fR" 4 | |
| 277 .IX Item "-fsource=VERSION" | |
| 278 This option is used to choose the source version accepted by | |
| 279 \&\fBgcj\fR. The default is \fB1.5\fR. | |
| 280 .Sh "Encodings" | |
| 281 .IX Subsection "Encodings" | |
| 282 The Java programming language uses Unicode throughout. In an effort to | |
| 283 integrate well with other locales, \fBgcj\fR allows \fI.java\fR files | |
| 284 to be written using almost any encoding. \fBgcj\fR knows how to | |
| 285 convert these encodings into its internal encoding at compile time. | |
| 286 .PP | |
| 287 You can use the \f(CW\*(C`\-\-encoding=\f(CINAME\f(CW\*(C'\fR option to specify an | |
| 288 encoding (of a particular character set) to use for source files. If | |
| 289 this is not specified, the default encoding comes from your current | |
| 290 locale. If your host system has insufficient locale support, then | |
| 291 \&\fBgcj\fR assumes the default encoding to be the \fB\s-1UTF\-8\s0\fR encoding | |
| 292 of Unicode. | |
| 293 .PP | |
| 294 To implement \f(CW\*(C`\-\-encoding\*(C'\fR, \fBgcj\fR simply uses the host | |
| 295 platform's \f(CW\*(C`iconv\*(C'\fR conversion routine. This means that in practice | |
| 296 \&\fBgcj\fR is limited by the capabilities of the host platform. | |
| 297 .PP | |
| 298 The names allowed for the argument \f(CW\*(C`\-\-encoding\*(C'\fR vary from platform | |
| 299 to platform (since they are not standardized anywhere). However, | |
| 300 \&\fBgcj\fR implements the encoding named \fB\s-1UTF\-8\s0\fR internally, so if | |
| 301 you choose to use this for your source files you can be assured that it | |
| 302 will work on every host. | |
| 303 .Sh "Warnings" | |
| 304 .IX Subsection "Warnings" | |
| 305 \&\fBgcj\fR implements several warnings. As with other generic | |
| 306 \&\fBgcc\fR warnings, if an option of the form \f(CW\*(C`\-Wfoo\*(C'\fR enables a | |
| 307 warning, then \f(CW\*(C`\-Wno\-foo\*(C'\fR will disable it. Here we've chosen to | |
| 308 document the form of the warning which will have an effect \*(-- the | |
| 309 default being the opposite of what is listed. | |
| 310 .IP "\fB\-Wredundant\-modifiers\fR" 4 | |
| 311 .IX Item "-Wredundant-modifiers" | |
| 312 With this flag, \fBgcj\fR will warn about redundant modifiers. For | |
| 313 instance, it will warn if an interface method is declared \f(CW\*(C`public\*(C'\fR. | |
| 314 .IP "\fB\-Wextraneous\-semicolon\fR" 4 | |
| 315 .IX Item "-Wextraneous-semicolon" | |
| 316 This causes \fBgcj\fR to warn about empty statements. Empty statements | |
| 317 have been deprecated. | |
| 318 .IP "\fB\-Wno\-out\-of\-date\fR" 4 | |
| 319 .IX Item "-Wno-out-of-date" | |
| 320 This option will cause \fBgcj\fR not to warn when a source file is | |
| 321 newer than its matching class file. By default \fBgcj\fR will warn | |
| 322 about this. | |
| 323 .IP "\fB\-Wno\-deprecated\fR" 4 | |
| 324 .IX Item "-Wno-deprecated" | |
| 325 Warn if a deprecated class, method, or field is referred to. | |
| 326 .IP "\fB\-Wunused\fR" 4 | |
| 327 .IX Item "-Wunused" | |
| 328 This is the same as \fBgcc\fR's \f(CW\*(C`\-Wunused\*(C'\fR. | |
| 329 .IP "\fB\-Wall\fR" 4 | |
| 330 .IX Item "-Wall" | |
| 331 This is the same as \f(CW\*(C`\-Wredundant\-modifiers \-Wextraneous\-semicolon | |
| 332 \&\-Wunused\*(C'\fR. | |
| 333 .Sh "Linking" | |
| 334 .IX Subsection "Linking" | |
| 335 To turn a Java application into an executable program, | |
| 336 you need to link it with the needed libraries, just as for C or \*(C+. | |
| 337 The linker by default looks for a global function named \f(CW\*(C`main\*(C'\fR. | |
| 338 Since Java does not have global functions, and a | |
| 339 collection of Java classes may have more than one class with a | |
| 340 \&\f(CW\*(C`main\*(C'\fR method, you need to let the linker know which of those | |
| 341 \&\f(CW\*(C`main\*(C'\fR methods it should invoke when starting the application. | |
| 342 You can do that in any of these ways: | |
| 343 .IP "\(bu" 4 | |
| 344 Specify the class containing the desired \f(CW\*(C`main\*(C'\fR method | |
| 345 when you link the application, using the \f(CW\*(C`\-\-main\*(C'\fR flag, | |
| 346 described below. | |
| 347 .IP "\(bu" 4 | |
| 348 Link the Java package(s) into a shared library (dll) rather than an | |
| 349 executable. Then invoke the application using the \f(CW\*(C`gij\*(C'\fR program, | |
| 350 making sure that \f(CW\*(C`gij\*(C'\fR can find the libraries it needs. | |
| 351 .IP "\(bu" 4 | |
| 352 Link the Java packages(s) with the flag \f(CW\*(C`\-lgij\*(C'\fR, which links | |
| 353 in the \f(CW\*(C`main\*(C'\fR routine from the \f(CW\*(C`gij\*(C'\fR command. | |
| 354 This allows you to select the class whose \f(CW\*(C`main\*(C'\fR method you | |
| 355 want to run when you run the application. You can also use | |
| 356 other \f(CW\*(C`gij\*(C'\fR flags, such as \f(CW\*(C`\-D\*(C'\fR flags to set properties. | |
| 357 Using the \f(CW\*(C`\-lgij\*(C'\fR library (rather than the \f(CW\*(C`gij\*(C'\fR program | |
| 358 of the previous mechanism) has some advantages: it is compatible with | |
| 359 static linking, and does not require configuring or installing libraries. | |
| 360 .PP | |
| 361 These \f(CW\*(C`gij\*(C'\fR options relate to linking an executable: | |
| 362 .IP "\fB\-\-main=\fR\fI\s-1CLASSNAME\s0\fR" 4 | |
| 363 .IX Item "--main=CLASSNAME" | |
| 364 This option is used when linking to specify the name of the class whose | |
| 365 \&\f(CW\*(C`main\*(C'\fR method should be invoked when the resulting executable is | |
| 366 run. | |
| 367 .IP "\fB\-D\fR\fIname\fR\fB[=\fR\fIvalue\fR\fB]\fR" 4 | |
| 368 .IX Item "-Dname[=value]" | |
| 369 This option can only be used with \f(CW\*(C`\-\-main\*(C'\fR. It defines a system | |
| 370 property named \fIname\fR with value \fIvalue\fR. If \fIvalue\fR is not | |
| 371 specified then it defaults to the empty string. These system properties | |
| 372 are initialized at the program's startup and can be retrieved at runtime | |
| 373 using the \f(CW\*(C`java.lang.System.getProperty\*(C'\fR method. | |
| 374 .IP "\fB\-lgij\fR" 4 | |
| 375 .IX Item "-lgij" | |
| 376 Create an application whose command-line processing is that | |
| 377 of the \f(CW\*(C`gij\*(C'\fR command. | |
| 378 .Sp | |
| 379 This option is an alternative to using \f(CW\*(C`\-\-main\*(C'\fR; you cannot use both. | |
| 380 .IP "\fB\-static\-libgcj\fR" 4 | |
| 381 .IX Item "-static-libgcj" | |
| 382 This option causes linking to be done against a static version of the | |
| 383 libgcj runtime library. This option is only available if | |
| 384 corresponding linker support exists. | |
| 385 .Sp | |
| 386 \&\fBCaution:\fR Static linking of libgcj may cause essential parts | |
| 387 of libgcj to be omitted. Some parts of libgcj use reflection to load | |
| 388 classes at runtime. Since the linker does not see these references at | |
| 389 link time, it can omit the referred to classes. The result is usually | |
| 390 (but not always) a \f(CW\*(C`ClassNotFoundException\*(C'\fR being thrown at | |
| 391 runtime. Caution must be used when using this option. For more | |
| 392 details see: | |
| 393 <\fBhttp://gcc.gnu.org/wiki/Statically%20linking%20libgcj\fR> | |
| 394 .Sh "Code Generation" | |
| 395 .IX Subsection "Code Generation" | |
| 396 In addition to the many \fBgcc\fR options controlling code generation, | |
| 397 \&\fBgcj\fR has several options specific to itself. | |
| 398 .IP "\fB\-C\fR" 4 | |
| 399 .IX Item "-C" | |
| 400 This option is used to tell \fBgcj\fR to generate bytecode | |
| 401 (\fI.class\fR files) rather than object code. | |
| 402 .IP "\fB\-\-resource\fR \fIresource-name\fR" 4 | |
| 403 .IX Item "--resource resource-name" | |
| 404 This option is used to tell \fBgcj\fR to compile the contents of a | |
| 405 given file to object code so it may be accessed at runtime with the core | |
| 406 protocol handler as \fBcore:/\fR\fIresource-name\fR. Note that | |
| 407 \&\fIresource-name\fR is the name of the resource as found at runtime; for | |
| 408 instance, it could be used in a call to \f(CW\*(C`ResourceBundle.getBundle\*(C'\fR. | |
| 409 The actual file name to be compiled this way must be specified | |
| 410 separately. | |
| 411 .IP "\fB\-ftarget=\fR\fI\s-1VERSION\s0\fR" 4 | |
| 412 .IX Item "-ftarget=VERSION" | |
| 413 This can be used with \fB\-C\fR to choose the version of bytecode | |
| 414 emitted by \fBgcj\fR. The default is \fB1.5\fR. When not | |
| 415 generating bytecode, this option has no effect. | |
| 416 .IP "\fB\-d\fR \fIdirectory\fR" 4 | |
| 417 .IX Item "-d directory" | |
| 418 When used with \f(CW\*(C`\-C\*(C'\fR, this causes all generated \fI.class\fR files | |
| 419 to be put in the appropriate subdirectory of \fIdirectory\fR. By | |
| 420 default they will be put in subdirectories of the current working | |
| 421 directory. | |
| 422 .IP "\fB\-fno\-bounds\-check\fR" 4 | |
| 423 .IX Item "-fno-bounds-check" | |
| 424 By default, \fBgcj\fR generates code which checks the bounds of all | |
| 425 array indexing operations. With this option, these checks are omitted, which | |
| 426 can improve performance for code that uses arrays extensively. Note that this | |
| 427 can result in unpredictable behavior if the code in question actually does | |
| 428 violate array bounds constraints. It is safe to use this option if you are | |
| 429 sure that your code will never throw an \f(CW\*(C`ArrayIndexOutOfBoundsException\*(C'\fR. | |
| 430 .IP "\fB\-fno\-store\-check\fR" 4 | |
| 431 .IX Item "-fno-store-check" | |
| 432 Don't generate array store checks. When storing objects into arrays, a runtime | |
| 433 check is normally generated in order to ensure that the object is assignment | |
| 434 compatible with the component type of the array (which may not be known | |
| 435 at compile-time). With this option, these checks are omitted. This can | |
| 436 improve performance for code which stores objects into arrays frequently. | |
| 437 It is safe to use this option if you are sure your code will never throw an | |
| 438 \&\f(CW\*(C`ArrayStoreException\*(C'\fR. | |
| 439 .IP "\fB\-fjni\fR" 4 | |
| 440 .IX Item "-fjni" | |
| 441 With \fBgcj\fR there are two options for writing native methods: \s-1CNI\s0 | |
| 442 and \s-1JNI\s0. By default \fBgcj\fR assumes you are using \s-1CNI\s0. If you are | |
| 443 compiling a class with native methods, and these methods are implemented | |
| 444 using \s-1JNI\s0, then you must use \f(CW\*(C`\-fjni\*(C'\fR. This option causes | |
| 445 \&\fBgcj\fR to generate stubs which will invoke the underlying \s-1JNI\s0 | |
| 446 methods. | |
| 447 .IP "\fB\-fno\-assert\fR" 4 | |
| 448 .IX Item "-fno-assert" | |
| 449 Don't recognize the \f(CW\*(C`assert\*(C'\fR keyword. This is for compatibility | |
| 450 with older versions of the language specification. | |
| 451 .IP "\fB\-fno\-optimize\-static\-class\-initialization\fR" 4 | |
| 452 .IX Item "-fno-optimize-static-class-initialization" | |
| 453 When the optimization level is greater or equal to \f(CW\*(C`\-O2\*(C'\fR, | |
| 454 \&\fBgcj\fR will try to optimize the way calls into the runtime are made | |
| 455 to initialize static classes upon their first use (this optimization | |
| 456 isn't carried out if \f(CW\*(C`\-C\*(C'\fR was specified.) When compiling to native | |
| 457 code, \f(CW\*(C`\-fno\-optimize\-static\-class\-initialization\*(C'\fR will turn this | |
| 458 optimization off, regardless of the optimization level in use. | |
| 459 .IP "\fB\-\-disable\-assertions[=\fR\fIclass-or-package\fR\fB]\fR" 4 | |
| 460 .IX Item "--disable-assertions[=class-or-package]" | |
| 461 Don't include code for checking assertions in the compiled code. | |
| 462 If \f(CW\*(C`=\f(CIclass\-or\-package\f(CW\*(C'\fR is missing disables assertion code | |
| 463 generation for all classes, unless overridden by a more | |
| 464 specific \f(CW\*(C`\-\-enable\-assertions\*(C'\fR flag. | |
| 465 If \fIclass-or-package\fR is a class name, only disables generating | |
| 466 assertion checks within the named class or its inner classes. | |
| 467 If \fIclass-or-package\fR is a package name, disables generating | |
| 468 assertion checks within the named package or a subpackage. | |
| 469 .Sp | |
| 470 By default, assertions are enabled when generating class files | |
| 471 or when not optimizing, and disabled when generating optimized binaries. | |
| 472 .IP "\fB\-\-enable\-assertions[=\fR\fIclass-or-package\fR\fB]\fR" 4 | |
| 473 .IX Item "--enable-assertions[=class-or-package]" | |
| 474 Generates code to check assertions. The option is perhaps misnamed, | |
| 475 as you still need to turn on assertion checking at run-time, | |
| 476 and we don't support any easy way to do that. | |
| 477 So this flag isn't very useful yet, except to partially override | |
| 478 \&\f(CW\*(C`\-\-disable\-assertions\*(C'\fR. | |
| 479 .IP "\fB\-findirect\-dispatch\fR" 4 | |
| 480 .IX Item "-findirect-dispatch" | |
| 481 \&\fBgcj\fR has a special binary compatibility \s-1ABI\s0, which is enabled | |
| 482 by the \f(CW\*(C`\-findirect\-dispatch\*(C'\fR option. In this mode, the code | |
| 483 generated by \fBgcj\fR honors the binary compatibility guarantees | |
| 484 in the Java Language Specification, and the resulting object files do | |
| 485 not need to be directly linked against their dependencies. Instead, | |
| 486 all dependencies are looked up at runtime. This allows free mixing of | |
| 487 interpreted and compiled code. | |
| 488 .Sp | |
| 489 Note that, at present, \f(CW\*(C`\-findirect\-dispatch\*(C'\fR can only be used | |
| 490 when compiling \fI.class\fR files. It will not work when compiling | |
| 491 from source. \s-1CNI\s0 also does not yet work with the binary compatibility | |
| 492 \&\s-1ABI\s0. These restrictions will be lifted in some future release. | |
| 493 .Sp | |
| 494 However, if you compile \s-1CNI\s0 code with the standard \s-1ABI\s0, you can call | |
| 495 it from code built with the binary compatibility \s-1ABI\s0. | |
| 496 .IP "\fB\-fbootstrap\-classes\fR" 4 | |
| 497 .IX Item "-fbootstrap-classes" | |
| 498 This option can be use to tell \f(CW\*(C`libgcj\*(C'\fR that the compiled classes | |
| 499 should be loaded by the bootstrap loader, not the system class loader. | |
| 500 By default, if you compile a class and link it into an executable, it | |
| 501 will be treated as if it was loaded using the system class loader. | |
| 502 This is convenient, as it means that things like | |
| 503 \&\f(CW\*(C`Class.forName()\*(C'\fR will search \fB\s-1CLASSPATH\s0\fR to find the | |
| 504 desired class. | |
| 505 .IP "\fB\-freduced\-reflection\fR" 4 | |
| 506 .IX Item "-freduced-reflection" | |
| 507 This option causes the code generated by \fBgcj\fR to contain a | |
| 508 reduced amount of the class meta-data used to support runtime | |
| 509 reflection. The cost of this savings is the loss of | |
| 510 the ability to use certain reflection capabilities of the standard | |
| 511 Java runtime environment. When set all meta-data except for that | |
| 512 which is needed to obtain correct runtime semantics is eliminated. | |
| 513 .Sp | |
| 514 For code that does not use reflection (i.e. serialization, \s-1RMI\s0, \s-1CORBA\s0 | |
| 515 or call methods in the \f(CW\*(C`java.lang.reflect\*(C'\fR package), | |
| 516 \&\f(CW\*(C`\-freduced\-reflection\*(C'\fR will result in proper operation with a | |
| 517 savings in executable code size. | |
| 518 .Sp | |
| 519 \&\s-1JNI\s0 (\f(CW\*(C`\-fjni\*(C'\fR) and the binary compatibility \s-1ABI\s0 | |
| 520 (\f(CW\*(C`\-findirect\-dispatch\*(C'\fR) do not work properly without full | |
| 521 reflection meta-data. Because of this, it is an error to use these options | |
| 522 with \f(CW\*(C`\-freduced\-reflection\*(C'\fR. | |
| 523 .Sp | |
| 524 \&\fBCaution:\fR If there is no reflection meta-data, code that uses | |
| 525 a \f(CW\*(C`SecurityManager\*(C'\fR may not work properly. Also calling | |
| 526 \&\f(CW\*(C`Class.forName()\*(C'\fR may fail if the calling method has no | |
| 527 reflection meta-data. | |
| 528 .Sh "Configure-time Options" | |
| 529 .IX Subsection "Configure-time Options" | |
| 530 Some \fBgcj\fR code generations options affect the resulting \s-1ABI\s0, and | |
| 531 so can only be meaningfully given when \f(CW\*(C`libgcj\*(C'\fR, the runtime | |
| 532 package, is configured. \f(CW\*(C`libgcj\*(C'\fR puts the appropriate options from | |
| 533 this group into a \fBspec\fR file which is read by \fBgcj\fR. These | |
| 534 options are listed here for completeness; if you are using \f(CW\*(C`libgcj\*(C'\fR | |
| 535 then you won't want to touch these options. | |
| 536 .IP "\fB\-fuse\-boehm\-gc\fR" 4 | |
| 537 .IX Item "-fuse-boehm-gc" | |
| 538 This enables the use of the Boehm \s-1GC\s0 bitmap marking code. In particular | |
| 539 this causes \fBgcj\fR to put an object marking descriptor into each | |
| 540 vtable. | |
| 541 .IP "\fB\-fhash\-synchronization\fR" 4 | |
| 542 .IX Item "-fhash-synchronization" | |
| 543 By default, synchronization data (the data used for \f(CW\*(C`synchronize\*(C'\fR, | |
| 544 \&\f(CW\*(C`wait\*(C'\fR, and \f(CW\*(C`notify\*(C'\fR) is pointed to by a word in each object. | |
| 545 With this option \fBgcj\fR assumes that this information is stored in a | |
| 546 hash table and not in the object itself. | |
| 547 .IP "\fB\-fuse\-divide\-subroutine\fR" 4 | |
| 548 .IX Item "-fuse-divide-subroutine" | |
| 549 On some systems, a library routine is called to perform integer | |
| 550 division. This is required to get exception handling correct when | |
| 551 dividing by zero. | |
| 552 .IP "\fB\-fcheck\-references\fR" 4 | |
| 553 .IX Item "-fcheck-references" | |
| 554 On some systems it's necessary to insert inline checks whenever | |
| 555 accessing an object via a reference. On other systems you won't need | |
| 556 this because null pointer accesses are caught automatically by the | |
| 557 processor. | |
| 558 .SH "SEE ALSO" | |
| 559 .IX Header "SEE ALSO" | |
| 560 \&\fIgcc\fR\|(1), \fIgcjh\fR\|(1), \fIgjnih\fR\|(1), \fIgij\fR\|(1), \fIjcf\-dump\fR\|(1), \fIgfdl\fR\|(7), | |
| 561 and the Info entries for \fIgcj\fR and \fIgcc\fR. | |
| 562 .SH "COPYRIGHT" | |
| 563 .IX Header "COPYRIGHT" | |
| 564 Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. | |
| 565 .PP | |
| 566 Permission is granted to copy, distribute and/or modify this document | |
| 567 under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.2 or | |
| 568 any later version published by the Free Software Foundation; with no | |
| 569 Invariant Sections, the Front-Cover Texts being (a) (see below), and | |
| 570 with the Back-Cover Texts being (b) (see below). | |
| 571 A copy of the license is included in the | |
| 572 man page \fIgfdl\fR\|(7). | |
| 573 .PP | |
| 574 (a) The \s-1FSF\s0's Front-Cover Text is: | |
| 575 .PP | |
| 576 .Vb 1 | |
| 577 \& A GNU Manual | |
| 578 .Ve | |
| 579 .PP | |
| 580 (b) The \s-1FSF\s0's Back-Cover Text is: | |
| 581 .PP | |
| 582 .Vb 3 | |
| 583 \& You have freedom to copy and modify this GNU Manual, like GNU | |
| 584 \& software. Copies published by the Free Software Foundation raise | |
| 585 \& funds for GNU development. | |
| 586 .Ve |