| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.services.bytecode.BCJava |
| 4 | |
| 5 | Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.services.bytecode; |
| 22 | |
| 23 | import org.apache.derby.iapi.services.compiler.JavaFactory; |
| 24 | import org.apache.derby.iapi.services.compiler.ClassBuilder; |
| 25 | import org.apache.derby.iapi.services.compiler.MethodBuilder; |
| 26 | import org.apache.derby.iapi.services.loader.ClassFactory; |
| 27 | import org.apache.derby.iapi.services.classfile.ClassHolder; |
| 28 | |
| 29 | import org.apache.derby.iapi.services.cache.Cacheable; |
| 30 | import org.apache.derby.iapi.services.cache.CacheableFactory; |
| 31 | |
| 32 | import org.apache.derby.iapi.services.cache.CacheFactory; |
| 33 | import org.apache.derby.iapi.services.cache.CacheManager; |
| 34 | |
| 35 | import org.apache.derby.iapi.services.monitor.Monitor; |
| 36 | import org.apache.derby.iapi.services.monitor.ModuleControl; |
| 37 | |
| 38 | import org.apache.derby.iapi.error.StandardException; |
| 39 | |
| 40 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 41 | |
| 42 | import org.apache.derby.iapi.services.classfile.VMDescriptor; |
| 43 | |
| 44 | import java.util.Properties; |
| 45 | import java.util.Hashtable; |
| 46 | |
| 47 | /** |
| 48 | <p> |
| 49 | <b>Debugging problems with generated classes</b> |
| 50 | <p> |
| 51 | When the code has been generated incorrectly, all sorts of |
| 52 | odd things can go wrong. This is one recommended approach to |
| 53 | finding the problem. |
| 54 | <p> |
| 55 | First, turn on ByteCodeGenInstr and DumpClassFile. Look |
| 56 | for missing files (right now they are consecutively numbered |
| 57 | by the activation class builder; later on they won't be, but |
| 58 | BytCodeGenInstr dumps messages about the classes it has). |
| 59 | Look at the log to make sure that all "GEN starting class/method" |
| 60 | messages are paired with a "GEN ending class/method" message. |
| 61 | If a file is missing or the pairing is missing, then something |
| 62 | went wrong when the system tried to generate the bytecodes. |
| 63 | Resort to your favorite debugging tool to step through |
| 64 | the faulty statement. |
| 65 | <p> |
| 66 | If you get class files but the system crashes on you (I had |
| 67 | an OS segmentation fault once) or you get funny messages like |
| 68 | JDBC Excpetion: ac5 where ac5 is just the name of a generated |
| 69 | class, then one of the following is likely: |
| 70 | <ul> |
| 71 | <li> you are calling INVOKEVIRTUAL when |
| 72 | you are supposed to call INVOKEINTERFACE |
| 73 | <li> you have an inexact match on a method argument or |
| 74 | return type. |
| 75 | <li> you are trying to get to a superclass's field using |
| 76 | a subclass. |
| 77 | </ul> |
| 78 | The best way to locate the problem here is to do this (replace |
| 79 | ac5.class with the name of your class file): |
| 80 | <ol> |
| 81 | <li> javap -c -v ac5 >ac5.gp<br> |
| 82 | if javap reports "Class not found", and the file ac5.class does |
| 83 | exist in the current directory, then the .class file is probably |
| 84 | corrupt. Try running mocha on it to see if that works. The |
| 85 | problem will be in the code that generates the entries for |
| 86 | the class file -- most likely the ConstantPool is bad, an |
| 87 | attribute got created incorrectly, or |
| 88 | perhaps the instruction streams are goofed up. |
| 89 | <li> java mocha.Decompiler ac5.class<br> |
| 90 | if mocha cannot create good java source, then you really |
| 91 | need to go back and examine the calls creating the java |
| 92 | constructs; a parameter might have been null when it should |
| 93 | have, a call to turn an expression into a statement may be |
| 94 | missing, or something else may be wrong. |
| 95 | <li> mv ac5.mocha ac5.java |
| 96 | <li> vi ac5.java ; you will have to fix any new SQLBoolean(1, ...) |
| 97 | calls to be new SQLBoolean(true, ...). Also mocha |
| 98 | occasionally messes up other stuff too. Just iterate on it |
| 99 | until it builds or you figure out what is wrong with |
| 100 | the generated code. |
| 101 | <li> javac ac5.java |
| 102 | <li> javap -v -c ac5 >ac5.jp |
| 103 | <li> sed '1,$s/#[0-9]* </# </' ac5.gp > ac5.gn |
| 104 | <li> sed '1,$s/#[0-9]* </# </' ac5.jp > ac5.jn<br> |
| 105 | These seds are to get rid of constant pool entry numbers, |
| 106 | which will be wildly different on the two files. |
| 107 | <li> vdiff32 ac5.gn ac5.jn<br> |
| 108 | this tool shows you side-by-side diffs. If you change |
| 109 | to the window that interleaves the diffs, you can see the |
| 110 | length of the line. Look for places where there are |
| 111 | invokevirtual vs. invokeinterface differences, differences |
| 112 | in the class name of a field, differences in the class name |
| 113 | of a method parameter or return type. The generated code |
| 114 | *will* have some unavoidable differences from the |
| 115 | compiled code, such as: |
| 116 | <ul> |
| 117 | <li> it will have goto's at the end of try blocks |
| 118 | rather than return's. |
| 119 | <li> it will do a getstatic on a static final field |
| 120 | rather than inlining the static final field's value |
| 121 | <li> it will have more checkcast's in it, since it |
| 122 | doesn't see if the checkcast will always succeed |
| 123 | and thus remove it. |
| 124 | </ul> |
| 125 | Once you find a diff, you need to track down where |
| 126 | the call was generated and modify it appropriately: |
| 127 | change newMethodCall to newInterfaceMethodCall; |
| 128 | add newCastExpression to get a argument into the right |
| 129 | type for the parameter; ensure the return type given for |
| 130 | the method is its declared return type. |
| 131 | </ol> |
| 132 | @see org.apache.derby.iapi.services.compiler.JavaFactory |
| 133 | |
| 134 | @author ames |
| 135 | */ |
| 136 | public class BCJava implements JavaFactory, CacheableFactory, ModuleControl { |
| 137 | |
| 138 | ////////////////////////////////////////////////////////////// |
| 139 | // |
| 140 | // MEMBERS |
| 141 | // |
| 142 | ////////////////////////////////////////////////////////////// |
| 143 | |
| 144 | /* Cache of Java class names versus VM type names */ |
| 145 | private CacheManager vmTypeIdCache; |
| 146 | |
| 147 | // |
| 148 | // class interface |
| 149 | // |
| 150 | public BCJava() { |
| 151 | } |
| 152 | |
| 153 | // |
| 154 | // ModuleControl interface |
| 155 | // |
| 156 | /** |
| 157 | Start this module. We need a read/write version of the class utilities |
| 158 | |
| 159 | @exception StandardException standard cloudscape policy |
| 160 | */ |
| 161 | public void boot(boolean create, Properties properties) throws StandardException { |
| 162 | |
| 163 | CacheFactory cf = |
| 164 | (CacheFactory) Monitor.startSystemModule(org.apache.derby.iapi.reference.Module.CacheFactory); |
| 165 | |
| 166 | /* |
| 167 | ** The initial and maximum cache sizes are based on experiments |
| 168 | ** that I did with some of the language tests. I found that |
| 169 | ** the size quickly grew to about 40, then continued to grow |
| 170 | ** slowly after that. |
| 171 | ** |
| 172 | ** - Jeff |
| 173 | */ |
| 174 | vmTypeIdCache = |
| 175 | cf.newCacheManager( |
| 176 | this, |
| 177 | "VMTypeIdCache", |
| 178 | 64, |
| 179 | 256); |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | Stop this module. In this case, nothing needs to be done. |
| 184 | */ |
| 185 | public void stop() { |
| 186 | } |
| 187 | |
| 188 | // |
| 189 | // JavaFactory interface |
| 190 | // |
| 191 | |
| 192 | /** |
| 193 | * a class. Once it is created, fields, methods, |
| 194 | * interfaces, static initialization code, |
| 195 | * and constructors can be added to it. |
| 196 | * <verbatim> |
| 197 | Java: package #packageName; |
| 198 | #modifiers #className extends #superClass { } |
| 199 | // modifiers is the | of the JVM constants for |
| 200 | // the modifiers such as static, public, etc. |
| 201 | </verbatim> |
| 202 | * |
| 203 | * See java.lang.reflect.Modifiers |
| 204 | * @param packageName the name of the package the class is in. |
| 205 | * null if it is in the default package. |
| 206 | * @param modifiers the | of the Modifiers |
| 207 | * constants representing the visibility and control of this |
| 208 | * method. |
| 209 | * @param className the name of the class or interface |
| 210 | * @param superClass the name of the superclass or superinterface |
| 211 | * |
| 212 | * @return the class builder. |
| 213 | */ |
| 214 | public ClassBuilder newClassBuilder(ClassFactory cf, String packageName, |
| 215 | int modifiers, String className, String superClass) { |
| 216 | |
| 217 | return new BCClass(cf, packageName, modifiers, className, superClass, this); |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | ** CacheableFactory interface |
| 222 | */ |
| 223 | public Cacheable newCacheable(CacheManager cm) { |
| 224 | return new VMTypeIdCacheable(); |
| 225 | } |
| 226 | |
| 227 | /////////////////////////////////////////// |
| 228 | // |
| 229 | // UTILITIES specific to this implementation |
| 230 | // |
| 231 | //////////////////////////////////////////// |
| 232 | |
| 233 | /** |
| 234 | * Get the VM Type ID that corresponds with the given java type name. |
| 235 | * This uses the cache of VM type ids. |
| 236 | * |
| 237 | * @param javaType The java type name to translate to a java VM type id |
| 238 | * |
| 239 | * @return The java VM type ID |
| 240 | */ |
| 241 | Type type(String javaType) { |
| 242 | |
| 243 | Type retval; |
| 244 | |
| 245 | try { |
| 246 | |
| 247 | VMTypeIdCacheable vtic = (VMTypeIdCacheable) vmTypeIdCache.find(javaType); |
| 248 | |
| 249 | retval = (Type) vtic.descriptor(); |
| 250 | |
| 251 | vmTypeIdCache.release(vtic); |
| 252 | |
| 253 | return retval; |
| 254 | |
| 255 | } catch (StandardException se) { |
| 256 | if (SanityManager.DEBUG) { |
| 257 | SanityManager.THROWASSERT("Unexpected exception " + se, se); |
| 258 | } |
| 259 | |
| 260 | /* |
| 261 | ** If we're running a sane server, let's act as if the |
| 262 | ** exception didn't happen, and just get the vmTypeId the |
| 263 | ** slow way, without caching. |
| 264 | */ |
| 265 | retval = new Type(javaType, ClassHolder.convertToInternalDescriptor(javaType)); |
| 266 | } |
| 267 | |
| 268 | return retval; |
| 269 | } |
| 270 | |
| 271 | String vmType(BCMethodDescriptor md) { |
| 272 | String retval; |
| 273 | |
| 274 | try { |
| 275 | |
| 276 | VMTypeIdCacheable vtic = (VMTypeIdCacheable) vmTypeIdCache.find(md); |
| 277 | |
| 278 | retval = vtic.descriptor().toString(); |
| 279 | |
| 280 | vmTypeIdCache.release(vtic); |
| 281 | |
| 282 | } catch (StandardException se) { |
| 283 | if (SanityManager.DEBUG) { |
| 284 | SanityManager.THROWASSERT("Unexpected exception " + se, se); |
| 285 | } |
| 286 | |
| 287 | /* |
| 288 | ** If we're running a sane server, let's act as if the |
| 289 | ** exception didn't happen, and just get the vmTypeId the |
| 290 | ** slow way, without caching. |
| 291 | */ |
| 292 | retval = md.buildMethodDescriptor(); |
| 293 | } |
| 294 | |
| 295 | return retval; |
| 296 | } |
| 297 | /** |
| 298 | * Map vm types as strings to vm types as the VM |
| 299 | * handles, with int ids. Used in mapping opcodes |
| 300 | * based on type of operand/stack entry available. |
| 301 | */ |
| 302 | static short vmTypeId(String vmTypeS) { |
| 303 | char vmTypeC = vmTypeS.charAt(0); |
| 304 | switch(vmTypeC) { |
| 305 | case VMDescriptor.C_CLASS : return BCExpr.vm_reference; |
| 306 | case VMDescriptor.C_BYTE : return BCExpr.vm_byte; |
| 307 | case VMDescriptor.C_CHAR : return BCExpr.vm_char; |
| 308 | case VMDescriptor.C_DOUBLE : return BCExpr.vm_double; |
| 309 | case VMDescriptor.C_FLOAT : return BCExpr.vm_float; |
| 310 | case VMDescriptor.C_INT : return BCExpr.vm_int; |
| 311 | case VMDescriptor.C_LONG : return BCExpr.vm_long; |
| 312 | case VMDescriptor.C_SHORT : return BCExpr.vm_short; |
| 313 | case VMDescriptor.C_BOOLEAN : return BCExpr.vm_int; |
| 314 | case VMDescriptor.C_ARRAY : return BCExpr.vm_reference; |
| 315 | case VMDescriptor.C_VOID : return BCExpr.vm_void; |
| 316 | default: |
| 317 | if (SanityManager.DEBUG) |
| 318 | SanityManager.THROWASSERT("No type match for "+vmTypeS); |
| 319 | } |
| 320 | return BCExpr.vm_void; |
| 321 | } |
| 322 | } |