1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package com.sun.tools.jextract;
  24 
  25 import java.foreign.Libraries;
  26 import java.lang.invoke.MethodHandles;
  27 import java.lang.invoke.MethodHandles.Lookup;
  28 import java.lang.reflect.Method;
  29 
  30 import jdk.internal.org.objectweb.asm.FieldVisitor;
  31 import jdk.internal.org.objectweb.asm.ClassWriter;
  32 import jdk.internal.org.objectweb.asm.MethodVisitor;
  33 import jdk.internal.org.objectweb.asm.Type;
  34 import com.sun.tools.jextract.tree.EnumTree;
  35 import com.sun.tools.jextract.tree.FieldTree;
  36 import com.sun.tools.jextract.tree.FunctionTree;
  37 import com.sun.tools.jextract.tree.MacroTree;
  38 import com.sun.tools.jextract.tree.VarTree;
  39 
  40 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_FINAL;
  41 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
  42 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PRIVATE;
  43 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_STATIC;
  44 import static jdk.internal.org.objectweb.asm.Opcodes.CHECKCAST;
  45 import static jdk.internal.org.objectweb.asm.Opcodes.GETSTATIC;
  46 import static jdk.internal.org.objectweb.asm.Opcodes.ILOAD;
  47 import static jdk.internal.org.objectweb.asm.Opcodes.INVOKEINTERFACE;
  48 import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESTATIC;
  49 import static jdk.internal.org.objectweb.asm.Opcodes.IRETURN;
  50 import static jdk.internal.org.objectweb.asm.Opcodes.PUTSTATIC;
  51 import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;
  52 import static jdk.internal.org.objectweb.asm.Opcodes.V1_8;
  53 
  54 /**
  55  * This extended factory generates a class with only static methods and fields. A native
  56  * library interface instance (of the given header file) is kept as a static private field.
  57  * One static method is generated for every library interface method. Enum and macro constants
  58  * are mapped to static final fields. By importing the "static forwarder" class, the user code
  59  * looks more or less like C code. Libraries.bind and header interface usage is hidden.
  60  */
  61 final class AsmCodeFactoryExt extends AsmCodeFactory {
  62     private final String headerClassNameDesc;
  63     private final ClassWriter cw;
  64     // suffix for static forwarder class name
  65     private static final String STATICS_CLASS_NAME_SUFFIX = "_h";
  66     // field name for the header interface instance.
  67     private static final String STATICS_LIBRARY_FIELD_NAME = "_theLibrary";
  68 
  69     AsmCodeFactoryExt(Context ctx, HeaderFile header) {
  70         super(ctx, header);
  71         logger.info(() -> "Instantiate StaticForwarderGenerator for " + header.path);
  72         this.headerClassNameDesc = "L" + headerClassName + ";";
  73         this.cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
  74         this.cw.visit(V1_8, ACC_PUBLIC | ACC_FINAL, getClassName(),
  75             null, "java/lang/Object", null);
  76         staticsInitializer();
  77     }
  78 
  79     @Override
  80     public Boolean visitVar(VarTree varTree, JType jt) {
  81         if (super.visitVar(varTree, jt)) {
  82             String fieldName = varTree.name();
  83             assert !fieldName.isEmpty();
  84 
  85             emitStaticForwarder(fieldName + "$get",
  86                 "()" + jt.getDescriptor(), "()" + jt.getSignature(false));
  87 
  88             emitStaticForwarder(fieldName + "$set",
  89                 "(" + jt.getDescriptor() + ")V",
  90                 "(" + jt.getSignature(true) + ")V");
  91             JType ptrType = JType.GenericType.ofPointer(jt);
  92             emitStaticForwarder(fieldName + "$ptr",
  93                 "()" + ptrType.getDescriptor(), "()" + ptrType.getSignature(false));
  94 
  95             return true;
  96         } else {
  97             return false;
  98         }
  99     }
 100 
 101     @Override
 102     public Boolean visitEnum(EnumTree enumTree, JType jt) {
 103         if (super.visitEnum(enumTree, jt)) {
 104             enumTree.constants().forEach(constant -> addEnumConstant(constant));
 105             return true;
 106         } else {
 107             return false;
 108         }
 109     }
 110 
 111     @Override
 112     public Boolean visitFunction(FunctionTree funcTree, JType jt) {
 113         if (super.visitFunction(funcTree, jt)) {
 114             assert (jt instanceof JType.Function);
 115             JType.Function fn = (JType.Function)jt;
 116             logger.fine(() -> "Add method: " + fn.getSignature(false));
 117             emitStaticForwarder(funcTree.name(), fn.getDescriptor(), fn.getSignature(false));
 118             return true;
 119         } else {
 120             return false;
 121         }
 122     }
 123 
 124     @Override
 125     public Boolean visitMacro(MacroTree macroTree, JType jt) {
 126         if (super.visitMacro(macroTree, jt)) {
 127             String name = macroTree.name();
 128             Object value = macroTree.value().get();
 129             logger.fine(() -> "Adding macro " + name);
 130             Class<?> macroType = Utils.unboxIfNeeded(value.getClass());
 131             String sig = Type.getType(macroType).getDescriptor();
 132             FieldVisitor fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, sig, null, value);
 133             fv.visitEnd();
 134             return true;
 135         } else {
 136             return false;
 137         }
 138     }
 139 
 140     @Override
 141     protected synchronized void produce() {
 142         super.produce();
 143         types.put(getSimpleClassName(), getClassBytes());
 144     }
 145 
 146     // Internals only below this point
 147     // not fully qualified
 148     private String getSimpleClassName() {
 149         return headerFile.clsName + STATICS_CLASS_NAME_SUFFIX;
 150     }
 151 
 152     private String getClassName() {
 153         return headerClassName + STATICS_CLASS_NAME_SUFFIX;
 154     }
 155 
 156     // return the generated static forwarder class bytes
 157     private byte[] getClassBytes() {
 158         cw.visitEnd();
 159         return cw.toByteArray();
 160     }
 161 
 162     // map each C enum constant as a static final field of the static forwarder class
 163     private void addEnumConstant(FieldTree fieldTree) {
 164         assert (fieldTree.isEnumConstant());
 165         String name = fieldTree.name();
 166         String desc = dict.lookup(fieldTree.type()).getDescriptor();
 167         if (desc.length() != 1) {
 168             throw new AssertionError("expected single char descriptor: " + desc);
 169         }
 170         FieldVisitor fv = null;
 171         switch (desc.charAt(0)) {
 172             case 'J':
 173                 long lvalue = fieldTree.enumConstant().get();
 174                 fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, desc, null, lvalue);
 175                 break;
 176             case 'I':
 177                 int ivalue = fieldTree.enumConstant().get().intValue();
 178                 fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, desc, null, ivalue);
 179                 break;
 180             default:
 181                 throw new AssertionError("should not reach here");
 182         }
 183         fv.visitEnd();
 184     }
 185 
 186     // emit library interface static field and <clinit> initializer for that field
 187     private void staticsInitializer() {
 188         // library interface field
 189         FieldVisitor fv = cw.visitField(ACC_PRIVATE|ACC_STATIC|ACC_FINAL,
 190             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc, null, null);
 191         fv.visitEnd();
 192 
 193         // <clinit> to bind library interface field
 194         MethodVisitor mv = cw.visitMethod(ACC_STATIC,
 195             "<clinit>", "()V", null, null);
 196         mv.visitCode();
 197 
 198         // MethodHandles.lookup()
 199         Method lookupMethod = null;
 200         try {
 201             lookupMethod = MethodHandles.class.getMethod("lookup");
 202         } catch (NoSuchMethodException nsme) {
 203             throw new RuntimeException(nsme);
 204         }
 205         mv.visitMethodInsn(INVOKESTATIC,
 206             Type.getInternalName(MethodHandles.class), "lookup",
 207             Type.getMethodDescriptor(lookupMethod), false);
 208 
 209         // ldc library-interface-class
 210         mv.visitLdcInsn(Type.getObjectType(headerClassName));
 211 
 212         // Libraries.bind(lookup, class);
 213         Method bindMethod = null;
 214         try {
 215             bindMethod = Libraries.class.getMethod("bind", Lookup.class, Class.class);
 216         } catch (NoSuchMethodException nsme) {
 217             throw new RuntimeException(nsme);
 218         }
 219         mv.visitMethodInsn(INVOKESTATIC,
 220             Type.getInternalName(Libraries.class), "bind",
 221             Type.getMethodDescriptor(bindMethod), false);
 222 
 223         // store it in library interface field
 224         mv.visitTypeInsn(CHECKCAST, headerClassName);
 225         mv.visitFieldInsn(PUTSTATIC, getClassName(),
 226             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc);
 227 
 228         mv.visitInsn(RETURN);
 229         mv.visitMaxs(0, 0);
 230         mv.visitEnd();
 231     }
 232 
 233     // emit static forwarder method for a specific library interface method
 234     private void emitStaticForwarder(String name, String desc, String signature) {
 235         MethodVisitor mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC,
 236             name, desc, signature, null);
 237         mv.visitCode();
 238 
 239         // load library interface (static) field
 240         mv.visitFieldInsn(GETSTATIC, getClassName(),
 241             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc);
 242 
 243         // forward the call to the interface
 244         Type[] argTypes = Type.getArgumentTypes(desc);
 245         Type retType = Type.getReturnType(desc);
 246 
 247         int loadIdx = 0;
 248         for (int i = 0; i < argTypes.length; i++) {
 249             mv.visitVarInsn(argTypes[i].getOpcode(ILOAD), loadIdx);
 250             loadIdx += argTypes[i].getSize();
 251         }
 252         mv.visitMethodInsn(INVOKEINTERFACE, headerClassName, name, desc, true);
 253         mv.visitInsn(retType.getOpcode(IRETURN));
 254 
 255         mv.visitMaxs(0, 0);
 256         mv.visitEnd();
 257     }
 258 }