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src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java

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@@ -1,7 +1,7 @@
  /*
-  * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
+  * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this

@@ -144,10 +144,11 @@
      /** Access to files. */
      private final JavaFileManager fileManager;
  
      /** The tags and constants used in compressed stackmap. */
      static final int SAME_FRAME_SIZE = 64;
+     static final int EARLY_LARVAL = 246;
      static final int SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247;
      static final int SAME_FRAME_EXTENDED = 251;
      static final int FULL_FRAME = 255;
      static final int MAX_LOCAL_LENGTH_DIFF = 4;
  

@@ -220,11 +221,11 @@
      public static String flagNames(long flags) {
          StringBuilder sbuf = new StringBuilder();
          int i = 0;
          long f = flags & StandardFlags;
          while (f != 0) {
-             if ((f & 1) != 0) {
+             if ((f & 1) != 0 && flagName[i] != "") {
                  sbuf.append(" ");
                  sbuf.append(flagName[i]);
              }
              f = f >> 1;
              i++;

@@ -232,11 +233,12 @@
          return sbuf.toString();
      }
      //where
          private static final String[] flagName = {
              "PUBLIC", "PRIVATE", "PROTECTED", "STATIC", "FINAL",
-             "SUPER", "VOLATILE", "TRANSIENT", "NATIVE", "INTERFACE",
+             // the empty position should be for synchronized but right now we don't have any test checking it
+             "", "VOLATILE", "TRANSIENT", "NATIVE", "INTERFACE",
              "ABSTRACT", "STRICTFP"};
  
  /* ****************************************************************
   * Output routines
   ******************************************************************/

@@ -840,13 +842,12 @@
      void writeInnerClasses() {
          int alenIdx = writeAttr(names.InnerClasses);
          databuf.appendChar(poolWriter.innerClasses.size());
          for (ClassSymbol inner : poolWriter.innerClasses) {
              inner.markAbstractIfNeeded(types);
-             int flags = adjustFlags(inner.flags_field);
+             int flags = adjustFlags(inner, inner.flags_field);
              if ((flags & INTERFACE) != 0) flags |= ABSTRACT; // Interfaces are always ABSTRACT
-             flags &= ~STRICTFP; //inner classes should not have the strictfp flag set.
              if (dumpInnerClassModifiers) {
                  PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
                  pw.println("INNERCLASS  " + inner.name);
                  pw.println("---" + flagNames(flags));
              }

@@ -858,10 +859,21 @@
              databuf.appendChar(flags);
          }
          endAttr(alenIdx);
      }
  
+      /** Write out "LoadableDescriptors" attribute by enumerating the value classes encountered in field/method descriptors during this compilation.
+       */
+      void writeLoadableDescriptorsAttribute() {
+         int alenIdx = writeAttr(names.LoadableDescriptors);
+         databuf.appendChar(poolWriter.loadableDescriptors.size());
+         for (Symbol c : poolWriter.loadableDescriptors) {
+             databuf.appendChar(poolWriter.putDescriptor(c));
+         }
+         endAttr(alenIdx);
+      }
+ 
      int writeRecordAttribute(ClassSymbol csym) {
          int alenIdx = writeAttr(names.Record);
          Scope s = csym.members();
          databuf.appendChar(csym.getRecordComponents().size());
          for (VarSymbol v: csym.getRecordComponents()) {

@@ -971,19 +983,26 @@
      }
  
      /** Write field symbol, entering all references into constant pool.
       */
      void writeField(VarSymbol v) {
-         int flags = adjustFlags(v.flags());
+         int flags = adjustFlags(v, v.flags());
          databuf.appendChar(flags);
          if (dumpFieldModifiers) {
              PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
              pw.println("FIELD  " + v.name);
              pw.println("---" + flagNames(v.flags()));
          }
          databuf.appendChar(poolWriter.putName(v.name));
          databuf.appendChar(poolWriter.putDescriptor(v));
+         Type fldType = v.erasure(types);
+         if (fldType.requiresLoadableDescriptors(v.owner)) {
+             poolWriter.enterLoadableDescriptorsClass(fldType.tsym);
+             if (preview.isPreview(Source.Feature.VALUE_CLASSES)) {
+                 preview.markUsesPreview(null);
+             }
+         }
          int acountIdx = beginAttrs();
          int acount = 0;
          if (v.getConstValue() != null) {
              int alenIdx = writeAttr(names.ConstantValue);
              databuf.appendChar(poolWriter.putConstant(v.getConstValue()));

@@ -996,19 +1015,35 @@
      }
  
      /** Write method symbol, entering all references into constant pool.
       */
      void writeMethod(MethodSymbol m) {
-         int flags = adjustFlags(m.flags());
+         int flags = adjustFlags(m, m.flags());
          databuf.appendChar(flags);
          if (dumpMethodModifiers) {
              PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
              pw.println("METHOD  " + m.name);
              pw.println("---" + flagNames(m.flags()));
          }
          databuf.appendChar(poolWriter.putName(m.name));
          databuf.appendChar(poolWriter.putDescriptor(m));
+         MethodType mtype = (MethodType) m.externalType(types);
+         for (Type t : mtype.getParameterTypes()) {
+             if (t.requiresLoadableDescriptors(m.owner)) {
+                 poolWriter.enterLoadableDescriptorsClass(t.tsym);
+                 if (preview.isPreview(Source.Feature.VALUE_CLASSES)) {
+                     preview.markUsesPreview(null);
+                 }
+             }
+         }
+         Type returnType = mtype.getReturnType();
+         if (returnType.requiresLoadableDescriptors(m.owner)) {
+             poolWriter.enterLoadableDescriptorsClass(returnType.tsym);
+             if (preview.isPreview(Source.Feature.VALUE_CLASSES)) {
+                 preview.markUsesPreview(null);
+             }
+         }
          int acountIdx = beginAttrs();
          int acount = 0;
          if (m.code != null) {
              int alenIdx = writeAttr(names.Code);
              writeCode(m.code);

@@ -1295,20 +1330,26 @@
          }
  
      /** An entry in the JSR202 StackMapTable */
      abstract static class StackMapTableFrame {
          abstract int getFrameType();
+         int pc;
+ 
+         StackMapTableFrame(int pc) {
+             this.pc = pc;
+         }
  
          void write(ClassWriter writer) {
              int frameType = getFrameType();
              writer.databuf.appendByte(frameType);
-             if (writer.debugstackmap) System.out.print(" frame_type=" + frameType);
+             if (writer.debugstackmap) System.out.println(" frame_type=" + frameType + " bytecode offset " + pc);
          }
  
          static class SameFrame extends StackMapTableFrame {
              final int offsetDelta;
-             SameFrame(int offsetDelta) {
+             SameFrame(int pc, int offsetDelta) {
+                 super(pc);
                  this.offsetDelta = offsetDelta;
              }
              int getFrameType() {
                  return (offsetDelta < SAME_FRAME_SIZE) ? offsetDelta : SAME_FRAME_EXTENDED;
              }

@@ -1325,11 +1366,12 @@
          }
  
          static class SameLocals1StackItemFrame extends StackMapTableFrame {
              final int offsetDelta;
              final Type stack;
-             SameLocals1StackItemFrame(int offsetDelta, Type stack) {
+             SameLocals1StackItemFrame(int pc, int offsetDelta, Type stack) {
+                 super(pc);
                  this.offsetDelta = offsetDelta;
                  this.stack = stack;
              }
              int getFrameType() {
                  return (offsetDelta < SAME_FRAME_SIZE) ?

@@ -1353,11 +1395,12 @@
          }
  
          static class ChopFrame extends StackMapTableFrame {
              final int frameType;
              final int offsetDelta;
-             ChopFrame(int frameType, int offsetDelta) {
+             ChopFrame(int pc, int frameType, int offsetDelta) {
+                 super(pc);
                  this.frameType = frameType;
                  this.offsetDelta = offsetDelta;
              }
              int getFrameType() { return frameType; }
              @Override

@@ -1372,11 +1415,12 @@
  
          static class AppendFrame extends StackMapTableFrame {
              final int frameType;
              final int offsetDelta;
              final Type[] locals;
-             AppendFrame(int frameType, int offsetDelta, Type[] locals) {
+             AppendFrame(int pc, int frameType, int offsetDelta, Type[] locals) {
+                 super(pc);
                  this.frameType = frameType;
                  this.offsetDelta = offsetDelta;
                  this.locals = locals;
              }
              int getFrameType() { return frameType; }

@@ -1396,11 +1440,12 @@
  
          static class FullFrame extends StackMapTableFrame {
              final int offsetDelta;
              final Type[] locals;
              final Type[] stack;
-             FullFrame(int offsetDelta, Type[] locals, Type[] stack) {
+             FullFrame(int pc, int offsetDelta, Type[] locals, Type[] stack) {
+                 super(pc);
                  this.offsetDelta = offsetDelta;
                  this.locals = locals;
                  this.stack = stack;
              }
              int getFrameType() { return FULL_FRAME; }

@@ -1425,45 +1470,76 @@
                      writer.writeStackMapType(stack[i]);
                  }
              }
          }
  
+         static class EarlyLarvalFrame extends StackMapTableFrame {
+             final StackMapTableFrame base;
+             Set<VarSymbol> unsetFields;
+ 
+             EarlyLarvalFrame(StackMapTableFrame base, Set<VarSymbol> unsetFields) {
+                 super(base.pc);
+                 Assert.check(!(base instanceof EarlyLarvalFrame));
+                 this.base = base;
+                 this.unsetFields = unsetFields == null ? Set.of() : unsetFields;
+             }
+ 
+             int getFrameType() { return EARLY_LARVAL; }
+ 
+             @Override
+             void write(ClassWriter writer) {
+                 super.write(writer);
+                 writer.databuf.appendChar(unsetFields.size());
+                 if (writer.debugstackmap) {
+                     System.out.println("    # writing: EarlyLarval stackmap frame with " + unsetFields.size() + " fields");
+                 }
+                 for (VarSymbol vsym : unsetFields) {
+                     int index = writer.poolWriter.putNameAndType(vsym);
+                     writer.databuf.appendChar(index);
+                     if (writer.debugstackmap) {
+                         System.out.println("    #writing unset field: " + index + ", with name: " + vsym.name.toString());
+                     }
+                 }
+                 base.write(writer);
+             }
+         }
+ 
         /** Compare this frame with the previous frame and produce
          *  an entry of compressed stack map frame. */
          static StackMapTableFrame getInstance(Code.StackMapFrame this_frame,
-                                               int prev_pc,
-                                               Type[] prev_locals,
-                                               Types types) {
+                                               Code.StackMapFrame prevFrame,
+                                               Types types,
+                                               int pc) {
              Type[] locals = this_frame.locals;
              Type[] stack = this_frame.stack;
-             int offset_delta = this_frame.pc - prev_pc - 1;
+             int offset_delta = this_frame.pc - prevFrame.pc - 1;
              if (stack.length == 1) {
-                 if (locals.length == prev_locals.length
-                     && compare(prev_locals, locals, types) == 0) {
-                     return new SameLocals1StackItemFrame(offset_delta, stack[0]);
+                 if (locals.length == prevFrame.locals.length
+                     && compare(prevFrame.locals, locals, types) == 0) {
+                     return new SameLocals1StackItemFrame(pc, offset_delta, stack[0]);
                  }
              } else if (stack.length == 0) {
-                 int diff_length = compare(prev_locals, locals, types);
+                 int diff_length = compare(prevFrame.locals, locals, types);
                  if (diff_length == 0) {
-                     return new SameFrame(offset_delta);
+                     return new SameFrame(pc, offset_delta);
                  } else if (-MAX_LOCAL_LENGTH_DIFF < diff_length && diff_length < 0) {
                      // APPEND
                      Type[] local_diff = new Type[-diff_length];
-                     for (int i=prev_locals.length, j=0; i<locals.length; i++,j++) {
+                     for (int i=prevFrame.locals.length, j=0; i<locals.length; i++,j++) {
                          local_diff[j] = locals[i];
                      }
-                     return new AppendFrame(SAME_FRAME_EXTENDED - diff_length,
+                     return new AppendFrame(pc, SAME_FRAME_EXTENDED - diff_length,
                                             offset_delta,
                                             local_diff);
                  } else if (0 < diff_length && diff_length < MAX_LOCAL_LENGTH_DIFF) {
                      // CHOP
-                     return new ChopFrame(SAME_FRAME_EXTENDED - diff_length,
+                     return new ChopFrame(pc, SAME_FRAME_EXTENDED - diff_length,
                                           offset_delta);
                  }
              }
              // FULL_FRAME
-             return new FullFrame(offset_delta, locals, stack);
+             return new FullFrame(pc, offset_delta, locals, stack);
          }
  
          static boolean isInt(Type t) {
              return (t.getTag().isStrictSubRangeOf(INT)  || t.hasTag(BOOLEAN));
          }

@@ -1582,14 +1658,15 @@
  
          int flags;
          if (c.owner.kind == MDL) {
              flags = ACC_MODULE;
          } else {
-             flags = adjustFlags(c.flags() & ~DEFAULT);
+             long originalFlags = c.flags();
+             flags = adjustFlags(c, c.flags() & ~(DEFAULT | STRICTFP));
              if ((flags & PROTECTED) != 0) flags |= PUBLIC;
-             flags = flags & ClassFlags & ~STRICTFP;
-             if ((flags & INTERFACE) == 0) flags |= ACC_SUPER;
+             flags = flags & ClassFlags;
+             flags |= (originalFlags & IDENTITY_TYPE) != 0 ? ACC_IDENTITY : flags;
          }
  
          if (dumpClassModifiers) {
              PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
              pw.println();

@@ -1711,10 +1788,15 @@
          if (!poolWriter.innerClasses.isEmpty()) {
              writeInnerClasses();
              acount++;
          }
  
+         if (!poolWriter.loadableDescriptors.isEmpty()) {
+             writeLoadableDescriptorsAttribute();
+             acount++;
+         }
+ 
          endAttrs(acountIdx, acount);
  
          out.write(poolbuf.elems, 0, poolbuf.length);
  
          poolWriter.writePool(out);

@@ -1741,11 +1823,11 @@
              i += hook.applyAsInt(sym);
          }
          return i;
      }
  
-     int adjustFlags(final long flags) {
+     int adjustFlags(Symbol sym, final long flags) {
          int result = (int)flags;
  
          // Elide strictfp bit in class files
          if (target.obsoleteAccStrict())
              result &= ~STRICTFP;

@@ -1754,10 +1836,18 @@
              result |= ACC_BRIDGE;
          if ((flags & VARARGS) != 0)
              result |= ACC_VARARGS;
          if ((flags & DEFAULT) != 0)
              result &= ~ABSTRACT;
+         if ((flags & IDENTITY_TYPE) != 0) {
+             result |= ACC_IDENTITY;
+         }
+         if (sym.kind == VAR) {
+             if ((flags & STRICT) != 0) {
+                 result |= ACC_STRICT;
+             }
+         }
          return result;
      }
  
      long getLastModified(FileObject filename) {
          return filename.getLastModified();
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