[llvm-commits] CVS: llvm-java/docs/object-layout.txt

[Alkis Evlogimenos]

Changes in directory llvm-java/docs:

object-layout.txt added (r1.1)

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Log message:

Initial checking of the llvm java-frontend. This contains a skeleton and a preliminary ClassFile parsing library


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Diffs of the changes:  (+59 -0)

Index: llvm-java/docs/object-layout.txt
diff -c /dev/null llvm-java/docs/object-layout.txt:1.1
*** /dev/null	Thu Apr 15 16:01:00 2004
--- llvm-java/docs/object-layout.txt	Thu Apr 15 16:00:49 2004
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*** 0 ****
--- 1,59 ----
+ Object layout for Java objects and array objects
+ ------------------------------------------------
+ 
+ 1) objects
+ 
+     Need extensible header for the use of:
+ 
+     a) VM: locking, hashing, dynamic type checking, virtual function
+            invocation.
+ 
+     b) GC: garbage collection (can be the reference count for a
+            reference counting garbage collector)
+ 
+     obj_t : { <header_t>, <field_t1>, <field_t2>, ..., <field_tN> }
+ 
+     +--------+ <-- pointer to object
+     | header |
+     +--------+
+     | field1 |
+     +--------+
+     | field2 |
+     +--------+
+     | ...... |
+     +--------+
+     | fieldN |
+     +--------+
+ 
+ 2) arrays
+ 
+     +--------+ <-- pointer to array object
+     |  len   |
+     +--------+
+     | header |
+     +--------+
+     | obj_t* |
+     +--------+
+     | ...... |
+     +--------+
+     | ...... |
+     +--------+
+ 
+     array_object_t : { uint, <header_t>, [ 0 x <obj_t>* ] }
+ 
+ 
+ Type information for java objects
+ ---------------------------------
+ 
+ VM_Class object for each class. This object needs at least the
+ following fields:
+ 
+ a) pointer to VM_Class object of its super class
+ b) list of interfaces implemented
+ c) list of field descriptors
+ d) list of methods (static, constructor, virtual, finalizer)
+ e) list of attributes (constant value, code, exceptions, inner
+ classes, synthetic, source file, line number table, local variable
+ table, deprecated)
+ 
+ We would most likely need a method dispatch table as well (vtable).