[RFC] Number of insn slots used for method compilation

[Keith Seitz <keiths at redhat dot com>]

Hi,

Before moving on with the next patch, I have a question for the gurus 
out there...

As you know, when _Jv_InterpMethod compiles a method, the number of insn 
slots may change relative to the number of bytecode instructions that 
comprise the method, i.e., code_length is not a valid indication of how 
many insn_slots are contained in _Jv_InterpMethod->prepared.

Other than adding a variable to hold this information (a la the attached 
patch), is there another way that won't require using any more memory? I 
don't think that code_length can safely be changed to store this 
information.

[I plan to use this information to form code indices for reporting 
Locations in JDWP. So when the debugger says "set a breakpoint at code 
index N" in some method, it is easy for us to use 
_Jv_InterpMethod->prepared[N] to get at the actual insn.]

Keith
Index: include/java-interp.h
===================================================================
--- include/java-interp.h	(revision 109918)
+++ include/java-interp.h	(working copy)
@@ -145,6 +145,7 @@
   _Jv_LineTableEntry *line_table;
 
   void *prepared;
+  int number_insn_slots;
 
   unsigned char* bytecode () 
   {
Index: interpret.cc
===================================================================
--- interpret.cc	(revision 109918)
+++ interpret.cc	(working copy)
@@ -330,6 +330,7 @@
       if (! first_pass)
 	{
 	  insns = (insn_slot *) _Jv_AllocBytes (sizeof (insn_slot) * next);
+	  number_insn_slots = next;
 	  next = 0;
 	}