[jboss-user] [Javassist user questions] - Problem with branches and ldc/ldc_w

Hello, i'm working with javassist for quite some time now and I must say it is really impressive what this thing can do, and with what ease! Anyways, I'm confronted with one problem: My tool inserts an arbitrary series of conditional branches and some code afterwards. This means I have to precalculate the number of bytes inserted for all following conditions and the code in respect to set the branch offset. All works well unless I load a string constant using addLdc(String). In this case I am unable to precalculate whether there are 3 bytes (ldc) or 4 bytes (ldc_w) inserted, since this depends on the ConstTables state at insertion time. I've developed a workaround for my case by extending the Bytecode class and altering its behaviour with | private ArrayList<Integer> m_branches; | ... | | public void addBranch(int code, int branchOffset) { | // branch opcode is inserted at offset getSize() | m_branches.add(getSize()); | addOpcode(code); | add16bit(branchOffset); | } | | private void adjustBranches(int end, int shift) { | for (Integer pos : m_branches) { | int branchOffset = read16bit(pos + 1); | if ((pos + branchOffset) <= end) continue; | write16bit(pos + 1, branchOffset + shift); | } | } | | @Override | public void addLdc(int i) { | if (i > 0xFF) { | adjustBranches(getSize(), 1); | addOpcode(LDC_W); | addIndex(i); | } else { | addOpcode(LDC); | add(i); | } | } | I think this is could be extended to a general solution, if it would be well defined how many bytes one should asume to be inserted. Is there a way around this problem that I've overseen or is this really a "bug"? --- By the way, is there any reason there is no | public void add16bit(int value) { | value = value % 65536; | add(value >> 8); | add(value % 256); | } | defined in Bytecode? Since it is required for inserting branch offsets... View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4243340#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...