Re: Re: How to insert instrcutions at the beginning and/or at the end of each basic block?

Hi Leo, "LabelNode" defines the start of a new basic block.

So you could cycle through the opcodes, on finding a LabelNode
then instrument what you like, and I've listed the branching
instructions so you can instrument at that point too...

Good luck..

while (j.hasNext()) {
  AbstractInsnNode node = (AbstractInsnNode) j.next();
  int opcode = node.getOpcode();

  if (in instanceof LabelNode) {
                if (j.hasNext()) {
                // instrument.
                }
   }

   switch(opcode) {
            case IFEQ:
            case IFNE:
            case IFLT:
            case IFGE:
            case IFGT:
            case IFLE:
            case IFNULL:
            case IFNONNULL:
            case IF_ICMPEQ:
            case IF_ICMPNE:
            case IF_ICMPLT:
            case IF_ICMPGE:
            case IF_ICMPGT:
            case IF_ICMPLE:
            case IF_ACMPEQ:
            case IF_ACMPNE:
            case JSR:
            case GOTO:

             //instrument after branching instructions.
          break;
  }
}

Buu Vinh wrote:
> You can insert your logic at method's entry and exit using 
> onMethodEntry and onMethodExit.
>
> Hope this helps.
>
> Buu Vinh
>
> --- On *Wed, 7/6/11, Leo Romanoff /<[email protected]>/* wrote:
>
>
>     From: Leo Romanoff <[email protected]>
>     Subject: [asm] How to insert instrcutions at the beginning and/or
>     at the end of each basic block?
>     To: [email protected]
>     Date: Wednesday, July 6, 2011, 10:32 AM
>
>
>     Hi,
>
>     I'd like to instrument my java classes and insert certain sequences of
>     instructions at the beginning and/or at the end of each basic block
>     (specifically, these instructions are supposed to call a static
>     method of
>     predefined class).
>
>     How this can be done?
>
>     Do I need to use classes from the org.objectweb.asm.tree.analysis
>     for it? I
>     undrestand how I can obtain frames using something like:
>     Analyzer a = new Analyzer(new BasicInterpreter());
>     ...
>     a.analyze(owner, mn);   
>     Frame[] frames = a.getFrames();
>
>     But how do I get from frames to instructuions contained in this
>     basic block,
>     so that I can insert new ones?
>
>     May be there are some existing examples for this kind of
>     instrumentation
>     already?
>
>     Thanks for any help,
>     Leo
>     -- 
>     View this message in context:
>     http://old.nabble.com/How-to-insert-instrcutions-at-the-beginning-and-or-at-the-end-of-each-basic-block--tp32005881p32005881.html
>     Sent from the ASM mailing list archive at Nabble.com.
>
>
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