Need help with Pcode BlockMap, BlockIfElse, BlockGraph

[anzosasuke]

I am trying to use pcodes to detect the if/else loop in the program. I came across the BlockIfElse in ghidra. It seems it needs blockgraph and blockmap, but i am having trouble with finding the way to make a blockgraph and blockmap. I have made a basicblock of pcode using highfunction in decompilerutils. I am trying to figure out how to proceed further. Could someone help me with this please? That would be great!

snippet of pcodebasicblock:

pcodeblock = res.getHighFunction().getBasicBlocks()

[d-millar]

@anzosasuke Up until recently, this place I would have recommended you look was the GraphASTAndFlowScript, which built combined data- and control-flow graphs. This functionality was recently re-factored into the PCodeCfgGraphTask and PCodeDfgGraphTasks in Ghidra/Features/Decompiler/src/main/java/ghidra/app/plugin/core/decomple/actions.

[ghidracadabra]

@anzosasuke It's possible that the method DecompInterface.structureGraph is what you are looking for. There's an example of its use in DecompilerNestedLayout.performInitialGridLayout, but that example builds the ingraph argument from the Function object and not the HighFunction. You'd probably want to build it from the basic blocks from the HighFunction.

[anzosasuke]

Thanks for that @ghidracadabra . To make a blockgraph instead of a ingraph using the basicblocks, I need to make edges to insert in the graph. There are two methods addBlock() and addEdge(). Since there are no getDestination like methods in pcodeblockbasic and also i couldnot get the address of the particular Pcode Instruction. I could get the address of the varnode using getPCAddress() but not relevant i think. Since I am not able to make any edges, I am unable to make the block graph as you suggested and get the structure graph. Any help on this is greatly appreciated.

[d-millar]

OK, I think (and correct me if I’m wrong) you are looking for the logic underlying the PCodeCfg/DfgGraphTasks. Take a look at PCodeCombinedGraphTask::buildGraph, particularly the last two loops, and see if the iterator logic is what you are looking for.

[ghidracadabra]

@anzosasuke So admittedly this API could use a bit of smoothing over.

I found some old code where I was experimenting with the graph structuring, here's the method I used to create the BlockGraph:

private BlockGraph createInGraph(HighFunction highFunction) {
        Map<PcodeBlockBasic, PcodeBlock> highToGraph = new HashMap<>();
        BlockGraph inGraph = new BlockGraph();
        for (PcodeBlockBasic highBlock : highFunction.getBasicBlocks()) {
            PcodeBlock graphBlock = new BlockCopy(highBlock, highBlock.getStart());
            inGraph.addBlock(graphBlock);
            highToGraph.put(highBlock, graphBlock);
        }

       for (PcodeBlockBasic highBlock : highFunction.getBasicBlocks()) {
            for (int i = 0; i < highBlock.getOutSize(); i++) {
                inGraph.addEdge(highToGraph.get(highBlock), highToGraph.get(highBlock.getOut(i)));
            }
        }
        inGraph.setIndices();
        return inGraph;
    }

[anzosasuke]

Thanks @d-millar. and thanks @ghidracadabra for the above code. Junggraph is needed. I tried making a junggraph using jungdirectedvisualgraph(). But got the error 'can't instantiate abstract class (ghidra.graph.graphs.JungDirectedVisualGraph)'. I was trying to implement DecompilerNestedLayout.performInitialGridLayout. Am i doing something wrong?

[dragonmacher]

Regarding your email question about creating a Jung graph, you should be able to create a JungDirectedGraph (not the JungDirectedVisualGraph you mentioned).

[anzosasuke]

Thanks @dragonmacher . I went ahead with ur idea but got the error like this:
ingraph.addEdge(highBlock1, highBlock1.getOut(i)) TypeError: addEdge(): 2nd arg can't be coerced to java.util.Collection, edu.uci.ics.jung.graph.util.Pair

I also tried the Edge(highBlock1, highBlock1.getOut()) ad similarly with the codeblockEdge, I am still getting this error.

[decaduto]

hey @anzosasuke, have you found a way for doing this? I need the same for whiledo and dowhile blocks, do you think is possible to detect them and get the address of the block?