How to run through the BBL

[Arthur]

I would like to run through the Basic block

for i ; i++ {

  being i each instruction ?

}

[sharma...@google.com]

Hi,

The drmgr extension (https://dynamorio.org/page_drmgr.html#sec_drmgr_stages) offers various event callbacks where you can iterate through basic blocks. Depending on your use case, you can choose from any of these:

1. If you want to only analyse the basic blocks, but not add any instrumentation, use the analysis callback which is invoked for each basic block, and gets the instrlist_t (the instruction list with all instructions) for the fragment. E.g.  https://github.com/DynamoRIO/dynamorio/blob/27193828261be587d06bcbbca3eabc49726d441f/api/samples/inscount.cpp#L143. This sample also shows a for-loop that can iterate through all instructions in an instrlist_t.

2. If you want to add your own instrumentation to the basic block, use the drmgr insertion callback, which is invoked separately for each instruction in the fragment: https://github.com/DynamoRIO/dynamorio/blob/27193828261be587d06bcbbca3eabc49726d441f/api/samples/countcalls.c#L222

3. If you want to do app to app transformations, use the drmgr app2app callback, which is invoked for each basic block: https://github.com/DynamoRIO/dynamorio/blob/27193828261be587d06bcbbca3eabc49726d441f/api/samples/prefetch.c#L91

You can register your event callbacks using routines like drmgr_register_bb_instrumentation_event, drmgr_register_bb_app2app_event etc

Abhinav

[Arthur]

I've read most of the examples, https://dynamorio.org/page_drmgr.html#sec_drmgr_stages) , I will be reading this. but haven't found so far something exactly like I needed

I wanted something similar to this:

for (BBL bbl = TRACE_BblHead(trace); BBL_Valid(bbl); bbl = BBL_Next(bbl))

but I'm not sure if the dr trace event would be able.: dr_register_trace_event

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[Abhinav Sharma]

Hi,

Can you clarify whether you want to iterate over instructions or basic blocks in a trace?

You can iterate over the instructions in a trace using the for-loop like https://github.com/DynamoRIO/dynamorio/blob/27193828261be587d06bcbbca3eabc49726d441f/api/samples/inscount.cpp#L173. Also, the drmgr_register_bb_instrumentation_event, drmgr_register_bb_app2app_event etc callbacks have a 'for_trace` boolean argument that tells whether the given instr_t or instrlist_t is for a trace fragment. 

But as far as I know, there's no API that allows iterating over the basic blocks that make up a fragment. Would looking at instr_get_app_pc for the individual instructions help? (Basic block tags are basically their app PCs). Maybe more details about your use case will help.

Abhinav

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[Arthur]

I want to iterate over the trace,

Go from one BB to the next one.

While in the BB i will use the common iterarion that exists.

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