[LLVMdev] Determine branch coverage information

[Ahmed Raafat]

Hi Andreas,

Many thanks for the below detailed reply, i will try to follow the below
steps and contact you if i have any problems.

Thanks again.

BR,
Ahmed Raafat.

On Wed, Nov 4, 2009 at 4:20 PM, Andreas Neustifter <astifter-llvm at gmx.at>wrote:

> Hi Ahmed!
>
>
> Adventure wrote:
>
>> Hello everybody, I am a beginner in LLVM and need to know how to use LLVM
>> to instrument a C program and execute this instrumented program with
>> different test cases to determine the branch coverage information for each
>> test case. Any suggestion or help is more than welcomed. Thanks in advance.
>> Ahmed Raafat.
>>
>
> (In the following instructions you have to insert your own values for the
> <...> stuff.)
>
> To instrument the C Program you have to compile it into a single bytecode
> file, I do this by translating each C file to bytecode
>
> $> llvm-gcc -emit-llvm -c <sourcefile> -o <sourcefile>.bc
>
> and then link them all together
>
> $> llvm-ld -stats -time-passes -link-as-library -disable-opt *.bc -o
> <executable>.1.bc
>
> This gives you an unoptimised bytecode file which is preferable in this
> case since it retains a somewhat 1:1 relation to your code so you can figure
> out the results afterwards.
>
>
>
> Now its time to instrument the code, I do this by running
>
> $> opt -stats -time-passes -insert-optimal-edge-profiling <executable>.1.bc
> -o <executable>.2.bc
>
> and add the profiling runtime support
>
> $> llvm-ld -stats -time-passes -link-as-library -disable-opt <path to llvm
> install>/lib/libprofile_rt.bca <executable>.2.bc -o <executable>.3.bc
>
>
>
> You can then create a native executable by
>
> $> llc <executable>.3.bc <executable>.s
> $> gcc -g <executable>.s -o <executable>
>
>
>
> When you run this executable (with your parameters) it creates a file
> called llvmprof.out which contains an edge profiling of your code. With
>
> $> llvm-prof -print-all-code <executable>.1.bc
>
> you can dump a bytecode file which is annotated with the recorded profiling
> information.
>
> If you do several runs of your executable all runs are combined in the
> single llvmprof.out and the results are accumulated and you can check if
> every codepath was executed during your tests.
>
>
>
> There is a tool in <source tree>/utils/profile.pl which takes a single
> bytecode file and parameters and does all the work of instrumenting, running
> and executing llvm-prof in one go, but its a little outdated, I attached a
> newer version, but I guess its easier to write a script that does exactly
> the steps you need. YMMV.
>
> Andi
>
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