Assembly code for Sniper

[Newton]

Dear all,

I wrote a small c program (attached also).

#include "stdio.h"
int main()
{
    unsigned short a = 12343, b = 234, c = 345, d = 456, e = 567, f = 678, g = 789, h = 890;

    f = g + h;
    e = f + g;
    d = e + f;
    c = d + e;
    b = c + d;
    a = b + c;
}

1) Using gcc, i compiled the code and generated object file.
gcc -c
2) and then used objdump to check the assembly code and got output
objdumpASM.txt
3) To check the assembly code being run by sniper, i modified the
InstructionModeling::handleInstruction in instruction_modeling.cc
   std::cout << instruction->getDisassembly() << std::endl;
From this step, i got the assembly code being run by sniper as output sniperASM.txt
4) Then i compared the outputs from step 2 & 3 i.e. objdumpASM.txt sniperASM.txt
5) I found a lot of extra assembly code in sniperASM.txt which is not part of objdumpASM.txt.

Please, can anybody tell me the reason of this extra code.

[Trevor E. Carlson]

Newton,

What you are seeing is all of the setup code that starts before your main() function is actually called. If I remember correctly, Linux sets up an initial stack and calls _start() which then does some initialization before handing over control to main(). All of those instructions you are seeing is Pin capturing this process and feeding these instructions to Sniper.

Trevor

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<objdumpASM.txt><sniperASM.txt><c_x_86_sniper.c>

[Newton]

Dear Trevor,

Thanks for your reply.

Is there any way i can log only the assembly code which

is relevant to my program and exclude all setup and exit code.

Will ROI markers be useful here?
SimRoiStart();
SimNamedMarker(4, "begin");

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<objdumpASM.txt><sniperASM.txt><c_x_86_sniper.c>

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Thanks

Newton

Research Scholar, EE Dept.
IIT Bombay