[LLVMdev] RE : RE : Detect if a basicblock is part of a loop

[Rinaldini Julien]

This is my main.c (just a crappy test file):

#include <stdlib.h>

void foo() {
        foo();
}

int main(int argc,char** argv) {
        int a = 1;
        int b = 3;
        int c = a+b;

        int k;
        for(k=0;k<10;++k) {                          // The loop I'm trying to detect
                int sdf = 123123;
                c++;
        }

        if(c - atoi(argv[1]) < 4)
                c = 0;
        else
                c = 1;

        return c;
}

The ir code corresponding to the loop:

; <label>:7                                       ; preds = %13, %0
  %8 = load i32* %k, align 4
  %9 = icmp slt i32 %8, 10
  br i1 %9, label %10, label %16

; <label>:10                                      ; preds = %7
  store i32 123123, i32* %sdf, align 4
  %11 = load i32* %c, align 4
  %12 = add nsw i32 %11, 1
  store i32 %12, i32* %c, align 4
  br label %13

; <label>:13                                      ; preds = %10
  %14 = load i32* %k, align 4
  %15 = add nsw i32 %14, 1
  store i32 %15, i32* %k, align 4
  br label %7

> is LLVMobfuscationTest.so your own pass? What does it do?

Yes it's my own lib... It contains some obfuscation's passes. The one I'm trying to make now is making code flattening!

Cheers

ps: I tried Cristianno Martins solution, but it didn't work too :(

________________________________________
De : 陳韋任 [chenwj at iis.sinica.edu.tw]
Date d'envoi : vendredi 27 avril 2012 14:45
À : Rinaldini Julien
Cc: llvmdev at cs.uiuc.edu
Objet : Re: [LLVMdev] RE :  Detect if a basicblock is part of a loop

> Just as I said to Hal, nothing else than:
> $ clang -emit-llvm -S -o main.ll main.c
> $ ../build/Release/bin/opt -load ../build/Release/lib/LLVMobfuscationTest.so -flattening -S main.ll -o main.opt.ll

  Then you might need to past your main.c. Besides, is LLVMobfuscationTest.so
your own pass? What does it do?

Regards,
chenwj

--
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj