Help Needed: How to get source line number from .ll file LLVM

Clang Frontend Using Clang
#1

Hi,

I am working with LLVM 3.4 and want to obtain the line number information of source file from IR. The IR is generated from simple c code with Clang. I want to obtain the line number in source c file from the line in IR body.

I tried this -

  1. For Instruction BI, unsigned Line = Line = BI->getDebugLoc().getLine();
  2. For Loop L, std::cout << L->getStartLoc().getLine();

But, the result stored/printed is always 0. I don’t know how to obtain line number in the source from LLVM IR.

My Source C file is -

​#include <stdio.h>


int main()
{

 int i;

 int inbuf[100];
 int outbuf[100];

 for(i = 0; i < 100; ++i)        
        inbuf[i] ^= outbuf[i];

 inbuf[1] += 402;
 inbuf[6] += 107;
 inbuf[97] += 231;

 for(i = 0; i < 100; ++i)       
 {
         inbuf[i] += outbuf[i];
 }

 inbuf[47] += 312;  

    //print-statements 
 for (i=0;i<100;i++) {
        printf("inbuf[%d] = %d\n",i,inbuf[i]);              
}
return 0;

​}​

Command Used- ~/llvm/build/Release+Asserts/bin/clang -O3 -fno-unroll-loops -fno-vectorize -fno-slp-vectorize -S -emit-llvm sample.c -o sample.ll

I have working pass which can detect and analyze the loops and instructions. I am using it inside function - runOnLoop(Loop *L, LPPassManager &LPM)

I have also tried with -O0 and -fstandalone-debug option in the compile line. But, it is still printing 0.

The following is also not working out.

if (MDNode *N = I->getMetadata(“dbg”)) { // Here I is an LLVM instruction
DILocation Loc(N); // DILocation is in DebugInfo.h
unsigned Line = Loc.getLineNumber();
}

It would be great if anybody can kindly help me for the same. Thanks!

ᐧ

#2

you would need to build with debug info (-g) or similar (there are a few other options that enable the same source location info) to produce the debuglocs that will tell you about that