llvm dev - Oct 2012 - [LLVMdev] Lifetime analysis of variables within a module

Hi all,

I'm looking for a LLVM method/class/strategy to know the lifetime of 
every variable/value used in a given Module.
I want to know the variables that must be alive at the input and at the 
end of every function call (and every BasicBlock).

By creating a pass inheriting from  ModulePass I can reach up to here:

virtual bool runOnFunction(Function &F) {
...
   for (Function::iterator bbi = F.begin(), bbf = F.end(); bbi != bbf; 
bbi++)
         {
     ...
     for (BasicBlock::iterator insi = bbi->begin(), insf = bbi->end(); 
insi != insf; insi++)
             {
         ...
         for (User::op_iterator opi = insi->op_begin(), opf = 
insi->op_end(); opi != opf; opi++)
                 {

                 if(isa<Instruction>(opi) || isa<Argument>(opi))
                 {

                 // Here I am <==============
                 }

How can I use LiveIntervals/LiveVariables/LiveRange to obtain the live 
range for a given variable of interest?

BTW, do you know any working example of using MachineFunctionPass or 
LiveIntervals LLVM passes? Every time I use it, opt generates output 
such as:

opt: PassManager.cpp:597: void 
llvm::PMTopLevelManager::schedulePass(llvm::Pass*): Assertion `PI && 
"Expected required passes to be initialized"' failed.
0  libLLVM-3.1.so  0x00007f42eb6469ef
...
7  libLLVM-3.1.so  0x00007f42eb1ccafa 
llvm::PMTopLevelManager::schedulePass(llvm::Pass*) + 1226


Thank you in advance !!!!

On 10/31/2012 10:49 AM, Antonio Martínez Álvarez wrote:
>
> How can I use LiveIntervals/LiveVariables/LiveRange to obtain the live
> range for a given variable of interest?
These passes operate on machine instructions (registers).  You are 
trying to run them on bitcode.

-Krzysztof


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