[llvm-dev] Print 128 bit value at runtime using printf

[Jajoo, Malhar via llvm-dev]

Hi,


I was trying to print out a 128 bit result at runtime using a call to printf in LLVM.


I am able to print 32 uptil 64 bit integers using the format string "%d" in printf .



Please see the code in red below , as I am having a bit difficulty in trying to print the 128 bit value computed at runtime. The code in red is never executed since the value may never be casted to a ConstantInt.


( I saw this approach on SO - https://stackoverflow.com/questions/5315176/llvm-get-constant-integer-back-from-value )




//=========  Relevant code below ==========



Value* val = e->codegen() ;
if(!val)
{
return logError("Error evaluating argument to function call");
}

if(val->getType()->isIntegerTy() )
{
if(val->getType()->getIntegerBitWidth() <= 64)
{
tempString = tempString + "%+d,";
}

                          // Is this correct ?
else
{

if(ConstantInt* CI = dyn_cast<ConstantInt>(val))
{
// base 10 and signed
std::string res = CI->getValue().toString(10,true);
val=Builder.CreateGlobalStringPtr(res,"str");
tempString = tempString + "%+s,";
}

}

tempString = tempString + "%+d,";
}
// if any of the 6 floating point types
else if(val->getType()->isFloatingPointTy())
{
tempString = tempString + "%+f,";
//Apparently this is needed by printf,otehrwise prints 0.000
val = convertType(val,Type::getDoubleTy(TheContext));
}


argsValueVector.push_back(val);
++i;
}
formatString = formatString + tempString + "\n" ;


// For something like printf , insert a format string at the beginning.
if( F->isVarArg() )
{

// every string is declared as a "global constant" at the top of the module.
Value* val=Builder.CreateGlobalStringPtr(formatString,"str");

std::vector<Value*>::iterator it = argsValueVector.begin();

argsValueVector.insert(it,val);
}
return Builder.CreateCall(F,argsValueVector,"calltmp") ;

}


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