Is everything a pointer in LLVM IR?
I am iterating over global vars programs and interested in their types.
For a test, for example:
#include <stdio.h>
int i=0;
int main(){
printf("lala %d \n",i);
return 0;
}
What I get in the output:
Globals:
i Type: 14 //14 ==> POINTER TYPE ID !
StackLock: Stack1
Function Argument: i32* @i
My code:
for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I) {
std::cout << I->getName().str() << " Type: "<< I->getType()->getTypeID() << std::endl;
if (I->getType()->isPointerTy() ) {
std::string o1;
{
raw_string_ostream os1(o1);
I->printAsOperand(os1, true);
}
char* stackLoc = new char[50];
sprintf(stackLoc, "Stack%d", StackCounter++);
errs() << "StackLock: " << stackLoc << "\n";
errs() << "Function Argument: " << o1 << "\n";
}
}
What does it mean to set everything as pointers? Is there a way to take the "real" type? for example in my example: to get the Integer variable for the i variable.
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According to the LLVM IR Reference , globals define areas of memory allocated at compile time instead of run time, and they must be initialized.
As SSA values, global variables define the pointer values that are found in (i.e. dominate) all the basic blocks in the program. Global variables always define a pointer to their "content", because they describe a region of memory, and all memory objects in LLVM are accessed through pointers.
To get the actual type of your global variable, since the internal type of LLVM IR is a pointer, Type::getContainedType(int)
or Type::getPointerElementType()
can be used to get the type of a pointer of a pointer, since the type of a pointer is a derived type.
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