LLVM String Value objects: How can I retrieve the String from a Value?

Question

When building the IR from an existing AST, my AST has some string values (at compile-time they are built from std::string) and I want to set them safely as ll

Answer 1

Yes, ConstantArray is what you should use here. In order to retrieve the value later just use ConstantArray::getAsCString(). If you have assertions turned on, it will assert if something will went wrong (e.g. you will try to grab string from the array w/o zero terminator).

Answer 2

Running http://llvm.org/demo/ on the C code char *x = "asdf"; gives:

@.str = private unnamed_addr constant [5 x i8] c"asdf\00"
@x = global i8* getelementptr inbounds ([5 x i8]* @.str, i64 0, i64 0), align 8

Basically, to get the address of a string, you have to build a global containing it. You can switch http://llvm.org/demo/ to output C++ API calls if you have trouble figuring out how to do that.