How to iterate over basic blocks?

Question

I want to add an instruction to each of my basic blocks, I can use LLVMAppendBasicBlock for that once a bloc is specified. But how to iterate over all basic blocks in a function ? Are there iterators for that in the LLVM API ?

Answer 1

you can simply use iterator over function like :

 for (Function::iterator b = func->begin(), be = func->end(); b != be; ++b) {
BasicBlock* BB = b;
....
}

Answer 2

There's

LLVMBasicBlockRef   LLVMGetFirstBasicBlock (LLVMValueRef Fn)

and

LLVMGetNextBasicBlock (LLVMBasicBlockRef BB)

The documentation for LLVMGetFirstBasicBlock says:

Obtain the first basic block in a function.

The returned basic block can be used as an iterator. You will likely eventually call into LLVMGetNextBasicBlock() with it.

So call LLVMGetFirstBasicBlock once per function, and then LLVMGetNextBasicBlock repeatedly until you've gone through all the basic blocks of that function (juding by the source you'll get a nullptr when that happens).