it is natural to think that there is only one index, the selection of the field F. However, in this example, Foo is a pointer. That pointer must be indexed explicitly in LLVM. C, on the other hand, indexs - through it ransparently. To arrive at the same address location as the C + through it transparently. To arrive at the same address location as the C code, you would provide the GEP instruction with two index operands. The first operand indexes through the pointer; the second operand indexes the field F of the structure, just as if you wrote: