Method ConstGetElementPtrInBounds
- Namespace
- Ubiquity.NET.Llvm.Instructions
- Assembly
- Ubiquity.NET.Llvm.dll
ConstGetElementPtrInBounds(Value, params Value[])
Creates a Value that accesses an element of a type referenced by a pointer
public static Value ConstGetElementPtrInBounds(Value pointer, params Value[] args)
Parameters
pointer
Valuepointer to get an element from
args
Value[]additional indices for computing the resulting pointer
Returns
- Value
Value for the member access. This is a User as LLVM may optimize the expression to a ConstantExpression if it can so the actual type of the result may be ConstantExpression or GetElementPtr.
Note that
pointer
must be a pointer to a structure or an exception is thrown.
Remarks
For details on GetElementPointer (GEP) see The Often Misunderstood GEP Instruction. The basic gist is that the GEP instruction does not access memory, it only computes a pointer offset from a base. A common confusion is around the first index and what it means. For C and C++ programmers an expression like pFoo->bar seems to only have a single offset or index. However that is only syntactic sugar where the compiler implicitly hides the first index. That is, there is no difference between pFoo[0].bar and pFoo->bar except that the former makes the first index explicit. LLVM requires an explicit first index, even if it is zero, in order to properly compute the offset for a given element in an aggregate type.