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Llvm.NET LogoInstructionBuilderGetElementPtrInBounds Method (Value, IEnumerableValue)

[This is preliminary documentation and is subject to change.]

Creates a Value that accesses an element of a type referenced by a pointer

Namespace:  Llvm.NET.Instructions
Assembly:  Llvm.NET (in Llvm.NET.dll) Version: 3.8.6158
Syntax
C#
Copy
public Value GetElementPtrInBounds(
	Value pointer,
	IEnumerable<Value> args
)

Parameters

pointer
Type: Llvm.NET.ValuesValue
pointer to get an element from
args
Type: System.Collections.GenericIEnumerableValue
additional indices for computing the resulting pointer

Return Value

Type: Value

Value for the member access. This is a Value 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 http://llvm.org/docs/GetElementPtr.html. 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. In order to properly compute the offset for a given element in an aggregate type LLVM requires an explicit first index even if it is zero.
See Also