======== Glossary ======== .. contents:: :local: :depth: 1 .. _basic block: Basic block =========== A sequence of instructions inside a function. A basic block always starts with a :ref:`label` and ends with a :ref:`terminator <terminator>`. No other instruction inside the basic block can transfer control out of the block. .. _function declaration: Function declaration ==================== The specification of a function's prototype without an associated implementation. A declaration includes the argument types, return types and other information such as the calling convention. This is like an ``extern`` function declaration in C. .. _function definition: Function definition =================== A function's prototype, as in a :ref:`function declaration`, plus a body implementing the function. .. _getelementptr: getelementptr ============= An LLVM :ref:`instruction` that lets you get the address of a subelement of an aggregate data structure. See `the getelementptr instruction <https://releases.llvm.org/10.0.0/docs/LangRef.html#i-getelementptr>`_ in the official LLVM documentation. .. _global value: Global value ============ A named value accessible to all members of a module. .. _global variable: Global variable =============== A variable whose value is accessible to all members of a module. It is a constant pointer to a module-allocated slot of the given type. All global variables are global values. However, the opposite is not true---function declarations and function definitions are not global variables, they are only :ref:`global values <global value>`. .. _instruction: Instruction =========== The fundamental element used in implementing an LLVM function. LLVM instructions define a procedural, assembly-like language. .. _IR: .. _intermediate representation: Intermediate representation (IR) ================================ High-level assembly-language code describing to LLVM the program to be compiled to native code. .. _label: Label ===== A branch target inside a function. A label always denotes the start of a :ref:`basic block`. .. _metadata: Metadata ======== Optional information associated with LLVM instructions, functions and other code. Metadata provides information that is not critical to the compiling of an LLVM :ref:`intermediate representation <IR>`, such as the likelihood of a condition branch or the source code location corresponding to a given instruction. .. _module: Module ====== A compilation unit for LLVM :ref:`intermediate representation <IR>`. A module can contain any number of function declarations and definitions, global variables and metadata. .. _terminator: .. _terminator instruction: Terminator, terminator instruction ================================== A kind of :ref:`instruction` that explicitly transfers control to another part of the program instead of going to the next instruction after it is executed. Examples are branches and function returns.
