Add various terms to the glossary

src/appendix/glossary.md

@@ -19,7 +19,9 @@ DAG                     |  a directed acyclic graph is used during compilation t
 data-flow analysis      |  a static analysis that figures out what properties are true at each point in the control-flow of a program; see [the background chapter for more](./background.html#dataflow)
 DefId                   |  an index identifying a definition (see `librustc/hir/def_id.rs`). Uniquely identifies a `DefPath`.
 Double pointer          |  a pointer with additional metadata. See "fat pointer" for more.
+drop glue               |  (internal) compiler-generated instructions that handle calling the destructors (`Drop`) for data types.
 DST                     |  Dynamically-Sized Type. A type for which the compiler cannot statically know the size in memory (e.g. `str` or `[u8]`). Such types don't implement `Sized` and cannot be allocated on the stack. They can only occur as the last field in a struct. They can only be used behind a pointer (e.g. `&str` or `&[u8]`).
+early-bound lifetime    |  a lifetime region, which is bound in an item's `Generics` and substituted using a `Substs`. Contrast with **late-bound lifetime**. ([see more](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/enum.RegionKind.html#bound-regions))
 empty type              |  see "uninhabited type".
 Fat pointer             |  a two word value carrying the address of some value, along with some further information necessary to put the value to use. Rust includes two kinds of "fat pointers": references to slices, and trait objects. A reference to a slice carries the starting address of the slice and its length. A trait object carries a value's address and a pointer to the trait's implementation appropriate to that value. "Fat pointers" are also known as "wide pointers", and "double pointers".
 free variable           |  a "free variable" is one that is not bound within an expression or term; see [the background chapter for more](./background.html#free-vs-bound)
@@ -32,11 +34,16 @@ ICE                     |  internal compiler error. When the compiler crashes.
 ICH                     |  incremental compilation hash. ICHs are used as fingerprints for things such as HIR and crate metadata, to check if changes have been made. This is useful in incremental compilation to see if part of a crate has changed and should be recompiled.
 inference variable      |  when doing type or region inference, an "inference variable" is a kind of special type/region that represents what you are trying to infer. Think of X in algebra. For example, if we are trying to infer the type of a variable in a program, we create an inference variable to represent that unknown type.
 infcx                   |  the inference context (see `librustc/infer`)
+intern                  |  interning refers to storing certain frequently-used constant data, such as strings, and then referring to the data by an identifier (e.g. a `Symbol`) rather than the data itself, to reduce memory usage.
 IR                      |  Intermediate Representation. A general term in compilers. During compilation, the code is transformed from raw source (ASCII text) to various IRs. In Rust, these are primarily HIR, MIR, and LLVM IR. Each IR is well-suited for some set of computations. For example, MIR is well-suited for the borrow checker, and LLVM IR is well-suited for codegen because LLVM accepts it.
 IRLO                    |  `IRLO` or `irlo` is sometimes used as an abbreviation for [internals.rust-lang.org](https://internals.rust-lang.org).
+item                    |  a kind of "definition" in the language, such as a static, const, use statement, module, struct, etc. Concretely, this corresponds to the `Item` type.
+lang item               |  items that represent concepts intrinsic to the language itself, such as special built-in traits like `Sync` and `Send`; or traits representing operations such as `Add`; or functions that are called by the compiler. ([see more](https://doc.rust-lang.org/1.9.0/book/lang-items.html))
+late-bound lifetime     |  a lifetime region, which is bound in a HRTB and substituted with specific functions in the compiler, such as `liberate_late_bound_regions`. Contrast with **early-bound lifetime**. ([see more](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/enum.RegionKind.html#bound-regions))
 local crate             |  the crate currently being compiled.
 LTO                     |  Link-Time Optimizations. A set of optimizations offered by LLVM that occur just before the final binary is linked. These include optimizations like removing functions that are never used in the final program, for example. _ThinLTO_ is a variant of LTO that aims to be a bit more scalable and efficient, but possibly sacrifices some optimizations. You may also read issues in the Rust repo about "FatLTO", which is the loving nickname given to non-Thin LTO. LLVM documentation: [here][lto] and [here][thinlto]
 [LLVM]                  |  (actually not an acronym :P) an open-source compiler backend. It accepts LLVM IR and outputs native binaries. Various languages (e.g. Rust) can then implement a compiler front-end that output LLVM IR and use LLVM to compile to all the platforms LLVM supports.
+memoise                 |  memoisation is the process of storing the results of (pure) computations (such as pure function calls) to avoid having to repeat them in the future. This is generally a trade-off between execution speed and memory usage.
 MIR                     |  the Mid-level IR that is created after type-checking for use by borrowck and codegen ([see more](../mir/index.html))
 miri                    |  an interpreter for MIR used for constant evaluation ([see more](../miri.html))
 normalize               |  a general term for converting to a more canonical form, but in the case of rustc typically refers to [associated type normalization](../traits/associated-types.html#normalize)