3.1 Introduction to the Compiler

3.1.3 Increasing the efficiency of compiled code

• declare information to the Compiler

Adding declarations to your code allows the Compiler to produce more efficient code (see Section 3.2.8 on page 40).

• use type-specific operations

Addingtype declarations to your code eliminates run-time type checking and increases the speed of your code. If you declare the types of all the arguments and all the returned values of a Lisp expression, the Compiler can use type-specific arithmetic operators. This is especially useful for operations that use fixnum integers or hardware-supported floating-point numbers, as these operations are coded directly in machine language and are extremely fast (see Section 3.3 on page 49).

• use in-line constructs

Using in-line functions allows the Compiler to replace the procedure call to a function with the machine-language code for the body of that function. Calls to in-line functions are usually faster than normal procedure calls (see Section 3.2.6 on page 38).

• use constructs that the Compiler automatically optimizes

The Compiler automatically optimizes certain constructs, such as macros and tail-recursive functions. You can improve the performance of your code by identifying and using these constructs (see Section 3.4 on page 57).

• reduce consing

Reducing the amount of dynamic storage allocated by a program reduces the number of garbage collections and can improve the performance of your code. One way to reduce the amount of dynamic storage is by using stack-allocated lists (see Section 3.2.10 on page 47).

• use optimization declarations

Usingspeed optimization declarations increases the running speed of your code (see Section 3.2.8 on page 40).

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