ANSI C optimizing compiler user guide

October 1992
INMOS document number: 72-TDS-348-01
60 Pages

About this manual

This manual is the ANSI C Optimizing Compiler User Guide to the ANSI C toolset.

The manual provides reference and user information specific to the ANSI C optimizing compiler. It gives details of:

Examples of the local and global optimizations available are provided in the appendices.

This manual should be read in conjunction with the reference chapter for the standard ANSI C compiler, provided in the Tools Reference Manual. This is because details which are common to both compilers are not repeated in the Optimizing Compiler User Guide, including details of command line options and compiler pragmas.

Contents

	Preface
		Host versions
		About this manual
		About the toolset documentation set
		Other documents
		occam and FORTRAN toolsets
		Documentation conventions

User Guide

1	Introduction
	1.1	Overview
		1.1.1	Advantages of using the optimizing ANSI C compiler
		1.1.2	When optimization should not be used

2	User Interface
	2.1	Command line options
		2.1.1	Disable optimization O0
		2.1.2	Enable local optimization O1
		2.1.3	Enable local and global optimization O2
		2.1.4	Optimize for time QT
		2.1.5	Optimize for space QS
		2.1.6	Enable side effects information messages
		2.1.7	Disable warning messages
		2.1.8	Compiler map files
	2.2	Language considerations
		2.2.1	const keyword
		2.2.2	volatile keyword
		2.2.3	register keyword
	2.3	Pragmas
		2.3.1	No side effects
	2.4	Messages
		2.4.1	Severities
		2.4.2	Standard terms
			abstract declarator
		2.4.3	ANSI trigraphs
		2.4.4	Information messages
		2.4.5	Warning diagnostics
		2.4.6	Recoverable errors
		2.4.7	Serious errors

Appendices

A	Local optimization examples
	A.1	Peephole optimization
			Example
		A.1.1	Summary of effects
	A.2	Flowgraph optimizations
		A.2.1	Branch-chaining optimization
		A.2.2	Dead code elimination
		A.2.3	Summary of effects of flowgraph optimizations
	A.3	Redundant store elimination
			Example
		A.3.1	Summary of effects

B	Global optimization examples
	B.1	Common subexpression elimination
			Example
		B.1.1	Summary of effects
	B.2	Loop-invariant code optimization
			Example
		B.2.1	Summary of effects
	B.3	Global optimization example
	B.4	Tail-call and tail recursion optimization
		B.4.1	Example: (Tail-call optimization)
		B.4.2	Summary of effects: (Tail-call optimization)
		B.4.3	Example: (Tail-recursion optimization)
		B.4.4	Summary of effects: (Tail-recursion optimization)
	B.5	Workspace allocation by coloring

	Index

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