First Edition (April 1990) This edition applies to Version 1 .1 of the IBM AIX XL FORTRAN Compiler/6000 and to all subsequent releases and modifications until otherwise indicated in new editions. Changes are periodically made to the information herein; any such changes will be reported in subsequent revisions. References in this publication to IBM products, programs, or services do not imply that IBM intends to make these available in all countries in which IBM operates. Any reference to an IBM licensed program in this publication is not intended to state or imply that only IBM's licensed program may be used. Any functionally equivalent program may be used instead. This publication contains examples of data and reports used in daily business operations. To illustrate them as completely as possible, the examples include the names of individuals, companies, brands, and products. All of these names are fictitious and any similarity to the names and addresses used by an actual business enterprise is entirely coincidental. Note to US Government Users: Documentation related to restricted rights. Use, duplication or disclosure is subject to restrictions set forth in GSA ADP Schedule Contract with IBM Corporation. Publications are not stocked at the address given below. Requests for IBM publications should be made to your IBM representative or to the IBM branch office serving your locality. A form for reader's comments is provided at the back of this publication. If the form has been removed, comments may be addressed to: IBM Canada Ltd Information Development Department 849 1150 Eglinton Ave East North York, Ontario, Canada. M3C 1 H7 IBM may use or distribute whatever information you supply in any way it believes appropriate without incurring any obligation to you. ©Copyright International Business Machines Corporation 1990. All rights reserved. Trademarks and Acknowledgements The following trademarks and acknowledgements apply to this book: AIX is a trademark of International Business Machines Corporation. IBM is a registered trademark of International Business Machines Corporation. RISC System/6000 is a trademark of International Business Machines Corporation. RT PC and RT are registered trademarks of International Business Machines Corporation. Systems Application Architecture and SAA are trademarks of International Business Machines Corporation. Preface Iii iv User's Guide for XL FORTRAN Contents Chapter 1. Introduction . • • . 1 Who Should Use This Manual . 1 How to Use This Book . 1 How This Book is Organized . 1 How to Read the Syntax Diagrams . 3 A Note About Examples . 5 Related Documentation . 5 Chapter 2. The IBM AIX XL FORTRAN Compiler/6000 . • . • . 7 Features of the XL FORTRAN Compiler . 7 Language Support . 7 Compiler Features . 7 Compiler Options . 7 Symbolic Debugger (dbx) Support . 8 Source Code Conformance Flagging . 8 Generated Code Optimization . 8 OJJline Compiler Help . 8 Migration Characteristics . 8 System Configuration . 8 Compiler Installation . 8 Entering FORTRAN Source Programs . 9 FORTRAN Source Files . 9 The XL FORTRAN Character Set . 9 Names . 9 Keywords . 9 Statements . 9 Tabs . 11 Nonsignificant Blanks . 11 Statement Labels . 11 Chapter 3. Compiling, Linking, and Running Programs . • . 13 Invoking The Compiler . 13 Environment Variables . 14 Configuration File . 14 Input Files . 16 Output Files . 16 Compiler Options ............. '. 16 Specifying Options on the Command Line . 17 Specifying Options in the Source File . 17 Summary of the XL FORTRAN Compiler Options . 18 Conflicting Options . 23 Detailed Descriptions of the Options . 23 Invoking the Linkage Editor . 29 Running the Program . 30 FORTRAN Exception Handling . 30 © Copyright IBM Corp. 1990 Contents v The XL FORTRAN Run Time Environment . • . 31 AIX Shared Libraries . 32 Chapter 4. Input/Output . • . 33 File Formats . 33 File Names . 33 Preconnected Files . 34 File Positioning .............................................................· . 34 Chapter 5. Optimization . • . • • • . • • • • • • . 35 Optimization Levels . 35 Optimization Techniques . 35 Debugging Optimized Code . ..