Program Logic

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OS ALGOL (F) Compiler Logic

Program Numbers: 360S-AL-531 (Compiler)

I

360S- LM-532 (Library Routines) OS Release 21

This manual describes the internal logic of the ALGOL (F) Compiler. It is intended for the use of IBM field engineers, systems analysts and programmers.

The ALGOL (F) Compiler is a processing program of the IBM System/360 Operating System. It translates a source module written in the ALGOL language into an object module that can be processed into an executable load module by the Linkage Editor.

File Number S360-26 Order No. GC33-8000-0

y

Program Logic

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Page of GY'l3-8000-0 Revised January 15, 1972 By TNL GN33-8129

PREFACE

The IBM System/360 Operating System ALGOL Compiler consists of ten phases, or load modules. Chapter 1 of this manual provides an introductory survey of the main

functions of the several phases. A more detailed description of the individual phases is provided in the subsequent chap- ters, as follows:

Directory (IEXOO) Initialization (IEX10) Scan I/II (IEXll)

Identifier Table Manipulation (IEX20)

Diagnostic Output (IEX21) Scan III (IEX30)

Diagnostic Output (IEX31) Subscript Handling (IEX40) Compilation Phase (IEXSO) Termination Phase (IEXS1)

Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 9 Chapter 6 Chapter 9 Chapter 7 Chapter 8 Chapter 8 Two of the phases (Load Modules IEX21 and IEX31) are devoted exclusively to the editing and output of diagnostic messages.

Diagnostic output is also provided for in the Termination Phase (Load Module IEXS1).

The Error Message Editing Routine, which

First Edition (September 1967)

handles the output of diagnostic messages in the three phases mentioned, is described in Chapter 9.

Chapter 10 describes the ALGOL Library, which consists of a set of load modules representing standard I/O procedures, mathematical functions, and the Fixed Stor- age Area.

Chapter 11 describes the composition of the object module generated by the Compiler, and the organization of the load module at execution time.

Other publications that will be useful to the reader in understanding the Compiler are:

OS ALGOL Language, Order No.GC28-661S OS ALGOL Programmer's Guide,

Order No. GC33-4000

OS FORTRAN IV Library, Order No.

Order No. GC28-6S96

This edition applies to release 21 of the IBM System/360 Operating System, and to all subsequent modifications unless otherwise indicated in new editions or Technical Newsletters.

Changes are continually made to the specifications herein;

before using this publication in connection with the operation of IBM systems, consult the latest SRL Newsletter, Order No.

GN20-0360 for the editions that are applicable and current.

This publication was prepared for production using an IBM computer to update the text and to control the page and line format. Page impressions for photo-offset printing were ob- tained from an IBM 1403 printer using a special print chain.

Requests for copies of IBM publications should be made to your IBM representative or to the IBM branch office serving your locality.

A form is provided at the back of this publication for reader's comments. If the form has been removed, comments may be addressed to IBM Nordic Laboratory, Publications Development, Box 962, S-181 09 Lidingo 9, Sweden. Comments become the property of IBM.

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CHAPTER 1: INTRODU:TION. • • • 13 Purpose of the Compiler. • • 13 rhe Compiler and System/360 Operating

System. • • • • • 13

Machine System • • • 13

• • • 13 )rganization of the :ompiler •

Directory (IEXOO) • • • •

Initialization Phase (IEX10) • • Scan 1/11 Phase (IEX11) • • • • Identifier rable Manipulation Phase

• 13

• 15 (IEX20). • • • • • • • • • • • • 15 Diagnostic Output (IEX21) • • • 15 Scan III Phase (IEX30). • • • • • 15 Diagnostic output (IEX31) • • • • 15 Subscript Handling Phase (IEX40) • • • 15 Compihtion Phase (IEX50) • • • • • • 16 Termination (IEX51) • • • • • • • • • 16 Diagnostic Output (IEX21, IEX31,

and IEX51) • • • • • • • ALGOL Library •

The )bject Module.

Input/)utput Activity.

In~erphase Communication by Source rext and rable. • • •

Use of Main Storage. • • Area Occupied by Directory

Auxiliary Routines • • • • The Common ~ork Area • • • •

• 16 16

• • • 16

• 16 17

• 18

• 18 18 Area occupied by Operative Module • Private Area Acquired by Operative • 19

Module • • • • • • Common Area

conventions. • •

CHAPTER 2: DIRECTORY (IEXOO) Purpose of the Directory • • Organization of the Directory. •

Control Section IEXOOOOO • • • Initial Entry Routine. • Final Exit Routine • • • • Program Interrupt Routine

• 19

• 20

• 21

• • 21

· 21

• • 21 (PI ROUT). • • • • • • • • • • • • 21

1/0 Error Routine (SYNAD) • • • • • 22 Sysprint 110 Error Routine

(SYNPR) • • • • • • • • • • • • • 22 End of Data Routines (EODAD1,

EODAD2, EODAD3, AND EODADIN) • • • 22 Print Subroutine (PRINT) • • • • • 23 Data Control Blocks. • • • • • • • 23

CONTENTS

Control section IEX00001 (Common Work Area) • • • • • • • • •

Register Save Area • • • • DCB Addresses. • • • • • • • • End of Data Exit Addresses compiler Control Field

• • 23

• 23

• • 24

• • 24 (HCOMPMOD). • • • • • • • • • 24 Communication Area • • • • 24 Area Size Table (INBLKS). • • 24 Headline Storage Area (PAGEHEAD) • 24 Preliminary Error Pool • • • • • • 24 Data Control Blocks for SYSIN

and SYSUT1. • • • • • • • • • 25 Tables • • • • • • • • • 25 Other Data • • • • • • • • • • 25 CHAPTER 3: INITIALIZATION PHASE

(IEX10) • • • • • • • • 26 Purpose of the Phase •

. . .

• 26 Execution of the SPIE Macro. •

Processing Compiler Options., and Heading Information • •

:ompiler Options. • • DDnames • • • • • • • • Heading Information • •

DDnames,

Selection of Area Size Table (FNDARSIZ) • • • • • • • • • • Acquisition of Common Area • opening of Data Sets

CHAPrER 4: SCAN 1/11 PHASE (IEX11) • Purpose of the Phase

Scan 1/11 Phase Operations • • • • • Opening of Scopes • • •

processing of Declarations and

26

• • 26 27

• 28 28

• • 28 28

• • 28 30 30

• • 31

• • 33 Specifications • • • • • 34 Close of Scopes • • • • • • • 34

End of Phase. • 34

Phase Input/Output • • • • • • Identifier Table (ITAB) • •

Identifier Entries. •

Program Block Heading Entries • For Statement Heading and Closing

35

• • 35

• • 36

• 38 Entries. • • • • • • • • • • 39 processing of the Identifier Table. • 40 Scope Identification

Scope Handling Stack.

41

• 42 Modification Level 1 Source Text • • • • 43 Group Table (GPTAB). • • • • • • • 45

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Scope r3.ble (SprAB). • 45

Pro~r3.m Block Number Table (PBTAB1) • • • 46

processin~ of Opening Source Text • • • • 46 Close of Scan 1/11 Phase •

Switches

Constituent Routines of Scan 1/11 Ph3.se • • • • • • •

Phase Initialization.

M3.in Loop (TESTLOOP) • • • Blank (BLANK) • • • • • • Test 3.n~ Transfer Operator

46

• • 48

• 52

• 54

• 55 (rRANSOP).. • • • • • • • • • • 55

RIGHTP~R. • • • • • • • • • 55 POINr • • • • • • • • • • • • • • • 55 Decimal Point (DE:POINT). • 56

Assi~nment (ASSIGN) • • • 56 statement (Sr~rE) • • • • • • 56 Apostrophe (APOSTROF) • • • 56 Scale Factor (S:ALE). • • • 56 Bl3.nk after Apostrophe (BLKAPOS) • • • 56 Zeta after Apostrophe (ZETAAPO) • • • 57

Invali~ Character after Apostrophe

(NP~FrAPO) • • • • • • • • Colon (COLON) • • • • • • • • Label (LABEL) • • • • • • • • • Letter Delimiter (LETDEL) • • • Semicolon (SEMCO and SEMC60) • • Error Recording Routines. • • • Ch3.nge Input Buffer (:IB) • • • Identifier Test (IDCHECK1) • • • Change Output Buffer (COB and

• 57 57

• 57

• • • 57

• 57 57

• 59

• 59 COBSPEC) • • • • • • • • 59 Delimiter (DELIMIT) • • • • • • • 60 Delimiter Error Routine (EROUT) • 60 Type specification (TYPESPEC) • • • • 62 Comment (COMSPEC) • • • • • • • • 62 Opening Delimiter (STARTDEL) • • • • • 62 Begin (BEGIN) • • • • • • • • • 62 String (STRIN:;) • • • • • 62 Norm3.l ~ction (NORMAL). • • 62 Boolean Constant (BOLCON) • 62 Goto-If (GIF) • • • • • • • • • • • • 63 Then-Else-Do (rED). • • • • 63 First Be~in (FIRSTBE3) • • • • • • • • 63 Program Block (BEGl Subroutine) • 63 End (END) • • • • • • • • • • 63 Compound End (COMPDEND) • • • • • 63 For Statement End (FOREND). • 63 program Block End (PBLCKEND

Subroutine). • • • • • 64 Comment (COM) • • • • • • • • • 64 For statement (FOR) • • • • • • • • • 64 Type Declaration (TYPE) • • • • • • • 64 Identifier Error (IER). • 64 Code Procedure (CO;)E) • • • 65 Specification (SPEC) • • • • • • • • • 65 Parameter Specification (SPECENT

and IDCHECK) • • • • • • rype ~rray (rYPEARRY) • •

~rray Declaration (~RRAY)

Array/Switch List (LIST).

Point in List (PONTLST) • Right Parenthesis in List

• 65

• 66

(RIGHTP~RL). • • • • • • 66

Comma in List (COMMALST). • • • 66 Colon in List (COLONLST). • • 66 Semicolon in List (SEMCLST) • 66 Slash in List (SLASHLST). • 67 Switch Declaration (SWITCH) 67 Procedure Declaration (PROCEDUR) • • • 67 Procedure Identifier (PROCID) • • 67 Termination (EODADIN) • • • • • • 67 Generate Subroutine • • • • • 68 CHAPTER 5: IDENTIFIER TABLE

MANIPULATION PHASE (IEX20). 69 Purpose of the Phase • • • • • 69 Identifier Table Manipulation Phase

operations. • • • • • 69 Phase Input/Output • • • • 70

Identifier Table (ITAB). 70

Program Block Table II (PBTAB2) • • • • • 70 Constituent Routines of Identifier

Table Manipulation Phase. • • • Phase Initialization • • • • • • Identifier Scan (READBLIO • • • .•

Storage Allocation (ALLOSTOR) • • write Identifier Table (WRITITAB) Print Identifier Table (ITABPRNT) rermination (CLOSE) • • • • • • • CHAPTER 6: SCAN III PHASE (IEX30). • Purpose of the Phase • • • •

Scan III Phase Operations • • • • • • Opening and Close of Blocks and

Procedures • • • • • • • • • • • Identifier Handling • • • • • Number Handling • • • • • • • Array Subscript Handling. • • Handling of Other Operators • Phase Termination •

Phase Input/output • •

Processing of the Identifier Table • Classification of For Statements • • Processing of For Statements. • • Detection of Operators in For

List. . . . Recognition of Identifiers in

For Statements. • • • • • • •

71

• 71

• • 72

• • 73

• • 74 74

• • 75

• • 77

• • 77 77

• • 77

• • 78

• • 79 80 80 80 Optimizable subscript Expressions • • • • 81 For Statement Table (FSTAB). • • 81 Left Variable Table (LVTAB) • • • • 82 subscript Table (SUTAB) • • • 82 Critical Identifier Table (CRIDTAB). 82 Array Identifier Stack (ARIDSTAB) • • • • 84 Modification Level 2 Source Text • •• • • 84

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swi tches • • • • • • • • • • • • • • • • 85 constituent Routines of Scan III Phase • 86 Phase Initializati~n (INITIATE) • 86 General Test (GENTEST). • • • • • • • 88 Identifier Test (LETTER) • • • • • • • 88

IT~B Search (IDENT) • • • • • • • • • 88 Identifier Classification (FOLI) • • • 88 Noncritical Identifier (NOCRI) • • • • 89

Proce~ure/Parameter (PROFU) • 89 switch/Label (S~IL~) • • • • • • • • • 89 Critical Identifier (CRITI) • 89 Make Cridtab Entry (CRlMA). • • 90 CRIDTAB Overflow (CRIFLOW). • 90 Erase CRIDTAB (DELCRIV) • • 91

Up~ate CRIDT~B (CRIFODEL) • 91 Make LITTAB Entry (LETRAF) • • • 91 Nonzero Digit (DI3IT19) • 91 Zero Digit (DIGIrO) • • • • 92 Decimal Point (DECPOIN) • • 92 Scale Factor (SCAFACT). • • 93 Integer Conversion (INTCON) 93 Real Conversion (RE~LCON) • • 9~

Integer Handling (INTHAN) • • 9~

Real Handling (RE~LH~N) • • • 9~

Change Constant Pool (CPOLEX) • • 9~

output TXT Record ^(TXTTR~F) • 95 Generate (GENTXT) • • • • • • • 95 Apostrophe (~UOTE) • • • • • • • • • • 95 Block Be:Jin (BETA). • • • • • • • • • 95 Procedure Declaration (PIPHI) • • 95 Read ITAB Record (ITABMOVE) • • • • • 95 For statement (FOR) • • • • • • • • • 95 Program Block End (EPSILON) • 95 For Statement End (ETA) • • • 95 Do (DO) • • • • • • • • • • • 96 While (WHILE) • • • • • • • • 96 Semicolon/Delta (SEMIDELT). • 96 Opening Bracket (OPBRACK) • • 96 Comma (COMMA) • • • • • • • • • • 96 Closing Bracket (CLOBRACK). • 96 Scan subscript (S[JCRIDEL). • • • 96 Subscript Test (SUSCRITE) • 96 Operand Test (OPERAND). • • • • • 97 Multiplier-Operand (SUBMULT) • • • • • 97 Make SUTAB Entry (SUTABENT) • • • 98 Input Record End (ZETA) • • • • • 98 Change Input Buffer (ICHA). • 98 Code Procedure (G~MMA). • • 98 Program End (OMEGA) • • • • 98 Other Operators (OrHOP) • • • • • • • 98 Letter Delimiter (RHO). • • • • 99 Step (STEP) • • • • • • • • 99

~rray (ARR~Y) • • • • • • • 99 Switch (SWITCH) • • • • • • 99 Divide/Power(OIPOW) • • • • 99 Change output Buffer (OUCHA). • 99 Incorrect Operand (INCOROP) • 99 Store Error (MOIlERRO) • • • • • • 99 Move Operand (MOllE) • • • • • • • 99 Check-Write (CHECK) • • • • • • .100 write SUTAB/LITTAB Record (WRITE) • • • 100 CHAPTER 7: SUBSCRIPT HANDLING PHASE

(IEX~O). • • • • • • • • • • .101 Purpose of the Phase • • .101 subscript Handling Phase Operations. • .101

Phase Input/Output • .102

Optimization Table (OPTAB) • • .103 Subscript, Left Variable and For

Statement Tables. • • • • • • • • • 103 Constituent Routines of Subscript

Handling Phase • • • • • • • • • • • • • 103 Initializa tion. • • • • • 103 Read SUTAB. • • • • .105 Scan SU'TAB. • • • • • • • • • • .105 Sort SUTAB (SORTSU) • • • • • • .106 Read and Sort LVTAB (SORTLE and

SORTLE!) • • • • • • .106 Construct OPTAB (OPTAB) • • 106 Termination (TERMIN) • • • • • • • • • 107

~rite OPTAB (OTACHA) • • • • • • • • • 107 Read SUTAB/LVTAB (READ) • • • .107 Sort SUTAB/LVTAB (SORT) • • • .107 CHAPTER 8: COMPILATION PHASE (IEX50) • • 108 Purpose of the Phase •

Compilation Phase Operations • Phase Input/Output • • • • operator/Operand Stacks. •

Control of Object Time Registers Decision Matrices • • •

Compile Time Register Use.

Constituent Routines of the

• .108

• • • 110

• .110

• .113

• .116

• .116 Compilation Phase. • • • • • • 116 Phase Initialization. • .118 Scan to Next Operator (SNOT). • .119 Compare (CaMP). • • • • • • • • • • .119 Blocks and Compound Statements • • • • 120 Compiler Program No.O (CPO>' • • • 120 Compiler Program No.16 (CP16) • • • 120 Switches • • ' • • • • • • • • • • • • • 120 Compiler Program No.~ (CP~) • • • • 121 Compiler Program No.85 (CP85) • • • 122 Compiler program No.56 (CP56) • • • 122 Compiler Program No.59 (CP59) • • • 122 Compiler Program No.~l (CP~1) • • • 122 Compiler Program No.38 (CP38) • • • 122 Labels. • • • • • • • • • • • .122 Compiler Program No.1 (CP1) • • • • 122 Goto Statements • • • • • • • • • • • 123 Compiler Program No.6 (CP6) • • • • 123 Compiler Program No.56 (CP56) • • • 123 Compiler Program No.62 (CP62) • • • 123 Arrays • • • • • • • • • • • • • • • • 124 Array Declarations • • • • • • • .125 Subscripted Variables • • • • • • • 126 Compiler Program No.~ (CP~) • • • • 127 Compiler Program No.52 (CP52) • • • 127 Compiler Program No.36 (CP36) • • • 128 compiler Program No.51 (CP51) • • • 128 Compiler Program No.5~ (CP5~) • • • 130 Compiler Program No.~l (CP41) • • • 130 Compiler Program No.38 (CP38) • • • 130

Procedures • • .131

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Proce:ture Declaration. • • • • .131 Procedure Call. • • • • • • • • .132 Compiler Program No.4 (CP4). .133 Operand Recognizer (OPDREC). .134 Compiler Program No.16 (CP16) • • • 134 Compiler Program No. 64 (CP64) • • • 134 compiler Program No.57 (CP57) • • • 134 Code Procedures. • • • • • • • • .135 Compiler Program No.83 (CP83) • • • 136 Standar:t Procedures. • • • • • • .136 Compiler Program No.64 (CP64) • • • 136 Compiler Program No.61 (CP61>. • .137 For statements • • • • • • • • • • • • .138

Counting Loops • .138

Elementary Loops • • .139

Normal Loops • • .140

Subscript Optimization • .143 Compiler Program No.6 (CP6). .144 Compiler Program No.40 (CP40). • .144 Compiler Program No.43 (CP43) • • • 147 Compiler Program No.45 (CP45) • • • 147 Compiler Program No.47 (CP47) • • • 147 Compiler Program No. 49 (CP49) • • • 148 Subscript Initialization Routine

(DwG3 or USAl) • • • • • • • • • • 148 subscript Incrementation Routine

(OVAl). • • • • • • • • • .151 Compiler Program No.81 (CP81) • • • 151

~ssignment statements.

Compiler Program Compiler Program Compiler Program Conditional Statements Compiler Program Compiler Program Compiler Program Compiler Program

• • • • • .151 No.12 (CP12) • • • 151 No.21 (CP21) • • • 151 No.20 (CP20) • • • 152 No.8 (Cp8) • • • No.78 (CP78) • • No.17 (CP17). • No.18 (CP18) • •

.153 .154 .154 .154

• 154 Conditional Expressions. • • • • • • • .154 COmpiler Program No. 64' (CP64). • .156 Compiler Program No.80 (CP80) • • • 156 Compiler Program No.34 (CP34) • • • 156 Compiler Program No.65 (CP65) • • • 156 Compiler Program No.78 (CP78) • • • 156 Compiler Program No. 87 (CP87) • • • 156 Compiler Program No.79 (CP79) • • • 157 Boolean Expressions. •

Compiler Program No. 64 Compiler Program No.65 Compiler program No.67 Compiler Program No.76 Compiler Program No.77

• . . . • . 157 (CP64) • • • 158 (CP65)' • • 158 (CP67). • .158 (CP76) ~ • • 158 (CP77) • • • 158

~rithmetic Expressions and Relations • .158 Compiler Program No.64 (CP64) • • • 158 Compiler Program No.66 (CP66) • • • 158 compiler Program No.67 (CP67) • • • 159 Compiler Program No.63 (CP63) • • • 159 Compiler Program No.68 (CP68) • • • 159 compiler Program No.69 (CP69) • • • 159 Integer-Integer Routine (OHZB1) • • 160 Integer Division Routine (ISB1) • • 160 Integer Multiplication Routine

Integer Power Routine (IUB1) Real-Real Routine (DHEB2).

Real-Integer Power Routine (IIB1) • • • • • • • • • • • Real Power Routine (HOB1) • • • Compiler Program No.68 (CP68).

.160

• .160 .160

• .161

• .161 Semicolon Handling • • • • • • • • • • • 161 Compiler Program No.24 (CP24) • • • 161 Compiler Program No.25 (CP25) • • • 161 Compiler Program No.23 (CP23) • • • 161 compiler Program No.7 (CP7) • • • • 161 context switching. • •

Compiler Program No.19 compiler Program No.22 Compiler Program No.33 Compiler Program No.70 Compiler Program No.71 Logical Error Recognition. • Compiler Program No.26 Compiler Program No.27 Compiler Program No.28 Compiler Program No.29 Compiler Program No.30 Compiler Program No. 31 Compiler Program No.72 Compiler Program No. 73 Compiler Program No.74 Compiler Program No.75 Compiler Program No.84 Compiler Program No.86

• • • • • • 161 (CP19). • .161 (CP22) • • • 162 (CP33) • • • 162 (CP70) • • • 162 (CP71). • .162

• • • • • • 162 (CP26) • • • 162 (CP27) • • • 162 (CP28) • • • 163 (CP29). • .163 (CP30) . . . . 163 (CP31> • • • 163 (CP72) • • • 163 (CP73) • • • 163 (CP74). • .163 (CP75) • • • 163 (CP84) • • • 163 (CP86). • .164 Close of Source Module • • • 164 Compiler Program No.3 (CP3) • • • • 164 Subroutine Pool . . . 164 Change Input Buffer (JBUFFER) • • • 164 Next OPTAB Entry (NXTOPT) • • • • • 164 Error Recording (SERR) • • • • • • 164 Conversion Integer-Real (TRINRE) .164 Conversion Real-Integer (TRREIN) .164 Generate Object Code (GENERATE) • • 165 Store Object Time Registers

(CLE~RG) • • • • • • • • • • Operand Recognizer (OPDREC) • • Update OS~ Pointer (MAXCH) Semicolon Handling (SCHDLl ROUTINEl • • • • • ROUTINE2 •

ROUTINE3 • ROUTINE4 • ROUTINES • ROUTINE6 •

ROUTINE7 • • • • .. .. • • • ROUTINE8 • • • • • • • ROUTINE9 •

ROUTINI0 • ROUTIN11 • ROUTIN12 • ROUTIN13 • ROUTIN14 • ROUTIN15 •

Program Block Number Handling (PBNHDL) • • • • • •

Parameterless procedure Statement (PLPRST).

• .165

• .165 ..165

• .165

• .166

• .167

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Pro3ram Block Table IV

(PBrAB4) • • • • • • • .167

L~bel ~ddress Table (LAT) • • .167 Data Set rable (DSTAB) • • • • • 168

~ddress Table and END Record .169 Statement of Object Time storage

Requirements • • • • • • • • • • • 169 Dia3nostic Output • • • • • • • • 169 End of CDmpilation. • • .169 CHAPrER 9: COMPILE TIME ERROR

DETECTI~N AND DIAGNOSTIC OUTPUT • .170 Error Detection. • • • • • • • • .170 Warnin3 Errors (Severity Code W) • • • 170 serious Errors (Severity Code S) • • • 170 Scan 1/11 Phase (IEXll) • • • 170 Identifier Table

Manipulation Phase

(IEX20) • • • • • • • • • • 170 Scan III Phase (IEX30). .170 Subscript Handling Phase

(IEX40) • • • • • • • • • • 170 Compilation Phase (IEX50) • • 170 Termination Phase (IEX51) • • 171 rerminatin3 Errors (severity Code

T) • • • • • • • • • • • • • • • 171 Diagnostic output • • • • • 171

Error Pool _{• .172}

Message POOl • • • • • • .172 Error Message • • • • .174 L03ic of the Error Message Editing

Routine. . • • • • • • • • • .174 CHAPTER 10: ALG~L LIBRARY • • •

FiKed Storage Area (IHIFSA) • • Common Data Area. • • • • • FiKed Storage Area Routines

Initialization (ALGIN) Prologue (PROLOG) • • • • Epilogue (EPILOG) • • •

• .176

• • • • 176

• • • • • 176

• .176

• • • 177

• • • .177

• .177 Call Actual Parameter, Part 1

(CAP1) • • . • • • • • • • • • • .177 Call Actual Parameter, Part 2

(CAP2) • • • • • • • • • Value Call (VALUCALL).

Return Routine (RETPR~G) • • C:'l.ll Switch Element, Part 1

(CSWE1) . • • • • • • • • .

C~ll Switch Element, Part 2 (CSWE2) . • • • • • • • Trace (TRACE).. • • • • Load Precompiled Procedure

(LOADPP) • • • • • • • • •

.178 .178 .178

• • .178

• 179 .179

• .179 standard Procedure Declaration

(SPDECL) • • • . • • • • • • Get Main Stora3e (GETMSTO) • Program Interrupt (PIEROUT).

FSAERR • • • • . • • • • • rermination (ALGrRt-lN) • • • • Integer tD Real Conversion

(CNVIRD) • • • • • • • • • • Real to Integer ConVersion

.179

• • .179 .179

• .179 .179 .179

(CNVRDI/ENTIER) • .179

Input/output Procedures • • • • .180

PUT/GET (IHIGPR) PUT • • • GET • • •

~UTPUT • • INPUT • •

~PENGP • • CLOSEGP • OPENEXIT.

CAP1GP • • rHUNKOUT.

THUNKIN •

INARRAY/INTARRAY(IHIIAR) INBARRAY (IHIIBA).

INBOOLEAN (IHIBO) • • INREAL/ININTEGER (IHIIDE).

INSYMBOL (IHIISY).

OUTREAL (IHISOR) OUTREAL (IHILOR) OUTARRAY (IHIOAR) • • OUTBARRAY (IHIOBA) • • OUTBOOLEAN (IHIOBO) • • • OUTINTEGER (IHIOIN) • • OUTSTRING (IHIOST)

OUTSYI~OL (IHIOSY) • OUTTARRAY (IHIOTA) •

• .180

• .181

• .181 .181

• .181

• .182 .182

• .182

• .183

• .183 SYSACT (IHISYS). • • • • • • .183

• • • • • • • 183

• • • 183

• .183

• • • • • .183

• .183 .184

• .184

• .184 SYSACT. •

SYSACTl SYSACT2 SYSACT3 SYSACr4 SYShCT5 SYSACT6 SYShCT7 • SYSACT8 SYSACT9 • SYSACT10.

SYSACTll.

SYSACT12.

SySACT13 • SYSACT14.

SYSACT15.

• • • • • • • • .184

• • • • • • • • • • • .184

Subroutine Pool (IHIIOR) • CLEARNOTTAB •

CLOSE • • CLOSEPE • CONVERT • DCBEXIT • ENDOFDATA ENTRYNOTTAB • EVDSN • • NEXTREC •

~PEN.

SYNAD • •

• .184

• .185

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~~them~tical Standard Functions. • .185 Jbject Time Error Routine (IHIERR) • • .186 CHAPTER 11: rHE OBJE:r MODULE. .181

Jbject Module. .181

Load Module. • • • • • • .188 Jbject Time Tables. • • .188 .188 .189 Program Block rable (PBT)

L~bel Address Table (LAT) Data Set rable (DSTAB) • •

~ote Table (NOTTAB) • • • • •

D~t~ storage Area (DSA) • storage Mapping Function (SMF) • Return Address Stack (RAS) • Object rime Register Use. •

.190

• .191 .191

• 193 .193

• .194 FLOwCHARrs • • • • • • • • • • • • • • • 196 APPENDIX I-A: CHARACrER SET -- FIRST

TRA~SLATI0N JF THE SOUR:E MODULE IN rHE SCAN I/II PHASE • • • • • • • • • APPENDIX I-B: CHARACTER SET --

MJDIFICArION LEVEL 1 rEXr • • APPENDIX I-C: CHARACrER SET --

MJDIFICATION LEVEL 2 TEXT • •

APPENDIX 1-0: CHARA:TER SET -- STACK OPERArORS USED IN rHE COMPILATION p H~SE • • • • • • • • • • • • • • • • APPENDIX II: INrERNAL REPRESENTATION

.212 .212 .212

.273 OF JPERANDS • • • • • • • • • • • • • .274

APPE~DIX III: INTERNAL REPRESENTATION

OF SrANDARD PROCEDURE DESIGNATORS • • • 275

APPENDIX Ill: COMPILER CONTROL FIELD

(HCOMPMOD). • • • • • • • • • • • • .276 APPENDIX V-A: PROGRAM CONTEXT MATRIX • • 278 APPENDIX V-B: STATEMENT CONTEXT MATRIX .279 APPENDIX V-C: EXPRESSION CONTEXT

MATRIX.

· · ^{· ·} · ^· · · · ·

APPENDIX VI: COMPILE TIME ERROR DErECTION •

· · · ^· · · · · ^{· ·}

APPENDIX VII: OBJECT TIME ERROR DErECTION

. · · · · · · ^· ·

APPENDIX VIII: COMPILE TIME WORK AREA SIZES, AS A FUNCTION OF THE SIZE

.219 .280 .283

oprION • • • • • • • • • • • • • • • • • 285 APPENDIX IX-A: STORAGE MAPS OF THE

CO~STITUENT LOAD MODULES OF THE ALGOL COMPILER. • • • • • • • • • • • • •

IEXOO - Directory. • • • • • IEX10 - Initialization Phase • IEX11 - Scan 1/11 Phase. • IEX20 - Identifier Table

Manipulation Phase. • • • IEX21 - Diagnostic output.

IEX30 - Scan III Phase • • IEX31 - Diagnostic Output.

• .286 .286

• .287

• .288

• .289 .290 .290 .291 .292 .293 IEX40 - Subscript Handling Phase IEX50 - Compilation Phase. •

IEX51 - Termination Phase. • .294 APPENDIX IX-B: STORAGE MAP OF THE

OBJECT MODULE (AT EXECUTION) • • APPENDIX X: SUMMARY OF COMPILER

PRJ GRAMS. • • • • • • • • APPENDIX XI: INDEX OF ROUTINES •

.295

• .296

• .307

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Figure 1. Constituent phases of the

AL30L Compiler. • • • • • • • • • • 14 Figure 2. I/O Activity by Data set and

Phase • • • • • • • • • • • • • • • • • 17 Figure 3. Activity Table showing the

processing of source text and tables

by phase. • • • • • • • • • • • 18 Figure !I. Use of main storage by

ALG~L Compiler. • • • • • • • 19 Figure 5. Jption, DDname and Heading

fields, and pointers • • • • • • • • • • 27 Figure 6. PARMLIST Table entry for a

Compiler option key-word. • • • • 27 Figure 7. Scan 1/11 Phase. Diagram

illustrating functions • • • • • • • • • 32 Figure 8. Scan 1/11 Phase

Input/Output. • • • • • • • • • • • • • 35 Figure 9. Identifier Characteristic. 36 Figure 10. Identifier Table entry for

all identifiers except declared

~rr~y, procedure and switch

identifiers and labels. • • • • • 37 Figure 11. Identifier Table entry as

constructed in the Scan 1/11 Phase

for ~ declared array identifier • • 37 Figure 12. Identifier Table entry for

a declared procedure identifier • • • • 38 Figure 13. Identifier Table entry

for ~ declared switch identifier • • • • 38 Figure 14. Identifier Table Entry

for a declared label • • • • • • • • • • 38 Figure 15. Program block heading entry • 39 Figure 16. Program block heading

entry, as transmitted to the SYSUT3

d~t~ set. . • • • • • • • • • • • • 39 Figure 17. For statement heading

entry • • • • • • • • • • • • • • • 39 Figure 18. For statement closing

entry • • • • • • • • • • • • • • 39 Figure 19. Diagram illustrating the

processing of the Identifier Table • • • !l0 Figure 20. Scope Handling Stack

oper~tors • • • • . • • • • . • • • • • !l2 Figure 21. Group Table entries for a

for statement and for a block or

procedure • • • • • • • • • • • • • • • 45 Figure 22. One-byte Scope Table entry. !l6 Figure 23. One-byte Program Block

Number rable entry. • • • • • . • • • 46 Figure 2!1. Chart showing the logical

flow in the search for the opening

delimiter • • • • • • • • • • ~ • • 47 Figure 25. Exits from Scan 1/11 Phase. 49 Figure 26. Private ^~reaacquired by

the 3c:in 1/11 Phase, showing pointers initialized. • • • • • • • • • • • 52 Figure 27. Source text buffers and

pointers. • • • • • • • • • • . . • 53 Figure 28. Heading Entry constructed

at irritialization in Identifier Table for Program Block 0 • • • • • • • • • • 53

FIGURES

Figure 29. Switches used in Scan 1/11 Phase • • • • • • • • • • • 53 Figure 30. Branch Address Table

BPRTAB. • • • • • • • • • • 54 Figure 31. KEYTAB keys used in

TRANSOP routine • • • • • • • 55 Figure 32. Delimiter Table (WITAB) • • • 61 Figure 33. Internal Names of boolean

constants 'TRUE' and 'FALSE' • • • • • • 63 Figure 3!1. Identifier Table

Manipulation Phase. Diagram

illustrating the functions of the

principal constituent routines. • • 69 Figure 35. Identifier Table

Manipulation Phase Input/Output • • • • 70 Figure 36. Identifier Table (ITAB)

entry, showing the identifier's Data Storage Area displacement address, as inserted by the Identifier Table Manipulation Phase in bytes 9 and 10, for all identifiers except those of declared procedures, switches and

labels. • • • • • • • • • • • • • • • • 70 Figure 37. Two-byte entry in Program

Block Table II (PBTAB2) • • • • • • • • 71 Figure 38. Private Area acquired by

the Identifier Table Manipulation

Phase • • • • • • • • • • • • • • • 72 Figure 39. Scan III Phase • • • • • • • • 76 Figure !l0. Scan III Phase input/output. 78 Figure 41. Function of pointers NOTER

and NOTEW in inputloutput operations

on the SYSUT3 data set • • • • • • ' • • • 78 Figure 42. Diagram illustrating the

handling of Identifier Table (ITAB)

records • • • • • • • • • • • • • 79 Figure 43. Entry in Left Variable

Table • • • • • • • . • • • • • • • 82 Figure 44. Fourteen-byte Subscript

Table entry • • • • • • 83 Figure 45. Entry in Critical

Identifier Table (CRIDTAB). • • 83 Figure 46. Entry for an array

identifier in the Array Identifier

Stack (ARIDSTAB). • • • • • • • • • 8!1 Figure 47. Private Area acquired by

Scan III Phase. • • • • • • • • • • • • 87 Figure 48. Subscript Handling Phase • • • 102 Figure 49. Subscript Handling Phase

Input/Output • • • • • • • • • • • • • • 103 Figure 50. Optimization Table (OPTAB)

entry • • • • • • • • • • • • • • • • • 10!l Figure 51. Diagram illustrating use of

the private area • • • • • • • • • • • • 104 Figure 52. Compilation Phase. Diagram

illustrating phase operations. • .109 Figure 53. Compilation Phase

Input/Output. • • • • • • • • • .110

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Fi~ure 54. Diagram illustrating the fUnction of the ~perator/Operand

stacks • • • • • • • • • • • • • • • • • 112 Figure 55. Five-byte operand

representing an intermediate value or address contained in an object time

re~ister or temporarily stored in the register's reserved storage field in a Data Stora~e ~rea • • • . • • • • • • • 113 Figure 56. Control Fields governing

use of object time general purpose

registers • • • • • • • • • • • • • • • 114 Figure 57. Control Fields governing

use of floating point registers, • • • • 115 Figure 58. Diagram showing the

compiler ^prograrr~• • • • • • • • • • • 117 Figure 59. Private Area acquired by

Control section IEX40001 for the

Compilation Phase (IEX50) • • • • .118

Fi~ure 60. Entry in Program Block

Table III (PBTAE3). • • • • • • • .120 Figure 61. Diagram showing code

generatej for switch declaration and

s~itch designator • • • • • • • • • • • 121 Figure 62. Object Time Storage

Mapping FUnction of an array • • • • • • 125 Figure 63. Code generated for declared

type procedure and procedure call • • • 132

Fi~ure 64. I/~ Table (IOT~B) • • .138 Figure 65. For statement

classification byte in the For

statement rable • • • • • • • • • .139 Figure 66. Logical structure of the

code generated for a Counting Loop • • • 141 Figure 67. Logical structure of the

code generated for an Elementary Loop or Normal Loop • • • • • • • • • • • • • 141

Fi~ure 68. Logical structure of the

code generated for a Counting Loop • • • 142 Figure 69. Logical structure of the

code generated for an Elementary Loop .145 Figure 70. Logical structure of the

code generated for an Elementary Loop .146 Figure 71. Entry in subscript Table-C

(SUTABC) • • • • • • • • • • • • • • • • 148

Figure 72. Logical structure of the

code generated for a Normal Loop. • • .149 Figure 73. Logical structure of code

generated for Elementary Loop or

Normal Loop • • • • • • • • • • • • • • 150 Figure 74. :omposition and execution

sequence of Load MOdules IEX21"

IEX31, and IEX51, containing the Error Message Editing Routine

(IEX60000) • • • • • • • • • • •

Figure 75. Error pattern stored in • • 171 Error Pool. • • • • • • • • • • • .172 Figure 76. Message Pool entry. • • .172 Figure 77. Three-byte Insertion Code

in the Message Pool entry (see Figure 76) • • • • • • • • • • • • .172 Figure 78. Format of the printed error

message • • . • • • • . • • • • • • • • 174 Figure 79. Four-byte parameter list

entry for a standard procedure call • • 180 Figure 80. Label of a PUT/GET record • • 180 Figure 81. Module names of

mathematical standard functions

contained in the ALGOL Library. .186 Figure 82. Composition of the object

module. • • • • • • • • • • • • • .187 Figure 83. Sketch showing the

organization of the load module • • • • 188 Figure 84. Object time Program Block

Table • • • • • • • • • • • • • • • • .189 Figure 85. Object time Label Address

rable (LAT) • • • • • • • • • • • • • • 189 Figure 86. Content of the data set

entries and the PUT/GET Control Field .190 Figure 87. Entry in the object time

Note Table (NOTTAB). • • • • • • • 191 Figure 88. Content of the Data

Storage Area • • • • • • • • • • • • • • 192 Figure 89. Content of the 8-byte

storage field of a formal parameter

called. . . ." .193 Figure 90. Entry in the object time

Return Address Stack (RAS) • • • • • • • 194 Figure 91. Object time register use. • .195

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~LGJL Compiler - Jverall ~low.

Directory (IEKOO) • • • • • • • Initialization Phase (IEX10) • Scan 1/11 Phase (IEK11) • . • • Identifier Table Manipulation Phase

.197 .198

• • .201

• • 203 (IEX20) • • • • • • • • • • • • • • • .215

Diagnostic Output (IEX21) • • • • Scan III Phase (IEX30) • • • • •

Dia~nostic Output (IEX31) • • • • subscript Handling Phase (IEX40) compilation Phase (IEX50) • • Termination Phase (IEX51) • •

ALGJL Library • • • • • • • • • • •

CHARTS

• .218

• .220

• .234

• .235

• • • 238

• .262

• • .265

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TITLE CHANGES Maintenance

Names of reference publications have been changed to reflect their current titles.

Page of GY33-BOOO-O Revised January 15, 1972 By TNL GN33-B129

SUMMARY OF AMENDMENTS FOR GY33-8000-0 OS Release 21

11

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PURPOSE OF THE COMPILER

The OS/360 ALGOL Compiler translates a source program written in the OS/360 ALGOL Language into an object module which may be linkage edited and executed by an IBM Systeru/360 computer. The final load module consists in part of code generated by the Compiler and, in part" of routines (in load module form) drawn from the ALGOL Library.

The Library is a data set containing ALGOL standard I/O procedures and mathematical functions, as well as auxiliary routines required by the object module at €xecution time. The Library routines are combined with the generated code at linkage edit time, to form an executable load module.

The Compiler prints out a listing of the source module and of the Identifier Table, if the SOURCE option is specified" and prints out diagnostic messages reflecting syntactical errors detected in the source module, as well as other errors occurring during compilation.

THE COMPILER AND SYSTE~1/360 OPERATING SYSTEI'l

The ALGOL Compiler is a processing program of the System/360 Operating System.

I t is executed under the control of the OS supervisor" and utilizes the I/O and other services of the OS Control Program.

A compilation is executed as a jOb step by means of the job control facilities of the Operating System. The use of the Compile!. is expla.ined in the OS AL~()~

l'rogt'~:r:~ s Gilide,.

MACHINE.SYSTEM

The m~n~mum machine configuration

required for execution of a compilation using the ALGOL compiler is as follows:

1. An IBM System/360 Model 30, 40, 50, 65, 75, or 91, or an IBM System/370 Model 135 (or higher} with the scientific instruction set and at least 64K bytes of main storage capacity.

2. At least one direct access input/output device; a printer; a con-

Page of GY33-8000-0 Revised January 15, 1972 By TNL GN33-8129

CHAPTER 1: INTRODUCTION

sole typewriter, device (magnetic reader) •

and tape

ORGANIZATION OF THE COMPILER

a sequential unit or card

Figure 1 indicates the modular structure of the ALGOL compiler as well as the essential operations performed in each of the constituent phases. The Compiler consists of ten load modules, the first of which, called the Directory" remains in main storage throughout compilation. The other nine modules" representing the Work- ing phases of the compiler" are loaded and executed in sequence.

DIRECTORY (IEXOO)

The Directory consists of a pre- assembled Common Work Area, used by .all phases, as well as a number of auxiliary routines providing interface with the Operating System. The latter include the initial entry and final exit routines which receive control from, and return control to, the Operating System.

INITIALIZATION PHASE (IEX10) The Initializatiqn Phase:

1. Sets up a control field in the Common Work Area. reflecting the opticns

specified in the EXEC Statement invok- ing the Compiler.

2. Determines the sizes of the private work areas required by the individual phases.

3. Acquires main storage for a source text input buffer and for the Error Pool.

4. Opens data sets.

5. Executes a SPIE macro which specifies the address of the program interrupt routine in the Directory.

Chapter 1: Introduction 13

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ALGOL COMPILER EXEC CALL/LINK/XCTl

ATTACH I EXOO IEXIO

LINK INITIALIZATION

I I

.oV.odified Identifier

XCTL Source Text Table

(ModiFication (lTAB) level 1)

SYSIN IEXII

Source

! !

oVtodule SCAN 1/11

PHASE r - - - ,

I ^I

---I lv1ain Storoge I SYSLIN/ SYSPRINT

I

^IError Pool I SYSPUNCH Source

XCTl I Group Table I ESDRecord fv\odule

r---, ^IScape Table I & TXT Records listing

IB) I lv1ain Storage I I P.B. No. Table I

of Constant

I Errof Pool I L ______ J _Pool

SYSUT3 I P.B. No. Table f-- IEX20

I I

Identifier L _ _ _ _ _ _ ..J

IDENTIFIER Table

(lTAB) TABLE

I I

/'MNIPULATION 1 - - - ,

PHASE ---1 lv1ain Storage I SYSUT3 SYSPRINT - - -

I

ⁱProg,Blk.Toblelll Identifier Identifier

XCTl I Error Pool I Table Table

L _ _ _ _ _ _ ...J IITAB) listing

r- - - , IEX2l SySPR!NT

I Main Storage I Diognostic

I Error Pool f-- Messoges Ie)

I I DIAGNOSTIC r---

L _ _ _ _ _ _ ...l

OUTPUT

IA) IB) (D)

SySUTl SYSUT3

I-Aodified Identifier

I

^SYSUT2

Source Text Table XCTl Modified

(Iv'oodification IITAB) Source Text

Levell) (Modification

r - - - , _{Level 2)}

I Main Storage I IEX30 I Scope Table I

I

I Group Table !--.

SCAN III

!

L _ _ _ _ _ _ ..J PHASE

r - - - ' l

I I

...j Main Storage I

I

I Error Pool I SYSLIN/ SYSUT3

I For Statement I

XCTl I Table I SYSPUNCH Subscript

L _ _ _ _ _ _ ...J

TXT Records Table (SUTAB) of Constant Left Variable

Pool Table (LVTAB)

r- - - - ----, IEX3l SYSPRINT I Main Storage I

Diagnostic

I Error Pool r-· DIAGNOSTIC I--- ^Messages

I I IE)

L _ _ _ _ _ _ --I

OUTPUT

IE)

!

SYSUTJ XCTL IF)

I~~TAB) r - - - ,

SYSUT3 I N\oin Storage I

IFor Statement I IEX4Q· Optimization

I i;bl 'iAB) I Table ~ Table

L _ _ _ _ _ _ -...l (OPTAB)

SuBSCRIPT

HANDLING PHASE 1 - - - ,

ID) IF) ..., Main Storage I

! I For Statement I

SYSUT2 SYSUT3 I Table I

fv\odiFied Optimization I

I

^I ^'

Source Text Table r - - - - - ' - l ^XCTl L _ _ _ _ _ _ J

(/IIoodification IOPTAB) I Ifv\o;n Storage I SYSLIN/

Level 2) Iprog.Blk.Table II I SYSPUNCH

I For Statement r - IEX50

ITable I TXT & RLD

L _ _ _ _ _ _ -.J Records of

Generated

COMPILATION Obiect Code

PHASE r - - - i

---1 fv\oin Storage I I Prog.Blk.T!;Oblel1ll

I

I I/O Table I

XCTl

I label Addr.Tablel SYSPRINT muw

L~r~ ~~I _ _ _ J Storage ~ END, ESD, TXT

~~~ui~;~es~f~ Records for ^&^RlD

- - - -- l IEX5l Messages Loble Address,

I Program Block,

f-_ TFR/ ATtn ~d~~e~~ti abr~s

I

! l

__ J

ij,~~;,i;;~'~;;

.

RETURN I

Figure 1. Constituent phases of the ALGOL Compiler

Program Logic

OS ALGOL (F) Compiler Logic

Program Numbers: 360S-AL-531 (Compiler)

360S- LM-532 (Library Routines) OS Release 21

y

Program Logic

. . .

· · · · · · · · · ·

· · · · · · · · · ·

. · · · · · · · ·

I I

! !

I I

I

I I

I

I

I

!

I I

I

!

I

I

! l

.

· · ^{· ·} · ^· · · · ·

· · · ^· · · · · ^{· ·}

. · · · · · · ^· ·

I ^I