Intel i960 Series User manual
i960Processor Compiler
User's Guide
Order Number: 651230-002
Revision Revision History Date
-001 Original Issue. 02/96
-002 Revised for release 5.1 01/97
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Contents
iii
Chapter 1 The CTOOLS Compilation System
Features........................................................................1-1
Compatibility and Conformance to Standards....................1-2
About this Manual..............................................................1-4
Audience Description.....................................................1-6
Licensing and Copyrights..............................................1-6
UNIX and Windows Conventions...................................1-6
Customer Service...............................................................1-7
Where Do You Go From Here?..........................................1-7
Chapter 2 gcc960 Compiler Driver
Controlling the Compilation System with gcc960 ...............2-1
Invoking the Compiler with gcc960................................2-2
gcc960 Sample Command Lines...................................2-3
gcc960 Linker Options...................................................2-5
gcc960 and Predefined Macros.....................................2-6
gcc960 and File Use ..........................................................2-8
Input Files......................................................................2-8
Include Files..................................................................2-9
Output Files...................................................................2-9
.GLD Files..........................................................................2-11
gcc960 Options..................................................................2-13
Option Arguments and Syntax...........................................2-15
i960 Processor Compiler User's Guide
iv
Chapter 3 ic960 Compiler Driver
Controlling the Compilation System with ic960...................3-1
Invoking the Compiler with ic960...................................3-2
ic960 Sample Command Lines......................................3-3
ic960 Linker Options......................................................3-4
ic960 and Predefined Macros........................................3-6
ic960 and Environment Variables..................................3-8
ic960 and File Use .............................................................3-11
Input Files......................................................................3-11
Include Files ..................................................................3-11
Temporary Files.............................................................3-12
Output Files...................................................................3-12
ic960 Options.....................................................................3-15
Option Arguments and Syntax ...........................................3-17
Chapter 4 Program-wide Analysis and Optimization
Introduction ........................................................................4-1
Individual and Program-wide Optimizations...................4-1
About Profiling...............................................................4-2
Creating Program-wide and Module-local Optimizations....4-2
Specifying the Program Database Directory..................4-2
Compiling for Program-wide Optimization with the fdb
Option............................................................................4-3
Global Decision Making and Optimization Using the
gcdm Option..................................................................4-3
Selecting Modules for Optimization with Substitution
Specifications ................................................................4-4
Contents
v
Profiling Your Program.......................................................4-5
Compiling for Profile Instrumentation with -fprof............4-5
Collecting a Profile.........................................................4-5
Building Self-contained Profiles with gmpf960...............4-6
Using Profiles During Global Decision Making and
Optimization with -gcdm,iprof ........................................4-7
Obtaining Program Coverage Analysis with gcov960....4-7
Using make To Perform Program-wide Optimizations........4-7
Adapting Makefiles for Program-wide Optimization.......4-8
Using Makefiles with Program-wide Optimizations for
Common Development Tasks .......................................4-10
Runtime Support for Profile Collection...............................4-15
Profile Initialization.........................................................4-15
Chapter 5 Profile Data Merging and Data Format (gmpf960)
Merging Profile Data ..........................................................5-1
gmpf960 Invocation............................................................5-2
Profile Format Specification ...............................................5-4
Profile Data Structures ..................................................5-4
default.pf File Format.....................................................5-4
Creating a Runtime Report with gmpf960..........................5-6
Chapter 6 gcdm Decision Maker Option
gcdm Option Syntax...........................................................6-1
gcdm Option Arguments ....................................................6-2
Substitution Controls .....................................................6-2
Whole-program Optimization Option (Category 1).........6-3
Module-local Optimization Options (Category 2)...........6-3
Miscellaneous Substitution Options (Category 3)..........6-5
External Reference Controls .........................................6-7
i960 Processor Compiler User's Guide
vi
Inline Level Control........................................................6-7
Input Profile Control.......................................................6-8
Fast Memory Controls ...................................................6-8
Dryrun Control ...............................................................6-9
Report Controls .............................................................6-9
Module-set Specification....................................................6-13
Chapter 7 Language Implementation
Data Representation..........................................................7-1
Scalars...........................................................................7-1
Aggregates....................................................................7-4
Other Type Keywords....................................................7-14
Calling Conventions ...........................................................7-14
Definitions......................................................................7-15
Parameter Assignment to Registers..............................7-17
Argument Blocks ...........................................................7-17
Return Values................................................................7-18
Compiler Implementation...............................................7-18
Object Module Section Use................................................7-19
Pragmas.............................................................................7-20
#pragma align [for gcc960 driver]..................................7-20
#pragma align [for ic960, or for gcc960 with
ic960 option]..................................................................7-22
#pragma cave................................................................7-26
#pragma compress........................................................7-30
#pragma i960_align [for gcc960 and ic960]...................7-31
#pragma inline...............................................................7-31
#pragma interrupt..........................................................7-32
#pragma isr....................................................................7-34
Contents
vii
#pragma optimize..........................................................7-34
#pragma pack................................................................7-35
#pragma pure................................................................7-37
#pragma section............................................................7-38
#pragma system............................................................7-38
Language Extensions ........................................................7-39
Statements and Declarations Inside of Expressions .....7-40
Naming an Expression’s Type.......................................7-40
Referring to a Type with typeof......................................7-41
Generalized Lvalues......................................................7-42
Conditional Expressions with Omitted Middle
Operands.......................................................................7-44
Arrays of Length Zero....................................................7-44
Non-lvalue Arrays Can Have Subscripts........................7-45
Arithmetic on Pointers to void and Pointers to
Functions.......................................................................7-45
Non-constant Initializers................................................7-46
Constructor Expressions ...............................................7-46
Declaring Attributes of Functions...................................7-47
Inquiring about Alignment..............................................7-48
Inline Functions Are as Fast as Macros.........................7-48
Controlling Names Used in Assembly Code..................7-50
Specifying Registers for Local Variables.......................7-51
Alternate Keywords .......................................................7-51
Inline Assembly Language.................................................7-52
Introduction....................................................................7-52
Resource Usage............................................................7-52
asm Statements ............................................................7-53
asm Functions...............................................................7-70
i960 Processor Compiler User's Guide
viii
Chapter 8 gcc960/ic960 Compatibility
char and short Parameters............................................8-1
enum Variable Byte Count.............................................8-1
char Types.....................................................................8-2
Identifying Architectures ................................................8-2
#pragma align................................................................8-3
mic3.0-compat Option....................................................8-3
mic2.0-compat Option....................................................8-3
Chapter 9 Position Independence and Reentrancy
Position-independent Code and Data ................................9-1
Position-independent Data............................................9-1
Position-independent Code...........................................9-2
Example: Position-independent ROM Code.................9-3
Guidelines for Writing Relocatable Programs................9-5
Reentrant Functions...........................................................9-6
Designing Reentrant Functions .....................................9-6
Chapter 10 Initializing the Execution Environment
Startup Code......................................................................10-1
RAM-based Initialization................................................10-4
ROM-based Initialization................................................10-4
Linker Configuration Files...................................................10-5
RAM-based Configuration File.......................................10-6
ROM-based Configuration File ......................................10-6
Chapter 11 Optimization
Optimization Categories and Mechanisms.........................11-1
Constants and Expression Evaluation................................11-3
Common Sub-expression Elimination............................11-3
Constant Expression Evaluation (Constant Folding) .....11-4
Dead-code Elimination...................................................11-5
Identity Collapsing.........................................................11-5
Constant Propagation....................................................11-6
Contents
ix
Calls, Jumps, and Branches ..............................................11-9
Branch Optimizations ....................................................11-9
Branch Prediction..........................................................11-10
Identification of Leaf Functions......................................11-11
Inline Function Expansion .............................................11-11
Tail-call Elimination........................................................11-12
Loop Optimizations ............................................................11-14
Movement of Loop-invariant Code ................................11-14
Induction Variable Elimination.......................................11-14
Loop Unrolling...............................................................11-15
Memory Optimizations........................................................11-15
Global Alias Analysis.....................................................11-15
Variable Shadowing ......................................................11-16
Register Use ......................................................................11-16
Local Variable Promotion ..............................................11-17
Register Management...................................................11-17
Register Spilling.............................................................11-17
Instruction Selection and Sequencing................................11-18
Code Compression........................................................11-18
Code Scheduling...........................................................11-18
Specialized-instruction Selection...................................11-20
Program-level Optimization................................................11-20
Inter-module Function Inlining.......................................11-20
Superblock Formation ...................................................11-21
Profile-based Branch-prediction Bit Setting...................11-22
Chapter 12 Caveats
Aliasing Assumptions.........................................................12-1
Alignment Assumptions......................................................12-3
Volatile Objects..................................................................12-4
Known Problems Using the Compiler.................................12-6
Type Promotion.............................................................12-6
Prototype Scope............................................................12-6
i960 Processor Compiler User's Guide
x
longjmp and Volatile Data..............................................12-7
Incorrect debug information generated for arrays with
unspecified bounds........................................................12-7
C Version Incompatibilities.................................................12-8
String Constants Read-only...........................................12-8
No Macro Argument Substitution in Strings...................12-8
External Variables and Functions in Blocks...................12-8
Combining long with typedef Names .............................12-9
Using typedef Names in Function Parameters ..............12-9
Whitespace in Compound Assignment Operators.........12-9
Flagging Unterminated Character Constants.................12-10
Disguised varargs or stdarg Routines............................12-10
Troubleshooting .................................................................12-10
Undefined References...................................................12-10
C Interrupt Service Routine Failures..............................12-11
Preventing Structure Padding........................................12-12
Breakpoints Inside Interrupt Handlers ...........................12-15
Chapter 13 Messages
Messages on the Standard Error Device.......................13-2
Messages in the Listing File ..........................................13-3
Index
Figures 7-1 Natural Alignment......................................................7-8
7-2 User-constrained Alignment ......................................7-9
7-3 Optimal Natural Alignment of std_struct....................7-12
7-4 Backward-compatible Natural Alignment of
std_struct...................................................................7-13
7-5 #pragma noalign Alignment of std_struct..................7-13
7-6 #pragma align Alignment of std_struct......................7-14
9-1 Memory for Hypothetical Position-independent
Application.................................................................9-4
11-1 Superblock Formation Process..................................11-21
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