An Overview of the SUIF2 System

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An Overview of the SUIF2 System

• Monica Lam
• Stanford University
• http//suif.stanford.edu/

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The SUIF System
PGI Fortran
Java
EDG C
Interprocedural Analysis Parallelization Locality
Opt
Inst. Scheduling Register Allocation
SUIF2
Alpha
x86
C
3
Research Infrastructure Support at 3 Levels

• I. Compose compiler with existing passes
• Front ends passes
• Easy expression of compiler compositions
  (dynamically)
• II. Develop new passes
• User concentrates on algorithmic issues
• Infrastructure takes care of common
  functionalities
• Standard intermediate representation and
  associate tools
• Common utilities and data structures
• III. Develop new IR (new language constructs or
  analyses)
• Easy definition of IR nodes
• Old code works with new IR without recompilation

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I Compose Compiler with Existing Passes

• Previous system
• Each pass is an independent program that
  reads/writes SUIF in a file
• Advantages modular, visibility of intermediate
  results
• Disadvantages expensive disk access
• New system
• write code once, can run on program on disk or in
  memory
• simple development, efficient deployment
• How?
• A pass a common driver module
• A compound pass
• a common driver series of modules loaded
  dynamically

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Modular Compiler System
COMPILER
A driver that imports applies modules to
program in memory
A series of stand-alone programs
Suif-file1
Suif-file1
drivermodule1
Suif-file2
Suifdriver imports/executes module1 module2
module3
drivermodule2
Suif-file3
drivermodule3
Suif-file4
Suif-file4
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SUIF Driver

• gt suifdriver
• suifgt import basicnodes suifnodes
• suifgt import mylibrary
• suifgt load test.suif
• suifgt mylibrary_pass1
• suifgt print test.out
• suifgt save test.tsuif
• Suifdriver
• accepts a simple scripting language
• pre-registered modules (import, load, print,
  save)
• loads libraries dynamically which can register
  new modules (new commands)

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The SUIF Architecture
MODULES
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Components

• Kernel provides all basic functionality
• iokernel implements I/O
• suifkernel hides iokernel and provides modules
  support, cloning, command line parsing, list of
  factories, etc.
• Modules
• passes provides a pass framework
• IR basic program representations
• Suifdriver
• provides execution control over modules and
  passes using a scripting language

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II. Develop a New Pass

• Kernel provides all basic functionality
• iokernel implements I/O
• suifkernel hides iokernel and provides modules
  support, cloning, command line parsing, list of
  factories, etc.
• Modules
• passes provides a pass framework lt-- Derive from
  this framework
• IR basic program representations
• Suifdriver
• provides execution control over modules and
  passes using a scripting language

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Compilation System SuifEnv Modules

• SuifEnv
• Keeps the states of the compilation
• Holds onto the representation (FileSetBlock) and
  the loaded modules
• A module is a C class
• that implements either a pass or a set of nodes
  in IR
• must have a unique module_name
• no global variables
• one or more modules make up a dll
• each library includes a function (init_ltdllnamegt)
  to register all modules dynamically
• Registration is based on a prototype object

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Example Pass Count Statements in Procedures

• class mypass public Pass
• public
• mypass(SuifEnv env, const Lstring name)
  Pass(env, name)
• virtual mypass()
• Module clone() const return(Module) this
• void do_procedure_definition (ProcedureDefinition
  proc_def)
• cout ltlt proc_def-gtget_procedure_symbol()
  -gtget_name()
• cout ltlt object_iteratorltExecutionObjectgt(proc_
  def).length()
• extern C void init_mypass (SuifEnv suif_env)
• suif_env-gtget_module_subsystem()-gtregister_module
  
• (new mypass (suif_env, mypass))

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Tools for writing passes

• Traversing and manipulating data structures
• Visitors dispatch method according to type
• Iterators simple iteration of certain objects
• Walkers user-controllable traversal of data
  structures
• Data structures
• Infinite precision integers
• strings
• lists, sets, hash maps
• assertion/error handling

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Program Representation

• Multiple representations for semantics at
  different abstraction levels
• e.g. FOR loops or statement list with branches
  and jumps
• High-level representation useful for high-level
  transformations
• gt Superset representation
• mixture of high-level and low-level constructs
• Dismantlers lower representation
• Allow analysis to operate at different levels of
  abstraction
• e.g. analysis may/may not care about specific
  arithmetic operators
• gt Uses object-oriented class hierarchy

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SUIF IR Design

• Root Object
• Uniform functionality
• Fields accessed with get_ltfieldgt, and set_ltfieldgt
• printing
• I/O to disk
• cloning
• iterators
• walkers
• Memory management aid
• object creation via factories
• owner edges embed a tree into program
  representation

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Supports Code with Abstraction
ExecutionObject
Statement
get_child_statements
IfStatement
WhileStatement
get_then_part get_else_part
get_body

• Maximize reuse by abstract fields
• allow uniform access to different child
  components

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III. Extending the IR

• Goals
• Support extension by different research groups
• Code written for a high-level IR should work on
  refined IR (without recompilation!)
• Easy specification of new extensions
• Grammar-based specification
• How?
• Meta-class system
• Objects contain information describing
  representation
• If environment does not include definitions of
  refinements
• information retained even if methods are not
  available
• written out when representation saved

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Insulating the User from the Implementation
Object Definition (.hoof)
SUIF Macro Generator a general grammar-based tool
Meta-Class System reading writing to file in
machine-independent format
Interface for user (.h) Implementation in
Meta-Class System (.cpp)

• Easy for the programmer
• Easy for the implementor to develop the system

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Example of a Hoof Definition

• concrete New
• int x
• class New public SuifObject
• public
• int get_x()
• void set_x(int the_value)
• example()
• void print()
• static const Lstring get_class_name()
• Uniform data access functions (get_ set_)
• Automatic generation of meta class information
  etc.

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Examples of Suif Nodes

• abstract Statement ExecutionObject
• virtual listltStatement ownergt
  child_statements
• ...
• concrete IfStatement Statement
• Expression condition in source_ops
• Statement owner then_part in
  child_statements
• Statement owner else_part in
  child_statements

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Documentation

• The SUIF2 Infrastructure Guide (an index to all
  documentation)
• Overview of the SUIF Infrastructure
• The SUIF Representation Guide
• The Basic SUIF Programmers Guide
• Web page http//suif.stanford.edu/suif2