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OSUIF: A Closer LookHolger Kienle

UCSBhttp://www.cs.ucsb.edu/~osuif

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OSUIF: The Basic Idea

• thin layer on top of SUIF for OO languages -> extension of SUIF IR nodes

• lowering OSUIF -> SUIF

• set of basic passes

• client (e.g., C++/Java front end/extension) has to extend OSUIF skeleton

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Language Independence

• three extension points for language-specific functionality:– front-end

(e.g., subclass ClassSymbolTable for lookup)– lowering passes

(e.g., dispatch table construction)– IR

(language-specific nodes)

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Language Independence (cont.)

• design goal:put only language-independent parts in OSUIF; rest in front end / lowering

• example:OSUIF has inheritance links but leaves semantics to be implemented by front end (abstract lookup() method)

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OSUIF IR Extensions (1)

new constructs:

• classes and inheritance

• methods and fields (static and instance)

• method calls(dispatching and non-dispatching)

• (exception-handling)

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OSUIF IR Extensions (2)

DataTypeGroupType

StructTypeClassType

SingleInheritanceClassType

• encapsulates methods and fields

• symbol table interface

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OSUIF IR Extensions (3)

SuifObjectAnnotableObject

InheritanceLink

• models relationships between classes

• first-class entity

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OSUIF IR Extensions (4)

ProcedureSymbol VariableSymbol

InstanceMethodSymbol FieldSymbol

StaticMethodSymbol InstanceFieldSymbol

StaticFieldSymbol

• reference to owning class

• LString attributes(e.g., to model access modifiers)

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OSUIF IR Extensions (5)

StatementCallStatement

InstanceMethodCallStatementStaticMethodCallStatement

• static and instance methods(this-ref vs. no this-ref)

• dispatching vs. non-dispatching calls

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InstanceMethodCallStatement

concrete InstanceMethodSymbol : ProcedureSymbol {ClassType * reference owning_class omitted;bool is_dispatched default {true};

... };concrete InstanceMethodCallStatement :

CallStatement { InstanceMethodSymbol * reference target_method;bool is_dispatched default {true};

};

• single receiver (i.e., no multiple dispatch)• dispatching and non-dispatching call

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Lowering (and “Raising”)• symbols

– moved in higher symbol table(reversible)

– name mangling

• InstanceMethodCallStatement– dispatching code– toggle is_dispatched flag and set callee_address

Note: OSUIF classes are not replaced bySUIF classes!

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Lowering Passes (1)

• lower_osuif_symbols-lower-instance-methods-lower-static-fields-lower-static-methods-lower-per-class-symbol-table-symtab external|file_set|file_block|one-up-mangle-name <how>-ignore-lowering-name-annote

• lower_static_method_call_expressions

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Lowering Passes (2)

• layout_single_inheritance_instance_fields-mangle-name <how>-ignore-lowering-name-annote

• build_single_inheritance_vtbl-construct-vtbls-attach-vtbl-slot-number-annotes-ignore-no-vtbl-annote

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OSUIF passes

• use "as is" (default behavior)-> command line switches

• front-end controls behavior of pass with SUIF annotations

• customize pass via C++ subclassing

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OSUIF front-ends

• Java (j2s)– alpha-version– several bigger applications compile

• C++– back-end reasonably stable– front-end does not implement complete

language yet– lowering to SUIF in place

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j2s Goals

• full Java support for off-line compilation

• provide a good platform forOO/Java-related compiler research

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j2s Caveats

• compiles class files

• has its own runtime system (SPARC only!)– JNI– reflection– class initialization– ...

• requires Java 1.2beta2

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j2s Caveats (cont'd)

restrictions:

• exception-handling

• threads and synchronization

• dynamic loading of classes

• accurate GC

• floating-point computations

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j2s EnvironmentJava .class file

j2s

OSUIF

OSUIF Lowering

OSUIFTransformations

(OSUIF and j2s)

SUIF

SUIFCompiler System

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j2s Compilation

Helloworld.class

HelloWorld.osuif

HelloWorld.suif

HelloWorld.c

HelloWorld_glue.suif HelloWorld_main.suif

HelloWorld_glue.c HelloWorld_main.c

j2s-fej2s-glue j2s-main

o2s

s2c s2cs2c

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j2s Compilation: Link-Step

HelloWorld'stransitive closure:

HelloWorld.o

java_lang_String.o

java_math_BigInteger.o

...

(~360 classes)

ldlibj2s_runtime.so

HelloWorld_glue.o

HelloWorld_main.o

libjvm.solibjava.so...

libc.so

hw

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j2s OSUIF extensions

ClassTypeSingleInheritanceClassType

JavaAbstractClassTypeJavaClassJavaInterfaceJavaArray

• distinguished Java constructs

• tiny layer on top of OSUIF

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j2s Status

• generates C code (s2c)

• running applications:– javac (538 classes)– SPECjvm98 benchmarks:

•_201_compress•_202_db•_202_jess

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How to get started...

• "The j2s User Manual"– restrictions– modified class files– setup

•$J2SHOME and $PATH•$JAVAHOME and $JVMCLASSPATH•$LD_LIBRARY_PATH

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How to get started... (2)

• compilation process (jmake)>jmake Helloworldbuilds Makefile.deps (dependencies)

• user-customized MakefileTARGETNAME = hwCCFLAGS = -o2...include $J2SHOME/Makefile.driver.confinclude Makefile.deps

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HelloWorld.java

public class HelloWorld

{

public static void main(String[] args)

{

System.out.println("Hello world!");

}

}

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hw Stats

loop% size ./hw

text data bss dec hex filename

3033666 436664 196 3470526 34f4be ./hw

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hw Libsloop% ldd ./hw

libthread.so.1 => /usr/lib/libthread.so.1

libj2s_runtime.so => ...prj/suif2b/j2s/solib/libj2s_runtime.so

libjvm.so => /fs/oo1/local/src/jdk1.2/lib/sparc/green_threads/libjvm.so

libjava.so => /fs/oo1/local/src/jdk1.2/lib/sparc/libjava.so

libdl.so.1 => /usr/lib/libdl.so.1

libnet.so => /fs/oo1/local/src/jdk1.2/lib/sparc/libnet.so

libzip.so => /fs/oo1/local/src/jdk1.2/lib/sparc/libzip.so

libmath.so => /fs/oo1/local/src/jdk1.2/lib/sparc/libmath.so

libc.so.1 => /usr/lib/libc.so.1

libw.so.1 => /usr/lib/libw.so.1

libm.so.1 => /usr/lib/libm.so.1

libsocket.so.1 => /usr/lib/libsocket.so.1

libnsl.so.1 => /usr/lib/libnsl.so.1

libmp.so.2 => /usr/lib/libmp.so.2

/usr/platform/SUNW,Ultra-5_10/lib/libc_psr.so.1

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hw Run (finally ;-))

loop% ./hw

RTS: <clinit> executed: java/lang/System

RTS: <clinit> executed: java/util/Properties

RTS: <clinit> executed: java/io/FileInputStream

RTS: <clinit> executed: java/io/FileDescriptor

RTS: <clinit> executed: java/io/FileOutputStream

...

RTS: <clinit> executed: java/lang/Integer

RTS: <clinit> executed: java/lang/ref/CachedReference

RTS: <clinit> executed: java/lang/Runtime

RTS: <clinit> executed: java/io/BufferedWriter

Hello world!

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hw Run (Stats)

rt_type_test_cnt: 746 checkcast_cnt: 0

rt_checkcast_class_cnt: 0 rt_checkcast_iface_cnt: 0

rt_checkcast_array_cnt: 0 instanceof_cnt: 14

rt_instanceof_class_cnt: 14 rt_instanceof_iface_cnt: 0

rt_instanceof_array_cnt: 0 rt_aastore_cnt: 732

ci_check_cnt: 1408 rt_init_class_cnt: 1382

Constructor_newInstance: 0 Class_newInstance_cnt: 2

Class_forName_cnt: 2 Method_invoke_cnt: 0

GetStaticMethodID_cnt: 0 GetMethodID_cnt: 0

GetStaticFieldID_cnt: 0 GetFieldID_cnt: 0

Field_set_static_cnt: 0 Field_get_static_cnt: 0

static_field_acc_rts_cn: 8 ci_check_succeeded_cnt: 14

rt_new_cnt: 519 rt_new_array_cnt: 161

obj_alloc_cnt: 680 Class_bcNew_cnt: 3371

rt_intf_lookup_cnt: 0

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Resources http://www.cs.ucsb.edu/~osuif

• The j2s User Manual• IL docu

(osuif, osuifextension, j2s)

• A SUIF Java Compiler, UCSB, TRCS98-18(inner workings of j2s; partly outdated)

• Runtime Support for a Static Java Compiler,Master's Thesis by Andy Rutz