OSUIF: A Closer Look

1
OSUIF A Closer Look

• Holger KienleUCSBhttp//www.cs.ucsb.edu/osuif

2
OSUIF The Basic Idea

• thin layer on top of SUIF for OO languages -gt
  extension of SUIF IR nodes
• lowering OSUIF -gt SUIF
• set of basic passes
• client (e.g., C/Java front end/extension) has
  to extend OSUIF skeleton

3
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)

4
Language Independence (cont.)

• design goalput only language-independent parts
  in OSUIF rest in front end / lowering
• exampleOSUIF has inheritance links but leaves
  semantics to be implemented by front end
  (abstract lookup() method)

5
OSUIF IR Extensions (1)

• new constructs
• classes and inheritance
• methods and fields (static and instance)
• method calls(dispatching and non-dispatching)
• (exception-handling)

6
OSUIF IR Extensions (2)

• DataType
• GroupType
• StructType
• ClassType
• SingleInheritanceClassType
• encapsulates methods and fields
• symbol table interface

7
OSUIF IR Extensions (3)

• SuifObject
• AnnotableObject
• InheritanceLink
• models relationships between classes
• first-class entity

8
OSUIF IR Extensions (4)

• ProcedureSymbol VariableSymbol
• InstanceMethodSymbol FieldSymbol
• StaticMethodSymbol InstanceFieldSymbol
• StaticFieldSymbol
• reference to owning class
• LString attributes(e.g., to model access
  modifiers)

9
OSUIF IR Extensions (5)

• Statement
• CallStatement
• InstanceMethodCallStatement
• StaticMethodCallStatement
• static and instance methods(this-ref vs. no
  this-ref)
• dispatching vs. non-dispatching calls

10
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

11
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 by
• SUIF classes!

12
Lowering Passes (1)

• lower_osuif_symbols-lower-instance-methods-lower
  -static-fields-lower-static-methods-lower-per-cl
  ass-symbol-table-symtab externalfile_setfile_b
  lockone-up-mangle-name lthowgt-ignore-lowering-na
  me-annote
• lower_static_method_call_expressions

13
Lowering Passes (2)

• layout_single_inheritance_instance_fields-mangle-
  name lthowgt-ignore-lowering-name-annote
• build_single_inheritance_vtbl-construct-vtbls-at
  tach-vtbl-slot-number-annotes-ignore-no-vtbl-anno
  te

14
OSUIF passes

• use "as is" (default behavior)-gt command line
  switches
• front-end controls behavior of pass with SUIF
  annotations
• customize pass via C subclassing

15
OSUIF front-ends

• Java (j2s)
• alpha-version
• several bigger applications compile
• C
• back-end reasonably stable
• front-end does not implement completelanguage
  yet
• lowering to SUIF in place

16
j2s Goals

• full Java support for off-line compilation
• provide a good platform forOO/Java-related
  compiler research

17
j2s Caveats

• compiles class files
• has its own runtime system (SPARC only!)
• JNI
• reflection
• class initialization
• ...
• requires Java 1.2beta2

18
j2s Caveats (cont'd)

• restrictions
• exception-handling
• threads and synchronization
• dynamic loading of classes
• accurate GC
• floating-point computations

19
j2s Environment
Java .class file
j2s
OSUIF
Transformations (OSUIF and j2s)
OSUIF
OSUIF Lowering
SUIF
SUIF Compiler System
20
j2s Compilation
Helloworld.class
j2s-fe
j2s-glue
j2s-main
HelloWorld.osuif
o2s
HelloWorld.suif
HelloWorld_glue.suif
HelloWorld_main.suif
s2c
s2c
s2c
HelloWorld_main.c
HelloWorld.c
HelloWorld_glue.c
21
j2s Compilation Link-Step
(360 classes)
HelloWorld'stransitive closure
java_math_BigInteger.o
...
HelloWorld.o
libc.so
java_lang_String.o
ld
hw
libj2s_runtime.so
HelloWorld_glue.o
libjvm.so libjava.so ...
HelloWorld_main.o
22
j2s OSUIF extensions

• ClassType
• SingleInheritanceClassType
• JavaAbstractClassType
• JavaClass
• JavaInterface
• JavaArray
• distinguished Java constructs
• tiny layer on top of OSUIF

23
j2s Status

• generates C code (s2c)
• running applications
• javac (538 classes)
• SPECjvm98 benchmarks
• _201_compress
• _202_db
• _202_jess

24
How to get started...

• "The j2s User Manual"
• restrictions
• modified class files
• setup
• J2SHOME and PATH
• JAVAHOME and JVMCLASSPATH
• LD_LIBRARY_PATH

25
How to get started... (2)

• compilation process (jmake)gtjmake
  Helloworldbuilds Makefile.deps (dependencies)
• user-customized MakefileTARGETNAME hwCCFLAGS
  -o2...include J2SHOME/Makefile.driver.confin
  clude Makefile.deps

26
HelloWorld.java

• public class HelloWorld
• public static void main(String args)
• System.out.println("Hello world!")

27
hw Stats

• loop size ./hw
• text data bss dec hex filename
• 3033666 436664 196 3470526 34f4be ./hw

28
hw Libs

• loop ldd ./hw
• libthread.so.1 gt
  /usr/lib/libthread.so.1
• libj2s_runtime.so gt ...prj/suif2b/j2s/sol
  ib/libj2s_runtime.so
• libjvm.so gt /fs/oo1/local/src/jdk1.2/
  lib/sparc/green_threads/libjvm.so
• libjava.so gt /fs/oo1/local/src/jdk1.2/
  lib/sparc/libjava.so
• libdl.so.1 gt /usr/lib/libdl.so.1
• libnet.so gt /fs/oo1/local/src/jdk1.2/
  lib/sparc/libnet.so
• libzip.so gt /fs/oo1/local/src/jdk1.2/
  lib/sparc/libzip.so
• libmath.so gt /fs/oo1/local/src/jdk1.2/
  lib/sparc/libmath.so
• libc.so.1 gt /usr/lib/libc.so.1
• libw.so.1 gt /usr/lib/libw.so.1
• libm.so.1 gt /usr/lib/libm.so.1
• libsocket.so.1 gt
  /usr/lib/libsocket.so.1
• libnsl.so.1 gt /usr/lib/libnsl.so.1
• libmp.so.2 gt /usr/lib/libmp.so.2
• /usr/platform/SUNW,Ultra-5_10/lib/libc_psr
  .so.1

29
hw Run (finally -))

• loop ./hw
• RTS ltclinitgt executed java/lang/System
• RTS ltclinitgt executed java/util/Properties
• RTS ltclinitgt executed java/io/FileInputStream
• RTS ltclinitgt executed java/io/FileDescriptor
• RTS ltclinitgt executed java/io/FileOutputStream
• ...
• RTS ltclinitgt executed java/lang/Integer
• RTS ltclinitgt executed java/lang/ref/CachedRefere
  nce
• RTS ltclinitgt executed java/lang/Runtime
• RTS ltclinitgt executed java/io/BufferedWriter
• Hello world!

30
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

31
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