The document discusses using the Zero and Shark optimizations in OpenJDK6. It shows commands to configure OpenJDK6 to enable Zero and Shark, but Shark is not supported in the current release. The document also provides code snippets showing how Shark compiles bytecode to LLVM IR using the SharkCompiler and registers the native code using ExecutionEngine.

2. 6 JVM (OpenJDK6) Zero/
Shark
http://today.java.net/pub/a/today/2009/05/21/zero-
and-shark-openjdk-port.html

7. hg clone http://icedtea.classpath.org/hg/release/
icedtea6-1.11
sh autogen.sh
./configure --enable-zero --enable-shark
:
checking for a JamVM source zip... not specified
checking whether to disable optimizations and build
with -O0 -g... no
checking whether to use the Shark JIT... yes
configure: error: shark is unsupported in this
release

8. void TemplateTable::initialize() {
def(Bytecodes::_iadd , ____|____|____|____, itos, itos,
iop2 , add );
def(Bytecodes::_ladd , ____|____|____|____, ltos, ltos,
lop2 , add );
0 templateTable.hpp <global> 267 static void invokevirtual(int
byte_no);
1 templateTable_sparc.cpp invokevirtual 2947 void
TemplateTable::invokevirtual(int byte_no)
{
2 templateTable_x86_32.cpp invokevirtual 2993 void
TemplateTable::invokevirtual(int byte_no)
{
3 templateTable_x86_64.cpp invokevirtual 3001 void
TemplateTable::invokevirtual(int byte_no)
{
4 templateTable.cpp initialize 441 def
(Bytecodes::_invokevirtual ,
ubcp|disp|clvm|____, vtos,
vtos, invokevirtual
, f2_byte );

9. 0 cpu/sparc/vm/templateTable_sparc.cpp
1 cpu/sparc/vm/templateTable_sparc.hpp
2 cpu/x86/vm/templateTable_x86_32.cpp
3 cpu/x86/vm/templateTable_x86_32.hpp
4 cpu/x86/vm/templateTable_x86_64.cpp
5 cpu/x86/vm/templateTable_x86_64.hpp
6 cpu/zero/vm/templateTable_zero.cpp // empty
7 cpu/zero/vm/templateTable_zero.hpp // empty
8 share/vm/interpreter/templateTable.cpp
9 share/vm/interpreter/templateTable.hpp

10. No template interpreter for zero...
$ more cpu/zero/vm/*
...
SharkFrame : public ZeroFrame
ZeroStack
$ ls share/vm/shark
llvmHeaders.hpp sharkEntry.hpp sharkStack.cpp
llvmValue.hpp sharkFunction.cpp sharkStack.hpp
sharkBlock.cpp sharkFunction.hpp sharkState.cpp
sharkBlock.hpp sharkInliner.cpp sharkState.hpp
sharkBuilder.cpp sharkInliner.hpp sharkStateScanner.cpp

11. ** llvmHeaders.hpp
#include <llvm/Argument.h>
#include <llvm/Constants.h>
#include <llvm/DerivedTypes.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/Instructions.h>
#include <llvm/LLVMContext.h>
#include <llvm/Module.h>
#if SHARK_LLVM_VERSION < 27
#include <llvm/ModuleProvider.h>
#endif

12. IRBuilder
Builder.CreateAdd
Builder.CreateCall
Builder.CreateRet
Function::Create
BasicBlock::Create
fcmp
uitofp
sitofp
call
ret
FunctionPassManager OurFPM(TheModule);
// Set up the optimizer pipeline. Start with registering info about how
the
// target lays out data structures.
OurFPM.add(new TargetData(*TheExecutionEngine->getTargetData()));
// Do simple "peephole" optimizations and bit-twiddling optzns.
OurFPM.add(createInstructionCombiningPass());

13. // Create the JIT. This takes ownership of the module.
TheExecutionEngine = EngineBuilder(TheModule).create();
--- back to shark
$ grep ExecutionEngine *
llvmHeaders.hpp:#include <llvm/ExecutionEngine/ExecutionEngine.h>
llvmHeaders.hpp:#include <llvm/ExecutionEngine/JITMemoryManager.h>
llvmHeaders.hpp:#include <llvm/ExecutionEngine/JIT.h>
sharkCompiler.cpp: _execution_engine_lock = new Monitor(Mutex::leaf,
"SharkExecutionEngineLock");
sharkCompiler.cpp: _execution_engine = ExecutionEngine::createJIT(
sharkCompiler.hpp: llvm::ExecutionEngine* _execution_engine;
sharkCompiler.hpp: llvm::ExecutionEngine* execution_engine() const {

14. SharkCompiler::compile_method()
SharkFunction::build() native code register_method.
class SharkFunction : public SharkTargetInvariants {
friend class SharkStackWithNormalFrame;
public:
static llvm::Function* build(ciEnv* env,
SharkBuilder* builder,
ciTypeFlow* flow,
const char* name) {
SharkFunction function(env, builder, flow, name);
return function.function();
}

15. sharkBlock.cpp:void SharkBlock::parse_bytecode(int start, int limit)
case Bytecodes::_iadd:
b = pop();
a = pop();
push(SharkValue::create_jint(
builder()->CreateAdd(a->jint_value(), b->jint_value()), false));
// Create the JIT
std::string ErrorMsg;
EngineBuilder builder(_normal_context->module());
builder.setMCPU(MCPU);
builder.setMAttrs(MAttrs);
builder.setJITMemoryManager(memory_manager());
builder.setEngineKind(EngineKind::JIT);
builder.setErrorStr(&ErrorMsg);
_execution_engine = builder.create();