void JITCompiler::compileEntry()
{
// This code currently matches the old JIT. In the function header we need to
// save return address and call frame via the prologue and perform a fast stack check.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=56292
// We'll need to convert the remaining cti_ style calls (specifically the stack
// check) which will be dependent on stack layout. (We'd need to account for this in
// both normal return code and when jumping to an exception handler).
emitFunctionPrologue();
emitPutImmediateToCallFrameHeader(m_codeBlock, JSStack::CodeBlock);
jitAssertTagsInPlace();
}
void JITCompiler::compileEntry()
{
// This code currently matches the old JIT. In the function header we need to
// pop the return address (since we do not allow any recursion on the machine
// stack), and perform a fast stack check.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=56292
// We'll need to convert the remaining cti_ style calls (specifically the stack
// check) which will be dependent on stack layout. (We'd need to account for this in
// both normal return code and when jumping to an exception handler).
preserveReturnAddressAfterCall(GPRInfo::regT2);
emitPutReturnPCToCallFrameHeader(GPRInfo::regT2);
emitPutImmediateToCallFrameHeader(m_codeBlock, JSStack::CodeBlock);
}
void JITCompiler::compileFunction(JITCode& entry, MacroAssemblerCodePtr& entryWithArityCheck)
{
// === Stage 1 - Function header code generation ===
//
// This code currently matches the old JIT. In the function header we need to
// pop the return address (since we do not allow any recursion on the machine
// stack), and perform a fast register file check.
// This is the main entry point, without performing an arity check.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=56292
// We'll need to convert the remaining cti_ style calls (specifically the register file
// check) which will be dependent on stack layout. (We'd need to account for this in
// both normal return code and when jumping to an exception handler).
preserveReturnAddressAfterCall(GPRInfo::regT2);
emitPutToCallFrameHeader(GPRInfo::regT2, RegisterFile::ReturnPC);
// If we needed to perform an arity check we will already have moved the return address,
// so enter after this.
Label fromArityCheck(this);
// Setup a pointer to the codeblock in the CallFrameHeader.
emitPutImmediateToCallFrameHeader(m_codeBlock, RegisterFile::CodeBlock);
// Plant a check that sufficient space is available in the RegisterFile.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=56291
addPtr(Imm32(m_codeBlock->m_numCalleeRegisters * sizeof(Register)), GPRInfo::callFrameRegister, GPRInfo::regT1);
Jump registerFileCheck = branchPtr(Below, AbsoluteAddress(m_globalData->interpreter->registerFile().addressOfEnd()), GPRInfo::regT1);
// Return here after register file check.
Label fromRegisterFileCheck = label();
// === Stage 2 - Function body code generation ===
//
// We generate the speculative code path, followed by the non-speculative
// code for the function. Next we need to link the two together, making
// bail-outs from the speculative path jump to the corresponding point on
// the non-speculative one (and generating any code necessary to juggle
// register values around, rebox values, and ensure spilled, to match the
// non-speculative path's requirements).
#if DFG_JIT_BREAK_ON_EVERY_FUNCTION
// Handy debug tool!
breakpoint();
#endif
// First generate the speculative path.
Label speculativePathBegin = label();
SpeculativeJIT speculative(*this);
#if !DFG_DEBUG_LOCAL_DISBALE_SPECULATIVE
bool compiledSpeculative = speculative.compile();
#else
bool compiledSpeculative = false;
#endif
// Next, generate the non-speculative path. We pass this a SpeculationCheckIndexIterator
// to allow it to check which nodes in the graph may bail out, and may need to reenter the
// non-speculative path.
if (compiledSpeculative) {
SpeculationCheckIndexIterator checkIterator(speculative.speculationChecks());
NonSpeculativeJIT nonSpeculative(*this);
nonSpeculative.compile(checkIterator);
// Link the bail-outs from the speculative path to the corresponding entry points into the non-speculative one.
linkSpeculationChecks(speculative, nonSpeculative);
} else {
// If compilation through the SpeculativeJIT failed, throw away the code we generated.
m_calls.clear();
rewindToLabel(speculativePathBegin);
SpeculationCheckVector noChecks;
SpeculationCheckIndexIterator checkIterator(noChecks);
NonSpeculativeJIT nonSpeculative(*this);
nonSpeculative.compile(checkIterator);
}
// === Stage 3 - Function footer code generation ===
//
// Generate code to lookup and jump to exception handlers, to perform the slow
// register file check (if the fast one in the function header fails), and
// generate the entry point with arity check.
// Iterate over the m_calls vector, checking for exception checks,
// and linking them to here.
unsigned exceptionCheckCount = 0;
for (unsigned i = 0; i < m_calls.size(); ++i) {
Jump& exceptionCheck = m_calls[i].m_exceptionCheck;
if (exceptionCheck.isSet()) {
exceptionCheck.link(this);
++exceptionCheckCount;
}
}
// If any exception checks were linked, generate code to lookup a handler.
if (exceptionCheckCount) {
// lookupExceptionHandler is passed two arguments, exec (the CallFrame*), and
// an identifier for the operation that threw the exception, which we can use
// to look up handler information. The identifier we use is the return address
// of the call out from JIT code that threw the exception; this is still
// available on the stack, just below the stack pointer!
move(GPRInfo::callFrameRegister, GPRInfo::argumentGPR0);
peek(GPRInfo::argumentGPR1, -1);
m_calls.append(CallRecord(call(), lookupExceptionHandler));
// lookupExceptionHandler leaves the handler CallFrame* in the returnValueGPR,
// and the address of the handler in returnValueGPR2.
jump(GPRInfo::returnValueGPR2);
}
// Generate the register file check; if the fast check in the function head fails,
// we need to call out to a helper function to check whether more space is available.
// FIXME: change this from a cti call to a DFG style operation (normal C calling conventions).
registerFileCheck.link(this);
move(stackPointerRegister, GPRInfo::argumentGPR0);
poke(GPRInfo::callFrameRegister, OBJECT_OFFSETOF(struct JITStackFrame, callFrame) / sizeof(void*));
Call callRegisterFileCheck = call();
jump(fromRegisterFileCheck);
// The fast entry point into a function does not check the correct number of arguments
// have been passed to the call (we only use the fast entry point where we can statically
// determine the correct number of arguments have been passed, or have already checked).
// In cases where an arity check is necessary, we enter here.
// FIXME: change this from a cti call to a DFG style operation (normal C calling conventions).
Label arityCheck = label();
preserveReturnAddressAfterCall(GPRInfo::regT2);
emitPutToCallFrameHeader(GPRInfo::regT2, RegisterFile::ReturnPC);
branch32(Equal, GPRInfo::regT1, Imm32(m_codeBlock->m_numParameters)).linkTo(fromArityCheck, this);
move(stackPointerRegister, GPRInfo::argumentGPR0);
poke(GPRInfo::callFrameRegister, OBJECT_OFFSETOF(struct JITStackFrame, callFrame) / sizeof(void*));
Call callArityCheck = call();
move(GPRInfo::regT0, GPRInfo::callFrameRegister);
jump(fromArityCheck);
// === Stage 4 - Link ===
//
// Link the code, populate data in CodeBlock data structures.
LinkBuffer linkBuffer(*m_globalData, this, m_globalData->executableAllocator);
#if DFG_DEBUG_VERBOSE
fprintf(stderr, "JIT code start at %p\n", linkBuffer.debugAddress());
#endif
// Link all calls out from the JIT code to their respective functions.
for (unsigned i = 0; i < m_calls.size(); ++i)
linkBuffer.link(m_calls[i].m_call, m_calls[i].m_function);
if (m_codeBlock->needsCallReturnIndices()) {
m_codeBlock->callReturnIndexVector().reserveCapacity(exceptionCheckCount);
for (unsigned i = 0; i < m_calls.size(); ++i) {
if (m_calls[i].m_exceptionCheck.isSet()) {
unsigned returnAddressOffset = linkBuffer.returnAddressOffset(m_calls[i].m_call);
unsigned exceptionInfo = m_calls[i].m_exceptionInfo;
m_codeBlock->callReturnIndexVector().append(CallReturnOffsetToBytecodeOffset(returnAddressOffset, exceptionInfo));
}
}
}
// FIXME: switch the register file check & arity check over to DFGOpertaion style calls, not JIT stubs.
linkBuffer.link(callRegisterFileCheck, cti_register_file_check);
linkBuffer.link(callArityCheck, m_codeBlock->m_isConstructor ? cti_op_construct_arityCheck : cti_op_call_arityCheck);
entryWithArityCheck = linkBuffer.locationOf(arityCheck);
entry = linkBuffer.finalizeCode();
}