linguist/samples/C/main.c

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/runtime/runtime-utils.h"

#include "src/arguments.h"
#include "src/compiler.h"
#include "src/deoptimizer.h"
#include "src/frames-inl.h"
#include "src/full-codegen/full-codegen.h"
#include "src/isolate-inl.h"
#include "src/messages.h"
#include "src/v8threads.h"
#include "src/vm-state-inl.h"

namespace v8 {
namespace internal {

RUNTIME_FUNCTION(Runtime_CompileLazy) {
	HandleScope scope(isolate);
	DCHECK_EQ(1, args.length());
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);

#ifdef DEBUG
	if (FLAG_trace_lazy && !function->shared()->is_compiled()) {
		PrintF("[unoptimized: ");
		function->PrintName();
		PrintF("]\n");
	}
#endif

	StackLimitCheck check(isolate);
	if (check.JsHasOverflowed(1 * KB)) return isolate->StackOverflow();
	if (!Compiler::Compile(function, Compiler::KEEP_EXCEPTION)) {
		return isolate->heap()->exception();
	}
	DCHECK(function->is_compiled());
	return function->code();
}

RUNTIME_FUNCTION(Runtime_CompileBaseline) {
	HandleScope scope(isolate);
	DCHECK_EQ(1, args.length());
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
	StackLimitCheck check(isolate);
	if (check.JsHasOverflowed(1 * KB)) return isolate->StackOverflow();
	if (!Compiler::CompileBaseline(function)) {
		return isolate->heap()->exception();
	}
	DCHECK(function->is_compiled());
	return function->code();
}

RUNTIME_FUNCTION(Runtime_CompileOptimized_Concurrent) {
	HandleScope scope(isolate);
	DCHECK_EQ(1, args.length());
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
	StackLimitCheck check(isolate);
	if (check.JsHasOverflowed(1 * KB)) return isolate->StackOverflow();
	if (!Compiler::CompileOptimized(function, Compiler::CONCURRENT)) {
		return isolate->heap()->exception();
	}
	DCHECK(function->is_compiled());
	return function->code();
}


RUNTIME_FUNCTION(Runtime_CompileOptimized_NotConcurrent) {
	HandleScope scope(isolate);
	DCHECK_EQ(1, args.length());
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
	StackLimitCheck check(isolate);
	if (check.JsHasOverflowed(1 * KB)) return isolate->StackOverflow();
	if (!Compiler::CompileOptimized(function, Compiler::NOT_CONCURRENT)) {
		return isolate->heap()->exception();
	}
	DCHECK(function->is_compiled());
	return function->code();
}


RUNTIME_FUNCTION(Runtime_NotifyStubFailure) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 0);
	Deoptimizer* deoptimizer = Deoptimizer::Grab(isolate);
	DCHECK(AllowHeapAllocation::IsAllowed());
	delete deoptimizer;
	return isolate->heap()->undefined_value();
}


class ActivationsFinder : public ThreadVisitor {
public:
	Code* code_;
	bool has_code_activations_;

	explicit ActivationsFinder(Code* code)
		: code_(code), has_code_activations_(false) {}

	void VisitThread(Isolate* isolate, ThreadLocalTop* top) {
		JavaScriptFrameIterator it(isolate, top);
		VisitFrames(&it);
	}

	void VisitFrames(JavaScriptFrameIterator* it) {
		for (; !it->done(); it->Advance()) {
			JavaScriptFrame* frame = it->frame();
			if (code_->contains(frame->pc())) has_code_activations_ = true;
		}
	}
};


RUNTIME_FUNCTION(Runtime_NotifyDeoptimized) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	CONVERT_SMI_ARG_CHECKED(type_arg, 0);
	Deoptimizer::BailoutType type =
		static_cast<Deoptimizer::BailoutType>(type_arg);
	Deoptimizer* deoptimizer = Deoptimizer::Grab(isolate);
	DCHECK(AllowHeapAllocation::IsAllowed());
	TimerEventScope<TimerEventDeoptimizeCode> timer(isolate);
	TRACE_EVENT0("v8", "V8.DeoptimizeCode");

	Handle<JSFunction> function = deoptimizer->function();
	Handle<Code> optimized_code = deoptimizer->compiled_code();

	DCHECK(optimized_code->kind() == Code::OPTIMIZED_FUNCTION);
	DCHECK(type == deoptimizer->bailout_type());

	// Make sure to materialize objects before causing any allocation.
	JavaScriptFrameIterator it(isolate);
	deoptimizer->MaterializeHeapObjects(&it);
	delete deoptimizer;

	// Ensure the context register is updated for materialized objects.
	JavaScriptFrameIterator top_it(isolate);
	JavaScriptFrame* top_frame = top_it.frame();
	isolate->set_context(Context::cast(top_frame->context()));

	if (type == Deoptimizer::LAZY) {
		return isolate->heap()->undefined_value();
	}

	// Search for other activations of the same optimized code.
	// At this point {it} is at the topmost frame of all the frames materialized
	// by the deoptimizer. Note that this frame does not necessarily represent
	// an activation of {function} because of potential inlined tail-calls.
	ActivationsFinder activations_finder(*optimized_code);
	activations_finder.VisitFrames(&it);
	isolate->thread_manager()->IterateArchivedThreads(&activations_finder);

	if (!activations_finder.has_code_activations_) {
		if (function->code() == *optimized_code) {
			if (FLAG_trace_deopt) {
				PrintF("[removing optimized code for: ");
				function->PrintName();
				PrintF("]\n");
			}
			function->ReplaceCode(function->shared()->code());
		}
		// Evict optimized code for this function from the cache so that it
		// doesn't get used for new closures.
		function->shared()->EvictFromOptimizedCodeMap(*optimized_code, "notify deoptimized");
	} else {
		// TODO(titzer): we should probably do DeoptimizeCodeList(code)
		// unconditionally if the code is not already marked for deoptimization.
		// If there is an index by shared function info, all the better.
		Deoptimizer::DeoptimizeFunction(*function);
	}

	return isolate->heap()->undefined_value();
}


static bool IsSuitableForOnStackReplacement(
	Isolate* isolate,
	Handle<JSFunction> function
) {
	// Keep track of whether we've succeeded in optimizing.
	if (function->shared()->optimization_disabled()) return false;
	// If we are trying to do OSR when there are already optimized
	// activations of the function, it means (a) the function is directly or
	// indirectly recursive and (b) an optimized invocation has been
	// deoptimized so that we are currently in an unoptimized activation.
	// Check for optimized activations of this function.
	for (JavaScriptFrameIterator it(isolate); !it.done(); it.Advance()) {
		JavaScriptFrame* frame = it.frame();
		if (frame->is_optimized() && frame->function() == *function) return false;
	}

	return true;
}


RUNTIME_FUNCTION(Runtime_CompileForOnStackReplacement) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
	Handle<Code> caller_code(function->shared()->code());

	// We're not prepared to handle a function with arguments object.
	DCHECK(!function->shared()->uses_arguments());

	RUNTIME_ASSERT(FLAG_use_osr);

	// Passing the PC in the javascript frame from the caller directly is
	// not GC safe, so we walk the stack to get it.
	JavaScriptFrameIterator it(isolate);
	JavaScriptFrame* frame = it.frame();
	if (!caller_code->contains(frame->pc())) {
		// Code on the stack may not be the code object referenced by the shared
		// function info.	It may have been replaced to include deoptimization data.
		caller_code = Handle<Code>(frame->LookupCode());
	}

	uint32_t pc_offset =
		static_cast<uint32_t>(frame->pc() - caller_code->instruction_start());

#ifdef DEBUG
	DCHECK_EQ(frame->function(), *function);
	DCHECK_EQ(frame->LookupCode(), *caller_code);
	DCHECK(caller_code->contains(frame->pc()));
#endif	// DEBUG

	BailoutId ast_id = caller_code->TranslatePcOffsetToAstId(pc_offset);
	DCHECK(!ast_id.IsNone());

	MaybeHandle<Code> maybe_result;
	if (IsSuitableForOnStackReplacement(isolate, function)) {
		if (FLAG_trace_osr) {
			PrintF("[OSR - Compiling: ");
			function->PrintName();
			PrintF(" at -*- scheme -*- %d]\n", ast_id.ToInt());
		}
		maybe_result = Compiler::GetOptimizedCodeForOSR(function, ast_id, frame);
	}

	// Revert the patched back edge table, regardless of whether OSR succeeds.
	BackEdgeTable::Revert(isolate, *caller_code);

	// Check whether we ended up with usable optimized code.
	Handle<Code> result;
	if (maybe_result.ToHandle(&result)
	&& result->kind() == Code::OPTIMIZED_FUNCTION) {
		DeoptimizationInputData* data =
			DeoptimizationInputData::cast(result->deoptimization_data());
		
		if (data->OsrPcOffset()->value() >= 0) {
			DCHECK(BailoutId(data->OsrAstId()->value()) == ast_id);
			if (FLAG_trace_osr) {
				PrintF("[OSR - Entry at AST id %d, offset %d in optimized code]\n",
					ast_id.ToInt(), data->OsrPcOffset()->value());
			}
			// TODO(titzer): this is a massive hack to make the deopt counts
			// match. Fix heuristics for reenabling optimizations!
			function->shared()->increment_deopt_count();

			if (result->is_turbofanned()) {
				// TurboFanned OSR code cannot be installed into the function.
				// But the function is obviously hot, so optimize it next time.
				function->ReplaceCode(
					isolate->builtins()->builtin(Builtins::kCompileOptimized));
			} else {
				// Crankshafted OSR code can be installed into the function.
				function->ReplaceCode(*result);
			}
			return *result;
		}
	}

	// Failed.
	if (FLAG_trace_osr) {
		PrintF("[OSR - Failed: ");
		function->PrintName();
		PrintF(" at AST id %d]\n", ast_id.ToInt());
	}

	if (!function->IsOptimized()) {
		function->ReplaceCode(function->shared()->code());
	}
	return NULL;
}


RUNTIME_FUNCTION(Runtime_TryInstallOptimizedCode) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);

	// First check if this is a real stack overflow.
	StackLimitCheck check(isolate);
	if (check.JsHasOverflowed()) {
		SealHandleScope shs(isolate);
		return isolate->StackOverflow();
	}

	isolate->optimizing_compile_dispatcher()->InstallOptimizedFunctions();
	return (function->IsOptimized())
		? function->code()
		: function->shared()->code();
}


bool CodeGenerationFromStringsAllowed(
	Isolate* isolate,
	Handle<Context> context
){
	DCHECK(context->allow_code_gen_from_strings()->IsFalse());
	// Check with callback if set.
	AllowCodeGenerationFromStringsCallback callback =
			isolate->allow_code_gen_callback();
	if (callback == NULL) {
		// No callback set and code generation disallowed.
		return false;
	} else {
		// Callback set. Let it decide if code generation is allowed.
		VMState<EXTERNAL> state(isolate);
		return callback(v8::Utils::ToLocal(context));
	}
}

static Object* CompileGlobalEval(
	Isolate* isolate,
	Handle<String> source,
	Handle<SharedFunctionInfo> outer_info,
	LanguageMode language_mode,
	int eval_scope_position,
	int eval_position
){
	Handle<Context> context = Handle<Context>(isolate->context());
	Handle<Context> native_context = Handle<Context>(context->native_context());

	// Check if native context allows code generation from
	// strings. Throw an exception if it doesn't.
	if (native_context->allow_code_gen_from_strings()->IsFalse() &&
	!CodeGenerationFromStringsAllowed(isolate, native_context)) {
		Handle<Object> error_message =
				native_context->ErrorMessageForCodeGenerationFromStrings();
		Handle<Object> error;
		MaybeHandle<Object> maybe_error = isolate->factory()->NewEvalError(
				MessageTemplate::kCodeGenFromStrings, error_message);
		if (maybe_error.ToHandle(&error)) isolate->Throw(*error);
		return isolate->heap()->exception();
	}

	// Deal with a normal eval call with a string argument. Compile it
	// and return the compiled function bound in the local context.
	static const ParseRestriction restriction = NO_PARSE_RESTRICTION;
	Handle<JSFunction> compiled;
	ASSIGN_RETURN_ON_EXCEPTION_VALUE(
		isolate, compiled,
		Compiler::GetFunctionFromEval(
			source, outer_info, context, language_mode,
			restriction, eval_scope_position, eval_position
		),
		isolate->heap()->exception()
	);
	return *compiled;
}


RUNTIME_FUNCTION(Runtime_ResolvePossiblyDirectEval) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 6);

	Handle<Object> callee = args.at<Object>(0);

	// If "eval" didn't refer to the original GlobalEval, it's not a
	// direct call to eval.
	// (And even if it is, but the first argument isn't a string, just let
	// execution default to an indirect call to eval, which will also return
	// the first argument without doing anything).
	if (*callee != isolate->native_context()->global_eval_fun() || !args[1]->IsString()) {
		return *callee;
	}

	DCHECK(args[3]->IsSmi());
	DCHECK(is_valid_language_mode(args.smi_at(3)));
	LanguageMode language_mode = static_cast<LanguageMode>(args.smi_at(3));
	DCHECK(args[4]->IsSmi());
	Handle<SharedFunctionInfo> outer_info(args.at<JSFunction>(2)->shared(), isolate);
	return CompileGlobalEval(
		isolate,
		args.at<String>(1),
		outer_info,
		language_mode,
		args.smi_at(4),
		args.smi_at(5)
	);
}
}	// namespace internal
}	// namespace v8

/* vim: set shiftwidth=4 softtabstop=0 cindent cinoptions={1s: */