Stowage/ladybird
2
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2025-10-19 23:53:20 +00:00
Code Issues Projects Releases Packages Wiki Activity
ladybird/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp

230 lines
7.7 KiB
C++
Raw Normal View History

LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
LibJS: Move bytecode debug spam behind JS_BYTECODE_DEBUG :^)
2021-06-07 15:17:37 +02:00
#include <AK/Debug.h>
LibJS: Store strings in a string table Instead of using Strings in the bytecode ops this adds a global string table to the Executable struct which individual operations can refer to using indices. This brings bytecode ops one step closer to being pointer free.
2021-06-09 10:02:01 +02:00
#include <AK/TemporaryChange.h>
LibJS: Generate bytecode in basic blocks instead of one big block This limits the size of each block (currently set to 1K), and gets us closer to a canonical, more easily analysable bytecode format. As a result of this, "Labels" are now simply entries to basic blocks. Since there is no more 'conditional' jump (as all jumps are always taken), JumpIf{True,False} are unified to JumpConditional, and JumpIfNullish is renamed to JumpNullish. Also fixes #7914 as a result of reimplementing the loop logic.
2021-06-09 06:49:58 +04:30
#include <LibJS/Bytecode/BasicBlock.h>
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
#include <LibJS/Bytecode/Instruction.h>
#include <LibJS/Bytecode/Interpreter.h>
LibJS: Move Bytecode::Instruction::execute() to the Op.h header ..and make sure it always gets inlined in the interpreter loop.
2021-06-09 09:19:34 +02:00
#include <LibJS/Bytecode/Op.h>
LibJS: Drop "Record" suffix from all the *Environment record classes "Records" in the spec are basically C++ classes, so let's drop this mouthful of a suffix.
2021-07-01 12:24:46 +02:00
#include <LibJS/Runtime/GlobalEnvironment.h>
LibJS: Add a VM accessor to Bytecode::Interpreter :^)
2021-06-03 18:26:13 +02:00
#include <LibJS/Runtime/GlobalObject.h>
LibJS: Move the GlobalEnvironment from GlobalObject to Realm This is where the spec wants to have it. Requires a couple of hacks as currently everything that needs a Realm actually has a GlobalObject, so we need to go via the Interpreter.
2021-09-11 20:27:36 +01:00
#include <LibJS/Runtime/Realm.h>
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
namespace JS::Bytecode {
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
static Interpreter* s_current;
LibJS: Move global "should dump bytecode" flag into LibJS This will allow us to trigger bytecode executable dumps when generating bytecode inside LibJS as well, not just in clients like js and test-js.
2021-10-24 13:34:46 +02:00
bool g_dump_bytecode = false;
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
Interpreter* Interpreter::current()
{
return s_current;
}
LibJS: Allocate a Realm next to GlobalObject in Interpreter::create() Also pass a Realm reference to the Bytecode::Interpreter constructor, just like we pass the GlobalObject.
2021-09-11 19:36:25 +01:00
Interpreter::Interpreter(GlobalObject& global_object, Realm& realm)
LibJS: Add a VM accessor to Bytecode::Interpreter :^)
2021-06-03 18:26:13 +02:00
: m_vm(global_object.vm())
, m_global_object(global_object)
LibJS: Allocate a Realm next to GlobalObject in Interpreter::create() Also pass a Realm reference to the Bytecode::Interpreter constructor, just like we pass the GlobalObject.
2021-09-11 19:36:25 +01:00
, m_realm(realm)
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
{
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
VERIFY(!s_current);
s_current = this;
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
}
Interpreter::~Interpreter()
{
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
VERIFY(s_current == this);
s_current = nullptr;
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
}
LibJS: Make Bytecode::Interpreter return the popped frame And use it to _correctly_ implement state saving for generators. Prior to this, we were capturing the caller frame, which is completely irrelevant to the generator frame.
2021-11-11 00:34:44 +03:30
Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& executable, BasicBlock const* entry_point)
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
{
LibJS: Rename Bytecode::ExecutionUnit => Bytecode::Executable
2021-06-09 09:11:20 +02:00
dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter will run unit {:p}", &executable);
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
LibJS: Store strings in a string table Instead of using Strings in the bytecode ops this adds a global string table to the Executable struct which individual operations can refer to using indices. This brings bytecode ops one step closer to being pointer free.
2021-06-09 10:02:01 +02:00
TemporaryChange restore_executable { m_current_executable, &executable };
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
VERIFY(m_saved_exception.is_null());
LibJS: Store strings in a string table Instead of using Strings in the bytecode ops this adds a global string table to the Executable struct which individual operations can refer to using indices. This brings bytecode ops one step closer to being pointer free.
2021-06-09 10:02:01 +02:00
LibJS: Always pop the execution context if we pushed one for bytecode
2022-02-07 17:12:09 +01:00
bool pushed_execution_context = false;
LibJS: Change ExecutionContext's arguments list to a MarkedValueList The test262 tests under RegExp/property-escapes/generated will invoke Reflect.apply with up to 10,000 arguments at a time. In LibJS, when the call stack reached VM::call_internal, we transfer those arguments from a MarkedValueList to the execution context's arguments Vector. Because these types differ (MarkedValueList is a Vector<Value, 32>), the arguments are copied rather than moved. By changing the arguments vector to a MarkedValueList, we can properly move the passed arguments over. This shaves about 2 seconds off the following test262 test (from 15sec): RegExp/property-escapes/generated/General_Category_-_Decimal_Number.js
2021-08-09 17:09:48 -04:00
ExecutionContext execution_context(vm().heap());
LibJS: Fix the execution context for the bytecode interpreter Because we now push an execution context when creating the "normal" interpreter without valid environments we have to check for that case as well when running the bytecode interpreter.
2022-01-22 13:03:06 +01:00
if (vm().execution_context_stack().is_empty() || !vm().running_execution_context().lexical_environment) {
// The "normal" interpreter pushes an execution context without environment so in that case we also want to push one.
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
execution_context.this_value = &global_object();
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
static FlyString global_execution_context_name = "(*BC* global execution context)";
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
execution_context.function_name = global_execution_context_name;
LibJS: Move the GlobalEnvironment from GlobalObject to Realm This is where the spec wants to have it. Requires a couple of hacks as currently everything that needs a Realm actually has a GlobalObject, so we need to go via the Interpreter.
2021-09-11 20:27:36 +01:00
execution_context.lexical_environment = &m_realm.global_environment();
execution_context.variable_environment = &m_realm.global_environment();
LibJS: Also set ExecutionContext::realm in Bytecode::Interpreter::run() I forgot to consider the bytecode Interpreter when adding a Realm to the ExecutionContext. This should make it a lot less crashy again :^)
2021-09-13 21:05:53 +01:00
execution_context.realm = &m_realm;
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
// FIXME: How do we know if we're in strict mode? Maybe the Bytecode::Block should know this?
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
// execution_context.is_strict_mode = ???;
LibJS: Convert push_execution_context() to ThrowCompletionOr
2021-11-14 12:20:49 +00:00
MUST(vm().push_execution_context(execution_context, global_object()));
LibJS: Always pop the execution context if we pushed one for bytecode
2022-02-07 17:12:09 +01:00
pushed_execution_context = true;
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
}
LibJS: Create a global/outermost CallFrame for Bytecode::Interpreter Note that we don't yet support nested calls using bytecode.
2021-06-05 15:11:00 +02:00
LibJS: Implement generator functions (only in bytecode mode)
2021-06-11 01:38:30 +04:30
auto block = entry_point ?: &executable.basic_blocks.first();
LibJS: Make Bytecode::Interpreter return the popped frame And use it to _correctly_ implement state saving for generators. Prior to this, we were capturing the caller frame, which is completely irrelevant to the generator frame.
2021-11-11 00:34:44 +03:30
if (!m_manually_entered_frames.is_empty() && m_manually_entered_frames.last()) {
m_register_windows.append(make<RegisterWindow>(m_register_windows.last()));
LibJS: Implement generator functions (only in bytecode mode)
2021-06-11 01:38:30 +04:30
} else {
m_register_windows.append(make<RegisterWindow>());
}
LibJS: Generate bytecode in basic blocks instead of one big block This limits the size of each block (currently set to 1K), and gets us closer to a canonical, more easily analysable bytecode format. As a result of this, "Labels" are now simply entries to basic blocks. Since there is no more 'conditional' jump (as all jumps are always taken), JumpIf{True,False} are unified to JumpConditional, and JumpIfNullish is renamed to JumpNullish. Also fixes #7914 as a result of reimplementing the loop logic.
2021-06-09 06:49:58 +04:30
LibJS: Make Bytecode::Interpreter return the popped frame And use it to _correctly_ implement state saving for generators. Prior to this, we were capturing the caller frame, which is completely irrelevant to the generator frame.
2021-11-11 00:34:44 +03:30
registers().resize(executable.number_of_registers);
registers()[Register::global_object_index] = Value(&global_object());
m_manually_entered_frames.append(false);
LibJS: Generate bytecode in basic blocks instead of one big block This limits the size of each block (currently set to 1K), and gets us closer to a canonical, more easily analysable bytecode format. As a result of this, "Labels" are now simply entries to basic blocks. Since there is no more 'conditional' jump (as all jumps are always taken), JumpIf{True,False} are unified to JumpConditional, and JumpIfNullish is renamed to JumpNullish. Also fixes #7914 as a result of reimplementing the loop logic.
2021-06-09 06:49:58 +04:30
for (;;) {
Bytecode::InstructionStreamIterator pc(block->instruction_stream());
bool will_jump = false;
bool will_return = false;
while (!pc.at_end()) {
auto& instruction = *pc;
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
auto ran_or_error = instruction.execute(*this);
if (ran_or_error.is_error()) {
auto exception_value = *ran_or_error.throw_completion().value();
m_saved_exception = make_handle(exception_value);
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
if (m_unwind_contexts.is_empty())
break;
auto& unwind_context = m_unwind_contexts.last();
LibJS: Propagate exceptions across bytecode executable boundaries To support situations like this: function foo() { throw 1; } try { foo(); } catch (e) { } Each unwind context now keeps track of its origin executable. When an exception is thrown, we return from run() immediately if the nearest unwind context isn't in the current executable. This causes a natural unwind to the point where we find the catch/finally block(s) to jump into.
2021-10-25 12:30:54 +02:00
if (unwind_context.executable != m_current_executable)
break;
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
if (unwind_context.handler) {
block = unwind_context.handler;
unwind_context.handler = nullptr;
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
accumulator() = exception_value;
m_saved_exception = {};
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
will_jump = true;
LibJS: Make bytecode interpreter leave unwind context immediately We were missing some "break" statements, causing us to actually finish executing everything within "try" blocks before actually jumping to the "catch" and/or "finally" blocks.
2021-10-24 23:52:39 +02:00
break;
}
if (unwind_context.finalizer) {
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
block = unwind_context.finalizer;
m_unwind_contexts.take_last();
will_jump = true;
LibJS: Make bytecode interpreter leave unwind context immediately We were missing some "break" statements, causing us to actually finish executing everything within "try" blocks before actually jumping to the "catch" and/or "finally" blocks.
2021-10-24 23:52:39 +02:00
break;
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
}
}
LibJS: Generate bytecode in basic blocks instead of one big block This limits the size of each block (currently set to 1K), and gets us closer to a canonical, more easily analysable bytecode format. As a result of this, "Labels" are now simply entries to basic blocks. Since there is no more 'conditional' jump (as all jumps are always taken), JumpIf{True,False} are unified to JumpConditional, and JumpIfNullish is renamed to JumpNullish. Also fixes #7914 as a result of reimplementing the loop logic.
2021-06-09 06:49:58 +04:30
if (m_pending_jump.has_value()) {
block = m_pending_jump.release_value();
will_jump = true;
break;
}
if (!m_return_value.is_empty()) {
will_return = true;
break;
}
++pc;
LibJS: Add basic support for while loops in the bytecode engine This introduces two new instructions: Jump and JumpIfFalse. Jumps are made to a Bytecode::Label, which is a simple object that represents a location in the bytecode stream. Note that you may not always know the target of a jump when adding the jump instruction itself, but we can just update the instruction later on during codegen once we know where the jump target is. The Bytecode::Interpreter now implements jumping via a jump slot that gets checked after each instruction to see if a jump is pending. If not, we just increment the PC as usual.
2021-06-04 12:07:38 +02:00
}
LibJS: Generate bytecode in basic blocks instead of one big block This limits the size of each block (currently set to 1K), and gets us closer to a canonical, more easily analysable bytecode format. As a result of this, "Labels" are now simply entries to basic blocks. Since there is no more 'conditional' jump (as all jumps are always taken), JumpIf{True,False} are unified to JumpConditional, and JumpIfNullish is renamed to JumpNullish. Also fixes #7914 as a result of reimplementing the loop logic.
2021-06-09 06:49:58 +04:30
if (will_return)
break;
if (pc.at_end() && !will_jump)
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
break;
LibJS: Stop bytecode execution after we've encountered an exception
2021-06-09 18:19:11 +02:00
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
if (!m_saved_exception.is_null())
LibJS: Stop bytecode execution after we've encountered an exception
2021-06-09 18:19:11 +02:00
break;
LibJS: Add basic support for while loops in the bytecode engine This introduces two new instructions: Jump and JumpIfFalse. Jumps are made to a Bytecode::Label, which is a simple object that represents a location in the bytecode stream. Note that you may not always know the target of a jump when adding the jump instruction itself, but we can just update the instruction later on during codegen once we know where the jump target is. The Bytecode::Interpreter now implements jumping via a jump slot that gets checked after each instruction to see if a jump is pending. If not, we just increment the PC as usual.
2021-06-04 12:07:38 +02:00
}
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
LibJS: Rename Bytecode::ExecutionUnit => Bytecode::Executable
2021-06-09 09:11:20 +02:00
dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter did run unit {:p}", &executable);
LibJS: Move bytecode debug spam behind JS_BYTECODE_DEBUG :^)
2021-06-07 15:17:37 +02:00
if constexpr (JS_BYTECODE_DEBUG) {
for (size_t i = 0; i < registers().size(); ++i) {
String value_string;
if (registers()[i].is_empty())
value_string = "(empty)";
else
value_string = registers()[i].to_string_without_side_effects();
dbgln("[{:3}] {}", i, value_string);
}
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
}
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
LibJS: Make Bytecode::Interpreter return the popped frame And use it to _correctly_ implement state saving for generators. Prior to this, we were capturing the caller frame, which is completely irrelevant to the generator frame.
2021-11-11 00:34:44 +03:30
OwnPtr<RegisterWindow> frame;
if (!m_manually_entered_frames.last()) {
frame = m_register_windows.take_last();
m_manually_entered_frames.take_last();
}
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
LibJS: Reset Bytecode::Interpreter's m_return_value when leaving run() Otherwise it will cause complete unwind since all parent run() loops will see the same m_return_value being non-empty and break out.
2021-06-07 13:57:02 +02:00
auto return_value = m_return_value.value_or(js_undefined());
m_return_value = {};
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
// NOTE: The return value from a called function is put into $0 in the caller context.
if (!m_register_windows.is_empty())
LibJS: Reset Bytecode::Interpreter's m_return_value when leaving run() Otherwise it will cause complete unwind since all parent run() loops will see the same m_return_value being non-empty and break out.
2021-06-07 13:57:02 +02:00
m_register_windows.last()[0] = return_value;
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
LibJS: Run the queued promise reaction jobs on bytecode interpreter exit This is the same as what the AST interpreter does.
2021-11-11 00:44:56 +03:30
// At this point we may have already run any queued promise jobs via on_call_stack_emptied,
// in which case this is a no-op.
vm().run_queued_promise_jobs();
LibJS: Always pop the execution context if we pushed one for bytecode
2022-02-07 17:12:09 +01:00
if (pushed_execution_context) {
VERIFY(&vm().running_execution_context() == &execution_context);
LibJS: Rename CallFrame => ExecutionContext This struct represents what the ECMAScript specification calls an "execution context" so let's use the same terminology. :^)
2021-06-24 19:17:45 +02:00
vm().pop_execution_context();
LibJS: Always pop the execution context if we pushed one for bytecode
2022-02-07 17:12:09 +01:00
}
LibJS: Compile ScriptFunctions into bytecode and run them that way :^) If there's a current Bytecode::Interpreter in action, ScriptFunction will now compile itself into bytecode and execute in that context. This patch also adds the Return bytecode instruction so that we can actually return values from called functions. :^) Return values are propagated from callee to caller via the caller's $0 register. Bytecode::Interpreter now keeps a stack of register "windows". These are not very efficient, but it should be pretty straightforward to convert them to e.g a sliding register window architecture later on. This is pretty dang cool! :^)
2021-06-05 15:53:36 +02:00
LibJS: Store and maintain an "execution generation" counter This counter is increased each time a synchronous execution sequence completes, and will allow us to emulate the abstract operations AddToKeptObjects & ClearKeptObjects efficiently.
2021-06-12 17:32:54 +03:00
vm().finish_execution_generation();
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
if (!m_saved_exception.is_null()) {
Value thrown_value = m_saved_exception.value();
m_saved_exception = {};
return { throw_completion(thrown_value), move(frame) };
}
LibJS+LibTest+js: Convert BC::Interpreter::run to ThrowCompletionOr<> Note that this is just a shallow API change.
2021-11-11 04:11:56 +03:30
LibJS: Make Bytecode::Interpreter return the popped frame And use it to _correctly_ implement state saving for generators. Prior to this, we were capturing the caller frame, which is completely irrelevant to the generator frame.
2021-11-11 00:34:44 +03:30
return { return_value, move(frame) };
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
}
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
void Interpreter::enter_unwind_context(Optional<Label> handler_target, Optional<Label> finalizer_target)
{
LibJS: Propagate exceptions across bytecode executable boundaries To support situations like this: function foo() { throw 1; } try { foo(); } catch (e) { } Each unwind context now keeps track of its origin executable. When an exception is thrown, we return from run() immediately if the nearest unwind context isn't in the current executable. This causes a natural unwind to the point where we find the catch/finally block(s) to jump into.
2021-10-25 12:30:54 +02:00
m_unwind_contexts.empend(m_current_executable, handler_target.has_value() ? &handler_target->block() : nullptr, finalizer_target.has_value() ? &finalizer_target->block() : nullptr);
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
}
void Interpreter::leave_unwind_context()
{
m_unwind_contexts.take_last();
}
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
ThrowCompletionOr<void> Interpreter::continue_pending_unwind(Label const& resume_label)
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
{
if (!m_saved_exception.is_null()) {
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
auto result = throw_completion(m_saved_exception.value());
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
m_saved_exception = {};
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
return result;
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
}
LibJS: Convert Instruction::execute in bytecode to ThrowCompletionOr This allows us to use TRY in these functions :^).
2022-02-07 14:36:45 +01:00
jump(resume_label);
return {};
LibJS: Implement bytecode generation for try..catch..finally EnterUnwindContext pushes an unwind context (exception handler and/or finalizer) onto a stack. LeaveUnwindContext pops the unwind context from that stack. Upon return to the interpreter loop we check whether the VM has an exception pending. If no unwind context is available we return from the loop. If an exception handler is available we clear the VM's exception, put the exception value into the accumulator register, clear the unwind context's handler and jump to the handler. If no handler is available but a finalizer is available we save the exception value + metadata (for later use by ContinuePendingUnwind), clear the VM's exception, pop the unwind context and jump to the finalizer. ContinuePendingUnwind checks whether a saved exception is available. If no saved exception is available it jumps to the resume label. Otherwise it stores the exception into the VM. The Jump after LeaveUnwindContext could be integrated into the LeaveUnwindContext instruction. I've kept them separate for now to make the bytecode more readable. > try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4 1: [ 0] EnterScope [ 10] EnterUnwindContext handler:@4 finalizer:@3 [ 38] EnterScope [ 48] LoadImmediate 1 [ 60] NewString 1 ("x") [ 70] Throw <for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here> 2: [ 0] LoadImmediate 4 3: [ 0] EnterScope [ 10] LoadImmediate 3 [ 28] ContinuePendingUnwind resume:@2 4: [ 0] SetVariable 0 (e) [ 10] EnterScope [ 20] LoadImmediate 2 [ 38] LeaveUnwindContext [ 3c] Jump @3 String Table: 0: e 1: x
2021-06-10 15:04:38 +02:00
}
LibJS: Add a basic pass manager and add some basic passes This commit adds a bunch of passes, the most interesting of which is a pass that merges blocks together, and a pass that places blocks that flow into each other next to each other, and a very simply pass that removes duplicate basic blocks. Note that this does not remove the jump at the end of each block in that pass to avoid scope creep in the passes.
2021-06-13 20:40:20 +04:30
AK::Array<OwnPtr<PassManager>, static_cast<UnderlyingType<Interpreter::OptimizationLevel>>(Interpreter::OptimizationLevel::__Count)> Interpreter::s_optimization_pipelines {};
Bytecode::PassManager& Interpreter::optimization_pipeline(Interpreter::OptimizationLevel level)
{
auto underlying_level = to_underlying(level);
VERIFY(underlying_level <= to_underlying(Interpreter::OptimizationLevel::__Count));
auto& entry = s_optimization_pipelines[underlying_level];
if (entry)
return *entry;
auto pm = make<PassManager>();
if (level == OptimizationLevel::Default) {
pm->add<Passes::GenerateCFG>();
pm->add<Passes::UnifySameBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::MergeBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::UnifySameBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::MergeBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::PlaceBlocks>();
} else {
VERIFY_NOT_REACHED();
}
auto& passes = *pm;
entry = move(pm);
return passes;
}
LibJS: Start fleshing out a bytecode for the JavaScript engine :^) This patch begins the work of implementing JavaScript execution in a bytecode VM instead of an AST tree-walk interpreter. It's probably quite naive, but we have to start somewhere. The basic idea is that you call Bytecode::Generator::generate() on an AST node and it hands you back a Bytecode::Block filled with instructions that can then be interpreted by a Bytecode::Interpreter. This first version only implements two instructions: Load and Add. :^) Each bytecode block has infinity registers, and the interpreter resizes its register file to fit the block being executed. Two new `js` options are added in this patch as well: `-d` will dump the generated bytecode `-b` will execute the generated bytecode Note that unless `-d` and/or `-b` are specified, none of the bytecode related stuff in LibJS runs at all. This is implemented in parallel with the existing AST interpreter. :^)
2021-06-03 10:46:30 +02:00
}
Reference in a new issue Copy permalink