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ladybird/Userland/Libraries/LibJS/Bytecode/BasicBlock.h

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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. :^)
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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Badge.h>
LibJS: Migrate DeprecatedString to String This changes BasicBlock's constructor and create().
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#include <AK/String.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. :^)
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#include <LibJS/Forward.h>
LibJS/Bytecode: Restore old environments when an exception is caught Unwind contexts now remember the lexical and variable environments in effect when they were created. If an exception is caught, we revert to those environments in the running execution context.
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#include <LibJS/Heap/Handle.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. :^)
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namespace JS::Bytecode {
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
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struct UnwindInfo {
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.
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Executable const* executable;
LibJS/Bytecode: Make Bytecode::Interpreter participate in GC marking Since the relationship between VM and Bytecode::Interpreter is now clear, we can have VM ask the Interpreter for roots in the GC marking pass. This avoids having to register and unregister handles and MarkedVectors over and over. Since GeneratorObject can also own a RegisterWindow, we share the code in a RegisterWindow::visit_edges() helper. ~4% speed-up on Kraken/stanford-crypto-ccm.js :^)
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JS::GCPtr<Environment> lexical_environment;
LibJS/Bytecode: Do not rethrow caught exception from `finally` If the exception from the `try` block has already been caught by `catch`, we need to clear the saved exception before entering `finally` so that ContinuePendingUnwind will not re-throw it. 9 new passes on test262 :^)
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bool handler_called { false };
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
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};
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.
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class BasicBlock {
LibJS: Automatically split linear bytecode into multiple blocks ...instead of crashing :^)
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AK_MAKE_NONCOPYABLE(BasicBlock);
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 05:46:30 -03:00
public:
LibJS: Migrate DeprecatedString to String This changes BasicBlock's constructor and create().
2023-10-27 00:57:51 -03:00
static NonnullOwnPtr<BasicBlock> create(String name);
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.
2021-06-08 23:19:58 -03:00
~BasicBlock();
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 05:46:30 -03:00
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 05:02:01 -03:00
void dump(Executable const&) const;
LibJS: Use a Vector<u8> for BasicBlock instruction storage This reduces the minimum size of a basic block from 4 KiB to 0 bytes. With this change, memory usage at the end of Speedometer is 1.2 GiB, down from 1.8 GiB.
2023-09-28 04:29:42 -03:00
ReadonlyBytes instruction_stream() const { return m_buffer.span(); }
u8* data() { return m_buffer.data(); }
u8 const* data() const { return m_buffer.data(); }
size_t size() const { return m_buffer.size(); }
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 05:46:30 -03:00
Revert "LibJS: Add bytecode instruction handles" This reverts commit a01bd35c67e35e9f0e33f46bb3a4431e49af1b60. This broke simple programs like: function sum(a, b) { return a + b; } console.log(sum(1, 2));
2021-06-08 19:50:42 -03:00
void grow(size_t additional_size);
LibJS: Devirtualize and pack the bytecode stream :^) This patch changes the LibJS bytecode to be a stream of instructions packed one-after-the-other in contiguous memory, instead of a vector of OwnPtr<Instruction>. This should be a lot more cache-friendly. :^) Instructions are also devirtualized and instead have a type field using a new Instruction::Type enum. To iterate over a bytecode stream, one must now use Bytecode::InstructionStreamIterator.
2021-06-07 10:12:43 -03:00
LibJS: Use a Vector<u8> for BasicBlock instruction storage This reduces the minimum size of a basic block from 4 KiB to 0 bytes. With this change, memory usage at the end of Speedometer is 1.2 GiB, down from 1.8 GiB.
2023-09-28 04:29:42 -03:00
void terminate(Badge<Generator>) { m_terminated = true; }
bool is_terminated() const { return m_terminated; }
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.
2021-06-08 23:19:58 -03:00
LibJS: Migrate DeprecatedString to String This changes BasicBlock's constructor and create().
2023-10-27 00:57:51 -03:00
String const& name() const { return m_name; }
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.
2021-06-08 23:19:58 -03:00
LibJS: Create static unwind mappings for `BasicBlock`s This is currently only used in the bytecode dump to annotate to where unwinds lead per block, but will be hooked up to the virtual machine in the next commit.
2023-10-19 18:18:54 -03:00
void set_handler(BasicBlock const& handler) { m_handler = &handler; }
void set_finalizer(BasicBlock const& finalizer) { m_finalizer = &finalizer; }
BasicBlock const* handler() const { return m_handler; }
BasicBlock const* finalizer() const { return m_finalizer; }
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 05:46:30 -03:00
private:
LibJS: Migrate DeprecatedString to String This changes BasicBlock's constructor and create().
2023-10-27 00:57:51 -03:00
explicit BasicBlock(String name);
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 05:46:30 -03:00
LibJS: Use a Vector<u8> for BasicBlock instruction storage This reduces the minimum size of a basic block from 4 KiB to 0 bytes. With this change, memory usage at the end of Speedometer is 1.2 GiB, down from 1.8 GiB.
2023-09-28 04:29:42 -03:00
Vector<u8> m_buffer;
LibJS: Create static unwind mappings for `BasicBlock`s This is currently only used in the bytecode dump to annotate to where unwinds lead per block, but will be hooked up to the virtual machine in the next commit.
2023-10-19 18:18:54 -03:00
BasicBlock const* m_handler { nullptr };
BasicBlock const* m_finalizer { nullptr };
LibJS: Migrate DeprecatedString to String This changes BasicBlock's constructor and create().
2023-10-27 00:57:51 -03:00
String m_name;
LibJS: Use a Vector<u8> for BasicBlock instruction storage This reduces the minimum size of a basic block from 4 KiB to 0 bytes. With this change, memory usage at the end of Speedometer is 1.2 GiB, down from 1.8 GiB.
2023-09-28 04:29:42 -03:00
bool m_terminated { false };
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 05:46:30 -03:00
};
}
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