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LibJS/JIT: Add fast path for LessThan Int32 < Int32

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This uses a new branch_if_both_int32() helper.

It's interesting to note that we can compare encoded Int32 values
without stripping the INT32_TAG, since it doesn't affect signedness
of values.
This commit is contained in:
Andreas Kling 2023-10-23 10:52:57 +02:00
parent 895c613400
commit 1fb95c7df9
3 changed files with 120 additions and 3 deletions
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82
Userland/Libraries/LibJS/JIT/Compiler.cpp
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@ -187,6 +187,35 @@ void Compiler::branch_if_int32(Assembler::Reg reg, Codegen codegen)
not_int32_case.link(m_assembler);
}
template<typename Codegen>
void Compiler::branch_if_both_int32(Assembler::Reg lhs, Assembler::Reg rhs, Codegen codegen)
{
// GPR0 = lhs >> 48;
m_assembler.mov(Assembler::Operand::Register(GPR0), Assembler::Operand::Register(lhs));
m_assembler.shift_right(Assembler::Operand::Register(GPR0), Assembler::Operand::Imm8(48));
// GPR1 = rhs >> 48;
m_assembler.mov(Assembler::Operand::Register(GPR1), Assembler::Operand::Register(rhs));
m_assembler.shift_right(Assembler::Operand::Register(GPR1), Assembler::Operand::Imm8(48));
// FIXME: Use one label once Assembler::Label supports multiple jumps to it.
auto not_int32_case1 = m_assembler.make_label();
auto not_int32_case2 = m_assembler.make_label();
m_assembler.jump_if_not_equal(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Imm32(INT32_TAG),
not_int32_case1);
m_assembler.jump_if_not_equal(
Assembler::Operand::Register(GPR1),
Assembler::Operand::Imm32(INT32_TAG),
not_int32_case2);
codegen();
not_int32_case1.link(m_assembler);
not_int32_case2.link(m_assembler);
}
void Compiler::compile_increment(Bytecode::Op::Increment const&)
{
load_vm_register(ARG1, Bytecode::Register::accumulator());
@ -422,9 +451,55 @@ static ThrowCompletionOr<Value> typed_equals(VM&, Value src1, Value src2)
check_exception(); \
}
JS_ENUMERATE_COMMON_BINARY_OPS(DO_COMPILE_COMMON_BINARY_OP)
JS_ENUMERATE_COMMON_BINARY_OPS_WITHOUT_FAST_PATH(DO_COMPILE_COMMON_BINARY_OP)
#undef DO_COMPILE_COMMON_BINARY_OP
static Value cxx_less_than(VM& vm, Value lhs, Value rhs)
{
return TRY_OR_SET_EXCEPTION(less_than(vm, lhs, rhs));
}
void Compiler::compile_less_than(Bytecode::Op::LessThan const& op)
{
load_vm_register(ARG1, op.lhs());
load_vm_register(ARG2, Bytecode::Register::accumulator());
// FIXME: Unify when we have multi-jump labels.
auto end1 = m_assembler.make_label();
auto end2 = m_assembler.make_label();
branch_if_both_int32(ARG1, ARG2, [&] {
// if (ARG1 < ARG2) return true;
// else return false;
auto true_case = m_assembler.make_label();
m_assembler.jump_if_less_than(
Assembler::Operand::Register(ARG1),
Assembler::Operand::Register(ARG2),
true_case);
m_assembler.mov(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Imm64(Value(false).encoded()));
store_vm_register(Bytecode::Register::accumulator(), GPR0);
m_assembler.jump(end1);
true_case.link(m_assembler);
m_assembler.mov(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Imm64(Value(true).encoded()));
store_vm_register(Bytecode::Register::accumulator(), GPR0);
m_assembler.jump(end2);
});
m_assembler.native_call((void*)cxx_less_than);
store_vm_register(Bytecode::Register::accumulator(), RET);
check_exception();
end1.link(m_assembler);
end2.link(m_assembler);
}
static ThrowCompletionOr<Value> not_(VM&, Value value)
{
return Value(!value.to_boolean());
@ -850,12 +925,15 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
case Bytecode::Instruction::Type::SetVariable:
compiler.compile_set_variable(static_cast<Bytecode::Op::SetVariable const&>(op));
break;
case Bytecode::Instruction::Type::LessThan:
compiler.compile_less_than(static_cast<Bytecode::Op::LessThan const&>(op));
break;
#define DO_COMPILE_COMMON_BINARY_OP(TitleCaseName, snake_case_name) \
case Bytecode::Instruction::Type::TitleCaseName: \
compiler.compile_##snake_case_name(static_cast<Bytecode::Op::TitleCaseName const&>(op)); \
break;
JS_ENUMERATE_COMMON_BINARY_OPS(DO_COMPILE_COMMON_BINARY_OP)
JS_ENUMERATE_COMMON_BINARY_OPS_WITHOUT_FAST_PATH(DO_COMPILE_COMMON_BINARY_OP)
#undef DO_COMPILE_COMMON_BINARY_OP
#define DO_COMPILE_COMMON_UNARY_OP(TitleCaseName, snake_case_name) \