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LibJS/JIT: Allow multiple jumps to the same Assembler::Label

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This commit is contained in:
Andreas Kling 2023-10-23 11:01:02 +02:00
parent 1fb95c7df9
commit 4b7f5f4ae7
2 changed files with 32 additions and 27 deletions
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37
Userland/Libraries/LibJS/JIT/Assembler.h
View file

@ -178,22 +178,31 @@ struct Assembler {
}
struct Label {
size_t offset_in_instruction_stream { 0 };
size_t offset_of_label_in_instruction_stream { 0 };
Vector<size_t> jump_slot_offsets_in_instruction_stream;
void add_jump(size_t offset)
{
jump_slot_offsets_in_instruction_stream.append(offset);
}
void link(Assembler& assembler)
{
auto offset = assembler.m_output.size() - offset_in_instruction_stream;
auto jump_slot = offset_in_instruction_stream - 4;
assembler.m_output[jump_slot + 0] = (offset >> 0) & 0xff;
assembler.m_output[jump_slot + 1] = (offset >> 8) & 0xff;
assembler.m_output[jump_slot + 2] = (offset >> 16) & 0xff;
assembler.m_output[jump_slot + 3] = (offset >> 24) & 0xff;
offset_of_label_in_instruction_stream = assembler.m_output.size();
for (auto offset_in_instruction_stream : jump_slot_offsets_in_instruction_stream) {
auto offset = offset_of_label_in_instruction_stream - offset_in_instruction_stream;
auto jump_slot = offset_in_instruction_stream - 4;
assembler.m_output[jump_slot + 0] = (offset >> 0) & 0xff;
assembler.m_output[jump_slot + 1] = (offset >> 8) & 0xff;
assembler.m_output[jump_slot + 2] = (offset >> 16) & 0xff;
assembler.m_output[jump_slot + 3] = (offset >> 24) & 0xff;
}
}
};
[[nodiscard]] Label make_label()
{
return { .offset_in_instruction_stream = m_output.size() };
return { .offset_of_label_in_instruction_stream = m_output.size() };
}
[[nodiscard]] Label jump()
@ -201,7 +210,9 @@ struct Assembler {
// jmp target (RIP-relative 32-bit offset)
emit8(0xe9);
emit32(0xdeadbeef);
return make_label();
auto label = make_label();
label.add_jump(m_output.size());
return label;
}
void jump(Label& label)
@ -209,7 +220,7 @@ struct Assembler {
// jmp target (RIP-relative 32-bit offset)
emit8(0xe9);
emit32(0xdeadbeef);
label.offset_in_instruction_stream = m_output.size();
label.add_jump(m_output.size());
}
void jump(Operand op)
@ -284,7 +295,7 @@ struct Assembler {
emit8(0x0f);
emit8(0x84);
emit32(0xdeadbeef);
label.offset_in_instruction_stream = m_output.size();
label.add_jump(m_output.size());
}
void jump_if_not_equal(Operand lhs, Operand rhs, Label& label)
@ -295,7 +306,7 @@ struct Assembler {
emit8(0x0f);
emit8(0x85);
emit32(0xdeadbeef);
label.offset_in_instruction_stream = m_output.size();
label.add_jump(m_output.size());
}
void jump_if_less_than(Operand lhs, Operand rhs, Label& label)
@ -306,7 +317,7 @@ struct Assembler {
emit8(0x0f);
emit8(0x8c);
emit32(0xdeadbeef);
label.offset_in_instruction_stream = m_output.size();
label.add_jump(m_output.size());
}
void bitwise_and(Operand dst, Operand src)

22
Userland/Libraries/LibJS/JIT/Compiler.cpp
View file

@ -198,22 +198,19 @@ void Compiler::branch_if_both_int32(Assembler::Reg lhs, Assembler::Reg rhs, Code
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();
auto not_int32_case = m_assembler.make_label();
m_assembler.jump_if_not_equal(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Imm32(INT32_TAG),
not_int32_case1);
not_int32_case);
m_assembler.jump_if_not_equal(
Assembler::Operand::Register(GPR1),
Assembler::Operand::Imm32(INT32_TAG),
not_int32_case2);
not_int32_case);
codegen();
not_int32_case1.link(m_assembler);
not_int32_case2.link(m_assembler);
not_int32_case.link(m_assembler);
}
void Compiler::compile_increment(Bytecode::Op::Increment const&)
@ -464,9 +461,7 @@ 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();
auto end = m_assembler.make_label();
branch_if_both_int32(ARG1, ARG2, [&] {
// if (ARG1 < ARG2) return true;
@ -482,7 +477,7 @@ void Compiler::compile_less_than(Bytecode::Op::LessThan const& op)
Assembler::Operand::Register(GPR0),
Assembler::Operand::Imm64(Value(false).encoded()));
store_vm_register(Bytecode::Register::accumulator(), GPR0);
m_assembler.jump(end1);
m_assembler.jump(end);
true_case.link(m_assembler);
m_assembler.mov(
@ -490,14 +485,13 @@ void Compiler::compile_less_than(Bytecode::Op::LessThan const& op)
Assembler::Operand::Imm64(Value(true).encoded()));
store_vm_register(Bytecode::Register::accumulator(), GPR0);
m_assembler.jump(end2);
m_assembler.jump(end);
});
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);
end.link(m_assembler);
}
static ThrowCompletionOr<Value> not_(VM&, Value value)