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LibJS/JIT: Bail in UnsignedRightShift fast path if result is negative

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This commit is contained in:
iliadsh 2023-11-07 20:09:03 +00:00 • committed by Andreas Kling
parent 0875ef770f
commit aef654592f
1 changed files with 27 additions and 7 deletions
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34
Userland/Libraries/LibJS/JIT/Compiler.cpp
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@ -849,27 +849,47 @@ void Compiler::compile_unsigned_right_shift(Bytecode::Op::UnsignedRightShift con
load_accumulator(ARG2); load_accumulator(ARG2);
Assembler::Label end {}; Assembler::Label end {};
Assembler::Label slow_case {};
branch_if_both_int32(ARG1, ARG2, [&] { branch_if_both_int32(ARG1, ARG2, [&] {
// GPR0 = ARG1
m_assembler.mov(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Register(ARG1));
// RCX = ARG2 // RCX = ARG2
m_assembler.mov( m_assembler.mov(
Assembler::Operand::Register(Assembler::Reg::RCX), Assembler::Operand::Register(Assembler::Reg::RCX),
Assembler::Operand::Register(ARG2)); Assembler::Operand::Register(ARG2));
// ARG1 >>>= CL (32-bit) // GPR0 >>>= CL (32-bit)
m_assembler.shift_right32(Assembler::Operand::Register(ARG1), {}); m_assembler.shift_right32(Assembler::Operand::Register(GPR0), {});
// accumulator = ARG1 | SHIFTED_INT32_TAG; // GPR1 = sign_extended(GPR0)
m_assembler.mov( m_assembler.mov32(
Assembler::Operand::Register(GPR1),
Assembler::Operand::Register(GPR0), Assembler::Operand::Register(GPR0),
Assembler::Extension::SignExtend);
// if (GPR1 < 0) goto slow_case;
m_assembler.jump_if(
Assembler::Operand::Register(GPR1),
Assembler::Condition::SignedLessThan,
Assembler::Operand::Imm(0),
slow_case);
// accumulator = GPR0 | SHIFTED_INT32_TAG;
m_assembler.mov(
Assembler::Operand::Register(GPR1),
Assembler::Operand::Imm(SHIFTED_INT32_TAG)); Assembler::Operand::Imm(SHIFTED_INT32_TAG));
m_assembler.bitwise_or( m_assembler.bitwise_or(
Assembler::Operand::Register(ARG1), Assembler::Operand::Register(GPR0),
Assembler::Operand::Register(GPR0)); Assembler::Operand::Register(GPR1));
store_accumulator(ARG1); store_accumulator(GPR0);
m_assembler.jump(end); m_assembler.jump(end);
}); });
slow_case.link(m_assembler);
native_call((void*)cxx_unsigned_right_shift); native_call((void*)cxx_unsigned_right_shift);
store_accumulator(RET); store_accumulator(RET);
check_exception(); check_exception();