LibJS/Bytecode: Add fast path for LeftShift with Int32 operands

lanmonster · Mar 4, 2024 · a5e1e66 · a5e1e66
1 parent 8e04791
commit a5e1e66
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Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -864,6 +864,20 @@ ThrowCompletionOr<void> RightShift::execute_impl(Bytecode::Interpreter& interpre
  return {};
 }
 
+ThrowCompletionOr<void> LeftShift::execute_impl(Bytecode::Interpreter& interpreter) const
+{
+ auto& vm = interpreter.vm();
+ auto const lhs = interpreter.get(m_lhs);
+ auto const rhs = interpreter.get(m_rhs);
+ if (lhs.is_int32() && rhs.is_int32() && rhs.as_i32() >= 0) {
+ auto const shift_count = static_cast<u32>(rhs.as_i32()) % 32;
+ interpreter.set(m_dst, Value(lhs.as_i32() << shift_count));
+ return {};
+ }
+ interpreter.set(m_dst, TRY(left_shift(vm, lhs, rhs)));
+ return {};
+}
+
 ThrowCompletionOr<void> LessThan::execute_impl(Bytecode::Interpreter& interpreter) const
 {
  auto& vm = interpreter.vm();

diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -59,6 +59,7 @@ class Mov final : public Instruction {
  O(BitwiseXor, bitwise_xor) \
  O(GreaterThan, greater_than) \
  O(GreaterThanEquals, greater_than_equals) \
+ O(LeftShift, left_shift) \
  O(LessThan, less_than) \
  O(LessThanEquals, less_than_equals) \
  O(Mul, mul) \
@@ -75,8 +76,7 @@ class Mov final : public Instruction {
  O(LooselyInequals, loosely_inequals) \
  O(LooselyEquals, loosely_equals) \
  O(StrictlyInequals, strict_inequals) \
- O(StrictlyEquals, strict_equals) \
- O(LeftShift, left_shift)
+ O(StrictlyEquals, strict_equals)
 
 #define JS_DECLARE_COMMON_BINARY_OP(OpTitleCase, op_snake_case) \
  class OpTitleCase final : public Instruction { \