LibJS: Add fast paths for bitwise ops on 2x Int32 JS::Value

~9% speed-up on Kraken/stanford-crypto-aes.js :^)
awesomekling · Jul 1, 2023 · 6e1b905 · 6e1b905
1 parent 9840439
commit 6e1b905
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Showing 2 changed files with 35 additions and 11 deletions.
diff --git a/Userland/Libraries/LibJS/Runtime/Value.cpp b/Userland/Libraries/LibJS/Runtime/Value.cpp
@@ -1344,6 +1344,10 @@ ThrowCompletionOr<Value> less_than_equals(VM& vm, Value lhs, Value rhs)
 // BitwiseANDExpression : BitwiseANDExpression & EqualityExpression
 ThrowCompletionOr<Value> bitwise_and(VM& vm, Value lhs, Value rhs)
 {
+    // OPTIMIZATION: Fast path when both values are Int32.
+    if (lhs.is_int32() && rhs.is_int32())
+        return Value(lhs.as_i32() & rhs.as_i32());
+
     // 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
     // 1-2, 6. N/A.
 
@@ -1377,6 +1381,10 @@ ThrowCompletionOr<Value> bitwise_and(VM& vm, Value lhs, Value rhs)
 // BitwiseORExpression : BitwiseORExpression | BitwiseXORExpression
 ThrowCompletionOr<Value> bitwise_or(VM& vm, Value lhs, Value rhs)
 {
+    // OPTIMIZATION: Fast path when both values are Int32.
+    if (lhs.is_int32() && rhs.is_int32())
+        return Value(lhs.as_i32() | rhs.as_i32());
+
     // 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
     // 1-2, 6. N/A.
 
@@ -1414,6 +1422,10 @@ ThrowCompletionOr<Value> bitwise_or(VM& vm, Value lhs, Value rhs)
 // BitwiseXORExpression : BitwiseXORExpression ^ BitwiseANDExpression
 ThrowCompletionOr<Value> bitwise_xor(VM& vm, Value lhs, Value rhs)
 {
+    // OPTIMIZATION: Fast path when both values are Int32.
+    if (lhs.is_int32() && rhs.is_int32())
+        return Value(lhs.as_i32() ^ rhs.as_i32());
+
     // 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
     // 1-2, 6. N/A.
 
@@ -1598,6 +1610,12 @@ ThrowCompletionOr<Value> left_shift(VM& vm, Value lhs, Value rhs)
 // ShiftExpression : ShiftExpression >> AdditiveExpression
 ThrowCompletionOr<Value> right_shift(VM& vm, Value lhs, Value rhs)
 {
+    // OPTIMIZATION: Fast path when both values are suitable Int32 values.
+    if (lhs.is_int32() && rhs.is_int32() && rhs.as_i32() > 0) {
+        auto shift_count = static_cast<u32>(rhs.as_i32()) % 32;
+        return Value(lhs.as_i32() >> shift_count);
+    }
+
     // 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
     // 1-2, 6. N/A.
 
@@ -1649,6 +1667,12 @@ ThrowCompletionOr<Value> right_shift(VM& vm, Value lhs, Value rhs)
 // ShiftExpression : ShiftExpression >>> AdditiveExpression
 ThrowCompletionOr<Value> unsigned_right_shift(VM& vm, Value lhs, Value rhs)
 {
+    // OPTIMIZATION: Fast path when both values are suitable Int32 values.
+    if (lhs.is_int32() && rhs.is_int32() && lhs.as_i32() >= 0 && rhs.as_i32() > 0) {
+        auto shift_count = static_cast<u32>(rhs.as_i32()) % 32;
+        return Value(static_cast<u32>(lhs.as_i32()) >> shift_count);
+    }
+
     // 13.15.3 ApplyStringOrNumericBinaryOperator ( lval, opText, rval ), https://tc39.es/ecma262/#sec-applystringornumericbinaryoperator
     // 1-2, 5-6. N/A.
 

diff --git a/Userland/Libraries/LibJS/Runtime/Value.h b/Userland/Libraries/LibJS/Runtime/Value.h
@@ -428,6 +428,17 @@ class Value {
 #endif
     }
 
+    // A double is any Value which does not have the full exponent and top mantissa bit set or has
+    // exactly only those bits set.
+    bool is_double() const { return (m_value.encoded & CANON_NAN_BITS) != CANON_NAN_BITS || (m_value.encoded == CANON_NAN_BITS); }
+    bool is_int32() const { return m_value.tag == INT32_TAG; }
+
+    i32 as_i32() const
+    {
+        VERIFY(is_int32());
+        return static_cast<i32>(m_value.encoded & 0xFFFFFFFF);
+    }
+
 private:
     Value(u64 tag, u64 val)
     {
@@ -459,17 +470,6 @@ class Value {
         }
     }
 
-    // A double is any Value which does not have the full exponent and top mantissa bit set or has
-    // exactly only those bits set.
-    bool is_double() const { return (m_value.encoded & CANON_NAN_BITS) != CANON_NAN_BITS || (m_value.encoded == CANON_NAN_BITS); }
-    bool is_int32() const { return m_value.tag == INT32_TAG; }
-
-    i32 as_i32() const
-    {
-        VERIFY(is_int32());
-        return static_cast<i32>(m_value.encoded & 0xFFFFFFFF);
-    }
-
     template<typename PointerType>
     PointerType* extract_pointer() const
     {