Benchmark: a+a vs 2*a vs a<<1

Script Preparation code:

var a=5559486755555,a2=0;

Tests:

+
a2=a+a;
*2
a2=a*2;
<<1
a2=a<<1;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
+
*2
<<1

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON benchmark definition and test cases.

**Benchmark Definition:**
The benchmark is designed to compare three different approaches for doubling a value in JavaScript:

1. `a+a`: This approach simply adds two instances of `a` together.
2. `2*a`: This approach multiplies the value of `a` by 2.
3. `a<<1`: This approach uses the bitwise left shift operator (`<<`) to double the value of `a`.

**Test Cases:**
Each test case represents a specific scenario where one of these approaches is used:

1. `a2=a+a;`: Tests the addition operation `+`.
2. `a2=a*2;`: Tests the multiplication operation `*2`.
3. `a2=a<<1;`: Tests the bitwise left shift operator (`<<`) for doubling.

**Options Compared:**
The benchmark compares three different approaches:

* Addition (`a+a`)
* Multiplication by 2 (`2*a`)
* Bitwise left shift (`a<<1`)

These options are compared to determine which approach is most efficient in terms of performance.

**Pros and Cons:**

* **Addition (`a+a`):** This approach is simple and easy to understand. However, it may not be the fastest option since adding two large numbers together can be computationally expensive.
* **Multiplication by 2 (`2*a`):** This approach is generally faster than addition because multiplying a number by 2 only requires one multiplication operation. However, if the result of `a` is very large, this approach may still be slow due to overflow issues.
* **Bitwise left shift (`a<<1`):** This approach is often the fastest option for doubling because it uses bitwise operations, which are typically faster than arithmetic operations. The left shift operator doubles the value by shifting the bits one position to the left.

**Library and Special JS Feature:**
None of the test cases use a specific library or special JavaScript feature beyond what's built into the language.

**Other Considerations:**

* **Overflow:** All three approaches can overflow if the result exceeds the maximum value that can be represented by the data type. However, bitwise left shift is less likely to overflow because it only shifts bits, not performs an arithmetic operation.
* **Cache locality:** The performance of the benchmark may also depend on cache locality, where the location and size of the data in memory affects access times.

**Alternatives:**
If you need more options or different scenarios for your benchmark, here are some alternative approaches:

* Comparison (`a==b`): Tests equality comparison.
* Bitwise AND (`a&b`): Tests bitwise AND operation.
* Integer division (`a/2`): Tests integer division.
* Floating-point multiplication (`a*a`): Tests floating-point multiplication.

Keep in mind that each of these alternatives may have different performance characteristics and requirements, so be sure to adjust your benchmark accordingly.

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.59 Safari/537.36 OPR/41.0.2353.46

Browser/OS: Opera 41 on Windows

View result in a separate tab

Test name	Executions per second
+	3382143.5 Ops/sec
*2	4692889.5 Ops/sec
<<1	4696572.5 Ops/sec

Related benchmarks:

a+a vs 2*a vs a<<1 (version: 1)

double the value

Comparing performance of: + vs *2 vs <<1

Created: 8 years ago by: Registered User

Jump to the latest result

+

*2

<<1

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):