A small program demonstrating how to use AsmJit to create a just-in-time mathematical expression evaluator. Further description of JitCalc and AsmJit can be found in this blog post.
The objectives are to demonstrate how to use AsmJit (right now there are few examples online) and to demonstrate how much faster JIT code generation can be.
For a more serious expression evaulator please see mathspresso.
This project uses a CMake build. You'll need a recent version of GCC or clang (C++11 features used).
# git checkout
git clone https://github.com/lukedodd/JitCalc.git
# make build directory
mdkir build-jitcalc
cd build-jitcalc/
# run cmake and compile
cmake ../JitCalc
make
# run an example
./jitcalc "((x y) (+ x (/ y 2)))" 5 20.5
Tested on x86-64 Linux only. I would expect x86-64 OSX to work too. Windows (visual studio 2010+) might just work (perhaps requring small tweaks) but it has not been tested yet, the same is true of 32bit.
Expressions are lisp like. Operations supported are addition, subtraction, multiplication and division (+, -, *, /).
Code should be supplied to the jitcalc command in the first argument. An S-Expression of this form is expected ((args...) (expr)). Subsequent command line arguments are bound to the function arguments of the supplied expression. Some examples should make this clear!
$ ./jitcalc "((x) (+ x 10))" 5 # add 10 to x, which is bound to 5
Interpreted output: 15
Code gen output: 15
$ ./jitcalc "((x y) (+ x y))" 100 1 # add two arguments
Interpreted output: 101
Code gen output: 101
$ ./jitcalc "((x y) (+ x (* y 2)))" 2 2.5 # multiply second argument by 2 and add to first argument
Interpreted output: 7
Code gen output: 7
$ # more complex expression
$ ./jitcalc "((x y) (+ (* (+ x 20) y) (/ x (+ y 1))))" 1 10
Interpreted output: 210.091
Code gen output: 210.091
Here are benchmark command examples and results.
$ ./jitcalc -benchmark "((x y) (* x (+ y 10)))" 5 10
Interpreted output: 100
Code gen output: 100
Benchmarking...
Duration for 10000000 repeated evaluations:
- Interpreted: 2532ms
- JIT: 19ms
$ ./jitcalc -benchmark "((x y) (+ (* (+ x 20) y) (/ x (+ y 1))))" 15.5 20
Interpreted output: 710.738
Code gen output: 710.738
Benchmarking...
Duration for 10000000 repeated evaluations:
- Interpreted: 5732ms
- JIT: 52ms
This code is under the BSD 2-Clause license.