llvm-calc is a small utility which compiles simple arithmetic expressions to LLVM and executes them using JIT.
To build this project, please ensure that clang and llvm in version 3.4 or newer are available:
- On Linux, install
clangand thellvm-devpackage. - On Mac OS, use homebrew to install the
llvmpackage and link it withbrew link llvm --force. - On Windows, get a VM.
For more information, please follow the instructions on Get Started.
Simply clone this repository and run make.
This should create an executable called calc in the project directory.
Call the program calc with an expression and any number of parameters.
$ ./calc [expression] [params...]
Valid expressions comprise:
- Constants: 64 bit integer values, like
42,4711or-1. Constant must not start with 0. - Variables: Parameters of the compiled function.
Variables either start with with an underscore, dollar or hash sign followed by the zero-based index of the parameter, e.g.
#0,_1,$2. - Operations: Operations are defined in infix notation with two expressions connected by an operator.
Possible operators are
+,-,*and/. - Parentheses: Use parantheses to create sub-expressions, e.g. to change operator precedence:
2 * (1 + $0).
The following example evaluates the expression (a + b) * (c - d) for the values a=1, b=2, c=5 and d=2:
$ ./calc '($0 + $1) * ($2 - $3)' 1 2 5 2
LLVM code compilation completed successfully.
---------
; ModuleID = 'test'
define i64 @calc(i64, i64, i64, i64) {
EntryBlock:
%ADD = add i64 %0, %1
%Sub = sub i64 %2, %3
%Mul = mul i64 %ADD, %Sub
ret i64 %Mul
}
---------
Starting calc with JIT ...
RESULT: 9