jeetah

jeetah is an experimental compiler for mathematical expressions in JavaScript with MP support

Depending on the outcome, it (might) replace (one day) partially (or fully) the current ExprTk backend in ExprTk.js

Project Goals

jeetah aims to solve the following goals:

• True compiler, producing machine code from mathematical expressions
• Always faster than V8, for any expression, even in mono-threaded sync mode
• True JavaScript syntax replacing the ExprTk syntax, working from V8 representation
• Support a subset of the JavaScript language with a single variable type per function as the current ExprTk syntax
• Support only TypedArrays
• Support array traversal with fusing of the expression logic into the array logic and zero subroutine calls
• (stretch goal) Add SSE to MIR (probably as manual custom instructions) and support SSE operations

Implementation

• Front-end parsing by acorn
• jeetah compiling to MIR - Medium Intermediate Representation
• Back-end register allocation and machine code assembly by MIR

Status

Not usable Very early stage Very small subset of the JS language functional

Example

Input

compile(function lapseRate(temp, height) {
    const g = 9.81;
    const c = 1005;
    const Gamma = g / c;
    return temp - height * Gamma;
});

Output

m_lapseRate:	module
export	lapseRate
lapseRate:	func d, d:temp, d:height
	local	d:g, d:c, d:Gamma, d:_expr_0, d:_expr_1, d:_expr_2
		dmov	g, 9.8100000000000005
		dmov	c, 1005.0000000000000000
		dmov	_expr_0, g
		ddiv	_expr_0, g, c
		dmov	Gamma, _expr_0
		dmov	_expr_1, temp
		dmov	_expr_2, height
		dmul	_expr_2, height, Gamma
		dsub	_expr_1, temp, _expr_2
		ret     _expr_1
	endfunc
endmodule

Performance

Preliminary results show performance very close to clang -O3 with an inline loop.