Opbinaryop and other minor optimizations

[geseq]

Nothing like the last optimisation but but it does add up to around 4% improvement. I've done some micro optimizations on the v.ip increments. While individually they don't amount to much, they do seem to add up on a fib(35) and likely on any long running script.

OLD:

---

fibonacci(35)

Result: 9227465
Go: 45.674312ms
Parser: 32.976µs
Compile: 104.373µs
VM: 2.597270621s

fibonacci(35) (tail-call #1)

Result: 9227465
Go: 62.044356ms
Parser: 20.597µs
Compile: 71.31µs
VM: 2.692990659s

fibonacci(35) (tail-call #2)

Result: 9227465
Go: 447ns
Parser: 37.322µs
Compile: 69.521µs
VM: 13.112µs

NEW:

---

fibonacci(35)

Result: 9227465
Go: 47.159815ms
Parser: 34.767µs
Compile: 115.81µs
VM: 2.44406141s

fibonacci(35) (tail-call #1)

Result: 9227465
Go: 62.935803ms
Parser: 19.642µs
Compile: 64.569µs
VM: 2.52746129s

fibonacci(35) (tail-call #2)

Result: 9227465
Go: 251ns
Parser: 17.535µs
Compile: 49.706µs
VM: 14.56µs

[d5]

Using opcodes as a parameter to another opcode doesn't feel right. Can we just add 1-byte operand to OpBinaryOp (for operator token) and delete all other binary opcodes (OpAdd, OpSub, ...)?

[geseq]

Using opcodes as a parameter to another opcode doesn't feel right. Can we just add 1-byte operand to OpBinaryOp (for operator token) and delete all other binary opcodes (OpAdd, OpSub, ...)?

I did try that originally but for some reason that I can't remember now I changed to this. Let me try it again and see how it goes.

[d5]

Also realized that we were failing to set v.errOffset properly.

filePos := v.fileSet.Position(v.curFrame.fn.SourceMap[v.ip-v.errOffset]) // <- this will not work

We can probably find a better way to handle this. I will think about this a little bit today.

[d5]

If we keep this panic-recover approach, we can replace this to if v.ip < len(v.curInsts)-1 and remove v.curIPLimit entirely,

[d5]

One solution to IP offset is to add the following method to CompiledFunction:

// SourcePos returns the source position of the instruction at ip.
func (o *CompiledFunction) SourcePos(ip int) source.Pos {
	for ip >= 0 {
		if p, ok := o.SourceMap[ip]; ok {
			return p
		}
		ip--
	}
	return source.NoPos
}

, and, change error handling code in VM to:

err = v.err
if err != nil {
	filePos := v.fileSet.Position(v.curFrame.fn.SourcePos(v.ip - 1))
	err = fmt.Errorf("Runtime Error: %s\n\tat %s", err.Error(), filePos)
	for v.framesIndex > 1 {
		v.framesIndex--
		v.curFrame = &v.frames[v.framesIndex-1]

		filePos = v.fileSet.Position(v.curFrame.fn.SourcePos(v.curFrame.ip - 1))
		err = fmt.Errorf("%s\n\tat %s", err.Error(), filePos)
	}
	return err
}

Then, we don't have to track IP offset (.errOffset) and remove it.

[d5]

Also, if we keep the proposed panic-recover approach, we can remove stack overflow checks too:

defer func() {
	if r := recover(); r != nil {
		if v.sp >= StackSize || v.framesIndex >= MaxFrames {
			v.err = ErrStackOverflow
			return
		}

		if v.ip < len(v.curInsts)-1 {
			if err, ok := r.(error); ok {
				v.err = err
			} else {
				v.err = fmt.Errorf("panic: %v", r)
			}
		}
	}
}()

[d5]

Should be

fmt.Errorf("invalid operation: %s %s %s",
 	left.TypeName(), tok.String(), right.TypeName())