zeux

A friend recently learned about Proebsting's law and mentioned it to me off hand. I knew about the law's existence but I never really asked myself - do I believe in it?

For people who aren't aware, Proebsting's law states:

Compiler Advances Double Computing Power Every 18 Years

Which is to say, if you upgrade your compiler every 18 years, you would expect on average your code to double in performance on the same hardware.

Let's C about this

zeux

State of Roblox graphics API across all platforms, with percentage deltas since EOY 2020. Updated December 31 2021.

Windows

API	Share
Direct3D 11+	92% (+3%)
Direct3D 10.1	5% (-2%)
Direct3D 10.0	3% (-0.5%)

zeux

export type any=any

export type nil=nil

export type string=string

export type number=number

export type boolean=boolean

zeux

source: vertex data 32064032 bytes, index data 24000000 bytes
pass 0: vertex data 18518385 bytes, index data 2332680 bytes
decode: vertex 9.31 ms (3.21 GB/sec), index 5.65 ms (3.95 GB/sec)
decode: vertex 9.43 ms (3.17 GB/sec), index 5.64 ms (3.96 GB/sec)
decode: vertex 9.44 ms (3.16 GB/sec), index 5.69 ms (3.93 GB/sec)
decode: vertex 9.47 ms (3.15 GB/sec), index 5.72 ms (3.91 GB/sec)
decode: vertex 9.50 ms (3.14 GB/sec), index 5.72 ms (3.91 GB/sec)
decode: vertex 9.36 ms (3.19 GB/sec), index 5.82 ms (3.84 GB/sec)
decode: vertex 9.57 ms (3.12 GB/sec), index 5.75 ms (3.89 GB/sec)
decode: vertex 9.47 ms (3.15 GB/sec), index 5.72 ms (3.91 GB/sec)

zeux

function fixupSimd(input) {
	var data = new Uint8Array(input);
	var read = 0;

	var result = new Uint8Array(data.length * 2); // worst case: opcode renumbering changes 1-byte to 2-byte
	var write = 0;

	var readByte = function() {
		read++;
		if (read >= data.length) {

zeux

Problem

meshoptimizer currently ships with index and vertex codecs with the API along these lines:

size_t encode(destination, destination_capacity, source, source_size)
void decode(destination, destination_size, source, source_size)

The next version of meshoptimizer needs to make backwards incompatible changes to the encoding format to allow for better compression.

zeux

State of Roblox graphics API across all platforms, with percentage deltas since EOY 2019. Updated December 27 2020.

Windows

API	Share
Direct3D 11+	89% (+4%)
Direct3D 10.1	7% (-2%)
Direct3D 10.0	3.5% (-1.5%)
Direct3D 9	0.5% (-0.5%)

zeux

type AdvancedDragger={
    AncestryChanged:Event,
    Archivable:boolean,
    AttributeChanged:Event,
    AttributesReplicate:string,
    AttributesSerialize:any,
    Changed:Event,
    ChildAdded:Event,
    ChildRemoved:Event,

zeux

# table type guard (memory safety)
cmp	dword ptr [rdi + 12], 6
jne	1072 <.text+0x5ea>
# load array index and convert to integer (+ exactness check)
movsd	xmm0, qword ptr [rdi + 256]
cvttsd2si	eax, xmm0
cvtsi2sd	xmm1, eax
ucomisd	xmm1, xmm0
jne	1046 <.text+0x5ea>
# indices are 1-based; could remove this one with runtime changes

zeux

unsigned int follow(std::vector<unsigned int>& ids, unsigned int v)
{
    unsigned int nv = v;
    while (ids[nv] != nv)
        nv = ids[nv];

    return ids[v] = nv;
}

size_t islandize(const std::vector<unsigned int>& indices, std::vector<unsigned int>& islands)