nxnfufunezn

Achieving warp speed with Rust

Contents:

• Number one optimization tip: don't
• Never optimize blindly
• Don't bother optimizing one-time costs
• Improve your algorithms
• CPU architecture primer
• Keep as much as possible in cache
• Keep as much as possible in registers

nxnfufunezn

Using <details> in GitHub

Suppose you're opening an issue and there's a lot noisey logs that may be useful.

Rather than wrecking readability, wrap it in a <details> tag!

<details>
 <summary>Summary Goes Here</summary>

nxnfufunezn

Registers
    Caller-saved                                Callee-saved
    RAX RCX RSP RDI RSI RDX R8 R9 R10 R11       RBP RBX R12 R13 R14 R15

    Args: RDI, RSI, RDX, RCX, R8, R9, XMM0–7
    Return: RAX

Simple Compile
    yasm -f macho64 foo.asm && gcc foo.c foo.o -Wall -Wextra -g -O1

nxnfufunezn

Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?

A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.

TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.

nxnfufunezn

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

nxnfufunezn

Keybase proof

I hereby claim:

• I am nxnfufunezn on github.
• I am nxnfufunezn (https://keybase.io/nxnfufunezn) on keybase.
• I have a public key whose fingerprint is 9369 D7F4 0F45 BBB3 6C27 C45A AFC9 CF33 B178 6FD6

To claim this, I am signing this object:

nxnfufunezn

#include <stdio.h>

#define STR2(x) #x
#define STR(x) STR2(x)

#define INCBIN(name, file) \
    __asm__(".section .rodata\n" \
            ".global incbin_" STR(name) "_start\n" \
            ".type incbin_" STR(name) "_start, @object\n" \
            ".balign 16\n" \

nxnfufunezn

./mach cargo-update -p brotli --precise 0.3.17


components/servo
thread '<main>' panicked at 'index 0 and/or 8 in `0.3.17` do not lie on character boundary', ../src/libcore/str/mod.rs:1284

nxnfufunezn

import brotli

def main(request, response):
    if "content" in request.GET:
        output = request.GET["content"]
    else:
        output = request.body
    output = brotli.compress(output)

    headers = [("Content-type", "text/plain"),

nxnfufunezn

from flask import after_this_request, request
from cStringIO import StringIO as IO
import gzip
import functools

def gzipped(f):
    @functools.wraps(f)
    def view_func(*args, **kwargs):
        @after_this_request
        def zipper(response):