Raunak Ramakrishnan rrampage

RVA23 vs ARMv9 a Small Experiment

I was curious to see how RISC-V and ARM compare in terms of dynamic instruction count and code density, so I devised a small experiment to compare the ISAs.

As a test codebase, I choose the chibicc C compiler, because it's a medium size project and is quite easy to compile. To benchmark chibicc I just used it to compile itself, which should be a quite realistic workload to simulate a complex non-regular application. I merged all files into one and did some minor modifications, the code can be found at: https://godbolt.org/z/xr3nEW8Wf

You may notice that I added unoptimized scalar implementations of the mem* and str* functions from musl-libc. This is because I decided to not include SIMD code in this experiment, in an effort to remove more unknown variables and focus on comparing the base ISAs.

This document explains how I would implement an SSA-based compiler if I was writing one today.

This document is intentionally opinionated. It just tells you how I would do it. This document is intended for anyone who has read about SSA and understands the concept, but is confused about how exactly to put it into practice. If you're that person, then I'm here to show you a way to do it that works well for me. If you're looking for a review of other ways to do it, I recommend this post.

My approach works well when implementing the compiler in any language that easily permits cyclic mutable data structures. I know from experience that it'll work great in C++, C#, or Java. The memory management of this approach is simple (and I'll explain it), so you won't have to stress about use after frees.

I like my approach because it leads to an ergonomic API by minimizing the amount of special cases you have to worry about. Most of the compiler is analyses and transformations ov

FAQ on the xz-utils backdoor (CVE-2024-3094)

This is a living document. Everything in this document is made in good faith of being accurate, but like I just said; we don't yet know everything about what's going on.

Update: I've disabled comments as of 2025-01-26 to avoid everyone having notifications for something a year on if someone wants to suggest a correction. Folks are free to email to suggest corrections still, of course.

Background

Binary Lambda Calculus

The Binary Lambda Calculus (BLC) is a minimal, pure functional programming language invented by John Tromp in 2004 [1] based on a binary encoding of the untyped lambda calculus in De Bruijn index notation.

So you want to write a sync system for a web app with offline and realtime support? Good luck. You might find the following resources useful.

Overview articles

Database in a browser, a spec (Stepan Parunashvili)

What problem are we trying to solve with a sync system?
The web of tomorrow (Nikita Prokopov)

This was a response to a Hacker News comment asking me what I've been up to since 2010. I'm posting it here since HN rejects it with "that comment is too long." I suppose that's fair, since this ended up being something of an autobiography.

--

What happened after 2010?

ELF Format Cheatsheet

Introduction

Executable and Linkable Format (ELF), is the default binary format on Linux-based systems.

Compilation

Guide: Run FreeBSD 13.1-RELEASE for ARM64 in QEMU on Apple Silicon Mac (MacBook Pro M1, etc) with HVF acceleration (Hypervisor.framework)

This guide was adapted from https://gist.github.com/niw/e4313b9c14e968764a52375da41b4278#running-ubuntu-server-for-arm64

Running FreeBSD 13.1-RELEASE for ARM64

Install Xcode from App Store or install Command Line Tools on your Mac running on Apple Silicon.


	.global _main
	.extern _putchar

	.align 4

	_main:
	; prolog; save fp,lr,x19
	stp x29, x30, [sp, #-0x20]!
	str x19, [sp, #0x10]

	# th30z@u1310:[Desktop]$ psql -h localhost -p 55432
	# Password:
	# psql (9.1.10, server 0.0.0)
	# WARNING: psql version 9.1, server version 0.0.
	# Some psql features might not work.
	# Type "help" for help.
	#
	# th30z=> select foo;
	# a \| b
	# ---+---