Sam James thesamesam

What is the Strict Aliasing Rule and Why do we care?

(OR Type Punning, Undefined Behavior and Alignment, Oh My!)

What is strict aliasing? First we will describe what is aliasing and then we can learn what being strict about it means.

In C and C++ aliasing has to do with what expression types we are allowed to access stored values through. In both C and C++ the standard specifies which expression types are allowed to alias which types. The compiler and optimizer are allowed to assume we follow the aliasing rules strictly, hence the term strict aliasing rule. If we attempt to access a value using a type not allowed it is classified as undefined behavior(UB). Once we have undefined behavior all bets are off, the results of our program are no longer reliable.

Unfortunately with strict aliasing violations, we will often obtain the results we expect, leaving the possibility the a future version of a compiler with a new optimization will break code we th

** text licensed under CC-BY 4.0 https://creativecommons.org/licenses/by/4.0/legalcode

porting gentoo (ppc32 musl example)

install crossdev
add musl repo to the system if doing musl port.
You don't have to enable it in system, just have a fresh checkout in /var/db/repos/musl
prepare crossdev repo

https://wiki.gentoo.org/wiki/Custom_ebuild_repository#Crossdev

A Selected List of Additions and Changes Coming With POSIX Issue 8

Last major change: 10th March 2023

See Also: http://mywiki.wooledge.org/POSIX#Utilities

New Commands

macOS Internals

Understand your Mac and iPhone more deeply by tracing the evolution of Mac OS X from prelease to Swift. John Siracusa delivers the details.

Starting Points

How to use this gist

You've got two main options:

How to cross-compile Rust for musl-based ppc and ppc64 Gentoo systems.

Right now, there are no prebuilt packages for Rust on ppc-musl and ppc64-musl, and bootstrap on the host machines (ppc or ppc64) cannot be done, because the Rust project doesn't publish the necessary prerequisite binary stage0s.

These targets are, however, supported by Rust, and it is possible to build binary packages of rustc by cross-compiling from a build system with a working Rust installation. After such bootstrap, Rust can be

	#!/usr/bin/env bash
	#
	# Author: Markus (MawKKe) ekkwam@gmail.com
	# Date: 2018-03-19
	#
	#
	# What?
	#
	# Linux dm-crypt + dm-integrity + dm-raid (RAID1)
	#

	#!/usr/bin/env bash

	#
	# This script attempts to recover a ZFS filesystem afflicted by the bug described in
	# the following GitHub issues:
	#
	# * https://github.com/openzfs/zfs/issues/13859
	# * https://github.com/openzfs/zfs/issues/13521
	# * https://github.com/openzfs/zfs/issues/13709
	#

	# ruby's git repo investigation zsh one-liner-ish thingy
	# (a starting point for investigating anomalous contributions in git repositories)

	echo "$(find . -type f ! -size 0 ! -path './.git*' -exec grep -IL . "{}" \;)" \| \
	sed -e "s/^\.\///g" \| \
	while read line; \
	do \
	echo ">>>>>>>>$line"; \
	echo "$(git log --follow --find-renames=40% --pretty=format:"%ad%x0A%h%x0A%an%x20<%ae>%x0A%s" -- "$line" \| head -n 4)"; \
	commitdates="$(git log --follow --find-renames=40% --pretty=format:"%ae" -- "$line" \| head -n 1 \| xargs -I {} git log --author={} --pretty=format:"%ad")"; \