Schrodinger ZHU Yifan SchrodingerZhu

UCRT Notes

Background

At LLVM libc, I am exploring a harder approach (than MinGW) to implement a brand new CRT. As such, I am reading the UCRT code (open sourced portion). This document is for recording some interesting findings I have come across in the codebase. I will also write down some thoughts that might be useful for future implementation, which does not restrict to the UCRT codebase.

The code is from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource.

	struct Lancern;

	struct QuaticCat;

	struct Float;

	union Union;

	struct Lancern
	{

	[nix-shell:~/CLionProjects/paguroidea]$ env RUSTFLAGS="-C target-cpu=native" PAG_RANDOM_SEED=0 cargo bench
	Compiling snmalloc-sys v0.3.3
	Compiling pag-lexer v0.1.0-alpha.1 (/home/schrodinger/CLionProjects/paguroidea/pag-lexer)
	Compiling serde_derive v1.0.163
	Compiling lalrpop v0.20.0
	Compiling pest_meta v2.6.0
	Compiling pest_generator v2.6.0
	Compiling pest_derive v2.6.0
	Compiling pag-parser v0.1.0-alpha.1 (/home/schrodinger/CLionProjects/paguroidea/pag-parser)
	Compiling serde v1.0.163

	// Type your code here, or load an example.
	pub fn square(num: i32) -> i32 {
	num * num
	}

	// If you use `main()`, declare it as `pub` to see it in the output:
	// pub fn main() { ... }
	pub mod parser {
	extern crate alloc;
	#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]

	#![no_std]
	extern crate alloc;

	use alloc::rc::Rc;
	use core::cell::UnsafeCell;
	use core::ptr::NonNull;

	struct Node {
	tree_parent: Option<NonNull<Self>>,
	tree_left: Option<NonNull<Self>>,

	#![no_std]
	extern crate alloc;

	use alloc::rc::Rc;
	use core::cell::UnsafeCell;
	use core::ptr::NonNull;

	struct Node {
	tree_parent: Option<NonNull<Self>>,
	tree_left: Option<NonNull<Self>>,

	#![feature(core_intrinsics)]

	use std::intrinsics::likely;
	use std::marker::PhantomData;
	use std::ptr::NonNull;
	use std::rc::{Rc, Weak};

	struct Node<T> {
	next: NonNull<Self>,
	prev: NonNull<Self>,

	pub trait AssocSet<X, Y: Clone + Default> {
	fn get(&self, target: X) -> Y;
	fn set(&mut self, key: X, val: Y);
	}

	pub trait DFSGraph {
	type Identifier: Clone + PartialEq + Eq + Copy;
	type Set<Y>: AssocSet<Self::Identifier, Y>
	where
	Y: Clone + Default;

	let mut postorder = Vec::new();
	let mut visited = HashSet::new();

	fn dfs(pool: &[BasicBlock], cursor: usize, visited: &mut HashSet<usize>, postorder: &mut Vec<usize>) {
	if visited.contains(&cursor) {
	return;
	}
	visited.insert(cursor);

	for i in pool[cursor].outgoing.iter() {