Struct Alias 

pub struct Alias<'a> { /* private fields */ }

The analysis over one function.

It borrows the function because nearly everything it asks is a question about one, and it borrows an Outside because the rest is a question about the module: whether two symbols are two objects, what a callee is declared to do, where a type node sits in the tree, and how wide an address is. That is a copy of four module facts rather than the module itself, so that a pass handed &mut module[id] can still build this. See crate::outside for why.

The escape analysis is run once when this is built, since every query may ask it and it is one walk over the function.

Implementations

impl<'a> Alias<'a>

pub fn new(func: &'a Func, outside: &'a Outside) -> Self

The analysis of this function, with the type-based layer on, which is GCC’s -O2.

pub fn with(func: &'a Func, outside: &'a Outside, options: Options) -> Self

The same, with the type-based layer where the command line left it.

pub const fn escapes(&self) -> &Escapes

Which locals escaped, for a caller that wants the fact on its own.

pub const fn counts(&self) -> &Counts

What each layer has answered so far.

pub fn reads(&self, inst: Inst) -> Option<Access>

The bytes this instruction reads, if it reads any.

pub fn writes(&self, inst: Inst) -> Option<Access>

The bytes this instruction writes, if it writes any.

pub fn query(&mut self, a: &Access, b: &Access) -> Answer

Whether these two references can touch the same byte.

pub fn clobbered_by(&mut self, reference: &Access, call: Inst) -> Answer

Whether this call can write the bytes the reference covers.

GCC’s call_may_clobber_ref_p_1. Without interprocedural summaries the honest answer for anything whose address escaped is yes, and section 8.4 says so plainly: the full mod and ref summary is ipa-modref, it is five and a half thousand lines, and it is document 34’s. What is here is the cheap part of it, which is the attributes a C programmer already wrote and the escape analysis.

pub fn read_by(&mut self, reference: &Access, call: Inst) -> Answer

Whether this call can read them.

GCC’s ref_maybe_used_by_call_p_1, and the same argument as Alias::clobbered_by.

Trait Implementations

impl<'a> Debug for Alias<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.