bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

CFI: Skip non-passed arguments

Browse source 
Rust will occasionally rely on fn((), X) -> Y being compatible with
fn(X) -> Y, since () is a non-passed argument. Relax CFI by choosing not
to encode non-passed arguments.
This commit is contained in:
Matthew Maurer 2024-02-17 14:47:44 +00:00
parent e3df96cfda
commit f2f0d255df
6 changed files with 65 additions and 39 deletions
Download patch file Download diff file Expand all files Collapse all files

22
compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
View file

@ -18,7 +18,7 @@ use rustc_middle::ty::{
use rustc_middle::ty::{GenericArg, GenericArgKind, GenericArgsRef};
use rustc_span::def_id::DefId;
use rustc_span::sym;
use rustc_target::abi::call::{Conv, FnAbi};
use rustc_target::abi::call::{Conv, FnAbi, PassMode};
use rustc_target::abi::Integer;
use rustc_target::spec::abi::Abi;
use std::fmt::Write as _;
@ -1040,19 +1040,27 @@ pub fn typeid_for_fnabi<'tcx>(
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
// Encode the parameter types
// We erase ZSTs as we go if the argument is skipped. This is an implementation detail of how
// MIR is currently treated by rustc, and subject to change in the future. Specifically, MIR
// interpretation today will allow skipped arguments to simply not be passed at a call-site.
if !fn_abi.c_variadic {
if !fn_abi.args.is_empty() {
for arg in fn_abi.args.iter() {
let ty = transform_ty(tcx, arg.layout.ty, transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
}
} else {
let mut pushed_arg = false;
for arg in fn_abi.args.iter().filter(|arg| arg.mode != PassMode::Ignore) {
pushed_arg = true;
let ty = transform_ty(tcx, arg.layout.ty, transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
}
if !pushed_arg {
// Empty parameter lists, whether declared as () or conventionally as (void), are
// encoded with a void parameter specifier "v".
typeid.push('v');
}
} else {
for n in 0..fn_abi.fixed_count as usize {
if fn_abi.args[n].mode == PassMode::Ignore {
continue;
}
let ty = transform_ty(tcx, fn_abi.args[n].layout.ty, transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
}