| use crate::v0; |
| use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher}; |
| use rustc_hir::def_id::CrateNum; |
| use rustc_middle::ty::{Instance, TyCtxt}; |
| |
| use std::fmt::Write; |
| |
| pub(super) fn mangle<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| instance: Instance<'tcx>, |
| instantiating_crate: Option<CrateNum>, |
| full_mangling_name: impl FnOnce() -> String, |
| ) -> String { |
| // The symbol of a generic function may be scattered in multiple downstream dylibs. |
| // If the symbol of a generic function still contains `crate name`, hash conflicts between the |
| // generic funcion and other symbols of the same `crate` cannot be detected in time during |
| // construction. This symbol conflict is left over until it occurs during run time. |
| // In this case, `instantiating-crate name` is used to replace `crate name` can completely |
| // eliminate the risk of the preceding potential hash conflict. |
| let crate_num = |
| if let Some(krate) = instantiating_crate { krate } else { instance.def_id().krate }; |
| |
| let mut symbol = "_RNxC".to_string(); |
| v0::push_ident(tcx.crate_name(crate_num).as_str(), &mut symbol); |
| |
| let hash = tcx.with_stable_hashing_context(|mut hcx| { |
| let mut hasher = StableHasher::new(); |
| full_mangling_name().hash_stable(&mut hcx, &mut hasher); |
| hasher.finish::<Hash64>().as_u64() |
| }); |
| |
| push_hash64(hash, &mut symbol); |
| |
| symbol |
| } |
| |
| // The hash is encoded based on `base-62` and the final terminator `_` is removed because it does |
| // not help prevent hash collisions |
| fn push_hash64(hash: u64, output: &mut String) { |
| let hash = v0::encode_integer_62(hash); |
| let hash_len = hash.len(); |
| let _ = write!(output, "{hash_len}H{}", &hash[..hash_len - 1]); |
| } |