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Rollup merge of #137410 - saethlin:stable-dep-tracking-hash, r=workingjubilee

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Use StableHasher + Hash64 for dep_tracking_hash

This is similar to https://github.com/rust-lang/rust/pull/137095. We currently have a +/- 1 byte jitter in the size of dep graphs reported on perf.rust-lang.org. I think this fixes that jitter.

When I introduced `Hash64`, I wired it through most of the compiler by making it an output of `StableHasher::finalize` then fixing the compile errors. I missed this case because the `u64` hash in this function is being produced by `DefaultHasher` instead. That seems pretty sketchy because the code seems confident that the hash needs to be stable, and we have a mechanism for stable hashing that we weren't using here.
This commit is contained in:
Matthias Krüger 2025-02-22 11:36:46 +01:00 • committed by GitHub
commit 1066af5b1a
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5 changed files with 20 additions and 16 deletions
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1
compiler/rustc_incremental/Cargo.toml
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@ -12,6 +12,7 @@ rustc_errors = { path = "../rustc_errors" }
rustc_fluent_macro = { path = "../rustc_fluent_macro" }
rustc_fs_util = { path = "../rustc_fs_util" }
rustc_graphviz = { path = "../rustc_graphviz" }
rustc_hashes = { path = "../rustc_hashes" }
rustc_hir = { path = "../rustc_hir" }
rustc_macros = { path = "../rustc_macros" }
rustc_middle = { path = "../rustc_middle" }

3
compiler/rustc_incremental/src/persist/load.rs
View file

@ -5,6 +5,7 @@ use std::sync::Arc;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::unord::UnordMap;
use rustc_hashes::Hash64;
use rustc_middle::dep_graph::{DepGraph, DepsType, SerializedDepGraph, WorkProductMap};
use rustc_middle::query::on_disk_cache::OnDiskCache;
use rustc_serialize::Decodable;
@ -154,7 +155,7 @@ fn load_dep_graph(sess: &Session) -> LoadResult<(Arc<SerializedDepGraph>, WorkPr
sess.dcx().emit_warn(errors::CorruptFile { path: &path });
return LoadResult::DataOutOfDate;
};
let prev_commandline_args_hash = u64::decode(&mut decoder);
let prev_commandline_args_hash = Hash64::decode(&mut decoder);
if prev_commandline_args_hash != expected_hash {
if sess.opts.unstable_opts.incremental_info {