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Merged
rust-bors merged 1 commit into from
Aug 4, 2026
+17 −20
Merged

Deduplicate target and host filesearch #160451

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37 changes: 17 additions & 20 deletions compiler/rustc_session/src/session.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -329,7 +329,7 @@ pub struct Session {
pub target: Target,
pub host: Target,
pub opts: config::Options,
pub target_tlib_path: Arc<SearchPath>,
pub target_tlib_path: SearchPath,
pub psess: ParseSess,
pub unstable_features: UnstableFeatures,
pub config: Cfg,
Expand Down Expand Up @@ -396,8 +396,8 @@ pub struct Session {
/// File paths accessed during the build.
pub file_depinfo: Lock<FxIndexSet<Symbol>>,

target_filesearch: FileSearch,
host_filesearch: FileSearch,
target_filesearch: Arc<FileSearch>,
host_filesearch: Arc<FileSearch>,

/// The names of intrinsics that the current codegen backend replaces
/// with its own implementations.
Expand Down Expand Up @@ -1328,15 +1328,8 @@ pub fn build_session(
let host_triple = config::host_tuple();
let target_triple = sopts.target_triple.tuple();
// FIXME use host sysroot?
let host_tlib_path =
Arc::new(SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), host_triple));
let target_tlib_path = if host_triple == target_triple {
// Use the same `SearchPath` if host and target triple are identical to avoid unnecessary
// rescanning of the target lib path and an unnecessary allocation.
Arc::clone(&host_tlib_path)
} else {
Arc::new(SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), target_triple))
};
let host_tlib_path = SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), host_triple);
let target_tlib_path = SearchPath::from_sysroot_and_triple(sopts.sysroot.path(), target_triple);

@petrochenkov petrochenkov Aug 4, 2026 •
edited by rustbot
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Nit: cloning SearchPath is still cheaper than calling SearchPath::from_sysroot_and_triple for the second time, even without the Arc, but the benefit may be so small that it doesn't matter.
I'll leave it to you whether to restore this optimization or not.

View changes since the review

@Kobzol Kobzol Aug 4, 2026

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I checked what it does and it seems to be very little work, so I think that complicating it with an Arc no longer makes sense.

@petrochenkov petrochenkov Aug 4, 2026 •
edited
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(I meant without adding an Arc, literally let host_tlib_path = target_tlib_path.clone().)

@Kobzol Kobzol Aug 4, 2026

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Ah, right. Well, it would still need the check for host == target, I don't think it's needed here.


let prof = SelfProfilerRef::new(
self_profiler,
Expand All @@ -1350,18 +1343,22 @@ pub fn build_session(
});

let asm_arch = if target.allow_asm { InlineAsmArch::from_arch(&target.arch) } else { None };
let target_filesearch = filesearch::FileSearch::new(
let target_filesearch = Arc::new(filesearch::FileSearch::new(
&sopts.search_paths,
&target_tlib_path,
&target,
sopts.unstable_opts.implicit_sysroot_deps,
);
let host_filesearch = filesearch::FileSearch::new(
&sopts.search_paths,
&host_tlib_path,
&host,
sopts.unstable_opts.implicit_sysroot_deps,
);
));
let host_filesearch = if target == host {
Arc::clone(&target_filesearch)
} else {
Arc::new(filesearch::FileSearch::new(
&sopts.search_paths,
&host_tlib_path,
&host,
sopts.unstable_opts.implicit_sysroot_deps,
))
};

let timings = TimingSectionHandler::new(sopts.json_timings);

Expand Down
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