From bf424c28d2fd9aa7480479c48b6414d6b07c8ebc Mon Sep 17 00:00:00 2001
From: Zalathar <Zalathar@users.noreply.github.com>
Date: Thu, 14 Dec 2023 11:55:35 +1100
Subject: [PATCH] coverage: Don't bother storing the source file in
 `Instrumentor`

We can just as easily look it up again from the source map and body span when
needed.
---
 compiler/rustc_mir_transform/src/coverage/mod.rs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 75e3f40689c..6c1dc243dea 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -24,7 +24,7 @@
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::source_map::SourceMap;
-use rustc_span::{ExpnKind, SourceFile, Span, Symbol};
+use rustc_span::{ExpnKind, Span, Symbol};
 
 /// Inserts `StatementKind::Coverage` statements that either instrument the binary with injected
 /// counters, via intrinsic `llvm.instrprof.increment`, and/or inject metadata used during codegen
@@ -69,7 +69,6 @@ fn run_pass(&self, tcx: TyCtxt<'tcx>, mir_body: &mut mir::Body<'tcx>) {
 struct Instrumentor<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     mir_body: &'a mut mir::Body<'tcx>,
-    source_file: Lrc<SourceFile>,
     fn_sig_span: Span,
     body_span: Span,
     function_source_hash: u64,
@@ -109,7 +108,6 @@ fn new(tcx: TyCtxt<'tcx>, mir_body: &'a mut mir::Body<'tcx>) -> Self {
         Self {
             tcx,
             mir_body,
-            source_file,
             fn_sig_span,
             body_span,
             function_source_hash,
@@ -160,9 +158,10 @@ fn create_mappings_and_inject_coverage_statements(
         let source_map = self.tcx.sess.source_map();
         let body_span = self.body_span;
 
+        let source_file = source_map.lookup_source_file(body_span.lo());
         use rustc_session::RemapFileNameExt;
         let file_name =
-            Symbol::intern(&self.source_file.name.for_codegen(self.tcx.sess).to_string_lossy());
+            Symbol::intern(&source_file.name.for_codegen(self.tcx.sess).to_string_lossy());
 
         let mut mappings = Vec::new();