From ef031c854da6432c86ac14c438ab96c7e349d85f Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 23 Feb 2025 23:01:04 +0000
Subject: [PATCH] Exclude global_asm from mir_keys

---
 compiler/rustc_mir_transform/src/lib.rs       |  4 +++
 .../asm/global-asm-isnt-really-a-mir-body.rs  | 26 +++++++++++++++++++
 tests/ui/asm/global-asm-with-error.stderr     |  2 +-
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/asm/global-asm-isnt-really-a-mir-body.rs

diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 5df12ac4d8bc..8aa14d15644b 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -316,6 +316,10 @@ fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
     // All body-owners have MIR associated with them.
     let mut set: FxIndexSet<_> = tcx.hir_body_owners().collect();
 
+    // Remove the fake bodies for `global_asm!`, since they're not useful
+    // to be emitted (`--emit=mir`) or encoded (in metadata).
+    set.retain(|&def_id| !matches!(tcx.def_kind(def_id), DefKind::GlobalAsm));
+
     // Coroutine-closures (e.g. async closures) have an additional by-move MIR
     // body that isn't in the HIR.
     for body_owner in tcx.hir_body_owners() {
diff --git a/tests/ui/asm/global-asm-isnt-really-a-mir-body.rs b/tests/ui/asm/global-asm-isnt-really-a-mir-body.rs
new file mode 100644
index 000000000000..b7636d116ec6
--- /dev/null
+++ b/tests/ui/asm/global-asm-isnt-really-a-mir-body.rs
@@ -0,0 +1,26 @@
+//@ revisions: emit_mir instrument cfi
+
+// Make sure we don't try to emit MIR for it.
+//@[emit_mir] compile-flags: --emit=mir
+
+// Make sure we don't try to instrument it.
+//@[instrument] compile-flags: -Cinstrument-coverage -Zno-profiler-runtime
+//@[instrument] only-linux
+
+// Make sure we don't try to CFI encode it.
+//@[cfi] compile-flags: -Zsanitizer=cfi -Ccodegen-units=1 -Clto -Ctarget-feature=-crt-static -Clink-dead-code=true
+//@[cfi] needs-sanitizer-cfi
+//@[cfi] no-prefer-dynamic
+// FIXME(#122848) Remove only-linux once OSX CFI binaries work
+//@[cfi] only-linux
+
+//@ build-pass
+//@ needs-asm-support
+
+use std::arch::global_asm;
+
+fn foo() {}
+
+global_asm!("/* {} */", sym foo);
+
+fn main() {}
diff --git a/tests/ui/asm/global-asm-with-error.stderr b/tests/ui/asm/global-asm-with-error.stderr
index 6c07a9f020da..3b76bfd19485 100644
--- a/tests/ui/asm/global-asm-with-error.stderr
+++ b/tests/ui/asm/global-asm-with-error.stderr
@@ -1,5 +1,5 @@
 error[E0425]: cannot find value `a` in this scope
-  --> $DIR/global-asm-with-error.rs:6:29
+  --> $DIR/global-asm-with-error.rs:8:29
    |
 LL | global_asm!("/* {} */", sym a);
    |                             ^ not found in this scope