From 4fdc1b5f6c88de001768822016603a2c48b4da8d Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 23 Feb 2025 22:54:36 +0000
Subject: [PATCH 1/2] Construct MIR error body for global_asm correctly

---
 compiler/rustc_mir_build/src/builder/mod.rs | 3 ++-
 tests/ui/asm/global-asm-with-error.rs       | 9 +++++++++
 tests/ui/asm/global-asm-with-error.stderr   | 9 +++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/asm/global-asm-with-error.rs
 create mode 100644 tests/ui/asm/global-asm-with-error.stderr

diff --git a/compiler/rustc_mir_build/src/builder/mod.rs b/compiler/rustc_mir_build/src/builder/mod.rs
index 949559549345f..dc869b885a038 100644
--- a/compiler/rustc_mir_build/src/builder/mod.rs
+++ b/compiler/rustc_mir_build/src/builder/mod.rs
@@ -612,7 +612,8 @@ fn construct_error(tcx: TyCtxt<'_>, def_id: LocalDefId, guar: ErrorGuaranteed) -
         | DefKind::AssocConst
         | DefKind::AnonConst
         | DefKind::InlineConst
-        | DefKind::Static { .. } => (vec![], tcx.type_of(def_id).instantiate_identity(), None),
+        | DefKind::Static { .. }
+        | DefKind::GlobalAsm => (vec![], tcx.type_of(def_id).instantiate_identity(), None),
         DefKind::Ctor(..) | DefKind::Fn | DefKind::AssocFn => {
             let sig = tcx.liberate_late_bound_regions(
                 def_id.to_def_id(),
diff --git a/tests/ui/asm/global-asm-with-error.rs b/tests/ui/asm/global-asm-with-error.rs
new file mode 100644
index 0000000000000..84e95c587ef36
--- /dev/null
+++ b/tests/ui/asm/global-asm-with-error.rs
@@ -0,0 +1,9 @@
+// Ensure that we don't ICE when constructing the fake MIR body for a global
+// asm when the body has errors. See #137470.
+
+use std::arch::global_asm;
+
+global_asm!("/* {} */", sym a);
+//~^ ERROR cannot find value `a` in this scope
+
+fn main() {}
diff --git a/tests/ui/asm/global-asm-with-error.stderr b/tests/ui/asm/global-asm-with-error.stderr
new file mode 100644
index 0000000000000..6c07a9f020da8
--- /dev/null
+++ b/tests/ui/asm/global-asm-with-error.stderr
@@ -0,0 +1,9 @@
+error[E0425]: cannot find value `a` in this scope
+  --> $DIR/global-asm-with-error.rs:6:29
+   |
+LL | global_asm!("/* {} */", sym a);
+   |                             ^ not found in this scope
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0425`.

From dc9d559f42b216a91ca2b45729b2f6d48b47e44f Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 23 Feb 2025 23:01:04 +0000
Subject: [PATCH 2/2] Exclude global_asm from mir_keys

---
 compiler/rustc_mir_transform/src/lib.rs       |  4 ++++
 .../asm/global-asm-isnt-really-a-mir-body.rs  | 23 +++++++++++++++++++
 2 files changed, 27 insertions(+)
 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 04c9375b83176..4168557e12cae 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 0000000000000..0b0f0319ad940
--- /dev/null
+++ b/tests/ui/asm/global-asm-isnt-really-a-mir-body.rs
@@ -0,0 +1,23 @@
+//@ 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 -Clink-dead-code=true
+//@[cfi] needs-sanitizer-cfi
+//@[cfi] no-prefer-dynamic
+
+//@ build-pass
+
+use std::arch::global_asm;
+
+fn foo() {}
+
+global_asm!("/* {} */", sym foo);
+
+fn main() {}