rust-lang · rust-bors · May 13, 2026 · May 9, 2026 · May 12, 2026 · May 12, 2026
diff --git a/Cargo.lock b/Cargo.lock
@@ -3831,7 +3831,6 @@ dependencies = [
  "rustc_metadata",
  "rustc_middle",
  "rustc_mir_build",
- "rustc_mir_transform",
  "rustc_parse",
  "rustc_public",
  "rustc_resolve",

diff --git a/compiler/rustc_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
@@ -27,7 +27,6 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_metadata = { path = "../rustc_metadata" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_mir_build = { path = "../rustc_mir_build" }
-rustc_mir_transform = { path = "../rustc_mir_transform" }
 rustc_parse = { path = "../rustc_parse" }
 rustc_public = { path = "../rustc_public", features = ["rustc_internal"] }
 rustc_resolve = { path = "../rustc_resolve" }

diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
@@ -6,6 +6,7 @@
 
 // tidy-alphabetical-start
 #![feature(decl_macro)]
+#![feature(file_buffered)]
 #![feature(panic_backtrace_config)]
 #![feature(panic_update_hook)]
 #![feature(trim_prefix_suffix)]
@@ -333,7 +334,7 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
             }
 
             if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
-                if let Err(error) = rustc_mir_transform::dump_mir::emit_mir(tcx) {
+                if let Err(error) = pretty::emit_mir(tcx) {
                     tcx.dcx().emit_fatal(CantEmitMIR { error });
                 }
             }

diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
@@ -2,6 +2,8 @@
 
 use std::cell::Cell;
 use std::fmt::Write;
+use std::fs::File;
+use std::io;
 
 use rustc_ast as ast;
 use rustc_ast_pretty::pprust as pprust_ast;
@@ -12,7 +14,7 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_mir_build::thir::print::{thir_flat, thir_tree};
 use rustc_public::rustc_internal::pretty::write_smir_pretty;
 use rustc_session::Session;
-use rustc_session::config::{OutFileName, PpHirMode, PpMode, PpSourceMode};
+use rustc_session::config::{OutFileName, OutputType, PpHirMode, PpMode, PpSourceMode};
 use rustc_span::{FileName, Ident};
 use tracing::debug;
 
@@ -340,3 +342,21 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
 
     write_or_print(&out, sess);
 }
+
+/// Implementation of `--emit=mir`.
+pub fn emit_mir(tcx: TyCtxt<'_>) -> io::Result<()> {
+    match tcx.output_filenames(()).path(OutputType::Mir) {
+        OutFileName::Stdout => {
+            let mut f = io::stdout();
+            write_mir_pretty(tcx, &mut f)?;
+        }
+        OutFileName::Real(path) => {
+            let mut f = File::create_buffered(&path)?;
+            write_mir_pretty(tcx, &mut f)?;
+            if tcx.sess.opts.json_artifact_notifications {
+                tcx.dcx().emit_artifact_notification(&path, "mir");
+            }
+        }
+    }
+    Ok(())
+}
diff --git a/compiler/rustc_mir_transform/src/dump_mir.rs b/compiler/rustc_mir_transform/src/dump_mir.rs
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -2,7 +2,6 @@
 #![feature(box_patterns)]
 #![feature(const_type_name)]
 #![feature(cow_is_borrowed)]
-#![feature(file_buffered)]
 #![feature(impl_trait_in_assoc_type)]
 #![feature(iterator_try_collect)]
 #![feature(try_blocks)]
@@ -91,8 +90,6 @@ macro_rules! declare_passes {
 
         static PASS_NAMES: LazyLock<FxIndexSet<&str>> = LazyLock::new(|| {
             let mut set = FxIndexSet::default();
-            // Fake marker pass
-            set.insert("PreCodegen");
             $(
                 $(
                     set.extend(pass_names!($mod_name : $pass_name $( { $($ident),* } )? ));
@@ -145,7 +142,6 @@ declare_passes! {
     };
     mod deref_separator : Derefer;
     mod dest_prop : DestinationPropagation;
-    pub mod dump_mir : Marker;
     mod early_otherwise_branch : EarlyOtherwiseBranch;
     mod erase_deref_temps : EraseDerefTemps;
     mod elaborate_box_derefs : ElaborateBoxDerefs;
@@ -771,8 +767,6 @@ pub(crate) fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'
             // Cleanup for human readability, off by default.
             &prettify::ReorderBasicBlocks,
             &prettify::ReorderLocals,
-            // Dump the end result for testing and debugging purposes.
-            &dump_mir::Marker("PreCodegen"),
         ],
         Some(MirPhase::Runtime(RuntimePhase::Optimized)),
         optimizations,

diff --git a/...-patterns/string.foo.PreCodegen.after.mir → ...ns/string.foo.runtime-optimized.after.mir b/...-patterns/string.foo.PreCodegen.after.mir → ...ns/string.foo.runtime-optimized.after.mir
@@ -1,4 +1,4 @@
-// MIR for `foo` after PreCodegen
+// MIR for `foo` after runtime-optimized
 
 fn foo(_1: Option<String>) -> i32 {
     debug s => _1;

diff --git a/tests/mir-opt/building/match/deref-patterns/string.rs b/tests/mir-opt/building/match/deref-patterns/string.rs
@@ -4,7 +4,7 @@
 #![feature(deref_patterns)]
 #![crate_type = "lib"]
 
-// EMIT_MIR string.foo.PreCodegen.after.mir
+// EMIT_MIR string.foo.runtime-optimized.after.mir
 pub fn foo(s: Option<String>) -> i32 {
     match s {
         Some("a") => 1234,

diff --git a/tests/mir-opt/building/while_storage.rs b/tests/mir-opt/building/while_storage.rs
@@ -7,7 +7,7 @@ fn get_bool(c: bool) -> bool {
     c
 }
 
-// EMIT_MIR while_storage.while_loop.PreCodegen.after.mir
+// EMIT_MIR while_storage.while_loop.runtime-optimized.after.mir
 fn while_loop(c: bool) {
     // CHECK-LABEL: fn while_loop(
     // CHECK: bb0: {

diff --git a/...ile_loop.PreCodegen.after.panic-abort.mir → ...p.runtime-optimized.after.panic-abort.mir b/...ile_loop.PreCodegen.after.panic-abort.mir → ...p.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `while_loop` after PreCodegen
+// MIR for `while_loop` after runtime-optimized
 
 fn while_loop(_1: bool) -> () {
     debug c => _1;

diff --git a/...le_loop.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...le_loop.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `while_loop` after PreCodegen
+// MIR for `while_loop` after runtime-optimized
 
 fn while_loop(_1: bool) -> () {
     debug c => _1;

diff --git a/...n.hello.PreCodegen.before.panic-abort.mir → ...o.runtime-optimized.after.panic-abort.mir b/...n.hello.PreCodegen.before.panic-abort.mir → ...o.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `hello` before PreCodegen
+// MIR for `hello` after runtime-optimized
 
 fn hello() -> () {
     let mut _0: ();

diff --git a/....hello.PreCodegen.before.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/....hello.PreCodegen.before.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `hello` before PreCodegen
+// MIR for `hello` after runtime-optimized
 
 fn hello() -> () {
     let mut _0: ();

diff --git a/tests/mir-opt/const_prop/control_flow_simplification.rs b/tests/mir-opt/const_prop/control_flow_simplification.rs
@@ -9,7 +9,7 @@ trait NeedsDrop: Sized {
 impl<This> NeedsDrop for This {}
 
 // EMIT_MIR control_flow_simplification.hello.GVN.diff
-// EMIT_MIR control_flow_simplification.hello.PreCodegen.before.mir
+// EMIT_MIR control_flow_simplification.hello.runtime-optimized.after.mir
 fn hello<T>() {
     // CHECK-LABEL: fn hello(
     // CHECK: bb0:

diff --git a/...ace.add.PreCodegen.before.panic-abort.mir → ...d.runtime-optimized.after.panic-abort.mir b/...ace.add.PreCodegen.before.panic-abort.mir → ...d.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `add` before PreCodegen
+// MIR for `add` after runtime-optimized
 
 fn add() -> u32 {
     let mut _0: u32;

diff --git a/...ce.add.PreCodegen.before.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...ce.add.PreCodegen.before.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `add` before PreCodegen
+// MIR for `add` after runtime-optimized
 
 fn add() -> u32 {
     let mut _0: u32;

diff --git a/tests/mir-opt/const_prop/return_place.rs b/tests/mir-opt/const_prop/return_place.rs
@@ -3,7 +3,7 @@
 //@ compile-flags: -C overflow-checks=on -Zdump-mir-exclude-alloc-bytes
 
 // EMIT_MIR return_place.add.GVN.diff
-// EMIT_MIR return_place.add.PreCodegen.before.mir
+// EMIT_MIR return_place.add.runtime-optimized.after.mir
 fn add() -> u32 {
     // CHECK-LABEL: fn add(
     // CHECK: _0 = const 4_u32;

diff --git a/...e.caller.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir b/...e.caller.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `caller` after PreCodegen
+// MIR for `caller` after runtime-optimized
 
 fn caller() -> () {
     let mut _0: ();

diff --git a/....caller.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/....caller.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `caller` after PreCodegen
+// MIR for `caller` after runtime-optimized
 
 fn caller() -> () {
     let mut _0: ();

diff --git a/tests/mir-opt/inline/rustc_no_mir_inline.rs b/tests/mir-opt/inline/rustc_no_mir_inline.rs
@@ -9,7 +9,7 @@
 pub fn callee() {}
 
 // EMIT_MIR rustc_no_mir_inline.caller.Inline.diff
-// EMIT_MIR rustc_no_mir_inline.caller.PreCodegen.after.mir
+// EMIT_MIR rustc_no_mir_inline.caller.runtime-optimized.after.mir
 pub fn caller() {
     // CHECK-LABEL: fn caller(
     // CHECK: callee()

diff --git a/tests/mir-opt/inline/unchecked_shifts.rs b/tests/mir-opt/inline/unchecked_shifts.rs
@@ -7,15 +7,15 @@
 // After MCP#693, though, that's the backend's problem, not something in MIR.
 
 // EMIT_MIR unchecked_shifts.unchecked_shl_unsigned_smaller.Inline.diff
-// EMIT_MIR unchecked_shifts.unchecked_shl_unsigned_smaller.PreCodegen.after.mir
+// EMIT_MIR unchecked_shifts.unchecked_shl_unsigned_smaller.runtime-optimized.after.mir
 pub unsafe fn unchecked_shl_unsigned_smaller(a: u16, b: u32) -> u16 {
     // CHECK-LABEL: fn unchecked_shl_unsigned_smaller(
     // CHECK: (inlined #[track_caller] core::num::<impl u16>::unchecked_shl)
     a.unchecked_shl(b)
 }
 
 // EMIT_MIR unchecked_shifts.unchecked_shr_signed_bigger.Inline.diff
-// EMIT_MIR unchecked_shifts.unchecked_shr_signed_bigger.PreCodegen.after.mir
+// EMIT_MIR unchecked_shifts.unchecked_shr_signed_bigger.runtime-optimized.after.mir
 pub unsafe fn unchecked_shr_signed_bigger(a: i64, b: u32) -> i64 {
     // CHECK-LABEL: fn unchecked_shr_signed_bigger(
     // CHECK: (inlined #[track_caller] core::num::<impl i64>::unchecked_shr)

diff --git a/..._smaller.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir b/..._smaller.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `unchecked_shl_unsigned_smaller` after PreCodegen
+// MIR for `unchecked_shl_unsigned_smaller` after runtime-optimized
 
 fn unchecked_shl_unsigned_smaller(_1: u16, _2: u32) -> u16 {
     debug a => _1;

diff --git a/...smaller.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...smaller.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `unchecked_shl_unsigned_smaller` after PreCodegen
+// MIR for `unchecked_shl_unsigned_smaller` after runtime-optimized
 
 fn unchecked_shl_unsigned_smaller(_1: u16, _2: u32) -> u16 {
     debug a => _1;

diff --git a/...d_bigger.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir b/...d_bigger.PreCodegen.after.panic-abort.mir → ...r.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `unchecked_shr_signed_bigger` after PreCodegen
+// MIR for `unchecked_shr_signed_bigger` after runtime-optimized
 
 fn unchecked_shr_signed_bigger(_1: i64, _2: u32) -> i64 {
     debug a => _1;

diff --git a/..._bigger.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/..._bigger.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `unchecked_shr_signed_bigger` after PreCodegen
+// MIR for `unchecked_shr_signed_bigger` after runtime-optimized
 
 fn unchecked_shr_signed_bigger(_1: i64, _2: u32) -> i64 {
     debug a => _1;

diff --git a/tests/mir-opt/inline/unwrap_unchecked.rs b/tests/mir-opt/inline/unwrap_unchecked.rs
@@ -4,7 +4,7 @@
 //@ compile-flags: -Zmir-opt-level=2 -Zinline-mir
 
 // EMIT_MIR unwrap_unchecked.unwrap_unchecked.Inline.diff
-// EMIT_MIR unwrap_unchecked.unwrap_unchecked.PreCodegen.after.mir
+// EMIT_MIR unwrap_unchecked.unwrap_unchecked.runtime-optimized.after.mir
 pub unsafe fn unwrap_unchecked<T>(slf: Option<T>) -> T {
     // CHECK-LABEL: fn unwrap_unchecked(
     // CHECK: (inlined #[track_caller] Option::<T>::unwrap_unchecked)

diff --git a/...nchecked.PreCodegen.after.panic-abort.mir → ...d.runtime-optimized.after.panic-abort.mir b/...nchecked.PreCodegen.after.panic-abort.mir → ...d.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `unwrap_unchecked` after PreCodegen
+// MIR for `unwrap_unchecked` after runtime-optimized
 
 fn unwrap_unchecked(_1: Option<T>) -> T {
     debug slf => _1;

diff --git a/...checked.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...checked.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `unwrap_unchecked` after PreCodegen
+// MIR for `unwrap_unchecked` after runtime-optimized
 
 fn unwrap_unchecked(_1: Option<T>) -> T {
     debug slf => _1;

diff --git a/...it.PreCodegen.after.32bit.panic-abort.mir → ...ime-optimized.after.32bit.panic-abort.mir b/...it.PreCodegen.after.32bit.panic-abort.mir → ...ime-optimized.after.32bit.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `num_to_digit` after PreCodegen
+// MIR for `num_to_digit` after runtime-optimized
 
 fn num_to_digit(_1: char) -> u32 {
     debug num => _1;

diff --git a/...t.PreCodegen.after.32bit.panic-unwind.mir → ...me-optimized.after.32bit.panic-unwind.mir b/...t.PreCodegen.after.32bit.panic-unwind.mir → ...me-optimized.after.32bit.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `num_to_digit` after PreCodegen
+// MIR for `num_to_digit` after runtime-optimized
 
 fn num_to_digit(_1: char) -> u32 {
     debug num => _1;

diff --git a/...it.PreCodegen.after.64bit.panic-abort.mir → ...ime-optimized.after.64bit.panic-abort.mir b/...it.PreCodegen.after.64bit.panic-abort.mir → ...ime-optimized.after.64bit.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `num_to_digit` after PreCodegen
+// MIR for `num_to_digit` after runtime-optimized
 
 fn num_to_digit(_1: char) -> u32 {
     debug num => _1;

diff --git a/...t.PreCodegen.after.64bit.panic-unwind.mir → ...me-optimized.after.64bit.panic-unwind.mir b/...t.PreCodegen.after.64bit.panic-unwind.mir → ...me-optimized.after.64bit.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `num_to_digit` after PreCodegen
+// MIR for `num_to_digit` after runtime-optimized
 
 fn num_to_digit(_1: char) -> u32 {
     debug num => _1;

diff --git a/tests/mir-opt/issues/issue_59352.rs b/tests/mir-opt/issues/issue_59352.rs
@@ -9,7 +9,7 @@
 // Once the optimizer can do that, this test case will need to be updated and codegen/issue-59352.rs
 // removed.
 
-// EMIT_MIR issue_59352.num_to_digit.PreCodegen.after.mir
+// EMIT_MIR issue_59352.num_to_digit.runtime-optimized.after.mir
 //@ compile-flags: -Z mir-opt-level=3 -Z span_free_formats
 
 pub fn num_to_digit(num: char) -> u32 {

diff --git a/...t/pattern_types.main.PreCodegen.after.mir → ...rn_types.main.runtime-optimized.after.mir b/...t/pattern_types.main.PreCodegen.after.mir → ...rn_types.main.runtime-optimized.after.mir
@@ -1,4 +1,4 @@
-// MIR for `main` after PreCodegen
+// MIR for `main` after runtime-optimized
 
 fn main() -> () {
     let mut _0: ();

diff --git a/tests/mir-opt/pattern_types.rs b/tests/mir-opt/pattern_types.rs
@@ -3,7 +3,7 @@
 
 use std::pat::pattern_type;
 
-// EMIT_MIR pattern_types.main.PreCodegen.after.mir
+// EMIT_MIR pattern_types.main.runtime-optimized.after.mir
 fn main() {
     // CHECK: debug x => const 2_u32 is 1..
     let x: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(2) };

diff --git a/....eq_ipv4.PreCodegen.after.panic-abort.mir → ...4.runtime-optimized.after.panic-abort.mir b/....eq_ipv4.PreCodegen.after.panic-abort.mir → ...4.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_ipv4` after PreCodegen
+// MIR for `eq_ipv4` after runtime-optimized
 
 fn eq_ipv4(_1: &[u8; 4], _2: &[u8; 4]) -> bool {
     debug a => _1;

diff --git a/...eq_ipv4.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...eq_ipv4.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_ipv4` after PreCodegen
+// MIR for `eq_ipv4` after runtime-optimized
 
 fn eq_ipv4(_1: &[u8; 4], _2: &[u8; 4]) -> bool {
     debug a => _1;

diff --git a/....eq_ipv6.PreCodegen.after.panic-abort.mir → ...6.runtime-optimized.after.panic-abort.mir b/....eq_ipv6.PreCodegen.after.panic-abort.mir → ...6.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_ipv6` after PreCodegen
+// MIR for `eq_ipv6` after runtime-optimized
 
 fn eq_ipv6(_1: &[u16; 8], _2: &[u16; 8]) -> bool {
     debug a => _1;

diff --git a/...eq_ipv6.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/...eq_ipv6.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_ipv6` after PreCodegen
+// MIR for `eq_ipv6` after runtime-optimized
 
 fn eq_ipv6(_1: &[u16; 8], _2: &[u16; 8]) -> bool {
     debug a => _1;

diff --git a/...d_length.PreCodegen.after.panic-abort.mir → ...h.runtime-optimized.after.panic-abort.mir b/...d_length.PreCodegen.after.panic-abort.mir → ...h.runtime-optimized.after.panic-abort.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_odd_length` after PreCodegen
+// MIR for `eq_odd_length` after runtime-optimized
 
 fn eq_odd_length(_1: &[u8; 3], _2: &[u8; 3]) -> bool {
     debug a => _1;

diff --git a/..._length.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir b/..._length.PreCodegen.after.panic-unwind.mir → ....runtime-optimized.after.panic-unwind.mir
@@ -1,4 +1,4 @@
-// MIR for `eq_odd_length` after PreCodegen
+// MIR for `eq_odd_length` after runtime-optimized
 
 fn eq_odd_length(_1: &[u8; 3], _2: &[u8; 3]) -> bool {
     debug a => _1;