Split phase change from MirPass

compiler/rustc_middle/src/mir/mod.rs

@@ -116,11 +116,6 @@ pub trait MirPass<'tcx> {
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
 
-    /// If this pass causes the MIR to enter a new phase, return that phase.
-    fn phase_change(&self) -> Option<MirPhase> {
-        None
-    }
-
     fn is_mir_dump_enabled(&self) -> bool {
         true
     }
@@ -145,6 +140,35 @@ impl MirPhase {
     }
 }
 
+impl Display for MirPhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            MirPhase::Built => write!(f, "built"),
+            MirPhase::Analysis(p) => write!(f, "analysis-{}", p),
+            MirPhase::Runtime(p) => write!(f, "runtime-{}", p),
+        }
+    }
+}
+
+impl Display for AnalysisPhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            AnalysisPhase::Initial => write!(f, "initial"),
+            AnalysisPhase::PostCleanup => write!(f, "post_cleanup"),
+        }
+    }
+}
+
+impl Display for RuntimePhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            RuntimePhase::Initial => write!(f, "initial"),
+            RuntimePhase::PostCleanup => write!(f, "post_cleanup"),
+            RuntimePhase::Optimized => write!(f, "optimized"),
+        }
+    }
+}
+
 /// Where a specific `mir::Body` comes from.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
@@ -207,6 +231,9 @@ pub struct Body<'tcx> {
     /// us to see the difference and forego optimization on the inlined promoted items.
     pub phase: MirPhase,
 
+    /// How many passses we have executed since starting the current phase. Used for debug output.
+    pub pass_count: usize,
+
     pub source: MirSource<'tcx>,
 
     /// A list of source scopes; these are referenced by statements
@@ -292,6 +319,7 @@ impl<'tcx> Body<'tcx> {
 
         let mut body = Body {
             phase: MirPhase::Built,
+            pass_count: 1,
             source,
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes,
@@ -325,6 +353,7 @@ impl<'tcx> Body<'tcx> {
     pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
         let mut body = Body {
             phase: MirPhase::Built,
+            pass_count: 1,
             source: MirSource::item(CRATE_DEF_ID.to_def_id()),
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes: IndexVec::new(),