Auto merge of #164077 - adwinwhite:phase-hack, r=<try>

replace `TypingEnv::post_analysis()` with `mir::Body::typing_env()`

Author: bors

compiler/rustc_middle/src/mir/mod.rs

@@ -200,6 +200,21 @@ pub enum MentionedItem<'tcx> {
     Closure(Ty<'tcx>),
 }
 
+/// Track what typing mode a MIR body should use at current stage.
+/// A MIR body usually starts with `PostTypeckThroughBorrowck`. After borrowck is done, it's set
+/// to `PostBorrowck`. In `PostAnalysisNormalize` pass, we reveal all opaques types and set the
+/// typing mode to `PostAnalysis`.
+///
+/// We can't directly use `ty::TypingMode` since it's not `TyEncodable/TyDecodable`.
+/// Previously we use MIR phase to derive this but it's inaccurate.
+#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(TyEncodable, TyDecodable, StableHash, TypeFoldable, TypeVisitable)]
+pub enum BodyTypingMode {
+    PostTypeckThroughBorrowck,
+    PostBorrowck,
+    PostAnalysis,
+}
+
 /// The lowered representation of a single function.
 #[derive(Clone, TyEncodable, TyDecodable, Debug, StableHash, TypeFoldable, TypeVisitable)]
 pub struct Body<'tcx> {
@@ -214,6 +229,9 @@ pub struct Body<'tcx> {
     /// us to see the difference and forego optimization on the inlined promoted items.
     pub phase: MirPhase,
 
+    /// See [`BodyTypingMode`] for more info.
+    pub typing_mode: BodyTypingMode,
+
     /// How many passes we have executed since starting the current phase. Used for debug output.
     pub pass_count: usize,
 
@@ -352,6 +370,7 @@ impl<'tcx> Body<'tcx> {
 
         let mut body = Body {
             phase: MirPhase::Built,
+            typing_mode: BodyTypingMode::PostTypeckThroughBorrowck,
             pass_count: 0,
             source,
             basic_blocks: BasicBlocks::new(basic_blocks),
@@ -383,6 +402,7 @@ impl<'tcx> Body<'tcx> {
     pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
         let mut body = Body {
             phase: MirPhase::Built,
+            typing_mode: BodyTypingMode::PostTypeckThroughBorrowck,
             pass_count: 0,
             source: MirSource::item(CRATE_DEF_ID.to_def_id()),
             basic_blocks: BasicBlocks::new(basic_blocks),
@@ -413,38 +433,35 @@ impl<'tcx> Body<'tcx> {
 
     pub fn typing_env(&self, tcx: TyCtxt<'tcx>) -> TypingEnv<'tcx> {
         if tcx.use_typing_mode_post_typeck_through_borrowck() {
-            match self.phase {
-                MirPhase::Built | MirPhase::Analysis(AnalysisPhase::Initial)
-                    if let Some(def_id) = self.source.def_id().as_local() =>
-                {
+            match self.typing_mode {
+                BodyTypingMode::PostTypeckThroughBorrowck => {
+                    let local_def_id =
+                        self.source.def_id().as_local().expect("We only build MIR for local body");
                     TypingEnv::new(
                         tcx.param_env(self.source.def_id()),
-                        ty::TypingMode::borrowck(tcx, def_id),
+                        ty::TypingMode::borrowck(tcx, local_def_id),
                     )
                 }
-                MirPhase::Analysis(AnalysisPhase::PostCleanup)
-                    if let Some(def_id) = self.source.def_id().as_local() =>
-                {
+                BodyTypingMode::PostBorrowck => {
+                    let local_def_id =
+                        self.source.def_id().as_local().expect("We only build MIR for local body");
                     TypingEnv::new(
                         tcx.param_env(self.source.def_id()),
-                        ty::TypingMode::post_borrowck_analysis(tcx, def_id),
+                        ty::TypingMode::post_borrowck_analysis(tcx, local_def_id),
                     )
                 }
-                MirPhase::Built | MirPhase::Analysis(_) => {
-                    // This branch happens for drop glue and fn ptr shims.
-                    // FIXME: why do we do any of this analysis on drop glue etc?
-                    // This should ideally all be skipped.
-                    TypingEnv::post_analysis(tcx, self.source.def_id())
-                }
-                MirPhase::Runtime(_) => TypingEnv::post_analysis(tcx, self.source.def_id()),
+                // We build shims like `drop_in_place` in post analysis typing mode.
+                BodyTypingMode::PostAnalysis => TypingEnv::post_analysis(tcx, self.source.def_id()),
             }
         } else {
-            match self.phase {
-                MirPhase::Built | MirPhase::Analysis(_) => TypingEnv::new(
-                    tcx.param_env(self.source.def_id()),
-                    ty::TypingMode::non_body_analysis(),
-                ),
-                MirPhase::Runtime(_) => TypingEnv::post_analysis(tcx, self.source.def_id()),
+            match self.typing_mode {
+                BodyTypingMode::PostTypeckThroughBorrowck | BodyTypingMode::PostBorrowck => {
+                    TypingEnv::new(
+                        tcx.param_env(self.source.def_id()),
+                        ty::TypingMode::non_body_analysis(),
+                    )
+                }
+                BodyTypingMode::PostAnalysis => TypingEnv::post_analysis(tcx, self.source.def_id()),
             }
         }
     }

compiler/rustc_mir_build/src/builder/custom/mod.rs

@@ -45,6 +45,7 @@ pub(super) fn build_custom_mir<'tcx>(
         basic_blocks: BasicBlocks::new(IndexVec::new()),
         source: MirSource::item(did),
         phase: MirPhase::Built,
+        typing_mode: BodyTypingMode::PostTypeckThroughBorrowck,
         source_scopes: IndexVec::new(),
         coroutine: None,
         local_decls: IndexVec::new(),
@@ -73,6 +74,9 @@ pub(super) fn build_custom_mir<'tcx>(
         local_data: ClearCrossCrate::Set(SourceScopeLocalData { lint_root: hir_id }),
     });
     body.injection_phase = Some(parse_attribute(dialect, phase));
+    if let Some(MirPhase::Runtime(_)) = body.injection_phase {
+        body.typing_mode = BodyTypingMode::PostAnalysis;
+    }
 
     let mut pctxt = ParseCtxt {
         tcx,

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -1,5 +1,5 @@
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::TyCtxt;
 use tracing::debug;
 
 use crate::patch::MirPatch;
@@ -41,9 +41,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddMovesForPackedDrops {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!("add_moves_for_packed_drops({:?} @ {:?})", body.source, body.span);
         let mut patch = MirPatch::new(body);
-        // FIXME(#132279): This is used during the phase transition from analysis
-        // to runtime, so we have to manually specify the correct typing mode.
-        let typing_env = ty::TypingEnv::post_analysis(tcx, body.source.def_id());
+        let typing_env = body.typing_env(tcx);
 
         for (bb, data) in body.basic_blocks.iter_enumerated() {
             let loc = Location { block: bb, statement_index: data.statements.len() };

compiler/rustc_mir_transform/src/elaborate_drops.rs

@@ -52,9 +52,7 @@ impl<'tcx> crate::MirPass<'tcx> for ElaborateDrops {
     #[instrument(level = "trace", skip(self, tcx, body))]
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!("elaborate_drops({:?} @ {:?})", body.source, body.span);
-        // FIXME(#132279): This is used during the phase transition from analysis
-        // to runtime, so we have to manually specify the correct typing mode.
-        let typing_env = ty::TypingEnv::post_analysis(tcx, body.source.def_id());
+        let typing_env = body.typing_env(tcx);
         // For types that do not need dropping, the behaviour is trivial. So we only need to track
         // init/uninit for types that do need dropping.
         let move_data = MoveData::gather_moves(body, tcx, |ty| ty.needs_drop(tcx, typing_env));

compiler/rustc_mir_transform/src/known_panics_lint.rs

@@ -181,9 +181,7 @@ impl<'tcx> ty::layout::HasTypingEnv<'tcx> for ConstPropagator<'_, 'tcx> {
 impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     fn new(body: &'mir Body<'tcx>, tcx: TyCtxt<'tcx>) -> ConstPropagator<'mir, 'tcx> {
         let def_id = body.source.def_id();
-        // FIXME(#132279): This is used during the phase transition from analysis
-        // to runtime, so we have to manually specify the correct typing mode.
-        let typing_env = ty::TypingEnv::post_analysis(tcx, body.source.def_id());
+        let typing_env = body.typing_env(tcx);
         let can_const_prop = CanConstProp::check(tcx, typing_env, body);
         let ecx = InterpCx::new(tcx, tcx.def_span(def_id), typing_env, DummyMachine);
 

compiler/rustc_mir_transform/src/lib.rs

@@ -20,9 +20,9 @@ use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::IndexVec;
 use rustc_middle::mir::{
-    AnalysisPhase, Body, CallSource, ClearCrossCrate, ConstOperand, ConstQualifs, LocalDecl,
-    MirPhase, Operand, Place, ProjectionElem, Promoted, RuntimePhase, Rvalue, START_BLOCK,
-    SourceInfo, Statement, StatementKind, TerminatorKind, WithRetag,
+    AnalysisPhase, Body, BodyTypingMode, CallSource, ClearCrossCrate, ConstOperand, ConstQualifs,
+    LocalDecl, MirPhase, Operand, Place, ProjectionElem, Promoted, RuntimePhase, Rvalue,
+    START_BLOCK, SourceInfo, Statement, StatementKind, TerminatorKind, WithRetag,
 };
 use rustc_middle::query;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
@@ -598,6 +598,7 @@ fn mir_drops_elaborated_and_const_checked(tcx: TyCtxt<'_>, def: LocalDefId) -> &
         _ => {}
     }
 
+    body.typing_mode = BodyTypingMode::PostBorrowck;
     run_analysis_to_runtime_passes(tcx, &mut body);
 
     tcx.alloc_steal_mir(body)
@@ -606,12 +607,13 @@ fn mir_drops_elaborated_and_const_checked(tcx: TyCtxt<'_>, def: LocalDefId) -> &
 // Made public so that `mir_drops_elaborated_and_const_checked` can be overridden
 // by custom rustc drivers, running all the steps by themselves. See #114628.
 pub fn run_analysis_to_runtime_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-    assert!(body.phase == MirPhase::Analysis(AnalysisPhase::Initial));
+    assert_eq!(body.typing_mode, BodyTypingMode::PostBorrowck);
+    assert_eq!(body.phase, MirPhase::Analysis(AnalysisPhase::Initial));
     let did = body.source.def_id();
 
     debug!("analysis_mir_cleanup({:?})", did);
     run_analysis_cleanup_passes(tcx, body);
-    assert!(body.phase == MirPhase::Analysis(AnalysisPhase::PostCleanup));
+    assert_eq!(body.phase, MirPhase::Analysis(AnalysisPhase::PostCleanup));
 
     // Do a little drop elaboration before const-checking if `const_precise_live_drops` is enabled.
     if check_consts::post_drop_elaboration::checking_enabled(&ConstCx::new(tcx, body)) {
@@ -629,11 +631,12 @@ pub fn run_analysis_to_runtime_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'
 
     debug!("runtime_mir_lowering({:?})", did);
     run_runtime_lowering_passes(tcx, body);
-    assert!(body.phase == MirPhase::Runtime(RuntimePhase::Initial));
+    assert_eq!(body.phase, MirPhase::Runtime(RuntimePhase::Initial));
 
     debug!("runtime_mir_cleanup({:?})", did);
     run_runtime_cleanup_passes(tcx, body);
-    assert!(body.phase == MirPhase::Runtime(RuntimePhase::PostCleanup));
+    assert_eq!(body.typing_mode, BodyTypingMode::PostAnalysis);
+    assert_eq!(body.phase, MirPhase::Runtime(RuntimePhase::PostCleanup));
 }
 
 // FIXME(JakobDegen): Can we make these lists of passes consts?
@@ -848,6 +851,7 @@ fn promoted_mir(tcx: TyCtxt<'_>, def: LocalDefId) -> &IndexVec<Promoted, Body<'_
     let mut promoted = tcx.mir_promoted(def).1.steal();
 
     for body in &mut promoted {
+        body.typing_mode = BodyTypingMode::PostBorrowck;
         run_analysis_to_runtime_passes(tcx, body);
     }
 

compiler/rustc_mir_transform/src/pass_manager.rs

@@ -5,7 +5,7 @@ use std::sync::atomic::Ordering;
 use rustc_attr_ir::OptimizeAttr;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_hir::def_id::DefId;
-use rustc_middle::mir::{Body, MirDumper, MirPhase, RuntimePhase};
+use rustc_middle::mir::{Body, BodyTypingMode, MirDumper, MirPhase, RuntimePhase};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_session::config::OptLevel;
@@ -388,6 +388,26 @@ fn run_passes_inner<'tcx>(
             panic!("Invalid MIR phase transition from {:?} to {:?}", body.phase, new_phase);
         }
 
+        // Custom MIR can skip analysis-to-runtime lowering where we update
+        // the typing mode for normal MIR body.
+        //
+        // FIXME: it's ugly that we set the typing mode of custom MIR in the
+        // runtime phase to `PostBorrowck` after borrowck and then back to
+        // `PostAnalysis` here.
+        if matches!(body.injection_phase, Some(MirPhase::Runtime(_)))
+            && matches!(new_phase, MirPhase::Runtime(_))
+        {
+            body.typing_mode = BodyTypingMode::PostAnalysis;
+        }
+
+        // We perform type mode transitions in MIR transform. But some bodies don't actually
+        // undergo analysis-to-runtime lowering, such as shims and sometimes custom MIR.
+        // We try to guard against future MIR building procedures that don't go through the usual
+        // lowering. The final validation is expected to run in `TypingMode::PostAnalysis`.
+        if new_phase == MirPhase::Runtime(RuntimePhase::Optimized) {
+            assert_eq!(body.typing_mode, BodyTypingMode::PostAnalysis);
+        }
+
         body.phase = new_phase;
         body.pass_count = 0;
 

compiler/rustc_mir_transform/src/post_analysis_normalize.rs

@@ -12,9 +12,8 @@ pub(super) struct PostAnalysisNormalize;
 
 impl<'tcx> crate::MirPass<'tcx> for PostAnalysisNormalize {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        // FIXME(#132279): This is used during the phase transition from analysis
-        // to runtime, so we have to manually specify the correct typing mode.
-        let typing_env = ty::TypingEnv::post_analysis(tcx, body.source.def_id());
+        body.typing_mode = BodyTypingMode::PostAnalysis;
+        let typing_env = body.typing_env(tcx);
         PostAnalysisNormalizeVisitor { tcx, typing_env }.visit_body_preserves_cfg(body);
     }
 

compiler/rustc_mir_transform/src/shim.rs

@@ -402,6 +402,8 @@ fn new_body<'tcx>(
     );
     // Shims do not directly mention any consts.
     body.set_required_consts(Vec::new());
+    // We don't do any analysis on shims.
+    body.typing_mode = BodyTypingMode::PostAnalysis;
     body
 }