Rollup merge of rust-lang#129929 - nnethercote:rustc_mir_transform-cleanups-2, r=cjgillot

`rustc_mir_transform` cleanups, round 2

More cleanups in the style of rust-lang#129738.

r? `@cjgillot`

Author: matthiaskrgr

compiler/rustc_mir_transform/src/abort_unwinding_calls.rs

@@ -20,7 +20,7 @@ use rustc_target::spec::PanicStrategy;
 /// This forces all unwinds, in panic=abort mode happening in foreign code, to
 /// trigger a process abort.
 #[derive(PartialEq)]
-pub struct AbortUnwindingCalls;
+pub(super) struct AbortUnwindingCalls;
 
 impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
@@ -50,9 +50,7 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
         // with a function call, and whose function we're calling may unwind.
         // This will filter to functions with `extern "C-unwind"` ABIs, for
         // example.
-        let mut calls_to_terminate = Vec::new();
-        let mut cleanups_to_remove = Vec::new();
-        for (id, block) in body.basic_blocks.iter_enumerated() {
+        for block in body.basic_blocks.as_mut() {
             if block.is_cleanup {
                 continue;
             }
@@ -61,7 +59,7 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
 
             let call_can_unwind = match &terminator.kind {
                 TerminatorKind::Call { func, .. } => {
-                    let ty = func.ty(body, tcx);
+                    let ty = func.ty(&body.local_decls, tcx);
                     let sig = ty.fn_sig(tcx);
                     let fn_def_id = match ty.kind() {
                         ty::FnPtr(..) => None,
@@ -86,33 +84,22 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
                 _ => continue,
             };
 
-            // If this function call can't unwind, then there's no need for it
-            // to have a landing pad. This means that we can remove any cleanup
-            // registered for it.
             if !call_can_unwind {
-                cleanups_to_remove.push(id);
-                continue;
-            }
-
-            // Otherwise if this function can unwind, then if the outer function
-            // can also unwind there's nothing to do. If the outer function
-            // can't unwind, however, we need to change the landing pad for this
-            // function call to one that aborts.
-            if !body_can_unwind {
-                calls_to_terminate.push(id);
+                // If this function call can't unwind, then there's no need for it
+                // to have a landing pad. This means that we can remove any cleanup
+                // registered for it.
+                let cleanup = block.terminator_mut().unwind_mut().unwrap();
+                *cleanup = UnwindAction::Unreachable;
+            } else if !body_can_unwind {
+                // Otherwise if this function can unwind, then if the outer function
+                // can also unwind there's nothing to do. If the outer function
+                // can't unwind, however, we need to change the landing pad for this
+                // function call to one that aborts.
+                let cleanup = block.terminator_mut().unwind_mut().unwrap();
+                *cleanup = UnwindAction::Terminate(UnwindTerminateReason::Abi);
             }
         }
 
-        for id in calls_to_terminate {
-            let cleanup = body.basic_blocks_mut()[id].terminator_mut().unwind_mut().unwrap();
-            *cleanup = UnwindAction::Terminate(UnwindTerminateReason::Abi);
-        }
-
-        for id in cleanups_to_remove {
-            let cleanup = body.basic_blocks_mut()[id].terminator_mut().unwind_mut().unwrap();
-            *cleanup = UnwindAction::Unreachable;
-        }
-
         // We may have invalidated some `cleanup` blocks so clean those up now.
         super::simplify::remove_dead_blocks(body);
     }

compiler/rustc_mir_transform/src/add_call_guards.rs

@@ -4,11 +4,11 @@ use rustc_middle::ty::TyCtxt;
 use tracing::debug;
 
 #[derive(PartialEq)]
-pub enum AddCallGuards {
+pub(super) enum AddCallGuards {
     AllCallEdges,
     CriticalCallEdges,
 }
-pub use self::AddCallGuards::*;
+pub(super) use self::AddCallGuards::*;
 
 /**
  * Breaks outgoing critical edges for call terminators in the MIR.
@@ -37,7 +37,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {
 }
 
 impl AddCallGuards {
-    pub fn add_call_guards(&self, body: &mut Body<'_>) {
+    pub(super) fn add_call_guards(&self, body: &mut Body<'_>) {
         let mut pred_count: IndexVec<_, _> =
             body.basic_blocks.predecessors().iter().map(|ps| ps.len()).collect();
         pred_count[START_BLOCK] += 1;

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -35,7 +35,7 @@ use crate::util;
 ///
 /// The storage instructions are required to avoid stack space
 /// blowup.
-pub struct AddMovesForPackedDrops;
+pub(super) struct AddMovesForPackedDrops;
 
 impl<'tcx> crate::MirPass<'tcx> for AddMovesForPackedDrops {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
@@ -44,7 +44,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddMovesForPackedDrops {
     }
 }
 
-pub fn add_moves_for_packed_drops<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+fn add_moves_for_packed_drops<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let patch = add_moves_for_packed_drops_patch(tcx, body);
     patch.apply(body);
 }

compiler/rustc_mir_transform/src/add_retag.rs

@@ -8,7 +8,7 @@ use rustc_hir::LangItem;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
-pub struct AddRetag;
+pub(super) struct AddRetag;
 
 /// Determine whether this type may contain a reference (or box), and thus needs retagging.
 /// We will only recurse `depth` times into Tuples/ADTs to bound the cost of this.

compiler/rustc_mir_transform/src/add_subtyping_projections.rs

@@ -1,15 +1,14 @@
-use rustc_index::IndexVec;
 use rustc_middle::mir::patch::MirPatch;
 use rustc_middle::mir::visit::MutVisitor;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 
-pub struct Subtyper;
+pub(super) struct Subtyper;
 
-pub struct SubTypeChecker<'a, 'tcx> {
+struct SubTypeChecker<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     patcher: MirPatch<'tcx>,
-    local_decls: &'a IndexVec<Local, LocalDecl<'tcx>>,
+    local_decls: &'a LocalDecls<'tcx>,
 }
 
 impl<'a, 'tcx> MutVisitor<'tcx> for SubTypeChecker<'a, 'tcx> {
@@ -52,7 +51,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for SubTypeChecker<'a, 'tcx> {
 // // gets transformed to
 // let temp: rval_ty = rval;
 // let place: place_ty = temp as place_ty;
-pub fn subtype_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+fn subtype_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let patch = MirPatch::new(body);
     let mut checker = SubTypeChecker { tcx, patcher: patch, local_decls: &body.local_decls };
 

compiler/rustc_mir_transform/src/check_alignment.rs

@@ -7,7 +7,7 @@ use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt};
 use rustc_session::Session;
 use tracing::{debug, trace};
 
-pub struct CheckAlignment;
+pub(super) struct CheckAlignment;
 
 impl<'tcx> crate::MirPass<'tcx> for CheckAlignment {
     fn is_enabled(&self, sess: &Session) -> bool {

compiler/rustc_mir_transform/src/check_const_item_mutation.rs

@@ -8,7 +8,7 @@ use rustc_span::Span;
 
 use crate::errors;
 
-pub struct CheckConstItemMutation;
+pub(super) struct CheckConstItemMutation;
 
 impl<'tcx> crate::MirLint<'tcx> for CheckConstItemMutation {
     fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -5,7 +5,7 @@ use rustc_middle::ty::{self, TyCtxt};
 
 use crate::{errors, util};
 
-pub struct CheckPackedRef;
+pub(super) struct CheckPackedRef;
 
 impl<'tcx> crate::MirLint<'tcx> for CheckPackedRef {
     fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {

compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs

@@ -21,7 +21,7 @@ use rustc_middle::mir::{Body, BorrowKind, CastKind, Rvalue, StatementKind, Termi
 use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::TyCtxt;
 
-pub struct CleanupPostBorrowck;
+pub(super) struct CleanupPostBorrowck;
 
 impl<'tcx> crate::MirPass<'tcx> for CleanupPostBorrowck {
     fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -17,7 +17,7 @@ use crate::ssa::SsaLocals;
 /// where each of the locals is only assigned once.
 ///
 /// We want to replace all those locals by `_a`, either copied or moved.
-pub struct CopyProp;
+pub(super) struct CopyProp;
 
 impl<'tcx> crate::MirPass<'tcx> for CopyProp {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {