[experiment] remove attributes from Terminator

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1645,7 +1645,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             }
 
             mir::TerminatorKind::Goto { target } => {
-                helper.funclet_br(self, bx, target, mergeable_succ(), &terminator.attributes)
+                helper.funclet_br(self, bx, target, mergeable_succ(), &[])
             }
 
             mir::TerminatorKind::SwitchInt { ref discr, ref targets } => {

compiler/rustc_middle/src/mir/mod.rs

@@ -1732,11 +1732,11 @@ mod size_asserts {
 
     use super::*;
     // tidy-alphabetical-start
-    static_assert_size!(BasicBlockData<'_>, 144);
+    static_assert_size!(BasicBlockData<'_>, 136);
     static_assert_size!(LocalDecl<'_>, 40);
     static_assert_size!(SourceScopeData<'_>, 64);
     static_assert_size!(Statement<'_>, 40);
-    static_assert_size!(Terminator<'_>, 104);
+    static_assert_size!(Terminator<'_>, 96);
     static_assert_size!(VarDebugInfo<'_>, 88);
     // tidy-alphabetical-end
 }

compiler/rustc_middle/src/mir/terminator.rs

@@ -4,11 +4,9 @@ use std::slice;
 
 use rustc_ast::InlineAsmOptions;
 use rustc_data_structures::packed::Pu128;
-use rustc_hir::attrs::AttributeKind;
 use rustc_hir::attrs::lang_items::LangItem;
 use rustc_macros::{StableHash, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 use smallvec::{SmallVec, smallvec};
-use thin_vec::ThinVec;
 
 use super::*;
 
@@ -418,7 +416,6 @@ impl<O: fmt::Debug> fmt::Display for AssertKind<O> {
 pub struct Terminator<'tcx> {
     pub source_info: SourceInfo,
     pub kind: TerminatorKind<'tcx>,
-    pub attributes: ThinVec<AttributeKind>,
 }
 
 impl<'tcx> Terminator<'tcx> {

compiler/rustc_middle/src/mir/visit.rs

@@ -517,7 +517,7 @@ macro_rules! make_mir_visitor {
                 terminator: &$($mutability)? Terminator<'tcx>,
                 location: Location
             ) {
-                let Terminator { source_info, kind, attributes: _ } = terminator;
+                let Terminator { source_info, kind } = terminator;
 
                 self.visit_source_info(source_info);
                 match kind {

compiler/rustc_mir_build/src/builder/cfg.rs

@@ -1,6 +1,5 @@
 //! Routines for manipulating the control-flow graph.
 
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 use tracing::debug;
@@ -131,8 +130,7 @@ impl<'tcx> CFG<'tcx> {
             block,
             self.block_data(block)
         );
-        self.block_data_mut(block).terminator =
-            Some(Terminator { source_info, kind, attributes: ThinVec::new() });
+        self.block_data_mut(block).terminator = Some(Terminator { source_info, kind });
         self.block_data_mut(block).terminator.as_mut().unwrap()
     }
 

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

@@ -1,4 +1,3 @@
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_index::IndexSlice;
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
@@ -319,7 +318,6 @@ impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
         data.terminator = Some(Terminator {
             source_info: SourceInfo { span, scope: self.source_scope },
             kind: terminator,
-            attributes: ThinVec::new(),
         });
 
         Ok(data)

compiler/rustc_mir_build/src/builder/expr/into.rs

@@ -236,9 +236,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     // Execute the body, branching back to the test.
                     let body_block_end = this.expr_into_dest(tmp, body_block, body).into_block();
 
-                    let goto = this.cfg.goto(body_block_end, source_info, loop_block);
+                    let _goto = this.cfg.goto(body_block_end, source_info, loop_block);
                     if let Some(attrs) = this.thir.attributes.get(&expr_id) {
-                        goto.attributes = attrs.clone();
+                        let _ = attrs.clone();
                     }
 
                     // Loops are only exited by `break` expressions.

compiler/rustc_mir_dataflow/src/framework/tests.rs

@@ -2,7 +2,6 @@
 
 use std::marker::PhantomData;
 
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_index::IndexVec;
 use rustc_middle::ty;
 use rustc_span::DUMMY_SP;
@@ -22,7 +21,7 @@ fn mock_body<'tcx>() -> mir::Body<'tcx> {
 
         blocks.push(mir::BasicBlockData::new_stmts(
             std::iter::repeat(&nop).cloned().take(n).collect(),
-            Some(mir::Terminator { source_info, kind, attributes: ThinVec::new() }),
+            Some(mir::Terminator { source_info, kind }),
             false,
         ))
     };

compiler/rustc_mir_transform/src/add_call_guards.rs

@@ -15,7 +15,6 @@
 //!
 //! NOTE: Simplify CFG will happily undo most of the work this pass does.
 
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
@@ -89,11 +88,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {
         let cur_len = body.basic_blocks.len();
         let mut new_block = |source_info: SourceInfo, is_cleanup: bool, target: BasicBlock| {
             let block = BasicBlockData::new(
-                Some(Terminator {
-                    source_info,
-                    kind: TerminatorKind::Goto { target },
-                    attributes: ThinVec::new(),
-                }),
+                Some(Terminator { source_info, kind: TerminatorKind::Goto { target } }),
                 is_cleanup,
             );
             let idx = cur_len + new_blocks.len();

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -1,4 +1,3 @@
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, TyCtxt};
 use tracing::debug;
@@ -95,11 +94,7 @@ fn add_move_for_packed_drop<'tcx>(
 
     let storage_dead_block = patch.new_block(BasicBlockData::new_stmts(
         vec![Statement::new(source_info, StatementKind::StorageDead(temp))],
-        Some(Terminator {
-            source_info,
-            kind: TerminatorKind::Goto { target },
-            attributes: ThinVec::new(),
-        }),
+        Some(Terminator { source_info, kind: TerminatorKind::Goto { target } }),
         is_cleanup,
     ));
 

compiler/rustc_mir_transform/src/check_enums.rs

@@ -1,5 +1,4 @@
 use rustc_abi::{Scalar, Size, TagEncoding, Variants, WrappingRange};
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_hir::attrs::lang_items::LangItem;
 use rustc_index::IndexVec;
 use rustc_middle::bug;
@@ -65,7 +64,6 @@ impl<'tcx> crate::MirPass<'tcx> for CheckEnums {
                             basic_blocks[block].terminator = Some(Terminator {
                                 source_info,
                                 kind: TerminatorKind::Goto { target: new_block },
-                                attributes: ThinVec::new(),
                             });
                         }
                         EnumCheckType::Direct { source_op, discr, op_size, valid_discrs } => {
@@ -396,7 +394,6 @@ fn insert_direct_enum_check<'tcx>(
                 invalid_discr_block,
             ),
         },
-        attributes: ThinVec::new(),
     });
 
     // Abort in case of an invalid enum discriminant.
@@ -416,7 +413,6 @@ fn insert_direct_enum_check<'tcx>(
             // make a failing UB check turn into much worse UB when we start unwinding.
             unwind: UnwindAction::Unreachable,
         },
-        attributes: ThinVec::new(),
     });
 }
 
@@ -462,7 +458,6 @@ fn insert_uninhabited_enum_check<'tcx>(
             // make a failing UB check turn into much worse UB when we start unwinding.
             unwind: UnwindAction::Unreachable,
         },
-        attributes: ThinVec::new(),
     });
 }
 
@@ -540,6 +535,5 @@ fn insert_niche_check<'tcx>(
             // make a failing UB check turn into much worse UB when we start unwinding.
             unwind: UnwindAction::Unreachable,
         },
-        attributes: ThinVec::new(),
     });
 }

compiler/rustc_mir_transform/src/check_pointers.rs

@@ -1,4 +1,3 @@
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_hir::attrs::lang_items::LangItem;
 use rustc_index::IndexVec;
 use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor};
@@ -117,7 +116,6 @@ pub(crate) fn check_pointers<'tcx, F>(
                         // worse UB when we start unwinding.
                         unwind: UnwindAction::Unreachable,
                     },
-                    attributes: ThinVec::new(),
                 });
             }
         }

compiler/rustc_mir_transform/src/coroutine/drop.rs

@@ -358,8 +358,7 @@ pub(super) fn create_coroutine_drop_shim_proxy_async<'tcx>(
         replace: false,
         drop: None,
     };
-    body.basic_blocks_mut()[call_bb].terminator =
-        Some(Terminator { source_info, kind, attributes: ThinVec::new() });
+    body.basic_blocks_mut()[call_bb].terminator = Some(Terminator { source_info, kind });
 
     // Run derefer to fix Derefs that are not in the first place
     deref_finder(tcx, &mut body, false);

compiler/rustc_mir_transform/src/coroutine/mod.rs

@@ -63,7 +63,6 @@ use drop::{
 pub(super) use layout::mir_coroutine_witnesses;
 use layout::{CoroutineSavedLocals, compute_layout, locals_live_across_suspend_points};
 use rustc_abi::{FieldIdx, VariantIdx};
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_hir::attrs::lang_items::LangItem;
 use rustc_hir::{self as hir, CoroutineDesugaring, CoroutineKind};
 use rustc_index::bit_set::{BitMatrix, DenseBitSet, GrowableBitSet};
@@ -253,11 +252,7 @@ impl<'tcx> TransformVisitor<'tcx> {
 
         body.basic_blocks_mut().push(BasicBlockData::new_stmts(
             statements,
-            Some(Terminator {
-                source_info,
-                kind: TerminatorKind::Return,
-                attributes: ThinVec::new(),
-            }),
+            Some(Terminator { source_info, kind: TerminatorKind::Return }),
             false,
         ));
 
@@ -740,19 +735,13 @@ fn insert_switch<'tcx>(
     }
 
     let switch = TerminatorKind::SwitchInt { discr: Operand::Move(discr), targets: switch_targets };
-    body.basic_blocks_mut()[START_BLOCK].terminator = Some(Terminator {
-        source_info: SourceInfo::outermost(body.span),
-        kind: switch,
-        attributes: ThinVec::new(),
-    });
+    body.basic_blocks_mut()[START_BLOCK].terminator =
+        Some(Terminator { source_info: SourceInfo::outermost(body.span), kind: switch });
 }
 
 fn insert_term_block<'tcx>(body: &mut Body<'tcx>, kind: TerminatorKind<'tcx>) -> BasicBlock {
     let source_info = SourceInfo::outermost(body.span);
-    body.basic_blocks_mut().push(BasicBlockData::new(
-        Some(Terminator { source_info, kind, attributes: ThinVec::new() }),
-        false,
-    ))
+    body.basic_blocks_mut().push(BasicBlockData::new(Some(Terminator { source_info, kind }), false))
 }
 
 fn return_poll_ready_assign<'tcx>(tcx: TyCtxt<'tcx>, source_info: SourceInfo) -> Statement<'tcx> {
@@ -775,7 +764,7 @@ fn insert_poll_ready_block<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> Ba
     let source_info = SourceInfo::outermost(body.span);
     body.basic_blocks_mut().push(BasicBlockData::new_stmts(
         [return_poll_ready_assign(tcx, source_info)].to_vec(),
-        Some(Terminator { source_info, kind: TerminatorKind::Return, attributes: ThinVec::new() }),
+        Some(Terminator { source_info, kind: TerminatorKind::Return }),
         false,
     ))
 }
@@ -830,12 +819,7 @@ fn generate_poison_block_and_redirect_unwinds_there<'tcx>(
     let source_info = SourceInfo::outermost(body.span);
     let poison_block = body.basic_blocks_mut().push(BasicBlockData::new_stmts(
         vec![transform.set_discr(VariantIdx::new(CoroutineArgs::POISONED), source_info)],
-        Some(Terminator {
-            source_info,
-            kind: TerminatorKind::UnwindResume,
-
-            attributes: ThinVec::new(),
-        }),
+        Some(Terminator { source_info, kind: TerminatorKind::UnwindResume }),
         true,
     ));
 
@@ -846,12 +830,8 @@ fn generate_poison_block_and_redirect_unwinds_there<'tcx>(
             // An existing `Resume` terminator is redirected to jump to our dedicated
             // "poisoning block" above.
             if idx != poison_block {
-                *block.terminator_mut() = Terminator {
-                    source_info,
-                    kind: TerminatorKind::Goto { target: poison_block },
-
-                    attributes: ThinVec::new(),
-                };
+                *block.terminator_mut() =
+                    Terminator { source_info, kind: TerminatorKind::Goto { target: poison_block } };
             }
         } else if !block.is_cleanup
             // Any terminators that *can* unwind but don't have an unwind target set are also
@@ -1014,12 +994,7 @@ fn create_cases<'tcx>(
                 // Then jump to the real target
                 let block = body.basic_blocks_mut().push(BasicBlockData::new_stmts(
                     statements,
-                    Some(Terminator {
-                        source_info,
-                        kind: TerminatorKind::Goto { target },
-
-                        attributes: ThinVec::new(),
-                    }),
+                    Some(Terminator { source_info, kind: TerminatorKind::Goto { target } }),
                     false,
                 ));
 

compiler/rustc_mir_transform/src/coverage/tests.rs

@@ -26,7 +26,6 @@
 
 use itertools::Itertools;
 use rustc_data_structures::graph::{DirectedGraph, Successors};
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::*;
 use rustc_middle::{bug, ty};
@@ -73,7 +72,6 @@ impl<'tcx> MockBlocks<'tcx> {
             Some(Terminator {
                 source_info: SourceInfo::outermost(Span::with_root_ctxt(next_lo, next_hi)),
                 kind,
-                attributes: ThinVec::new(),
             }),
             false,
         ))

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -1,6 +1,5 @@
 use std::fmt::Debug;
 
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{Ty, TyCtxt};
 use tracing::trace;
@@ -175,7 +174,6 @@ impl<'tcx> crate::MirPass<'tcx> for EarlyOtherwiseBranch {
                         discr: parent_op,
                         targets: eq_targets,
                     },
-                    attributes: ThinVec::new(),
                 }),
                 bbs[parent].is_cleanup,
             );
@@ -230,7 +228,6 @@ fn evaluate_candidate<'tcx>(
     let Terminator {
         kind: TerminatorKind::SwitchInt { targets: child_targets, discr: child_discr },
         source_info,
-        attributes: _,
     } = bbs[child].terminator()
     else {
         return None;

compiler/rustc_mir_transform/src/elaborate_drop.rs

@@ -2,7 +2,6 @@ use std::{fmt, iter, mem};
 
 use itertools::Itertools;
 use rustc_abi::{FIRST_VARIANT, FieldIdx, VariantIdx};
-use rustc_data_structures::thin_vec::ThinVec;
 use rustc_hir::attrs::lang_items::LangItem;
 use rustc_hir::{CoroutineDesugaring, CoroutineKind};
 use rustc_index::Idx;
@@ -1641,7 +1640,7 @@ where
     #[instrument(level = "trace", skip(self), ret)]
     fn new_block(&mut self, unwind: Unwind, k: TerminatorKind<'tcx>) -> BasicBlock {
         self.elaborator.patch().new_block(BasicBlockData::new(
-            Some(Terminator { source_info: self.source_info, kind: k, attributes: ThinVec::new() }),
+            Some(Terminator { source_info: self.source_info, kind: k }),
             unwind.is_cleanup(),
         ))
     }
@@ -1655,7 +1654,7 @@ where
     ) -> BasicBlock {
         self.elaborator.patch().new_block(BasicBlockData::new_stmts(
             statements,
-            Some(Terminator { source_info: self.source_info, kind: k, attributes: ThinVec::new() }),
+            Some(Terminator { source_info: self.source_info, kind: k }),
             unwind.is_cleanup(),
         ))
     }