Auto merge of #111082 - saethlin:box-assertkind, r=saethlin

Box AssertKind

r? `@nnethercote` this feels like your kind of thing

I want to add a new variant to `AssertKind` that needs 3 operands, and that ends up breaking a bunch of size assertions. So... what if we go the opposite direction first; shrinking `AssertKind` by boxing it?

compiler/rustc_borrowck/src/invalidation.rs

@@ -138,7 +138,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             TerminatorKind::Assert { cond, expected: _, msg, target: _, unwind: _ } => {
                 self.consume_operand(location, cond);
                 use rustc_middle::mir::AssertKind;
-                if let AssertKind::BoundsCheck { len, index } = msg {
+                if let AssertKind::BoundsCheck { len, index } = &**msg {
                     self.consume_operand(location, len);
                     self.consume_operand(location, index);
                 }

compiler/rustc_borrowck/src/lib.rs

@@ -738,7 +738,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
             TerminatorKind::Assert { cond, expected: _, msg, target: _, unwind: _ } => {
                 self.consume_operand(loc, (cond, span), flow_state);
                 use rustc_middle::mir::AssertKind;
-                if let AssertKind::BoundsCheck { len, index } = msg {
+                if let AssertKind::BoundsCheck { len, index } = &**msg {
                     self.consume_operand(loc, (len, span), flow_state);
                     self.consume_operand(loc, (index, span), flow_state);
                 }

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1404,7 +1404,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty);
                 }
 
-                if let AssertKind::BoundsCheck { len, index } = msg {
+                if let AssertKind::BoundsCheck { len, index } = &**msg {
                     if len.ty(body, tcx) != tcx.types.usize {
                         span_mirbug!(self, len, "bounds-check length non-usize {:?}", len)
                     }

compiler/rustc_codegen_cranelift/src/base.rs

@@ -335,7 +335,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                 fx.bcx.switch_to_block(failure);
                 fx.bcx.ins().nop();
 
-                match msg {
+                match &**msg {
                     AssertKind::BoundsCheck { ref len, ref index } => {
                         let len = codegen_operand(fx, len).load_scalar(fx);
                         let index = codegen_operand(fx, index).load_scalar(fx);

compiler/rustc_middle/src/mir/mod.rs

@@ -3073,13 +3073,13 @@ mod size_asserts {
     use super::*;
     use rustc_data_structures::static_assert_size;
     // tidy-alphabetical-start
-    static_assert_size!(BasicBlockData<'_>, 144);
+    static_assert_size!(BasicBlockData<'_>, 136);
     static_assert_size!(LocalDecl<'_>, 40);
     static_assert_size!(SourceScopeData<'_>, 72);
     static_assert_size!(Statement<'_>, 32);
     static_assert_size!(StatementKind<'_>, 16);
-    static_assert_size!(Terminator<'_>, 112);
+    static_assert_size!(Terminator<'_>, 104);
-    static_assert_size!(TerminatorKind<'_>, 96);
+    static_assert_size!(TerminatorKind<'_>, 88);
     static_assert_size!(VarDebugInfo<'_>, 80);
     // tidy-alphabetical-end
 }

compiler/rustc_middle/src/mir/syntax.rs

@@ -651,7 +651,7 @@ pub enum TerminatorKind<'tcx> {
     Assert {
         cond: Operand<'tcx>,
         expected: bool,
-        msg: AssertMessage<'tcx>,
+        msg: Box<AssertMessage<'tcx>>,
         target: BasicBlock,
         unwind: UnwindAction,
     },

compiler/rustc_mir_build/src/build/scope.rs

@@ -1172,7 +1172,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             TerminatorKind::Assert {
                 cond,
                 expected,
-                msg,
+                msg: Box::new(msg),
                 target: success_block,
                 unwind: UnwindAction::Continue,
             },

compiler/rustc_mir_transform/src/check_alignment.rs

@@ -224,10 +224,10 @@ fn insert_alignment_check<'tcx>(
             cond: Operand::Copy(is_ok),
             expected: true,
             target: new_block,
-            msg: AssertKind::MisalignedPointerDereference {
+            msg: Box::new(AssertKind::MisalignedPointerDereference {
                 required: Operand::Copy(alignment),
                 found: Operand::Copy(addr),
-            },
+            }),
             unwind: UnwindAction::Terminate,
         },
     });

compiler/rustc_mir_transform/src/generator.rs

@@ -1150,7 +1150,7 @@ fn insert_panic_block<'tcx>(
             literal: ConstantKind::from_bool(tcx, false),
         })),
         expected: true,
-        msg: message,
+        msg: Box::new(message),
         target: assert_block,
         unwind: UnwindAction::Continue,
     };

compiler/rustc_monomorphize/src/collector.rs

@@ -843,7 +843,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                 }
             }
             mir::TerminatorKind::Assert { ref msg, .. } => {
-                let lang_item = match msg {
+                let lang_item = match &**msg {
                     mir::AssertKind::BoundsCheck { .. } => LangItem::PanicBoundsCheck,
                     _ => LangItem::Panic,
                 };