Toggle assert_unsafe_precondition in codegen instead of expansion

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1984,6 +1984,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     ConstraintCategory::SizedBound,
                 );
             }
+            &Rvalue::NullaryOp(NullOp::DebugAssertions, _) => {}
 
             Rvalue::ShallowInitBox(operand, ty) => {
                 self.check_operand(operand, location);

compiler/rustc_codegen_cranelift/src/base.rs

@@ -767,6 +767,15 @@ fn codegen_stmt<'tcx>(
                         NullOp::OffsetOf(fields) => {
                             layout.offset_of_subfield(fx, fields.iter()).bytes()
                         }
+                        NullOp::DebugAssertions => {
+                            let val = fx.tcx.sess.opts.debug_assertions;
+                            let val = CValue::by_val(
+                                fx.bcx.ins().iconst(types::I8, i64::try_from(val).unwrap()),
+                                fx.layout_of(fx.tcx.types.bool),
+                            );
+                            lval.write_cvalue(fx, val);
+                            return;
+                        }
                     };
                     let val = CValue::by_val(
                         fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(val).unwrap()),

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -672,17 +672,23 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let val = match null_op {
                     mir::NullOp::SizeOf => {
                         assert!(bx.cx().type_is_sized(ty));
-                        layout.size.bytes()
+                        let val = layout.size.bytes();
+                        bx.cx().const_usize(val)
                     }
                     mir::NullOp::AlignOf => {
                         assert!(bx.cx().type_is_sized(ty));
-                        layout.align.abi.bytes()
+                        let val = layout.align.abi.bytes();
+                        bx.cx().const_usize(val)
                     }
                     mir::NullOp::OffsetOf(fields) => {
-                        layout.offset_of_subfield(bx.cx(), fields.iter()).bytes()
+                        let val = layout.offset_of_subfield(bx.cx(), fields.iter()).bytes();
+                        bx.cx().const_usize(val)
+                    }
+                    mir::NullOp::DebugAssertions => {
+                        let val = bx.tcx().sess.opts.debug_assertions;
+                        bx.cx().const_bool(val)
                     }
                 };
-                let val = bx.cx().const_usize(val);
                 let tcx = self.cx.tcx();
                 OperandRef {
                     val: OperandValue::Immediate(val),

compiler/rustc_codegen_ssa/src/mir/statement.rs

@@ -1,5 +1,6 @@
 use rustc_middle::mir;
 use rustc_middle::mir::NonDivergingIntrinsic;
+use rustc_session::config::OptLevel;
 
 use super::FunctionCx;
 use super::LocalRef;
@@ -67,8 +68,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 self.codegen_coverage(bx, coverage, statement.source_info.scope);
             }
             mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(ref op)) => {
-                let op_val = self.codegen_operand(bx, op);
-                bx.assume(op_val.immediate());
+                if !matches!(bx.tcx().sess.opts.optimize, OptLevel::No | OptLevel::Less) {
+                    let op_val = self.codegen_operand(bx, op);
+                    bx.assume(op_val.immediate());
+                }
             }
             mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(
                 mir::CopyNonOverlapping { ref count, ref src, ref dst },

compiler/rustc_const_eval/src/interpret/step.rs

@@ -246,13 +246,25 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     );
                 }
                 let val = match null_op {
-                    mir::NullOp::SizeOf => layout.size.bytes(),
-                    mir::NullOp::AlignOf => layout.align.abi.bytes(),
+                    mir::NullOp::SizeOf => {
+                        let val = layout.size.bytes();
+                        Scalar::from_target_usize(val, self)
+                    }
+                    mir::NullOp::AlignOf => {
+                        let val = layout.align.abi.bytes();
+                        Scalar::from_target_usize(val, self)
+                    }
                     mir::NullOp::OffsetOf(fields) => {
-                        layout.offset_of_subfield(self, fields.iter()).bytes()
+                        let val = layout.offset_of_subfield(self, fields.iter()).bytes();
+                        Scalar::from_target_usize(val, self)
+                    }
+                    mir::NullOp::DebugAssertions => {
+                        // The checks hidden behind this are always better done by the interpreter
+                        // itself, because it knows the runtime state better.
+                        Scalar::from_bool(false)
                     }
                 };
-                self.write_scalar(Scalar::from_target_usize(val, self), &dest)?;
+                self.write_scalar(val, &dest)?;
             }
 
             ShallowInitBox(ref operand, _) => {

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -544,7 +544,10 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
             Rvalue::Cast(_, _, _) => {}
 
-            Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_), _) => {}
+            Rvalue::NullaryOp(
+                NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_) | NullOp::DebugAssertions,
+                _,
+            ) => {}
             Rvalue::ShallowInitBox(_, _) => {}
 
             Rvalue::UnaryOp(_, operand) => {

compiler/rustc_const_eval/src/transform/validate.rs

@@ -1139,7 +1139,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             Rvalue::Repeat(_, _)
             | Rvalue::ThreadLocalRef(_)
             | Rvalue::AddressOf(_, _)
-            | Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _)
+            | Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::DebugAssertions, _)
             | Rvalue::Discriminant(_) => {}
         }
         self.super_rvalue(rvalue, location);

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -112,7 +112,8 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: DefId) -> hir
         | sym::forget
         | sym::black_box
         | sym::variant_count
-        | sym::ptr_mask => hir::Unsafety::Normal,
+        | sym::ptr_mask
+        | sym::debug_assertions => hir::Unsafety::Normal,
         _ => hir::Unsafety::Unsafe,
     };
 
@@ -461,6 +462,8 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                 (0, vec![Ty::new_imm_ptr(tcx, Ty::new_unit(tcx))], tcx.types.usize)
             }
 
+            sym::debug_assertions => (0, Vec::new(), tcx.types.bool),
+
             other => {
                 tcx.dcx().emit_err(UnrecognizedIntrinsicFunction { span: it.span, name: other });
                 return;

compiler/rustc_middle/src/mir/pretty.rs

@@ -907,6 +907,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                     NullOp::SizeOf => write!(fmt, "SizeOf({t})"),
                     NullOp::AlignOf => write!(fmt, "AlignOf({t})"),
                     NullOp::OffsetOf(fields) => write!(fmt, "OffsetOf({t}, {fields:?})"),
+                    NullOp::DebugAssertions => write!(fmt, "cfg!(debug_assertions)"),
                 }
             }
             ThreadLocalRef(did) => ty::tls::with(|tcx| {

compiler/rustc_middle/src/mir/syntax.rs

@@ -1361,6 +1361,8 @@ pub enum NullOp<'tcx> {
     AlignOf,
     /// Returns the offset of a field
     OffsetOf(&'tcx List<(VariantIdx, FieldIdx)>),
+    /// cfg!(debug_assertions), but expanded in codegen
+    DebugAssertions,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]

compiler/rustc_middle/src/mir/tcx.rs

@@ -194,6 +194,7 @@ impl<'tcx> Rvalue<'tcx> {
             Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..), _) => {
                 tcx.types.usize
             }
+            Rvalue::NullaryOp(NullOp::DebugAssertions, _) => tcx.types.bool,
             Rvalue::Aggregate(ref ak, ref ops) => match **ak {
                 AggregateKind::Array(ty) => Ty::new_array(tcx, ty, ops.len() as u64),
                 AggregateKind::Tuple => {

compiler/rustc_mir_dataflow/src/move_paths/builder.rs

@@ -429,7 +429,10 @@ impl<'b, 'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> Gatherer<'b, 'a, 'tcx, F> {
             | Rvalue::AddressOf(..)
             | Rvalue::Discriminant(..)
             | Rvalue::Len(..)
-            | Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..), _) => {}
+            | Rvalue::NullaryOp(
+                NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..) | NullOp::DebugAssertions,
+                _,
+            ) => {}
         }
     }
 

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -639,6 +639,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                     NullOp::OffsetOf(fields) => {
                         op_layout.offset_of_subfield(self, fields.iter()).bytes()
                     }
+                    NullOp::DebugAssertions => return None,
                 };
                 ImmTy::from_scalar(Scalar::from_target_usize(val, self), layout).into()
             }

compiler/rustc_mir_transform/src/gvn.rs

@@ -489,6 +489,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                     NullOp::OffsetOf(fields) => {
                         layout.offset_of_subfield(&self.ecx, fields.iter()).bytes()
                     }
+                    NullOp::DebugAssertions => return None,
                 };
                 let usize_layout = self.ecx.layout_of(self.tcx.types.usize).unwrap();
                 let imm = ImmTy::try_from_uint(val, usize_layout)?;

compiler/rustc_mir_transform/src/instsimplify.rs

@@ -2,10 +2,12 @@
 
 use crate::simplify::simplify_duplicate_switch_targets;
 use rustc_middle::mir::*;
+use rustc_middle::ty::layout;
 use rustc_middle::ty::layout::ValidityRequirement;
 use rustc_middle::ty::{self, GenericArgsRef, ParamEnv, Ty, TyCtxt};
 use rustc_span::symbol::Symbol;
 use rustc_target::abi::FieldIdx;
+use rustc_target::spec::abi::Abi;
 
 pub struct InstSimplify;
 
@@ -38,6 +40,7 @@ impl<'tcx> MirPass<'tcx> for InstSimplify {
                 block.terminator.as_mut().unwrap(),
                 &mut block.statements,
             );
+            ctx.simplify_nounwind_call(block.terminator.as_mut().unwrap());
             simplify_duplicate_switch_targets(block.terminator.as_mut().unwrap());
         }
     }
@@ -252,6 +255,28 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> {
         terminator.kind = TerminatorKind::Goto { target: destination_block };
     }
 
+    fn simplify_nounwind_call(&self, terminator: &mut Terminator<'tcx>) {
+        let TerminatorKind::Call { func, unwind, .. } = &mut terminator.kind else {
+            return;
+        };
+
+        let Some((def_id, _)) = func.const_fn_def() else {
+            return;
+        };
+
+        let body_ty = self.tcx.type_of(def_id).skip_binder();
+        let body_abi = match body_ty.kind() {
+            ty::FnDef(..) => body_ty.fn_sig(self.tcx).abi(),
+            ty::Closure(..) => Abi::RustCall,
+            ty::Coroutine(..) => Abi::Rust,
+            _ => bug!("unexpected body ty: {:?}", body_ty),
+        };
+
+        if !layout::fn_can_unwind(self.tcx, Some(def_id), body_abi) {
+            *unwind = UnwindAction::Unreachable;
+        }
+    }
+
     fn simplify_intrinsic_assert(
         &self,
         terminator: &mut Terminator<'tcx>,

compiler/rustc_mir_transform/src/lower_intrinsics.rs

@@ -21,6 +21,17 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
                     sym::unreachable => {
                         terminator.kind = TerminatorKind::Unreachable;
                     }
+                    sym::debug_assertions => {
+                        let target = target.unwrap();
+                        block.statements.push(Statement {
+                            source_info: terminator.source_info,
+                            kind: StatementKind::Assign(Box::new((
+                                *destination,
+                                Rvalue::NullaryOp(NullOp::DebugAssertions, tcx.types.bool),
+                            ))),
+                        });
+                        terminator.kind = TerminatorKind::Goto { target };
+                    }
                     sym::forget => {
                         if let Some(target) = *target {
                             block.statements.push(Statement {

compiler/rustc_mir_transform/src/promote_consts.rs

@@ -446,6 +446,7 @@ impl<'tcx> Validator<'_, 'tcx> {
                 NullOp::SizeOf => {}
                 NullOp::AlignOf => {}
                 NullOp::OffsetOf(_) => {}
+                NullOp::DebugAssertions => {}
             },
 
             Rvalue::ShallowInitBox(_, _) => return Err(Unpromotable),

compiler/rustc_smir/src/rustc_smir/convert/mir.rs

@@ -257,6 +257,7 @@ impl<'tcx> Stable<'tcx> for mir::NullOp<'tcx> {
             OffsetOf(indices) => stable_mir::mir::NullOp::OffsetOf(
                 indices.iter().map(|idx| idx.stable(tables)).collect(),
             ),
+            DebugAssertions => stable_mir::mir::NullOp::DebugAssertions,
         }
     }
 }

compiler/stable_mir/src/mir/body.rs

@@ -639,6 +639,7 @@ impl Rvalue {
             Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..), _) => {
                 Ok(Ty::usize_ty())
             }
+            Rvalue::NullaryOp(NullOp::DebugAssertions, _) => Ok(Ty::bool_ty()),
             Rvalue::Aggregate(ak, ops) => match *ak {
                 AggregateKind::Array(ty) => Ty::try_new_array(ty, ops.len() as u64),
                 AggregateKind::Tuple => Ok(Ty::new_tuple(
@@ -1005,6 +1006,8 @@ pub enum NullOp {
     AlignOf,
     /// Returns the offset of a field.
     OffsetOf(Vec<(VariantIdx, FieldIdx)>),
+    /// cfg!(debug_assertions), but at codegen time
+    DebugAssertions,
 }
 
 impl Operand {

library/alloc/src/raw_vec.rs

@@ -207,11 +207,7 @@ impl<T, A: Allocator> RawVec<T, A> {
             // Allocators currently return a `NonNull<[u8]>` whose length
             // matches the size requested. If that ever changes, the capacity
             // here should change to `ptr.len() / mem::size_of::<T>()`.
-            Self {
-                ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
-                cap: unsafe { Cap(capacity) },
-                alloc,
-            }
+            Self { ptr: Unique::from(ptr.cast()), cap: unsafe { Cap(capacity) }, alloc }
         }
     }
 
@@ -239,6 +235,11 @@ impl<T, A: Allocator> RawVec<T, A> {
         self.ptr.as_ptr()
     }
 
+    #[inline]
+    pub fn non_null(&self) -> NonNull<T> {
+        NonNull::from(self.ptr)
+    }
+
     /// Gets the capacity of the allocation.
     ///
     /// This will always be `usize::MAX` if `T` is zero-sized.
@@ -398,7 +399,7 @@ impl<T, A: Allocator> RawVec<T, A> {
         // Allocators currently return a `NonNull<[u8]>` whose length matches
         // the size requested. If that ever changes, the capacity here should
         // change to `ptr.len() / mem::size_of::<T>()`.
-        self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) };
+        self.ptr = Unique::from(ptr.cast());
         self.cap = unsafe { Cap(cap) };
     }
 

library/alloc/src/vec/into_iter.rs

@@ -136,7 +136,7 @@ impl<T, A: Allocator> IntoIter<T, A> {
         // struct and then overwriting &mut self.
         // this creates less assembly
         self.cap = 0;
-        self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
+        self.buf = RawVec::NEW.non_null();
         self.ptr = self.buf;
         self.end = self.buf.as_ptr();
 

library/alloc/src/vec/mod.rs

@@ -2861,16 +2861,16 @@ impl<T, A: Allocator> IntoIterator for Vec<T, A> {
     #[inline]
     fn into_iter(self) -> Self::IntoIter {
         unsafe {
-            let mut me = ManuallyDrop::new(self);
+            let me = ManuallyDrop::new(self);
             let alloc = ManuallyDrop::new(ptr::read(me.allocator()));
-            let begin = me.as_mut_ptr();
+            let buf = me.buf.non_null();
+            let begin = buf.as_ptr();
             let end = if T::IS_ZST {
                 begin.wrapping_byte_add(me.len())
             } else {
                 begin.add(me.len()) as *const T
             };
             let cap = me.buf.capacity();
-            let buf = NonNull::new_unchecked(begin);
             IntoIter { buf, phantom: PhantomData, cap, alloc, ptr: buf, end }
         }
     }

library/core/src/char/convert.rs

@@ -27,7 +27,7 @@ pub(super) const unsafe fn from_u32_unchecked(i: u32) -> char {
     unsafe {
         assert_unsafe_precondition!(
             "invalid value for `char`",
-            (i: u32) => char_try_from_u32(i).is_ok()
+            (i: u32 = i) => char_try_from_u32(i).is_ok()
         );
         transmute(i)
     }

library/core/src/hint.rs

@@ -148,7 +148,7 @@ pub const unsafe fn assert_unchecked(cond: bool) {
     unsafe {
         intrinsics::assert_unsafe_precondition!(
             "hint::assert_unchecked must never be called when the condition is false",
-            (cond: bool) => cond,
+            (cond: bool = cond) => cond,
         );
         crate::intrinsics::assume(cond);
     }