Make TypeId const comparable

compiler/rustc_codegen_cranelift/example/mini_core.rs

@@ -660,7 +660,7 @@ pub mod intrinsics {
     #[rustc_intrinsic]
     pub unsafe fn ctlz_nonzero<T>(x: T) -> u32;
     #[rustc_intrinsic]
-    pub fn needs_drop<T: ?::Sized>() -> bool;
+    pub const fn needs_drop<T: ?::Sized>() -> bool;
     #[rustc_intrinsic]
     pub fn bitreverse<T>(x: T) -> T;
     #[rustc_intrinsic]

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -1,4 +1,13 @@
-#![feature(no_core, lang_items, never_type, linkage, extern_types, thread_local, repr_simd)]
+#![feature(
+    no_core,
+    lang_items,
+    never_type,
+    linkage,
+    extern_types,
+    thread_local,
+    repr_simd,
+    rustc_private
+)]
 #![no_core]
 #![allow(dead_code, non_camel_case_types, internal_features)]
 
@@ -207,10 +216,14 @@ fn main() {
         assert_eq!(intrinsics::align_of::<u16>() as u8, 2);
         assert_eq!(intrinsics::align_of_val(&a) as u8, intrinsics::align_of::<&str>() as u8);
 
-        assert!(!intrinsics::needs_drop::<u8>());
-        assert!(!intrinsics::needs_drop::<[u8]>());
-        assert!(intrinsics::needs_drop::<NoisyDrop>());
-        assert!(intrinsics::needs_drop::<NoisyDropUnsized>());
+        let u8_needs_drop = const { intrinsics::needs_drop::<u8>() };
+        assert!(!u8_needs_drop);
+        let slice_needs_drop = const { intrinsics::needs_drop::<[u8]>() };
+        assert!(!slice_needs_drop);
+        let noisy_drop = const { intrinsics::needs_drop::<NoisyDrop>() };
+        assert!(noisy_drop);
+        let noisy_unsized_drop = const { intrinsics::needs_drop::<NoisyDropUnsized>() };
+        assert!(noisy_unsized_drop);
 
         Unique { pointer: NonNull(1 as *mut &str), _marker: PhantomData } as Unique<dyn SomeTrait>;
 

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -175,6 +175,13 @@ pub(crate) fn codegen_const_value<'tcx>(
                             fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
                         fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
                     }
+                    GlobalAlloc::Type { .. } => {
+                        return CValue::const_val(
+                            fx,
+                            layout,
+                            ScalarInt::try_from_target_usize(offset.bytes(), fx.tcx).unwrap(),
+                        );
+                    }
                     GlobalAlloc::Static(def_id) => {
                         assert!(fx.tcx.is_static(def_id));
                         let data_id = data_id_for_static(
@@ -360,6 +367,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
                     GlobalAlloc::Memory(alloc) => alloc,
                     GlobalAlloc::Function { .. }
                     | GlobalAlloc::Static(_)
+                    | GlobalAlloc::Type { .. }
                     | GlobalAlloc::VTable(..) => {
                         unreachable!()
                     }
@@ -471,6 +479,11 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
                         .principal()
                         .map(|principal| tcx.instantiate_bound_regions_with_erased(principal)),
                 ),
+                GlobalAlloc::Type { .. } => {
+                    // Nothing to do, the bytes/offset of this pointer have already been written together with all other bytes,
+                    // so we just need to drop this provenance.
+                    continue;
+                }
                 GlobalAlloc::Static(def_id) => {
                     if tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL)
                     {

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -812,21 +812,6 @@ fn codegen_regular_intrinsic_call<'tcx>(
             dest.write_cvalue(fx, val);
         }
 
-        sym::needs_drop | sym::type_id | sym::type_name | sym::variant_count => {
-            intrinsic_args!(fx, args => (); intrinsic);
-
-            let const_val = fx
-                .tcx
-                .const_eval_instance(
-                    ty::TypingEnv::fully_monomorphized(),
-                    instance,
-                    source_info.span,
-                )
-                .unwrap();
-            let val = crate::constant::codegen_const_value(fx, const_val, ret.layout().ty);
-            ret.write_cvalue(fx, val);
-        }
-
         sym::ptr_offset_from | sym::ptr_offset_from_unsigned => {
             intrinsic_args!(fx, args => (ptr, base); intrinsic);
             let ptr = ptr.load_scalar(fx);

compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs

@@ -6,6 +6,7 @@
 )]
 #![no_core]
 #![allow(dead_code, internal_features, non_camel_case_types)]
+#![rustfmt::skip]
 
 extern crate mini_core;
 
@@ -197,10 +198,10 @@ fn main() {
         assert_eq!(intrinsics::align_of::<u16>() as u8, 2);
         assert_eq!(intrinsics::align_of_val(&a) as u8, intrinsics::align_of::<&str>() as u8);
 
-        assert!(!intrinsics::needs_drop::<u8>());
-        assert!(!intrinsics::needs_drop::<[u8]>());
-        assert!(intrinsics::needs_drop::<NoisyDrop>());
-        assert!(intrinsics::needs_drop::<NoisyDropUnsized>());
+        assert!(!const { intrinsics::needs_drop::<u8>() });
+        assert!(!const { intrinsics::needs_drop::<[u8]>() });
+        assert!(const { intrinsics::needs_drop::<NoisyDrop>() });
+        assert!(const { intrinsics::needs_drop::<NoisyDropUnsized>() });
 
         Unique {
             pointer: 0 as *const &str,

compiler/rustc_codegen_gcc/src/common.rs

@@ -1,7 +1,6 @@
 use gccjit::{LValue, RValue, ToRValue, Type};
-use rustc_abi as abi;
-use rustc_abi::HasDataLayout;
 use rustc_abi::Primitive::Pointer;
+use rustc_abi::{self as abi, HasDataLayout};
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods, ConstCodegenMethods, MiscCodegenMethods, StaticCodegenMethods,
 };
@@ -303,6 +302,10 @@ impl<'gcc, 'tcx> ConstCodegenMethods for CodegenCx<'gcc, 'tcx> {
                         let init = self.const_data_from_alloc(alloc);
                         self.static_addr_of(init, alloc.inner().align, None)
                     }
+                    GlobalAlloc::Type { .. } => {
+                        let val = self.const_usize(offset.bytes());
+                        return self.context.new_cast(None, val, ty);
+                    }
                     GlobalAlloc::Static(def_id) => {
                         assert!(self.tcx.is_static(def_id));
                         self.get_static(def_id).get_address(None)

compiler/rustc_codegen_llvm/src/common.rs

@@ -3,9 +3,8 @@
 use std::borrow::Borrow;
 
 use libc::{c_char, c_uint};
-use rustc_abi as abi;
-use rustc_abi::HasDataLayout;
 use rustc_abi::Primitive::Pointer;
+use rustc_abi::{self as abi, HasDataLayout as _};
 use rustc_ast::Mutability;
 use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::traits::*;
@@ -284,7 +283,8 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
                                 self.const_bitcast(llval, llty)
                             };
                         } else {
-                            let init = const_alloc_to_llvm(self, alloc, /*static*/ false);
+                            let init =
+                                const_alloc_to_llvm(self, alloc.inner(), /*static*/ false);
                             let alloc = alloc.inner();
                             let value = match alloc.mutability {
                                 Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
@@ -316,15 +316,19 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
                                 }),
                             )))
                             .unwrap_memory();
-                        let init = const_alloc_to_llvm(self, alloc, /*static*/ false);
-                        let value = self.static_addr_of_impl(init, alloc.inner().align, None);
-                        value
+                        let init = const_alloc_to_llvm(self, alloc.inner(), /*static*/ false);
+                        self.static_addr_of_impl(init, alloc.inner().align, None)
                     }
                     GlobalAlloc::Static(def_id) => {
                         assert!(self.tcx.is_static(def_id));
                         assert!(!self.tcx.is_thread_local_static(def_id));
                         self.get_static(def_id)
                     }
+                    GlobalAlloc::Type { .. } => {
+                        // Drop the provenance, the offset contains the bytes of the hash
+                        let llval = self.const_usize(offset.bytes());
+                        return unsafe { llvm::LLVMConstIntToPtr(llval, llty) };
+                    }
                 };
                 let base_addr_space = global_alloc.address_space(self);
                 let llval = unsafe {
@@ -346,7 +350,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
     }
 
     fn const_data_from_alloc(&self, alloc: ConstAllocation<'_>) -> Self::Value {
-        const_alloc_to_llvm(self, alloc, /*static*/ false)
+        const_alloc_to_llvm(self, alloc.inner(), /*static*/ false)
     }
 
     fn const_ptr_byte_offset(&self, base_addr: Self::Value, offset: abi::Size) -> Self::Value {

compiler/rustc_codegen_llvm/src/consts.rs

@@ -27,10 +27,9 @@ use crate::{base, debuginfo};
 
 pub(crate) fn const_alloc_to_llvm<'ll>(
     cx: &CodegenCx<'ll, '_>,
-    alloc: ConstAllocation<'_>,
+    alloc: &Allocation,
     is_static: bool,
 ) -> &'ll Value {
-    let alloc = alloc.inner();
     // We expect that callers of const_alloc_to_llvm will instead directly codegen a pointer or
     // integer for any &ZST where the ZST is a constant (i.e. not a static). We should never be
     // producing empty LLVM allocations as they're just adding noise to binaries and forcing less
@@ -138,7 +137,7 @@ fn codegen_static_initializer<'ll, 'tcx>(
     def_id: DefId,
 ) -> Result<(&'ll Value, ConstAllocation<'tcx>), ErrorHandled> {
     let alloc = cx.tcx.eval_static_initializer(def_id)?;
-    Ok((const_alloc_to_llvm(cx, alloc, /*static*/ true), alloc))
+    Ok((const_alloc_to_llvm(cx, alloc.inner(), /*static*/ true), alloc))
 }
 
 fn set_global_alignment<'ll>(cx: &CodegenCx<'ll, '_>, gv: &'ll Value, mut align: Align) {

compiler/rustc_codegen_ssa/src/mir/intrinsic.rs

@@ -1,7 +1,7 @@
 use rustc_abi::WrappingRange;
-use rustc_middle::bug;
 use rustc_middle::mir::SourceInfo;
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::{bug, span_bug};
 use rustc_session::config::OptLevel;
 use rustc_span::sym;
 
@@ -98,6 +98,27 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             discr.to_atomic_ordering()
         };
 
+        if args.is_empty() {
+            match name {
+                sym::abort
+                | sym::unreachable
+                | sym::cold_path
+                | sym::breakpoint
+                | sym::assert_zero_valid
+                | sym::assert_mem_uninitialized_valid
+                | sym::assert_inhabited
+                | sym::ub_checks
+                | sym::contract_checks
+                | sym::atomic_fence
+                | sym::atomic_singlethreadfence
+                | sym::caller_location => {}
+                _ => {
+                    span_bug!(span, "nullary intrinsic {name} must either be in a const block or explicitly opted out because it is inherently a runtime intrinsic
+");
+                }
+            }
+        }
+
         let llval = match name {
             sym::abort => {
                 bx.abort();
@@ -150,10 +171,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
                 value
             }
-            sym::needs_drop | sym::type_id | sym::type_name | sym::variant_count => {
-                let value = bx.tcx().const_eval_instance(bx.typing_env(), instance, span).unwrap();
-                OperandRef::from_const(bx, value, result.layout.ty).immediate_or_packed_pair(bx)
-            }
             sym::arith_offset => {
                 let ty = fn_args.type_at(0);
                 let layout = bx.layout_of(ty);

compiler/rustc_codegen_ssa/src/mir/operand.rs

@@ -185,7 +185,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
         offset: Size,
     ) -> Self {
         let alloc_align = alloc.inner().align;
-        assert!(alloc_align >= layout.align.abi);
+        assert!(alloc_align >= layout.align.abi, "{alloc_align:?} < {:?}", layout.align.abi);
 
         let read_scalar = |start, size, s: abi::Scalar, ty| {
             match alloc.0.read_scalar(

compiler/rustc_const_eval/messages.ftl

@@ -78,6 +78,8 @@ const_eval_dealloc_kind_mismatch =
 
 const_eval_deref_function_pointer =
     accessing {$allocation} which contains a function
+const_eval_deref_typeid_pointer =
+    accessing {$allocation} which contains a `TypeId`
 const_eval_deref_vtable_pointer =
     accessing {$allocation} which contains a vtable
 const_eval_division_by_zero =
@@ -271,9 +273,6 @@ const_eval_non_const_try_block_from_output =
 const_eval_not_enough_caller_args =
     calling a function with fewer arguments than it requires
 
-const_eval_nullary_intrinsic_fail =
-    could not evaluate nullary intrinsic
-
 const_eval_offset_from_different_allocations =
     `{$name}` called on two different pointers that are not both derived from the same allocation
 const_eval_offset_from_out_of_bounds =

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -20,7 +20,7 @@ use crate::const_eval::CheckAlignment;
 use crate::interpret::{
     CtfeValidationMode, GlobalId, Immediate, InternKind, InternResult, InterpCx, InterpErrorKind,
     InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking, StackPopCleanup, create_static_alloc,
-    eval_nullary_intrinsic, intern_const_alloc_recursive, interp_ok, throw_exhaust,
+    intern_const_alloc_recursive, interp_ok, throw_exhaust,
 };
 use crate::{CTRL_C_RECEIVED, errors};
 
@@ -280,34 +280,6 @@ pub fn eval_to_const_value_raw_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::PseudoCanonicalInput<'tcx, GlobalId<'tcx>>,
 ) -> ::rustc_middle::mir::interpret::EvalToConstValueResult<'tcx> {
-    // We call `const_eval` for zero arg intrinsics, too, in order to cache their value.
-    // Catch such calls and evaluate them instead of trying to load a constant's MIR.
-    if let ty::InstanceKind::Intrinsic(def_id) = key.value.instance.def {
-        let ty = key.value.instance.ty(tcx, key.typing_env);
-        let ty::FnDef(_, args) = ty.kind() else {
-            bug!("intrinsic with type {:?}", ty);
-        };
-        return eval_nullary_intrinsic(tcx, key.typing_env, def_id, args).report_err().map_err(
-            |error| {
-                let span = tcx.def_span(def_id);
-
-                // FIXME(oli-obk): why don't we have any tests for this code path?
-                super::report(
-                    tcx,
-                    error.into_kind(),
-                    span,
-                    || (span, vec![]),
-                    |diag, span, _| {
-                        diag.span_label(
-                            span,
-                            crate::fluent_generated::const_eval_nullary_intrinsic_fail,
-                        );
-                    },
-                )
-            },
-        );
-    }
-
     tcx.eval_to_allocation_raw(key).map(|val| turn_into_const_value(tcx, val, key))
 }
 

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -2,7 +2,7 @@ use std::borrow::{Borrow, Cow};
 use std::fmt;
 use std::hash::Hash;
 
-use rustc_abi::{Align, Size};
+use rustc_abi::{Align, FieldIdx, Size};
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, IndexEntry};
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -403,6 +403,24 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
                 let cmp = ecx.guaranteed_cmp(a, b)?;
                 ecx.write_scalar(Scalar::from_u8(cmp), dest)?;
             }
+            sym::type_id_eq => {
+                let a = ecx.project_field(&args[0], FieldIdx::ZERO)?;
+                let b = ecx.project_field(&args[1], FieldIdx::ZERO)?;
+
+                let a = ecx.project_index(&a, 0)?;
+                let a = ecx.deref_pointer(&a)?;
+                let (a, offset_a) = a.ptr().into_parts();
+                let a = a.unwrap().alloc_id();
+                let GlobalAlloc::Type { ty: a } = ecx.tcx.global_alloc(a) else { bug!() };
+
+                let b = ecx.project_index(&b, 0)?;
+                let b = ecx.deref_pointer(&b)?;
+                let (b, offset_b) = b.ptr().into_parts();
+                let b = b.unwrap().alloc_id();
+                let GlobalAlloc::Type { ty: b } = ecx.tcx.global_alloc(b) else { bug!() };
+
+                ecx.write_scalar(Scalar::from_bool(a == b && offset_a == offset_b), dest)?;
+            }
             sym::const_allocate => {
                 let size = ecx.read_scalar(&args[0])?.to_target_usize(ecx)?;
                 let align = ecx.read_scalar(&args[1])?.to_target_usize(ecx)?;

compiler/rustc_const_eval/src/errors.rs

@@ -474,6 +474,7 @@ impl<'a> ReportErrorExt for UndefinedBehaviorInfo<'a> {
             WriteToReadOnly(_) => const_eval_write_to_read_only,
             DerefFunctionPointer(_) => const_eval_deref_function_pointer,
             DerefVTablePointer(_) => const_eval_deref_vtable_pointer,
+            DerefTypeIdPointer(_) => const_eval_deref_typeid_pointer,
             InvalidBool(_) => const_eval_invalid_bool,
             InvalidChar(_) => const_eval_invalid_char,
             InvalidTag(_) => const_eval_invalid_tag,
@@ -587,7 +588,10 @@ impl<'a> ReportErrorExt for UndefinedBehaviorInfo<'a> {
                 diag.arg("has", has.bytes());
                 diag.arg("msg", format!("{msg:?}"));
             }
-            WriteToReadOnly(alloc) | DerefFunctionPointer(alloc) | DerefVTablePointer(alloc) => {
+            WriteToReadOnly(alloc)
+            | DerefFunctionPointer(alloc)
+            | DerefVTablePointer(alloc)
+            | DerefTypeIdPointer(alloc) => {
                 diag.arg("allocation", alloc);
             }
             InvalidBool(b) => {