make it more clear which functions create fresh AllocId

Author: RalfJung

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -3,7 +3,7 @@
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir::interpret::{
-    read_target_uint, AllocId, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, Scalar,
+    read_target_uint, AllocId, ConstValue, ErrorHandled, GlobalAlloc, Scalar,
 };
 
 use cranelift_module::*;
@@ -200,17 +200,14 @@ pub(crate) fn codegen_const_value<'tcx>(
                 CValue::by_val(val, layout)
             }
         },
-        ConstValue::Indirect { alloc_id, offset } => {
-            let alloc = fx.tcx.global_alloc(alloc_id).unwrap_memory();
-            // FIXME: avoid creating multiple allocations for the same AllocId?
-            CValue::by_ref(
-                pointer_for_allocation(fx, alloc)
-                    .offset_i64(fx, i64::try_from(offset.bytes()).unwrap()),
-                layout,
-            )
-        }
+        ConstValue::Indirect { alloc_id, offset } => CValue::by_ref(
+            pointer_for_allocation(fx, alloc_id)
+                .offset_i64(fx, i64::try_from(offset.bytes()).unwrap()),
+            layout,
+        ),
         ConstValue::Slice { data, start, end } => {
-            let ptr = pointer_for_allocation(fx, data)
+            let alloc_id = fx.tcx.reserve_and_set_memory_alloc(data);
+            let ptr = pointer_for_allocation(fx, alloc_id)
                 .offset_i64(fx, i64::try_from(start).unwrap())
                 .get_addr(fx);
             let len = fx
@@ -224,9 +221,9 @@ pub(crate) fn codegen_const_value<'tcx>(
 
 fn pointer_for_allocation<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
-    alloc: ConstAllocation<'tcx>,
+    alloc_id: AllocId,
 ) -> crate::pointer::Pointer {
-    let alloc_id = fx.tcx.create_memory_alloc(alloc);
+    let alloc = fx.tcx.global_alloc(alloc_id).unwrap_memory();
     let data_id = data_id_for_alloc_id(
         &mut fx.constants_cx,
         &mut *fx.module,
@@ -357,6 +354,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
                         unreachable!()
                     }
                 };
+                // FIXME: should we have a cache so we don't do this multiple times for the same `ConstAllocation`?
                 let data_id = *cx.anon_allocs.entry(alloc_id).or_insert_with(|| {
                     module.declare_anonymous_data(alloc.inner().mutability.is_mut(), false).unwrap()
                 });

compiler/rustc_codegen_ssa/src/mir/operand.rs

@@ -105,7 +105,10 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
                     bug!("from_const: invalid ScalarPair layout: {:#?}", layout);
                 };
                 let a = Scalar::from_pointer(
-                    Pointer::new(bx.tcx().create_memory_alloc(data), Size::from_bytes(start)),
+                    Pointer::new(
+                        bx.tcx().reserve_and_set_memory_alloc(data),
+                        Size::from_bytes(start),
+                    ),
                     &bx.tcx(),
                 );
                 let a_llval = bx.scalar_to_backend(
@@ -118,7 +121,6 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
             }
             ConstValue::Indirect { alloc_id, offset } => {
                 let alloc = bx.tcx().global_alloc(alloc_id).unwrap_memory();
-                // FIXME: should we attempt to avoid building the same AllocId multiple times?
                 return Self::from_const_alloc(bx, layout, alloc, offset);
             }
         };
@@ -184,6 +186,8 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
             _ if layout.is_zst() => OperandRef::zero_sized(layout),
             _ => {
                 // Neither a scalar nor scalar pair. Load from a place
+                // FIXME: should we cache `const_data_from_alloc` to avoid repeating this for the
+                // same `ConstAllocation`?
                 let init = bx.const_data_from_alloc(alloc);
                 let base_addr = bx.static_addr_of(init, alloc_align, None);
 

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -84,7 +84,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         )
                         .ok_or_else(|| err_inval!(TooGeneric))?;
 
-                        let fn_ptr = self.create_fn_alloc_ptr(FnVal::Instance(instance));
+                        let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
                     }
                     _ => span_bug!(self.cur_span(), "reify fn pointer on {:?}", src.layout.ty),
@@ -116,7 +116,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             ty::ClosureKind::FnOnce,
                         )
                         .ok_or_else(|| err_inval!(TooGeneric))?;
-                        let fn_ptr = self.create_fn_alloc_ptr(FnVal::Instance(instance));
+                        let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
                     }
                     _ => span_bug!(self.cur_span(), "closure fn pointer on {:?}", src.layout.ty),

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -555,7 +555,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
         def_id: DefId,
     ) -> InterpResult<$tcx, Pointer> {
         // Use the `AllocId` associated with the `DefId`. Any actual *access* will fail.
-        Ok(Pointer::new(ecx.tcx.create_static_alloc(def_id), Size::ZERO))
+        Ok(Pointer::new(ecx.tcx.reserve_and_set_static_alloc(def_id), Size::ZERO))
     }
 
     #[inline(always)]

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -176,12 +176,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         M::adjust_alloc_base_pointer(self, ptr)
     }
 
-    pub fn create_fn_alloc_ptr(
-        &mut self,
-        fn_val: FnVal<'tcx, M::ExtraFnVal>,
-    ) -> Pointer<M::Provenance> {
+    pub fn fn_ptr(&mut self, fn_val: FnVal<'tcx, M::ExtraFnVal>) -> Pointer<M::Provenance> {
         let id = match fn_val {
-            FnVal::Instance(instance) => self.tcx.create_fn_alloc(instance),
+            FnVal::Instance(instance) => self.tcx.reserve_and_set_fn_alloc(instance),
             FnVal::Other(extra) => {
                 // FIXME(RalfJung): Should we have a cache here?
                 let id = self.tcx.reserve_alloc_id();

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -768,7 +768,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // We rely on mutability being set correctly in `data` to prevent writes
                 // where none should happen.
                 let ptr = Pointer::new(
-                    self.tcx.create_memory_alloc(data),
+                    self.tcx.reserve_and_set_memory_alloc(data),
                     Size::from_bytes(start), // offset: `start`
                 );
                 Operand::Immediate(Immediate::new_slice(

compiler/rustc_const_eval/src/interpret/traits.rs

@@ -27,7 +27,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         ensure_monomorphic_enough(*self.tcx, ty)?;
         ensure_monomorphic_enough(*self.tcx, poly_trait_ref)?;
 
-        let vtable_symbolic_allocation = self.tcx.create_vtable_alloc(ty, poly_trait_ref);
+        let vtable_symbolic_allocation = self.tcx.reserve_and_set_vtable_alloc(ty, poly_trait_ref);
         let vtable_ptr = self.global_base_pointer(Pointer::from(vtable_symbolic_allocation))?;
         Ok(vtable_ptr.into())
     }

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -389,7 +389,7 @@ impl<'s> AllocDecodingSession<'s> {
                     trace!("creating fn alloc ID");
                     let instance = ty::Instance::decode(decoder);
                     trace!("decoded fn alloc instance: {:?}", instance);
-                    let alloc_id = decoder.interner().create_fn_alloc(instance);
+                    let alloc_id = decoder.interner().reserve_and_set_fn_alloc(instance);
                     alloc_id
                 }
                 AllocDiscriminant::VTable => {
@@ -399,15 +399,16 @@ impl<'s> AllocDecodingSession<'s> {
                     let poly_trait_ref =
                         <Option<ty::PolyExistentialTraitRef<'_>> as Decodable<D>>::decode(decoder);
                     trace!("decoded vtable alloc instance: {ty:?}, {poly_trait_ref:?}");
-                    let alloc_id = decoder.interner().create_vtable_alloc(ty, poly_trait_ref);
+                    let alloc_id =
+                        decoder.interner().reserve_and_set_vtable_alloc(ty, poly_trait_ref);
                     alloc_id
                 }
                 AllocDiscriminant::Static => {
                     assert!(alloc_id.is_none());
                     trace!("creating extern static alloc ID");
                     let did = <DefId as Decodable<D>>::decode(decoder);
                     trace!("decoded static def-ID: {:?}", did);
-                    let alloc_id = decoder.interner().create_static_alloc(did);
+                    let alloc_id = decoder.interner().reserve_and_set_static_alloc(did);
                     alloc_id
                 }
             }
@@ -544,13 +545,13 @@ impl<'tcx> TyCtxt<'tcx> {
 
     /// Generates an `AllocId` for a static or return a cached one in case this function has been
     /// called on the same static before.
-    pub fn create_static_alloc(self, static_id: DefId) -> AllocId {
+    pub fn reserve_and_set_static_alloc(self, static_id: DefId) -> AllocId {
         self.reserve_and_set_dedup(GlobalAlloc::Static(static_id))
     }
 
     /// Generates an `AllocId` for a function. Depending on the function type,
     /// this might get deduplicated or assigned a new ID each time.
-    pub fn create_fn_alloc(self, instance: Instance<'tcx>) -> AllocId {
+    pub fn reserve_and_set_fn_alloc(self, instance: Instance<'tcx>) -> AllocId {
         // Functions cannot be identified by pointers, as asm-equal functions can get deduplicated
         // by the linker (we set the "unnamed_addr" attribute for LLVM) and functions can be
         // duplicated across crates.
@@ -575,7 +576,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     /// Generates an `AllocId` for a (symbolic, not-reified) vtable. Will get deduplicated.
-    pub fn create_vtable_alloc(
+    pub fn reserve_and_set_vtable_alloc(
         self,
         ty: Ty<'tcx>,
         poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
@@ -588,7 +589,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Statics with identical content will still point to the same `Allocation`, i.e.,
     /// their data will be deduplicated through `Allocation` interning -- but they
     /// are different places in memory and as such need different IDs.
-    pub fn create_memory_alloc(self, mem: ConstAllocation<'tcx>) -> AllocId {
+    pub fn reserve_and_set_memory_alloc(self, mem: ConstAllocation<'tcx>) -> AllocId {
         let id = self.reserve_alloc_id();
         self.set_alloc_id_memory(id, mem);
         id

compiler/rustc_middle/src/ty/context.rs

@@ -647,7 +647,7 @@ impl<'tcx> TyCtxt<'tcx> {
         // Create an allocation that just contains these bytes.
         let alloc = interpret::Allocation::from_bytes_byte_aligned_immutable(bytes);
         let alloc = self.mk_const_alloc(alloc);
-        self.create_memory_alloc(alloc)
+        self.reserve_and_set_memory_alloc(alloc)
     }
 
     /// Returns a range of the start/end indices specified with the

compiler/rustc_middle/src/ty/vtable.rs

@@ -84,7 +84,7 @@ pub(super) fn vtable_allocation_provider<'tcx>(
         let scalar = match entry {
             VtblEntry::MetadataDropInPlace => {
                 let instance = ty::Instance::resolve_drop_in_place(tcx, ty);
-                let fn_alloc_id = tcx.create_fn_alloc(instance);
+                let fn_alloc_id = tcx.reserve_and_set_fn_alloc(instance);
                 let fn_ptr = Pointer::from(fn_alloc_id);
                 Scalar::from_pointer(fn_ptr, &tcx)
             }
@@ -94,7 +94,7 @@ pub(super) fn vtable_allocation_provider<'tcx>(
             VtblEntry::Method(instance) => {
                 // Prepare the fn ptr we write into the vtable.
                 let instance = instance.polymorphize(tcx);
-                let fn_alloc_id = tcx.create_fn_alloc(instance);
+                let fn_alloc_id = tcx.reserve_and_set_fn_alloc(instance);
                 let fn_ptr = Pointer::from(fn_alloc_id);
                 Scalar::from_pointer(fn_ptr, &tcx)
             }
@@ -112,5 +112,5 @@ pub(super) fn vtable_allocation_provider<'tcx>(
     }
 
     vtable.mutability = Mutability::Not;
-    tcx.create_memory_alloc(tcx.mk_const_alloc(vtable))
+    tcx.reserve_and_set_memory_alloc(tcx.mk_const_alloc(vtable))
 }

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -950,7 +950,7 @@ impl<'tcx> Cx<'tcx> {
                 let kind = if self.tcx.is_thread_local_static(id) {
                     ExprKind::ThreadLocalRef(id)
                 } else {
-                    let alloc_id = self.tcx.create_static_alloc(id);
+                    let alloc_id = self.tcx.reserve_and_set_static_alloc(id);
                     ExprKind::StaticRef { alloc_id, ty, def_id: id }
                 };
                 ExprKind::Deref {

compiler/rustc_mir_transform/src/large_enums.rs

@@ -114,7 +114,7 @@ impl EnumSizeOpt {
             tcx.data_layout.ptr_sized_integer().align(&tcx.data_layout).abi,
             Mutability::Not,
         );
-        let alloc = tcx.create_memory_alloc(tcx.mk_const_alloc(alloc));
+        let alloc = tcx.reserve_and_set_memory_alloc(tcx.mk_const_alloc(alloc));
         Some((*adt_def, num_discrs, *alloc_cache.entry(ty).or_insert(alloc)))
     }
     fn optim<'tcx>(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {

compiler/rustc_smir/src/rustc_smir/alloc.rs

@@ -45,7 +45,7 @@ pub fn new_allocation<'tcx>(
             new_empty_allocation(align.abi)
         }
         ConstValue::Slice { data, start, end } => {
-            let alloc_id = tables.tcx.create_memory_alloc(data);
+            let alloc_id = tables.tcx.reserve_and_set_memory_alloc(data);
             let ptr = Pointer::new(alloc_id, rustc_target::abi::Size::from_bytes(start));
             let scalar_ptr = rustc_middle::mir::interpret::Scalar::from_pointer(ptr, &tables.tcx);
             let scalar_len = rustc_middle::mir::interpret::Scalar::from_target_usize(

src/tools/miri/src/eval.rs

@@ -382,7 +382,7 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
             .unwrap()
             .unwrap();
 
-            let main_ptr = ecx.create_fn_alloc_ptr(FnVal::Instance(entry_instance));
+            let main_ptr = ecx.fn_ptr(FnVal::Instance(entry_instance));
 
             // Inlining of `DEFAULT` from
             // https://github.com/rust-lang/rust/blob/master/compiler/rustc_session/src/config/sigpipe.rs.

src/tools/miri/src/machine.rs

@@ -711,7 +711,7 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
                 let layout = this.machine.layouts.const_raw_ptr;
                 let dlsym = Dlsym::from_str("signal".as_bytes(), &this.tcx.sess.target.os)?
                     .expect("`signal` must be an actual dlsym on android");
-                let ptr = this.create_fn_alloc_ptr(FnVal::Other(dlsym));
+                let ptr = this.fn_ptr(FnVal::Other(dlsym));
                 let val = ImmTy::from_scalar(Scalar::from_pointer(ptr, this), layout);
                 Self::alloc_extern_static(this, "signal", val)?;
                 // A couple zero-initialized pointer-sized extern statics.

src/tools/miri/src/shims/backtrace.rs

@@ -63,7 +63,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
                 // Note that we never actually read or write anything from/to this pointer -
                 // all of the data is represented by the pointer value itself.
-                let fn_ptr = this.create_fn_alloc_ptr(FnVal::Instance(instance));
+                let fn_ptr = this.fn_ptr(FnVal::Instance(instance));
                 fn_ptr.wrapping_offset(Size::from_bytes(pos.0), this)
             })
             .collect();
@@ -159,7 +159,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
 
         // Reconstruct the original function pointer,
         // which we pass to user code.
-        let fn_ptr = this.create_fn_alloc_ptr(FnVal::Instance(fn_instance));
+        let fn_ptr = this.fn_ptr(FnVal::Instance(fn_instance));
 
         let num_fields = dest.layout.fields.count();
 

src/tools/miri/src/shims/unix/foreign_items.rs

@@ -232,7 +232,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 let symbol = this.read_pointer(symbol)?;
                 let symbol_name = this.read_c_str(symbol)?;
                 if let Some(dlsym) = Dlsym::from_str(symbol_name, &this.tcx.sess.target.os)? {
-                    let ptr = this.create_fn_alloc_ptr(FnVal::Other(dlsym));
+                    let ptr = this.fn_ptr(FnVal::Other(dlsym));
                     this.write_pointer(ptr, dest)?;
                 } else {
                     this.write_null(dest)?;

src/tools/miri/src/shims/windows/foreign_items.rs

@@ -335,7 +335,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 this.read_target_isize(hModule)?;
                 let name = this.read_c_str(this.read_pointer(lpProcName)?)?;
                 if let Some(dlsym) = Dlsym::from_str(name, &this.tcx.sess.target.os)? {
-                    let ptr = this.create_fn_alloc_ptr(FnVal::Other(dlsym));
+                    let ptr = this.fn_ptr(FnVal::Other(dlsym));
                     this.write_pointer(ptr, dest)?;
                 } else {
                     this.write_null(dest)?;