Rollup merge of rust-lang#95620 - RalfJung:memory-no-extras, r=oli-obk

interpret: remove MemoryExtra in favor of giving access to the Machine

The Miri PR for this is upcoming.

r? ``@oli-obk``

Author: Dylan-DPC

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -1,4 +1,4 @@
-use super::{CompileTimeEvalContext, CompileTimeInterpreter, ConstEvalErr, MemoryExtra};
+use super::{CompileTimeEvalContext, CompileTimeInterpreter, ConstEvalErr};
 use crate::interpret::eval_nullary_intrinsic;
 use crate::interpret::{
     intern_const_alloc_recursive, Allocation, ConstAlloc, ConstValue, CtfeValidationMode, GlobalId,
@@ -100,8 +100,7 @@ pub(super) fn mk_eval_cx<'mir, 'tcx>(
         tcx,
         root_span,
         param_env,
-        CompileTimeInterpreter::new(tcx.const_eval_limit()),
-        MemoryExtra { can_access_statics },
+        CompileTimeInterpreter::new(tcx.const_eval_limit(), can_access_statics),
     )
 }
 
@@ -285,10 +284,9 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
         tcx,
         tcx.def_span(def.did),
         key.param_env,
-        CompileTimeInterpreter::new(tcx.const_eval_limit()),
         // Statics (and promoteds inside statics) may access other statics, because unlike consts
         // they do not have to behave "as if" they were evaluated at runtime.
-        MemoryExtra { can_access_statics: is_static },
+        CompileTimeInterpreter::new(tcx.const_eval_limit(), /*can_access_statics:*/ is_static),
     );
 
     let res = ecx.load_mir(cid.instance.def, cid.promoted);

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -93,10 +93,7 @@ pub struct CompileTimeInterpreter<'mir, 'tcx> {
 
     /// The virtual call stack.
     pub(crate) stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>,
-}
 
-#[derive(Copy, Clone, Debug)]
-pub struct MemoryExtra {
     /// We need to make sure consts never point to anything mutable, even recursively. That is
     /// relied on for pattern matching on consts with references.
     /// To achieve this, two pieces have to work together:
@@ -107,8 +104,12 @@ pub struct MemoryExtra {
 }
 
 impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx> {
-    pub(super) fn new(const_eval_limit: Limit) -> Self {
-        CompileTimeInterpreter { steps_remaining: const_eval_limit.0, stack: Vec::new() }
+    pub(super) fn new(const_eval_limit: Limit, can_access_statics: bool) -> Self {
+        CompileTimeInterpreter {
+            steps_remaining: const_eval_limit.0,
+            stack: Vec::new(),
+            can_access_statics,
+        }
     }
 }
 
@@ -233,8 +234,6 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
 
     type MemoryKind = MemoryKind;
 
-    type MemoryExtra = MemoryExtra;
-
     const PANIC_ON_ALLOC_FAIL: bool = false; // will be raised as a proper error
 
     fn load_mir(
@@ -345,7 +344,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
                     Err(err) => throw_ub_format!("align has to be a power of 2, {}", err),
                 };
 
-                let ptr = ecx.memory.allocate(
+                let ptr = ecx.allocate_ptr(
                     Size::from_bytes(size as u64),
                     align,
                     interpret::MemoryKind::Machine(MemoryKind::Heap),
@@ -365,14 +364,14 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
 
                 // If an allocation is created in an another const,
                 // we don't deallocate it.
-                let (alloc_id, _, _) = ecx.memory.ptr_get_alloc(ptr)?;
+                let (alloc_id, _, _) = ecx.ptr_get_alloc_id(ptr)?;
                 let is_allocated_in_another_const = matches!(
                     ecx.tcx.get_global_alloc(alloc_id),
                     Some(interpret::GlobalAlloc::Memory(_))
                 );
 
                 if !is_allocated_in_another_const {
-                    ecx.memory.deallocate(
+                    ecx.deallocate_ptr(
                         ptr,
                         Some((size, align)),
                         interpret::MemoryKind::Machine(MemoryKind::Heap),
@@ -472,7 +471,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
     }
 
     fn before_access_global(
-        memory_extra: &MemoryExtra,
+        machine: &Self,
         alloc_id: AllocId,
         alloc: ConstAllocation<'tcx>,
         static_def_id: Option<DefId>,
@@ -488,7 +487,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
             }
         } else {
             // Read access. These are usually allowed, with some exceptions.
-            if memory_extra.can_access_statics {
+            if machine.can_access_statics {
                 // Machine configuration allows us read from anything (e.g., `static` initializer).
                 Ok(())
             } else if static_def_id.is_some() {

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -56,7 +56,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         )
                         .ok_or_else(|| err_inval!(TooGeneric))?;
 
-                        let fn_ptr = self.memory.create_fn_alloc(FnVal::Instance(instance));
+                        let fn_ptr = self.create_fn_alloc_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
                     }
                     _ => span_bug!(self.cur_span(), "reify fn pointer on {:?}", src.layout.ty),
@@ -87,7 +87,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             substs,
                             ty::ClosureKind::FnOnce,
                         );
-                        let fn_ptr = self.memory.create_fn_alloc(FnVal::Instance(instance));
+                        let fn_ptr = self.create_fn_alloc_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
                     }
                     _ => span_bug!(self.cur_span(), "closure fn pointer on {:?}", src.layout.ty),
@@ -153,8 +153,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 return Ok(**src);
             } else {
                 // Casting the metadata away from a fat ptr.
-                assert_eq!(src.layout.size, 2 * self.memory.pointer_size());
-                assert_eq!(dest_layout.size, self.memory.pointer_size());
+                assert_eq!(src.layout.size, 2 * self.pointer_size());
+                assert_eq!(dest_layout.size, self.pointer_size());
                 assert!(src.layout.ty.is_unsafe_ptr());
                 return match **src {
                     Immediate::ScalarPair(data, _) => Ok(data.into()),

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -22,9 +22,9 @@ use rustc_span::{Pos, Span};
 use rustc_target::abi::{call::FnAbi, Align, HasDataLayout, Size, TargetDataLayout};
 
 use super::{
-    AllocCheck, AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine,
-    MemPlace, MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, Pointer,
-    PointerArithmetic, Provenance, Scalar, ScalarMaybeUninit, StackPopJump,
+    AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace,
+    MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, PointerArithmetic, Provenance,
+    Scalar, ScalarMaybeUninit, StackPopJump,
 };
 use crate::transform::validate::equal_up_to_regions;
 
@@ -413,13 +413,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         root_span: Span,
         param_env: ty::ParamEnv<'tcx>,
         machine: M,
-        memory_extra: M::MemoryExtra,
     ) -> Self {
         InterpCx {
             machine,
             tcx: tcx.at(root_span),
             param_env,
-            memory: Memory::new(tcx, memory_extra),
+            memory: Memory::new(),
             recursion_limit: tcx.recursion_limit(),
         }
     }
@@ -433,49 +432,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             .map_or(self.tcx.span, |f| f.current_span())
     }
 
-    #[inline(always)]
-    pub fn scalar_to_ptr(&self, scalar: Scalar<M::PointerTag>) -> Pointer<Option<M::PointerTag>> {
-        self.memory.scalar_to_ptr(scalar)
-    }
-
-    /// Test if this value might be null.
-    /// If the machine does not support ptr-to-int casts, this is conservative.
-    pub fn scalar_may_be_null(&self, scalar: Scalar<M::PointerTag>) -> bool {
-        match scalar.try_to_int() {
-            Ok(int) => int.is_null(),
-            Err(_) => {
-                // Can only happen during CTFE.
-                let ptr = self.scalar_to_ptr(scalar);
-                match self.memory.ptr_try_get_alloc(ptr) {
-                    Ok((alloc_id, offset, _)) => {
-                        let (size, _align) = self
-                            .memory
-                            .get_size_and_align(alloc_id, AllocCheck::MaybeDead)
-                            .expect("alloc info with MaybeDead cannot fail");
-                        // If the pointer is out-of-bounds, it may be null.
-                        // Note that one-past-the-end (offset == size) is still inbounds, and never null.
-                        offset > size
-                    }
-                    Err(_offset) => bug!("a non-int scalar is always a pointer"),
-                }
-            }
-        }
-    }
-
-    /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
-    /// the machine pointer to the allocation.  Must never be used
-    /// for any other pointers, nor for TLS statics.
-    ///
-    /// Using the resulting pointer represents a *direct* access to that memory
-    /// (e.g. by directly using a `static`),
-    /// as opposed to access through a pointer that was created by the program.
-    ///
-    /// This function can fail only if `ptr` points to an `extern static`.
-    #[inline(always)]
-    pub fn global_base_pointer(&self, ptr: Pointer) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
-        self.memory.global_base_pointer(ptr)
-    }
-
     #[inline(always)]
     pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] {
         M::stack(self)
@@ -949,9 +905,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             trace!(
                 "deallocating local {:?}: {:?}",
                 local,
-                self.memory.dump_alloc(ptr.provenance.unwrap().get_alloc_id())
+                self.dump_alloc(ptr.provenance.unwrap().get_alloc_id())
             );
-            self.memory.deallocate(ptr, None, MemoryKind::Stack)?;
+            self.deallocate_ptr(ptr, None, MemoryKind::Stack)?;
         };
         Ok(())
     }
@@ -1057,15 +1013,15 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug
                     }
                 }
 
-                write!(fmt, ": {:?}", self.ecx.memory.dump_allocs(allocs))
+                write!(fmt, ": {:?}", self.ecx.dump_allocs(allocs))
             }
             Place::Ptr(mplace) => match mplace.ptr.provenance.map(Provenance::get_alloc_id) {
                 Some(alloc_id) => write!(
                     fmt,
                     "by align({}) ref {:?}: {:?}",
                     mplace.align.bytes(),
                     mplace.ptr,
-                    self.ecx.memory.dump_alloc(alloc_id)
+                    self.ecx.dump_alloc(alloc_id)
                 ),
                 ptr => write!(fmt, " integral by ref: {:?}", ptr),
             },

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -318,7 +318,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // exception from the exception.)
                 // This is the dual to the special exception for offset-by-0
                 // in the inbounds pointer offset operation (see `ptr_offset_inbounds` below).
-                match (self.memory.ptr_try_get_alloc(a), self.memory.ptr_try_get_alloc(b)) {
+                match (self.ptr_try_get_alloc_id(a), self.ptr_try_get_alloc_id(b)) {
                     (Err(a), Err(b)) if a == b && a != 0 => {
                         // Both are the same non-null integer.
                         self.write_scalar(Scalar::from_machine_isize(0, self), dest)?;
@@ -335,13 +335,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             );
                         }
                         // And they must both be valid for zero-sized accesses ("in-bounds or one past the end").
-                        self.memory.check_ptr_access_align(
+                        self.check_ptr_access_align(
                             a,
                             Size::ZERO,
                             Align::ONE,
                             CheckInAllocMsg::OffsetFromTest,
                         )?;
-                        self.memory.check_ptr_access_align(
+                        self.check_ptr_access_align(
                             b,
                             Size::ZERO,
                             Align::ONE,
@@ -545,7 +545,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let min_ptr = if offset_bytes >= 0 { ptr } else { offset_ptr };
         let size = offset_bytes.unsigned_abs();
         // This call handles checking for integer/null pointers.
-        self.memory.check_ptr_access_align(
+        self.check_ptr_access_align(
             min_ptr,
             Size::from_bytes(size),
             Align::ONE,
@@ -577,7 +577,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let src = self.read_pointer(&src)?;
         let dst = self.read_pointer(&dst)?;
 
-        self.memory.copy(src, align, dst, align, size, nonoverlapping)
+        self.mem_copy(src, align, dst, align, size, nonoverlapping)
     }
 
     pub(crate) fn write_bytes_intrinsic(
@@ -600,7 +600,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             .ok_or_else(|| err_ub_format!("overflow computing total size of `write_bytes`"))?;
 
         let bytes = std::iter::repeat(byte).take(len.bytes_usize());
-        self.memory.write_bytes(dst, bytes)
+        self.write_bytes_ptr(dst, bytes)
     }
 
     pub(crate) fn raw_eq_intrinsic(
@@ -613,8 +613,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         let lhs = self.read_pointer(lhs)?;
         let rhs = self.read_pointer(rhs)?;
-        let lhs_bytes = self.memory.read_bytes(lhs, layout.size)?;
-        let rhs_bytes = self.memory.read_bytes(rhs, layout.size)?;
+        let lhs_bytes = self.read_bytes_ptr(lhs, layout.size)?;
+        let rhs_bytes = self.read_bytes_ptr(rhs, layout.size)?;
         Ok(Scalar::from_bool(lhs_bytes == rhs_bytes))
     }
 }