remove size field from Allocation

Author: RalfJung

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

@@ -27,8 +27,6 @@ pub struct Allocation<Tag = (), Extra = ()> {
     relocations: Relocations<Tag>,
     /// Denotes which part of this allocation is initialized.
     init_mask: InitMask,
-    /// The size of the allocation. Currently, must always equal `bytes.len()`.
-    pub size: Size,
     /// The alignment of the allocation to detect unaligned reads.
     /// (`Align` guarantees that this is a power of two.)
     pub align: Align,
@@ -94,7 +92,6 @@ impl<Tag> Allocation<Tag> {
             bytes,
             relocations: Relocations::new(),
             init_mask: InitMask::new(size, true),
-            size,
             align,
             mutability: Mutability::Not,
             extra: (),
@@ -110,7 +107,6 @@ impl<Tag> Allocation<Tag> {
             bytes: vec![0; size.bytes_usize()],
             relocations: Relocations::new(),
             init_mask: InitMask::new(size, false),
-            size,
             align,
             mutability: Mutability::Mut,
             extra: (),
@@ -127,7 +123,6 @@ impl Allocation<(), ()> {
     ) -> Allocation<T, E> {
         Allocation {
             bytes: self.bytes,
-            size: self.size,
             relocations: Relocations::from_presorted(
                 self.relocations
                     .iter()
@@ -150,7 +145,11 @@ impl Allocation<(), ()> {
 /// Raw accessors. Provide access to otherwise private bytes.
 impl<Tag, Extra> Allocation<Tag, Extra> {
     pub fn len(&self) -> usize {
-        self.size.bytes_usize()
+        self.bytes.len()
+    }
+
+    pub fn size(&self) -> Size {
+        Size::from_bytes(self.len())
     }
 
     /// Looks at a slice which may describe uninitialized bytes or describe a relocation. This differs

compiler/rustc_mir/src/interpret/memory.rs

@@ -244,7 +244,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         let new_ptr = self.allocate(new_size, new_align, kind);
         let old_size = match old_size_and_align {
             Some((size, _align)) => size,
-            None => self.get_raw(ptr.alloc_id)?.size,
+            None => self.get_raw(ptr.alloc_id)?.size(),
         };
         self.copy(ptr, new_ptr, old_size.min(new_size), /*nonoverlapping*/ true)?;
         self.deallocate(ptr, old_size_and_align, kind)?;
@@ -306,11 +306,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             );
         }
         if let Some((size, align)) = old_size_and_align {
-            if size != alloc.size || align != alloc.align {
+            if size != alloc.size() || align != alloc.align {
                 throw_ub_format!(
                     "incorrect layout on deallocation: {} has size {} and alignment {}, but gave size {} and alignment {}",
                     ptr.alloc_id,
-                    alloc.size.bytes(),
+                    alloc.size().bytes(),
                     alloc.align.bytes(),
                     size.bytes(),
                     align.bytes(),
@@ -319,11 +319,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         }
 
         // Let the machine take some extra action
-        let size = alloc.size;
+        let size = alloc.size();
         AllocationExtra::memory_deallocated(&mut alloc, ptr, size)?;
 
         // Don't forget to remember size and align of this now-dead allocation
-        let old = self.dead_alloc_map.insert(ptr.alloc_id, (alloc.size, alloc.align));
+        let old = self.dead_alloc_map.insert(ptr.alloc_id, (alloc.size(), alloc.align));
         if old.is_some() {
             bug!("Nothing can be deallocated twice");
         }
@@ -586,7 +586,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         // a) cause cycles in case `id` refers to a static
         // b) duplicate a global's allocation in miri
         if let Some((_, alloc)) = self.alloc_map.get(id) {
-            return Ok((alloc.size, alloc.align));
+            return Ok((alloc.size(), alloc.align));
         }
 
         // # Function pointers
@@ -614,7 +614,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Some(GlobalAlloc::Memory(alloc)) => {
                 // Need to duplicate the logic here, because the global allocations have
                 // different associated types than the interpreter-local ones.
-                Ok((alloc.size, alloc.align))
+                Ok((alloc.size(), alloc.align))
             }
             Some(GlobalAlloc::Function(_)) => bug!("We already checked function pointers above"),
             // The rest must be dead.

compiler/rustc_mir/src/util/pretty.rs

@@ -776,8 +776,8 @@ pub struct RenderAllocation<'a, 'tcx, Tag, Extra> {
 impl<Tag: Copy + Debug, Extra> std::fmt::Display for RenderAllocation<'a, 'tcx, Tag, Extra> {
     fn fmt(&self, w: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let RenderAllocation { tcx, alloc } = *self;
-        write!(w, "size: {}, align: {})", alloc.size.bytes(), alloc.align.bytes())?;
-        if alloc.size == Size::ZERO {
+        write!(w, "size: {}, align: {})", alloc.size().bytes(), alloc.align.bytes())?;
+        if alloc.size() == Size::ZERO {
             // We are done.
             return write!(w, " {{}}");
         }
@@ -822,9 +822,9 @@ fn write_allocation_bytes<Tag: Copy + Debug, Extra>(
     w: &mut dyn std::fmt::Write,
     prefix: &str,
 ) -> std::fmt::Result {
-    let num_lines = alloc.size.bytes_usize().saturating_sub(BYTES_PER_LINE);
+    let num_lines = alloc.size().bytes_usize().saturating_sub(BYTES_PER_LINE);
     // Number of chars needed to represent all line numbers.
-    let pos_width = format!("{:x}", alloc.size.bytes()).len();
+    let pos_width = format!("{:x}", alloc.size().bytes()).len();
 
     if num_lines > 0 {
         write!(w, "{}0x{:02$x} │ ", prefix, 0, pos_width)?;
@@ -845,7 +845,7 @@ fn write_allocation_bytes<Tag: Copy + Debug, Extra>(
         }
     };
 
-    while i < alloc.size {
+    while i < alloc.size() {
         // The line start already has a space. While we could remove that space from the line start
         // printing and unconditionally print a space here, that would cause the single-line case
         // to have a single space before it, which looks weird.
@@ -929,7 +929,7 @@ fn write_allocation_bytes<Tag: Copy + Debug, Extra>(
             i += Size::from_bytes(1);
         }
         // Print a new line header if the next line still has some bytes to print.
-        if i == line_start + Size::from_bytes(BYTES_PER_LINE) && i != alloc.size {
+        if i == line_start + Size::from_bytes(BYTES_PER_LINE) && i != alloc.size() {
             line_start = write_allocation_newline(w, line_start, &ascii, pos_width, prefix)?;
             ascii.clear();
         }