Rollup merge of #85412 - RalfJung:c_str, r=oli-obk

remove some functions that were only used by Miri

and Miri does not need them any more with rust-lang/miri#1805.

r? `@oli-obk`

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

@@ -275,29 +275,6 @@ impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
 
 /// Reading and writing.
 impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
-    /// Reads bytes until a `0` is encountered. Will error if the end of the allocation is reached
-    /// before a `0` is found.
-    ///
-    /// Most likely, you want to call `Memory::read_c_str` instead of this method.
-    pub fn read_c_str(
-        &self,
-        cx: &impl HasDataLayout,
-        ptr: Pointer<Tag>,
-    ) -> InterpResult<'tcx, &[u8]> {
-        let offset = ptr.offset.bytes_usize();
-        Ok(match self.bytes[offset..].iter().position(|&c| c == 0) {
-            Some(size) => {
-                let size_with_null = Size::from_bytes(size) + Size::from_bytes(1);
-                // Go through `get_bytes` for checks and AllocationExtra hooks.
-                // We read the null, so we include it in the request, but we want it removed
-                // from the result, so we do subslicing.
-                &self.get_bytes(cx, ptr, size_with_null)?[..size]
-            }
-            // This includes the case where `offset` is out-of-bounds to begin with.
-            None => throw_ub!(UnterminatedCString(ptr.erase_tag())),
-        })
-    }
-
     /// Validates that `ptr.offset` and `ptr.offset + size` do not point to the middle of a
     /// relocation. If `allow_uninit_and_ptr` is `false`, also enforces that the memory in the
     /// given range contains neither relocations nor uninitialized bytes.

compiler/rustc_mir/src/interpret/memory.rs

@@ -804,41 +804,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         self.get_raw(ptr.alloc_id)?.get_bytes(self, ptr, size)
     }
 
-    /// Reads a 0-terminated sequence of bytes from memory. Returns them as a slice.
-    ///
-    /// Performs appropriate bounds checks.
-    pub fn read_c_str(&self, ptr: Scalar<M::PointerTag>) -> InterpResult<'tcx, &[u8]> {
-        let ptr = self.force_ptr(ptr)?; // We need to read at least 1 byte, so we *need* a ptr.
-        self.get_raw(ptr.alloc_id)?.read_c_str(self, ptr)
-    }
-
-    /// Reads a 0x0000-terminated u16-sequence from memory. Returns them as a Vec<u16>.
-    /// Terminator 0x0000 is not included in the returned Vec<u16>.
-    ///
-    /// Performs appropriate bounds checks.
-    pub fn read_wide_str(&self, ptr: Scalar<M::PointerTag>) -> InterpResult<'tcx, Vec<u16>> {
-        let size_2bytes = Size::from_bytes(2);
-        let align_2bytes = Align::from_bytes(2).unwrap();
-        // We need to read at least 2 bytes, so we *need* a ptr.
-        let mut ptr = self.force_ptr(ptr)?;
-        let allocation = self.get_raw(ptr.alloc_id)?;
-        let mut u16_seq = Vec::new();
-
-        loop {
-            ptr = self
-                .check_ptr_access(ptr.into(), size_2bytes, align_2bytes)?
-                .expect("cannot be a ZST");
-            let single_u16 = allocation.read_scalar(self, ptr, size_2bytes)?.to_u16()?;
-            if single_u16 != 0x0000 {
-                u16_seq.push(single_u16);
-                ptr = ptr.offset(size_2bytes, self)?;
-            } else {
-                break;
-            }
-        }
-        Ok(u16_seq)
-    }
-
     /// Writes the given stream of bytes into memory.
     ///
     /// Performs appropriate bounds checks.
@@ -866,46 +831,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         self.get_raw_mut(ptr.alloc_id)?.write_bytes(&tcx, ptr, src)
     }
 
-    /// Writes the given stream of u16s into memory.
-    ///
-    /// Performs appropriate bounds checks.
-    pub fn write_u16s(
-        &mut self,
-        ptr: Scalar<M::PointerTag>,
-        src: impl IntoIterator<Item = u16>,
-    ) -> InterpResult<'tcx> {
-        let mut src = src.into_iter();
-        let (lower, upper) = src.size_hint();
-        let len = upper.expect("can only write bounded iterators");
-        assert_eq!(lower, len, "can only write iterators with a precise length");
-
-        let size = Size::from_bytes(lower);
-        let ptr = match self.check_ptr_access(ptr, size, Align::from_bytes(2).unwrap())? {
-            Some(ptr) => ptr,
-            None => {
-                // zero-sized access
-                assert_matches!(
-                    src.next(),
-                    None,
-                    "iterator said it was empty but returned an element"
-                );
-                return Ok(());
-            }
-        };
-        let tcx = self.tcx;
-        let allocation = self.get_raw_mut(ptr.alloc_id)?;
-
-        for idx in 0..len {
-            let val = Scalar::from_u16(
-                src.next().expect("iterator was shorter than it said it would be"),
-            );
-            let offset_ptr = ptr.offset(Size::from_bytes(idx) * 2, &tcx)?; // `Size` multiplication
-            allocation.write_scalar(&tcx, offset_ptr, val.into(), Size::from_bytes(2))?;
-        }
-        assert_matches!(src.next(), None, "iterator was longer than it said it would be");
-        Ok(())
-    }
-
     /// Expects the caller to have checked bounds and alignment.
     pub fn copy(
         &mut self,