use element count in slices, not size in bytes

This allows the indexing bounds check or other comparisons against an
element length to avoid a multiplication by the size.

3 files changed, 109 insertions, 21 deletions

diff --git a/src/libstd/rand/mod.rs b/src/libstd/rand/mod.rs
index b800c7b03af..1e76effd0d2 100644
--- a/src/libstd/rand/mod.rs
+++ b/src/libstd/rand/mod.rs
@@ -52,6 +52,8 @@ fn main () {
  ```
 */
 
+use sys::size_of;
+use unstable::raw::Slice;
 use cast;
 use container::Container;
 use iter::{Iterator, range};
@@ -133,10 +135,10 @@ pub trait Rng {
     ///    println!("{:?}", v);
     /// }
     /// ```
-    fn fill_bytes(&mut self, mut dest: &mut [u8]) {
-        // this relies on the lengths being transferred correctly when
-        // transmuting between vectors like this.
-        let as_u64: &mut &mut [u64] = unsafe { cast::transmute(&mut dest) };
+    fn fill_bytes(&mut self, dest: &mut [u8]) {
+        let mut slice: Slice<u64> = unsafe { cast::transmute_copy(&dest) };
+        slice.len /= size_of::<u64>();
+        let as_u64: &mut [u64] = unsafe { cast::transmute(slice) };
         for dest in as_u64.mut_iter() {
             *dest = self.next_u64();
         }
@@ -147,7 +149,9 @@ pub trait Rng {
 
         // space for a u32
         if remaining >= 4 {
-            let as_u32: &mut &mut [u32] = unsafe { cast::transmute(&mut dest) };
+            let mut slice: Slice<u32> = unsafe { cast::transmute_copy(&dest) };
+            slice.len /= size_of::<u32>();
+            let as_u32: &mut [u32] = unsafe { cast::transmute(slice) };
             as_u32[as_u32.len() - 1] = self.next_u32();
             remaining -= 4;
         }
diff --git a/src/libstd/repr.rs b/src/libstd/repr.rs
index ff2663fb1f7..49d5bb3918b 100644
--- a/src/libstd/repr.rs
+++ b/src/libstd/repr.rs
@@ -186,12 +186,7 @@ impl<'self> ReprVisitor<'self> {
         }
     }
 
-    pub fn write_vec_range(&mut self,
-                           _mtbl: uint,
-                           ptr: *(),
-                           len: uint,
-                           inner: *TyDesc)
-                           -> bool {
+    pub fn write_vec_range(&mut self, ptr: *(), len: uint, inner: *TyDesc) -> bool {
         let mut p = ptr as *u8;
         let (sz, al) = unsafe { ((*inner).size, (*inner).align) };
         self.writer.write(['[' as u8]);
@@ -213,13 +208,8 @@ impl<'self> ReprVisitor<'self> {
         true
     }
 
-    pub fn write_unboxed_vec_repr(&mut self,
-                                  mtbl: uint,
-                                  v: &raw::Vec<()>,
-                                  inner: *TyDesc)
-                                  -> bool {
-        self.write_vec_range(mtbl, ptr::to_unsafe_ptr(&v.data),
-                             v.fill, inner)
+    pub fn write_unboxed_vec_repr(&mut self, _: uint, v: &raw::Vec<()>, inner: *TyDesc) -> bool {
+        self.write_vec_range(ptr::to_unsafe_ptr(&v.data), v.fill, inner)
     }
 
     fn write_escaped_char(&mut self, ch: char, is_str: bool) {
@@ -377,19 +367,32 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
         }
     }
 
+    #[cfg(stage0)]
     fn visit_evec_slice(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
         do self.get::<raw::Slice<()>> |this, s| {
             this.writer.write(['&' as u8]);
             this.write_mut_qualifier(mtbl);
-            this.write_vec_range(mtbl, s.data, s.len, inner);
+            this.write_vec_range(s.data, s.len, inner);
+        }
+    }
+
+    #[cfg(not(stage0))]
+    fn visit_evec_slice(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
+        do self.get::<raw::Slice<()>> |this, s| {
+            this.writer.write(['&' as u8]);
+            this.write_mut_qualifier(mtbl);
+            let size = unsafe {
+                if (*inner).size == 0 { 1 } else { (*inner).size }
+            };
+            this.write_vec_range(s.data, s.len * size, inner);
         }
     }
 
     fn visit_evec_fixed(&mut self, n: uint, sz: uint, _align: uint,
-                        mtbl: uint, inner: *TyDesc) -> bool {
+                        _: uint, inner: *TyDesc) -> bool {
         let assumed_size = if sz == 0 { n } else { sz };
         do self.get::<()> |this, b| {
-            this.write_vec_range(mtbl, ptr::to_unsafe_ptr(b), assumed_size, inner);
+            this.write_vec_range(ptr::to_unsafe_ptr(b), assumed_size, inner);
         }
     }
 
diff --git a/src/libstd/vec.rs b/src/libstd/vec.rs
index 77e38b48067..93374d97db5 100644
--- a/src/libstd/vec.rs
+++ b/src/libstd/vec.rs
@@ -974,6 +974,7 @@ pub trait ImmutableVector<'self, T> {
 
 impl<'self,T> ImmutableVector<'self, T> for &'self [T] {
     #[inline]
+    #[cfg(stage0)]
     fn slice(&self, start: uint, end: uint) -> &'self [T] {
         assert!(start <= end);
         assert!(end <= self.len());
@@ -986,10 +987,27 @@ impl<'self,T> ImmutableVector<'self, T> for &'self [T] {
             }
         }
     }
+
+    #[inline]
+    #[cfg(not(stage0))]
+    fn slice(&self, start: uint, end: uint) -> &'self [T] {
+        assert!(start <= end);
+        assert!(end <= self.len());
+        do self.as_imm_buf |p, _len| {
+            unsafe {
+                cast::transmute(Slice {
+                    data: ptr::offset(p, start as int),
+                    len: (end - start)
+                })
+            }
+        }
+    }
+
     #[inline]
     fn slice_from(&self, start: uint) -> &'self [T] {
         self.slice(start, self.len())
     }
+
     #[inline]
     fn slice_to(&self, end: uint) -> &'self [T] {
         self.slice(0, end)
@@ -1130,10 +1148,18 @@ impl<'self,T> ImmutableVector<'self, T> for &'self [T] {
     }
 
     #[inline]
+    #[cfg(stage0)]
     fn as_imm_buf<U>(&self, f: &fn(*T, uint) -> U) -> U {
         let s = self.repr();
         f(s.data, s.len / sys::nonzero_size_of::<T>())
     }
+
+    #[inline]
+    #[cfg(not(stage0))]
+    fn as_imm_buf<U>(&self, f: &fn(*T, uint) -> U) -> U {
+        let s = self.repr();
+        f(s.data, s.len)
+    }
 }
 
 /// Extension methods for vectors contain `Eq` elements.
@@ -1899,6 +1925,7 @@ pub trait MutableVector<'self, T> {
 
 impl<'self,T> MutableVector<'self, T> for &'self mut [T] {
     #[inline]
+    #[cfg(stage0)]
     fn mut_slice(self, start: uint, end: uint) -> &'self mut [T] {
         assert!(start <= end);
         assert!(end <= self.len());
@@ -1913,6 +1940,21 @@ impl<'self,T> MutableVector<'self, T> for &'self mut [T] {
     }
 
     #[inline]
+    #[cfg(not(stage0))]
+    fn mut_slice(self, start: uint, end: uint) -> &'self mut [T] {
+        assert!(start <= end);
+        assert!(end <= self.len());
+        do self.as_mut_buf |p, _len| {
+            unsafe {
+                cast::transmute(Slice {
+                    data: ptr::mut_offset(p, start as int) as *T,
+                    len: (end - start)
+                })
+            }
+        }
+    }
+
+    #[inline]
     fn mut_slice_from(self, start: uint) -> &'self mut [T] {
         let len = self.len();
         self.mut_slice(start, len)
@@ -1991,11 +2033,18 @@ impl<'self,T> MutableVector<'self, T> for &'self mut [T] {
     }
 
     #[inline]
+    #[cfg(stage0)]
     fn as_mut_buf<U>(self, f: &fn(*mut T, uint) -> U) -> U {
         let Slice{ data, len } = self.repr();
         f(data as *mut T, len / sys::nonzero_size_of::<T>())
     }
 
+    #[inline]
+    #[cfg(not(stage0))]
+    fn as_mut_buf<U>(self, f: &fn(*mut T, uint) -> U) -> U {
+        let Slice{ data, len } = self.repr();
+        f(data as *mut T, len)
+    }
 }
 
 /// Trait for &[T] where T is Cloneable
@@ -2083,6 +2132,7 @@ pub mod raw {
      * not bytes).
      */
     #[inline]
+    #[cfg(stage0)]
     pub unsafe fn buf_as_slice<T,U>(p: *T,
                                     len: uint,
                                     f: &fn(v: &[T]) -> U) -> U {
@@ -2097,6 +2147,22 @@ pub mod raw {
      * not bytes).
      */
     #[inline]
+    #[cfg(not(stage0))]
+    pub unsafe fn buf_as_slice<T,U>(p: *T,
+                                    len: uint,
+                                    f: &fn(v: &[T]) -> U) -> U {
+        f(cast::transmute(Slice {
+            data: p,
+            len: len
+        }))
+    }
+
+    /**
+     * Form a slice from a pointer and length (as a number of units,
+     * not bytes).
+     */
+    #[inline]
+    #[cfg(stage0)]
     pub unsafe fn mut_buf_as_slice<T,U>(p: *mut T,
                                         len: uint,
                                         f: &fn(v: &mut [T]) -> U) -> U {
@@ -2107,6 +2173,21 @@ pub mod raw {
     }
 
     /**
+     * Form a slice from a pointer and length (as a number of units,
+     * not bytes).
+     */
+    #[inline]
+    #[cfg(not(stage0))]
+    pub unsafe fn mut_buf_as_slice<T,U>(p: *mut T,
+                                        len: uint,
+                                        f: &fn(v: &mut [T]) -> U) -> U {
+        f(cast::transmute(Slice {
+            data: p as *T,
+            len: len
+        }))
+    }
+
+    /**
      * Unchecked vector indexing.
      */
     #[inline]