Implement arithmetic overflow changes

src/libcollections/bit.rs

@@ -816,19 +816,19 @@ impl Bitv {
         let full_value = if value { !0 } else { 0 };
 
         // Correct the old tail word, setting or clearing formerly unused bits
-        let old_last_word = blocks_for_bits(self.nbits) - 1;
+        let num_cur_blocks = blocks_for_bits(self.nbits);
         if self.nbits % u32::BITS > 0 {
             let mask = mask_for_bits(self.nbits);
             if value {
-                self.storage[old_last_word] |= !mask;
+                self.storage[num_cur_blocks - 1] |= !mask;
             } else {
                 // Extra bits are already zero by invariant.
             }
         }
 
         // Fill in words after the old tail word
         let stop_idx = cmp::min(self.storage.len(), new_nblocks);
-        for idx in range(old_last_word + 1, stop_idx) {
+        for idx in range(num_cur_blocks, stop_idx) {
             self.storage[idx] = full_value;
         }
 

src/libcore/hash/sip.rs

@@ -71,17 +71,17 @@ macro_rules! u8to64_le {
 
 macro_rules! rotl {
     ($x:expr, $b:expr) =>
-    (($x << $b) | ($x >> (64 - $b)))
+    (($x << $b) | ($x >> (64.wrapping_sub($b))))
 }
 
 macro_rules! compress {
     ($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
     ({
-        $v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0;
+        $v0 = $v0.wrapping_add($v1); $v1 = rotl!($v1, 13); $v1 ^= $v0;
         $v0 = rotl!($v0, 32);
-        $v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2;
-        $v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0;
-        $v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2;
+        $v2 = $v2.wrapping_add($v3); $v3 = rotl!($v3, 16); $v3 ^= $v2;
+        $v0 = $v0.wrapping_add($v3); $v3 = rotl!($v3, 21); $v3 ^= $v0;
+        $v2 = $v2.wrapping_add($v1); $v1 = rotl!($v1, 17); $v1 ^= $v2;
         $v2 = rotl!($v2, 32);
     })
 }

src/libcore/intrinsics.rs

@@ -547,6 +547,15 @@ extern "rust-intrinsic" {
     pub fn u64_mul_with_overflow(x: u64, y: u64) -> (u64, bool);
 }
 
+#[cfg(not(stage0))]
+extern "rust-intrinsic" {
+    /// Returns (a + b) mod 2^N, where N is the width of N in bits.
+    pub fn overflowing_add<T>(a: T, b: T) -> T;
+    /// Returns (a - b) mod 2^N, where N is the width of N in bits.
+    pub fn overflowing_sub<T>(a: T, b: T) -> T;
+    /// Returns (a * b) mod 2^N, where N is the width of N in bits.
+    pub fn overflowing_mul<T>(a: T, b: T) -> T;
+}
 
 /// `TypeId` represents a globally unique identifier for a type
 #[lang="type_id"] // This needs to be kept in lockstep with the code in trans/intrinsic.rs and

src/libcore/num/mod.rs

@@ -29,6 +29,9 @@ use option::Option;
 use option::Option::{Some, None};
 use str::{FromStr, StrExt};
 
+#[experimental = "may be removed or relocated"]
+pub mod wrapping;
+
 /// A built-in signed or unsigned integer.
 #[stable]
 pub trait Int

src/libcore/num/wrapping.rs

@@ -0,0 +1,152 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+#![allow(missing_docs)]
+
+use ops::*;
+
+#[cfg(not(stage0))]
+use intrinsics::{overflowing_add, overflowing_sub, overflowing_mul};
+
+pub trait WrappingOps {
+    fn wrapping_add(self, rhs: Self) -> Self;
+    fn wrapping_sub(self, rhs: Self) -> Self;
+    fn wrapping_mul(self, rhs: Self) -> Self;
+}
+
+#[cfg(not(stage0))]
+macro_rules! wrapping_impl {
+    ($($t:ty)*) => ($(
+        impl WrappingOps for $t {
+            #[inline(always)]
+            fn wrapping_add(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_add(self, rhs)
+                }
+            }
+            #[inline(always)]
+            fn wrapping_sub(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_sub(self, rhs)
+                }
+            }
+            #[inline(always)]
+            fn wrapping_mul(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_mul(self, rhs)
+                }
+            }
+        }
+    )*)
+}
+
+#[cfg(stage0)]
+macro_rules! wrapping_impl {
+    ($($t:ty)*) => ($(
+        impl WrappingOps for $t {
+            #[inline(always)]
+            fn wrapping_add(self, rhs: $t) -> $t {
+                self + rhs
+            }
+            #[inline(always)]
+            fn wrapping_sub(self, rhs: $t) -> $t {
+                self - rhs
+            }
+            #[inline(always)]
+            fn wrapping_mul(self, rhs: $t) -> $t {
+                self * rhs
+            }
+        }
+    )*)
+}
+
+wrapping_impl! { uint u8 u16 u32 u64 int i8 i16 i32 i64 }
+
+#[derive(PartialEq,Eq,PartialOrd,Ord,Clone,Copy)]
+pub struct Wrapping<T>(pub T);
+
+impl<T:WrappingOps> Add for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn add(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_add(other.0))
+    }
+}
+
+impl<T:WrappingOps> Sub for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn sub(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_sub(other.0))
+    }
+}
+
+impl<T:WrappingOps> Mul for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn mul(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_mul(other.0))
+    }
+}
+
+impl<T:WrappingOps+Not<Output=T>> Not for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    fn not(self) -> Wrapping<T> {
+        Wrapping(!self.0)
+    }
+}
+
+impl<T:WrappingOps+BitXor<Output=T>> BitXor for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitxor(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 ^ other.0)
+    }
+}
+
+impl<T:WrappingOps+BitOr<Output=T>> BitOr for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitor(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 | other.0)
+    }
+}
+
+impl<T:WrappingOps+BitAnd<Output=T>> BitAnd for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitand(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 & other.0)
+    }
+}
+
+impl<T:WrappingOps+Shl<uint,Output=T>> Shl<uint> for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn shl(self, other: uint) -> Wrapping<T> {
+        Wrapping(self.0 << other)
+    }
+}
+
+impl<T:WrappingOps+Shr<uint,Output=T>> Shr<uint> for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn shr(self, other: uint) -> Wrapping<T> {
+        Wrapping(self.0 >> other)
+    }
+}

src/libcore/ops.rs

@@ -773,6 +773,7 @@ macro_rules! shr_impl {
 
 shr_impl! { uint u8 u16 u32 u64 int i8 i16 i32 i64 }
 
+
 /// The `Index` trait is used to specify the functionality of indexing operations
 /// like `arr[idx]` when used in an immutable context.
 ///

src/libcore/prelude.rs

@@ -32,6 +32,8 @@
 pub use marker::{Copy, Send, Sized, Sync};
 pub use ops::{Drop, Fn, FnMut, FnOnce, FullRange};
 
+pub use num::wrapping::{Wrapping, WrappingOps};
+
 // Reexported functions
 pub use iter::range;
 pub use mem::drop;

src/libcore/str/mod.rs

@@ -789,6 +789,7 @@ impl TwoWaySearcher {
     // critical factorization (u, v) and p = period(v)
     #[inline]
     fn maximal_suffix(arr: &[u8], reversed: bool) -> (uint, uint) {
+        use num::wrapping::WrappingOps;
         let mut left = -1; // Corresponds to i in the paper
         let mut right = 0; // Corresponds to j in the paper
         let mut offset = 1; // Corresponds to k in the paper
@@ -798,17 +799,17 @@ impl TwoWaySearcher {
             let a;
             let b;
             if reversed {
-                a = arr[left + offset];
+                a = arr[left.wrapping_add(offset)];
                 b = arr[right + offset];
             } else {
                 a = arr[right + offset];
-                b = arr[left + offset];
+                b = arr[left.wrapping_add(offset)];
             }
             if a < b {
                 // Suffix is smaller, period is entire prefix so far.
                 right += offset;
                 offset = 1;
-                period = right - left;
+                period = right.wrapping_sub(left);
             } else if a == b {
                 // Advance through repetition of the current period.
                 if offset == period {
@@ -825,7 +826,7 @@ impl TwoWaySearcher {
                 period = 1;
             }
         }
-        (left + 1, period)
+        (left.wrapping_add(1), period)
     }
 }