Aggressively replace pointer::offset with add and sub

Author: WaffleLapkin

compiler/rustc_arena/src/lib.rs

@@ -218,7 +218,7 @@ impl<T> TypedArena<T> {
             } else {
                 let ptr = self.ptr.get();
                 // Advance the pointer.
-                self.ptr.set(self.ptr.get().offset(1));
+                self.ptr.set(self.ptr.get().add(1));
                 // Write into uninitialized memory.
                 ptr::write(ptr, object);
                 &mut *ptr

compiler/rustc_codegen_cranelift/example/alloc_system.rs

@@ -94,7 +94,7 @@ mod platform {
     struct Header(*mut u8);
     const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
     unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
-        &mut *(ptr as *mut Header).offset(-1)
+        &mut *(ptr as *mut Header).sub(1)
     }
     unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
         let aligned = ptr.add(align - (ptr as usize & (align - 1)));

compiler/rustc_codegen_gcc/example/alloc_system.rs

@@ -156,7 +156,7 @@ mod platform {
     struct Header(*mut u8);
     const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
     unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
-        &mut *(ptr as *mut Header).offset(-1)
+        &mut *(ptr as *mut Header).sub(1)
     }
     unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
         let aligned = ptr.add(align - (ptr as usize & (align - 1)));

compiler/rustc_serialize/src/serialize.rs

@@ -273,7 +273,7 @@ impl<D: Decoder, T: Decodable<D>> Decodable<D> for Vec<T> {
         unsafe {
             let ptr: *mut T = vec.as_mut_ptr();
             for i in 0..len {
-                std::ptr::write(ptr.offset(i as isize), Decodable::decode(d));
+                std::ptr::write(ptr.add(i), Decodable::decode(d));
             }
             vec.set_len(len);
         }

library/alloc/src/alloc/tests.rs

@@ -15,7 +15,7 @@ fn allocate_zeroed() {
         let end = i.add(layout.size());
         while i < end {
             assert_eq!(*i, 0);
-            i = i.offset(1);
+            i = i.add(1);
         }
         Global.deallocate(ptr.as_non_null_ptr(), layout);
     }

library/alloc/src/collections/vec_deque/mod.rs

@@ -2447,8 +2447,8 @@ impl<T, A: Allocator> VecDeque<T, A> {
                     let mut right_offset = 0;
                     for i in left_edge..right_edge {
                         right_offset = (i - left_edge) % (cap - right_edge);
-                        let src: isize = (right_edge + right_offset) as isize;
-                        ptr::swap(buf.add(i), buf.offset(src));
+                        let src = right_edge + right_offset;
+                        ptr::swap(buf.add(i), buf.add(src));
                     }
                     let n_ops = right_edge - left_edge;
                     left_edge += n_ops;

library/alloc/src/slice.rs

@@ -1024,7 +1024,7 @@ where
             // Consume the greater side.
             // If equal, prefer the right run to maintain stability.
             unsafe {
-                let to_copy = if is_less(&*right.offset(-1), &*left.offset(-1)) {
+                let to_copy = if is_less(&*right.sub(1), &*left.sub(1)) {
                     decrement_and_get(left)
                 } else {
                     decrement_and_get(right)
@@ -1038,12 +1038,12 @@ where
 
     unsafe fn get_and_increment<T>(ptr: &mut *mut T) -> *mut T {
         let old = *ptr;
-        *ptr = unsafe { ptr.offset(1) };
+        *ptr = unsafe { ptr.add(1) };
         old
     }
 
     unsafe fn decrement_and_get<T>(ptr: &mut *mut T) -> *mut T {
-        *ptr = unsafe { ptr.offset(-1) };
+        *ptr = unsafe { ptr.sub(1) };
         *ptr
     }
 

library/alloc/src/vec/in_place_collect.rs

@@ -267,7 +267,7 @@ where
             // one slot in the underlying storage will have been freed up and we can immediately
             // write back the result.
             unsafe {
-                let dst = dst_buf.offset(i as isize);
+                let dst = dst_buf.add(i);
                 debug_assert!(dst as *const _ <= end, "InPlaceIterable contract violation");
                 ptr::write(dst, self.__iterator_get_unchecked(i));
                 // Since this executes user code which can panic we have to bump the pointer

library/alloc/src/vec/into_iter.rs

@@ -159,7 +159,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
             Some(unsafe { mem::zeroed() })
         } else {
             let old = self.ptr;
-            self.ptr = unsafe { self.ptr.offset(1) };
+            self.ptr = unsafe { self.ptr.add(1) };
 
             Some(unsafe { ptr::read(old) })
         }
@@ -271,7 +271,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
             // Make up a value of this ZST.
             Some(unsafe { mem::zeroed() })
         } else {
-            self.end = unsafe { self.end.offset(-1) };
+            self.end = unsafe { self.end.sub(1) };
 
             Some(unsafe { ptr::read(self.end) })
         }
@@ -285,7 +285,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
             self.end = self.end.wrapping_byte_sub(step_size);
         } else {
             // SAFETY: same as for advance_by()
-            self.end = unsafe { self.end.offset(step_size.wrapping_neg() as isize) };
+            self.end = unsafe { self.end.sub(step_size) };
         }
         let to_drop = ptr::slice_from_raw_parts_mut(self.end as *mut T, step_size);
         // SAFETY: same as for advance_by()

library/alloc/src/vec/mod.rs

@@ -542,8 +542,8 @@ impl<T> Vec<T> {
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
-    ///     for i in 0..len as isize {
-    ///         ptr::write(p.offset(i), 4 + i);
+    ///     for i in 0..len {
+    ///         ptr::write(p.add(i), 4 + i);
     ///     }
     ///
     ///     // Put everything back together into a Vec
@@ -702,8 +702,8 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
-    ///     for i in 0..len as isize {
-    ///         ptr::write(p.offset(i), 4 + i);
+    ///     for i in 0..len {
+    ///         ptr::write(p.add(i), 4 + i);
     ///     }
     ///
     ///     // Put everything back together into a Vec
@@ -1393,7 +1393,7 @@ impl<T, A: Allocator> Vec<T, A> {
                 if index < len {
                     // Shift everything over to make space. (Duplicating the
                     // `index`th element into two consecutive places.)
-                    ptr::copy(p, p.offset(1), len - index);
+                    ptr::copy(p, p.add(1), len - index);
                 } else if index == len {
                     // No elements need shifting.
                 } else {
@@ -1455,7 +1455,7 @@ impl<T, A: Allocator> Vec<T, A> {
                 ret = ptr::read(ptr);
 
                 // Shift everything down to fill in that spot.
-                ptr::copy(ptr.offset(1), ptr, len - index - 1);
+                ptr::copy(ptr.add(1), ptr, len - index - 1);
             }
             self.set_len(len - 1);
             ret
@@ -2408,7 +2408,7 @@ impl<T, A: Allocator> Vec<T, A> {
             // Write all elements except the last one
             for _ in 1..n {
                 ptr::write(ptr, value.next());
-                ptr = ptr.offset(1);
+                ptr = ptr.add(1);
                 // Increment the length in every step in case next() panics
                 local_len.increment_len(1);
             }