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mem.Allocator initializes bytes to undefined

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Andrew Kelley 2017-12-10 15:38:05 -05:00
parent 990db3c35a
commit 22dc713a2f
1 changed files with 13 additions and 1 deletions
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14
std/mem.zig
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@ -8,6 +8,7 @@ pub const Cmp = math.Cmp;
pub const Allocator = struct {
/// Allocate byte_count bytes and return them in a slice, with the
/// slice's pointer aligned at least to alignment bytes.
/// The returned newly allocated memory is undefined.
allocFn: fn (self: &Allocator, byte_count: usize, alignment: u29) -> %[]u8,
/// If `new_byte_count > old_mem.len`:
@ -17,6 +18,8 @@ pub const Allocator = struct {
/// If `new_byte_count <= old_mem.len`:
/// * this function must return successfully.
/// * alignment <= alignment of old_mem.ptr
///
/// The returned newly allocated memory is undefined.
reallocFn: fn (self: &Allocator, old_mem: []u8, new_byte_count: usize, alignment: u29) -> %[]u8,
/// Guaranteed: `old_mem.len` is the same as what was returned from `allocFn` or `reallocFn`
@ -40,6 +43,10 @@ pub const Allocator = struct {
{
const byte_count = %return math.mul(usize, @sizeOf(T), n);
const byte_slice = %return self.allocFn(self, byte_count, alignment);
// This loop should get optimized out in ReleaseFast mode
for (byte_slice) |*byte| {
*byte = undefined;
}
return ([]align(alignment) T)(@alignCast(alignment, byte_slice));
}
@ -54,8 +61,13 @@ pub const Allocator = struct {
return self.alloc(T, n);
}
const old_byte_slice = ([]u8)(old_mem);
const byte_count = %return math.mul(usize, @sizeOf(T), n);
const byte_slice = %return self.reallocFn(self, ([]u8)(old_mem), byte_count, alignment);
const byte_slice = %return self.reallocFn(self, old_byte_slice, byte_count, alignment);
// This loop should get optimized out in ReleaseFast mode
for (byte_slice[old_byte_slice.len..]) |*byte| {
*byte = undefined;
}
return ([]T)(@alignCast(alignment, byte_slice));
}