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Move memory location of doubleword storage values

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This commit is contained in:
Richard Feldman 2020-09-30 19:30:02 -04:00
parent 24bc0f6083
commit 95734c10c4
1 changed files with 8 additions and 13 deletions
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21
roc_std/src/lib.rs
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@ -80,17 +80,9 @@ impl<T> RocList<T> {
}
fn get_storage_ptr(&self) -> *const usize {
let elem_alignment = core::mem::align_of::<T>();
let ptr = self.elements as *const usize;
unsafe {
if elem_alignment <= core::mem::align_of::<usize>() {
let ptr = self.elements as *const usize;
ptr.offset(-1)
} else {
let ptr = self.elements as *const (usize, usize);
(ptr.offset(-1)) as *const usize
}
}
unsafe { ptr.offset(-1) }
}
fn get_storage_ptr_mut(&mut self) -> *mut usize {
@ -99,14 +91,17 @@ impl<T> RocList<T> {
fn get_element_ptr<Q>(elements: *const Q) -> *const usize {
let elem_alignment = core::mem::align_of::<T>();
let ptr = elements as *const usize;
unsafe {
if elem_alignment <= core::mem::align_of::<usize>() {
let ptr = elements as *const usize;
ptr.offset(1)
} else {
let ptr = elements as *const (usize, usize);
(ptr.offset(1)) as *const usize
// If elements have an alignment bigger than usize (e.g. an i128),
// we will have necessarily allocated two usize slots worth of
// space for the storage value (with the first usize slot being
// padding for alignment's sake), and we need to skip past both.
ptr.offset(2)
}
}
}