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Auto merge of #73882 - nnethercote:avoid-unwrap_or_else-in-allocate_in, r=Amanieu 

Avoid `unwrap_or_else` in `RawVec::allocate_in`.

This reduces the amount of LLVM IR generated by up to 1 or 2%.

r? @Amanieu
This commit is contained in:
bors 2020-07-03 03:18:28 +00:00
parent 5f4abc16e1 3f79d2f33e
commit cd1a46d644
1 changed files with 14 additions and 3 deletions
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17
src/liballoc/raw_vec.rs
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@ -170,10 +170,21 @@ impl<T, A: AllocRef> RawVec<T, A> {
if mem::size_of::<T>() == 0 {
Self::new_in(alloc)
} else {
let layout = Layout::array::<T>(capacity).unwrap_or_else(|_| capacity_overflow());
alloc_guard(layout.size()).unwrap_or_else(|_| capacity_overflow());
// We avoid `unwrap_or_else` here because it bloats the amount of
// LLVM IR generated.
let layout = match Layout::array::<T>(capacity) {
Ok(layout) => layout,
Err(_) => capacity_overflow(),
};
match alloc_guard(layout.size()) {
Ok(_) => {}
Err(_) => capacity_overflow(),
}
let memory = match alloc.alloc(layout, init) {
Ok(memory) => memory,
Err(_) => handle_alloc_error(layout),
};
let memory = alloc.alloc(layout, init).unwrap_or_else(|_| handle_alloc_error(layout));
Self {
ptr: unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) },
cap: Self::capacity_from_bytes(memory.size),