dnrops
/
rust
mirror of https://github.com/rust-lang/rust.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add invariant to VecDeque::pop_* that len < cap if pop successful 

Similar to #114370 for VecDeque instead of Vec. It now uses `core::hint::assert_unchecked`.
This commit is contained in:
Philippe-Cholet 2024-04-08 12:12:13 +02:00
parent 7a495cc13d
commit 7a2678de7d
2 changed files with 75 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
library/alloc/src/collections/vec_deque/mod.rs
View File

@ -1614,7 +1614,10 @@ impl<T, A: Allocator> VecDeque<T, A> {
let old_head = self.head;
self.head = self.to_physical_idx(1);
self.len -= 1;
Some(unsafe { self.buffer_read(old_head) })
unsafe {
core::hint::assert_unchecked(self.len < self.capacity());
Some(self.buffer_read(old_head))
}
}
}
@ -1638,7 +1641,10 @@ impl<T, A: Allocator> VecDeque<T, A> {
None
} else {
self.len -= 1;
Some(unsafe { self.buffer_read(self.to_physical_idx(self.len)) })
unsafe {
core::hint::assert_unchecked(self.len < self.capacity());
Some(self.buffer_read(self.to_physical_idx(self.len)))
}
}
}

67
tests/codegen/vecdeque_pop_push.rs Normal file
View File

@ -0,0 +1,67 @@
//@ compile-flags: -O
#![crate_type = "lib"]
use std::collections::VecDeque;
#[no_mangle]
// CHECK-LABEL: @noop_back(
pub fn noop_back(v: &mut VecDeque<u8>) {
// CHECK-NOT: grow
// CHECK: tail call void @llvm.assume
// CHECK-NOT: grow
// CHECK: ret
if let Some(x) = v.pop_back() {
v.push_back(x);
}
}
#[no_mangle]
// CHECK-LABEL: @noop_front(
pub fn noop_front(v: &mut VecDeque<u8>) {
// CHECK-NOT: grow
// CHECK: tail call void @llvm.assume
// CHECK-NOT: grow
// CHECK: ret
if let Some(x) = v.pop_front() {
v.push_front(x);
}
}
#[no_mangle]
// CHECK-LABEL: @move_byte_front_to_back(
pub fn move_byte_front_to_back(v: &mut VecDeque<u8>) {
// CHECK-NOT: grow
// CHECK: tail call void @llvm.assume
// CHECK-NOT: grow
// CHECK: ret
if let Some(x) = v.pop_front() {
v.push_back(x);
}
}
#[no_mangle]
// CHECK-LABEL: @move_byte_back_to_front(
pub fn move_byte_back_to_front(v: &mut VecDeque<u8>) {
// CHECK-NOT: grow
// CHECK: tail call void @llvm.assume
// CHECK-NOT: grow
// CHECK: ret
if let Some(x) = v.pop_back() {
v.push_front(x);
}
}
#[no_mangle]
// CHECK-LABEL: @push_back_byte(
pub fn push_back_byte(v: &mut VecDeque<u8>) {
// CHECK: call {{.*}}grow
v.push_back(3);
}
#[no_mangle]
// CHECK-LABEL: @push_front_byte(
pub fn push_front_byte(v: &mut VecDeque<u8>) {
// CHECK: call {{.*}}grow
v.push_front(3);
}