Unrolled build for rust-lang#123089

rust-timer · web-flow · commit cabc106c0c57 · 2024-04-08T12:24:53.000-04:00
Rollup merge of rust-lang#123089 - Philippe-Cholet:vecdeque_pop_assume_cap, r=Nilstrieb Add invariant to VecDeque::pop_* that len < cap if pop successful Similar to rust-lang#114370 for VecDeque instead of Vec. I initially come from rust-itertools/itertools#899 where we noticed that `pop_front;push_back;` was slower than expected so `@scottmcm` suggested I file an issue which lead to https://internals.rust-lang.org/t/vecdeque-pop-front-push-back/20483 where **kornel** mentionned rust-lang#114334 (fixed by rust-lang#114370). This is my first time with codegen tests, I based the test on what was done for Vec.
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
@@ -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)))
+            }
         }
     }
 
diff --git a/tests/codegen/vecdeque_pop_push.rs b/tests/codegen/vecdeque_pop_push.rs
@@ -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);
+}

Original file line number	Diff line number	Diff line change
`@@ -1614,7 +1614,10 @@ impl<T, A: Allocator> VecDeque<T, A> {`
`1614`	`1614`	`let old_head = self.head;`
`1615`	`1615`	`self.head = self.to_physical_idx(1);`
`1616`	`1616`	`self.len -= 1;`
`1617`		`- Some(unsafe { self.buffer_read(old_head) })`
	`1617`	`+ unsafe {`
	`1618`	`+ core::hint::assert_unchecked(self.len < self.capacity());`
	`1619`	`+ Some(self.buffer_read(old_head))`
	`1620`	`+ }`
`1618`	`1621`	`}`
`1619`	`1622`	`}`
`1620`	`1623`
`@@ -1638,7 +1641,10 @@ impl<T, A: Allocator> VecDeque<T, A> {`
`1638`	`1641`	`None`
`1639`	`1642`	`} else {`
`1640`	`1643`	`self.len -= 1;`
`1641`		`- Some(unsafe { self.buffer_read(self.to_physical_idx(self.len)) })`
	`1644`	`+ unsafe {`
	`1645`	`+ core::hint::assert_unchecked(self.len < self.capacity());`
	`1646`	`+ Some(self.buffer_read(self.to_physical_idx(self.len)))`
	`1647`	`+ }`
`1642`	`1648`	`}`
`1643`	`1649`	`}`
`1644`	`1650`