Auto merge of #151151 - Zalathar:rollup-kAQYrsB, r=Zalathar

Rollup of 2 pull requests

Successful merges:

 - rust-lang/rust#151150 (Revert "avoid phi node for pointers flowing into Vec appends rust-lang/rust#130998")
 - rust-lang/rust#151145 (Reduce rustdoc GUI flakyness, take 2)

r? @ghost

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -517,16 +517,7 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
         to_add.push(llvm::CreateAllocKindAttr(cx.llcx, AllocKindFlags::Free));
         // applies to argument place instead of function place
         let allocated_pointer = AttributeKind::AllocatedPointer.create_attr(cx.llcx);
-        let attrs: &[_] = if llvm_util::get_version() >= (21, 0, 0) {
-            // "Does not capture provenance" means "if the function call stashes the pointer somewhere,
-            // accessing that pointer after the function returns is UB". That is definitely the case here since
-            // freeing will destroy the provenance.
-            let captures_addr = AttributeKind::CapturesAddress.create_attr(cx.llcx);
-            &[allocated_pointer, captures_addr]
-        } else {
-            &[allocated_pointer]
-        };
-        attributes::apply_to_llfn(llfn, AttributePlace::Argument(0), attrs);
+        attributes::apply_to_llfn(llfn, AttributePlace::Argument(0), &[allocated_pointer]);
     }
     if let Some(align) = codegen_fn_attrs.alignment {
         llvm::set_alignment(llfn, align);

library/alloc/src/slice.rs

@@ -448,11 +448,9 @@ impl<T> [T] {
                 // SAFETY:
                 // allocated above with the capacity of `s`, and initialize to `s.len()` in
                 // ptr::copy_to_non_overlapping below.
-                if s.len() > 0 {
-                    unsafe {
-                        s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len());
-                        v.set_len(s.len());
-                    }
+                unsafe {
+                    s.as_ptr().copy_to_nonoverlapping(v.as_mut_ptr(), s.len());
+                    v.set_len(s.len());
                 }
                 v
             }

library/alloc/src/vec/mod.rs

@@ -2818,11 +2818,7 @@ impl<T, A: Allocator> Vec<T, A> {
         let count = other.len();
         self.reserve(count);
         let len = self.len();
-        if count > 0 {
-            unsafe {
-                ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count)
-            };
-        }
+        unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) };
         self.len += count;
     }
 

tests/codegen-llvm/lib-optimizations/append-elements.rs

@@ -1,30 +0,0 @@
-//@ compile-flags: -O -Zmerge-functions=disabled
-//@ min-llvm-version: 21
-#![crate_type = "lib"]
-
-//! Check that a temporary intermediate allocations can eliminated and replaced
-//! with memcpy forwarding.
-//! This requires Vec code to be structured in a way that avoids phi nodes from the
-//! zero-capacity length flowing into the memcpy arguments.
-
-// CHECK-LABEL: @vec_append_with_temp_alloc
-#[no_mangle]
-pub fn vec_append_with_temp_alloc(dst: &mut Vec<u8>, src: &[u8]) {
-    // CHECK-NOT: call void @llvm.memcpy
-    // CHECK: call void @llvm.memcpy.{{.*}}%dst.i{{.*}}%src.0
-    // CHECK-NOT: call void @llvm.memcpy
-    let temp = src.to_vec();
-    dst.extend(&temp);
-    // CHECK: ret
-}
-
-// CHECK-LABEL: @string_append_with_temp_alloc
-#[no_mangle]
-pub fn string_append_with_temp_alloc(dst: &mut String, src: &str) {
-    // CHECK-NOT: call void @llvm.memcpy
-    // CHECK: call void @llvm.memcpy.{{.*}}%dst.i{{.*}}%src.0
-    // CHECK-NOT: call void @llvm.memcpy
-    let temp = src.to_string();
-    dst.push_str(&temp);
-    // CHECK: ret
-}

tests/rustdoc-gui/utils.goml

@@ -29,9 +29,18 @@ define-function: (
     "open-settings-menu",
     [],
     block {
-        call-function: ("click-settings-button", {})
-        // Wait for the popover to appear...
-        wait-for-css: ("#settings", {"display": "block"})
+        store-count: ("#settings", nb_settings_menu)
+        if: (|nb_settings_menu| != 0, block {
+            store-css: ("#settings", {"display": settings_display})
+        })
+        else: block {
+            store-value: (settings_display, "none")
+        }
+        if: (|settings_display| != "block", block {
+            call-function: ("click-settings-button", {})
+            // Wait for the popover to appear...
+            wait-for-css: ("#settings", {"display": "block"})
+        })
     }
 )
 
@@ -39,9 +48,18 @@ define-function: (
     "close-settings-menu",
     [],
     block {
-        call-function: ("click-settings-button", {})
-        // Wait for the popover to disappear...
-        wait-for-css-false: ("#settings", {"display": "block"})
+        store-count: ("#settings", nb_settings_menu)
+        if: (|nb_settings_menu| != 0, block {
+            store-css: ("#settings", {"display": settings_display})
+        })
+        else: block {
+            store-value: (settings_display, "block")
+        }
+        if: (|settings_display| == "block", block {
+            call-function: ("click-settings-button", {})
+            // Wait for the popover to disappear...
+            wait-for-css-false: ("#settings", {"display": "block"})
+        })
     }
 )