Auto merge of #80290 - RalfJung:less-intrinsic-write, r=lcnr

implement ptr::write without dedicated intrinsic

This makes `ptr::write` more consistent with `ptr::write_unaligned`, `ptr::read`, `ptr::read_unaligned`, all of which are implemented in terms of `copy_nonoverlapping`.

This means we can also remove `move_val_init` implementations in codegen and Miri, and its special handling in the borrow checker.

Also see [this Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/ptr.3A.3Aread.20vs.20ptr.3A.3Awrite).

1 files changed, 0 insertions, 19 deletions

diff --git a/src/test/codegen/intrinsics/move-val-init.rs b/src/test/codegen/intrinsics/move-val-init.rs
deleted file mode 100644
index 6222536b506..00000000000
--- a/src/test/codegen/intrinsics/move-val-init.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-// compile-flags: -C no-prepopulate-passes
-
-#![feature(core_intrinsics)]
-#![crate_type = "lib"]
-
-// test that `move_val_init` actually avoids big allocas
-
-use std::intrinsics::move_val_init;
-
-pub struct Big {
-    pub data: [u8; 65536]
-}
-
-// CHECK-LABEL: @test_mvi
-#[no_mangle]
-pub unsafe fn test_mvi(target: *mut Big, make_big: fn() -> Big) {
-    // CHECK: call void %make_big(%Big*{{[^%]*}} %target)
-    move_val_init(target, make_big());
-}