From 90958a96eeea71dfefc43a08195292e5d3913e01 Mon Sep 17 00:00:00 2001
From: Mathieu Strypsteen <mathieu@strypsteen.me>
Date: Thu, 26 Dec 2024 10:01:52 +0100
Subject: [PATCH] Fix heap

---
 .../rustc_target/src/spec/targets/x86_64_unknown_os.rs     | 2 +-
 library/std/src/sys/alloc/os.rs                            | 7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_target/src/spec/targets/x86_64_unknown_os.rs b/compiler/rustc_target/src/spec/targets/x86_64_unknown_os.rs
index 376456ea28d..d9d2cc8aaa7 100644
--- a/compiler/rustc_target/src/spec/targets/x86_64_unknown_os.rs
+++ b/compiler/rustc_target/src/spec/targets/x86_64_unknown_os.rs
@@ -2,7 +2,7 @@ use crate::spec::{Target, TargetMetadata, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::os::opts();
-    base.cpu = "x86-64".into();
+    base.cpu = "x86-64-v2".into();
     Target {
         llvm_target: "x86_64-unknown-none".into(),
         metadata: TargetMetadata {
diff --git a/library/std/src/sys/alloc/os.rs b/library/std/src/sys/alloc/os.rs
index 68fcaa5a447..9814961a69c 100644
--- a/library/std/src/sys/alloc/os.rs
+++ b/library/std/src/sys/alloc/os.rs
@@ -19,11 +19,8 @@ unsafe impl GlobalAlloc for System {
         }
         let num_blocks =
             if layout.size() % 16 == 0 { layout.size() / 16 } else { (layout.size() / 16) + 1 };
-        HEAP_USED.fetch_add(num_blocks, Ordering::Relaxed);
-        let ptr = unsafe {
-            ptr::addr_of_mut!(HEAP_DATA.0[HEAP_USED.load(Ordering::Relaxed) - num_blocks])
-                as *mut u8
-        };
+        let heap_used = HEAP_USED.fetch_add(num_blocks, Ordering::SeqCst);
+        let ptr = unsafe { ptr::addr_of_mut!(HEAP_DATA.0[heap_used * 16]) as *mut u8 };
         ptr
     }