The libcore.rlib size more than doubled since 1.47 #80245

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 5b19bf6b80f..cc4344a30aa 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -284,7 +284,6 @@
 // `core_arch` depends on libcore, but the contents of this module are
 // set up in such a way that directly pulling it here works such that the
 // crate uses the this crate as its libcore.
-#[path = "../../stdarch/crates/core_arch/src/mod.rs"]
 #[allow(
     missing_docs,
     missing_debug_implementations,
@@ -297,7 +296,93 @@
 // merged. It currently cannot because bootstrap fails as the lint hasn't been defined yet.
 #[allow(clashing_extern_declarations)]
 #[unstable(feature = "stdsimd", issue = "48556")]
-mod core_arch;
+mod core_arch {
+    pub mod arch {
+        #[stable(feature = "a", since = "1.0.0")]
+        pub mod x86 {
+            #[allow(non_camel_case_types)]
+            #[stable(feature = "a", since = "1.0.0")]
+            #[derive(Copy, Clone)]
+            pub struct __m128i;
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_pause() {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_set1_epi8(_: i8) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_or_si128(_: __m128i, _: __m128i) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_movemask_epi8(_: __m128i) -> i32 {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_load_si128(_: *const __m128i) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_loadu_si128(_: *const __m128i) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_store_si128(_: *mut __m128i, _: __m128i) {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_cmpeq_epi8(_: __m128i, _: __m128i) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_cmpgt_epi8(_: __m128i, _: __m128i) -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _mm_setzero_si128() -> __m128i {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub fn has_cpuid() -> bool {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub struct CpuidResult {
+                /// EAX register.
+                #[stable(feature = "simd_x86", since = "1.27.0")]
+                pub eax: u32,
+                /// EBX register.
+                #[stable(feature = "simd_x86", since = "1.27.0")]
+                pub ebx: u32,
+                /// ECX register.
+                #[stable(feature = "simd_x86", since = "1.27.0")]
+                pub ecx: u32,
+                /// EDX register.
+                #[stable(feature = "simd_x86", since = "1.27.0")]
+                pub edx: u32,
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn __cpuid(_: u32) -> CpuidResult {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn __cpuid_count(_: u32, _: u32) -> CpuidResult {
+                todo!();
+            }
+            #[stable(feature = "a", since = "1.0.0")]
+            pub unsafe fn _xgetbv(_: u32) -> u64 {
+                todo!();
+            }
+        }
+        #[stable(feature = "a", since = "1.0.0")]
+        pub mod x86_64 {
+            #[stable(feature = "a", since = "1.0.0")]
+            pub use super::x86::*;
+        }
+    }
+}
 
 #[stable(feature = "simd_arch", since = "1.27.0")]
 pub use core_arch::arch;