Revert "Rollup merge of #146627 - madsmtm:jemalloc-simplify, r=jdonszelmann"

This reverts commit 5dc3c19417d0fbfd979c5a1ecd8bebe2d8d9110e, reversing
changes made to 11339a0ef5ed586bb7ea4f85a9b7287880caac3a.

Author: Kobzol

Cargo.toml

@@ -33,8 +33,8 @@ serde_json = { version = "1.0", optional = true }
 # But only for some targets, it fails for others. Rustc configures this in its CI, but we can't
 # easily use that since we support of-tree builds.
 [target.'cfg(any(target_os = "linux", target_os = "macos"))'.dependencies.tikv-jemalloc-sys]
-version = "0.6.1"
-features = ['override_allocator_on_supported_platforms']
+version = "0.6.0"
+features = ['unprefixed_malloc_on_supported_platforms']
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"

src/bin/miri.rs

@@ -20,11 +20,6 @@ extern crate rustc_middle;
 extern crate rustc_session;
 extern crate rustc_span;
 
-/// See docs in https://github.com/rust-lang/rust/blob/HEAD/compiler/rustc/src/main.rs
-/// and https://github.com/rust-lang/rust/pull/146627 for why we need this `use` statement.
-#[cfg(any(target_os = "linux", target_os = "macos"))]
-use tikv_jemalloc_sys as _;
-
 mod log;
 
 use std::env;
@@ -397,7 +392,48 @@ fn parse_range(val: &str) -> Result<Range<u32>, &'static str> {
     Ok(from..to)
 }
 
+#[cfg(any(target_os = "linux", target_os = "macos"))]
+fn jemalloc_magic() {
+    // These magic runes are copied from
+    // <https://github.com/rust-lang/rust/blob/e89bd9428f621545c979c0ec686addc6563a394e/compiler/rustc/src/main.rs#L39>.
+    // See there for further comments.
+    use std::os::raw::{c_int, c_void};
+
+    use tikv_jemalloc_sys as jemalloc_sys;
+
+    #[used]
+    static _F1: unsafe extern "C" fn(usize, usize) -> *mut c_void = jemalloc_sys::calloc;
+    #[used]
+    static _F2: unsafe extern "C" fn(*mut *mut c_void, usize, usize) -> c_int =
+        jemalloc_sys::posix_memalign;
+    #[used]
+    static _F3: unsafe extern "C" fn(usize, usize) -> *mut c_void = jemalloc_sys::aligned_alloc;
+    #[used]
+    static _F4: unsafe extern "C" fn(usize) -> *mut c_void = jemalloc_sys::malloc;
+    #[used]
+    static _F5: unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void = jemalloc_sys::realloc;
+    #[used]
+    static _F6: unsafe extern "C" fn(*mut c_void) = jemalloc_sys::free;
+
+    // On OSX, jemalloc doesn't directly override malloc/free, but instead
+    // registers itself with the allocator's zone APIs in a ctor. However,
+    // the linker doesn't seem to consider ctors as "used" when statically
+    // linking, so we need to explicitly depend on the function.
+    #[cfg(target_os = "macos")]
+    {
+        unsafe extern "C" {
+            fn _rjem_je_zone_register();
+        }
+
+        #[used]
+        static _F7: unsafe extern "C" fn() = _rjem_je_zone_register;
+    }
+}
+
 fn main() {
+    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    jemalloc_magic();
+
     let early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
 
     // Snapshot a copy of the environment before `rustc` starts messing with it.