tmp: try to use jemalloc via #[global_allocator]

Author: lqd

Cargo.lock

@@ -1885,6 +1885,16 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "jemallocator"
+version = "0.5.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0de374a9f8e63150e6f5e8a60cc14c668226d7a347d8aee1a45766e3c4dd3bc"
+dependencies = [
+ "jemalloc-sys",
+ "libc",
+]
+
 [[package]]
 name = "jobserver"
 version = "0.1.31"
@@ -3573,6 +3583,7 @@ name = "rustc_driver_impl"
 version = "0.0.0"
 dependencies = [
  "ctrlc",
+ "jemallocator",
  "libc",
  "rustc_ast",
  "rustc_ast_lowering",

compiler/rustc/Cargo.toml

@@ -27,7 +27,7 @@ features = ['unprefixed_malloc_on_supported_platforms']
 
 [features]
 # tidy-alphabetical-start
-jemalloc = ['dep:jemalloc-sys']
+jemalloc = ['dep:jemalloc-sys', 'rustc_driver_impl/jemalloc']
 llvm = ['rustc_driver_impl/llvm']
 max_level_info = ['rustc_driver_impl/max_level_info']
 rustc_use_parallel_compiler = ['rustc_driver_impl/rustc_use_parallel_compiler']

compiler/rustc_driver_impl/Cargo.toml

@@ -68,8 +68,14 @@ features = [
 ctrlc = "3.4.4"
 # tidy-alphabetical-end
 
+[dependencies.jemallocator]
+version = "0.5.4"
+optional = true
+features = ['unprefixed_malloc_on_supported_platforms']
+
 [features]
 # tidy-alphabetical-start
+jemalloc = ['dep:jemallocator']
 llvm = ['rustc_interface/llvm']
 max_level_info = ['rustc_log/max_level_info']
 rustc_use_parallel_compiler = [

compiler/rustc_driver_impl/src/lib.rs

@@ -1575,6 +1575,14 @@ pub fn install_ctrlc_handler() {
 }
 
 pub fn main() -> ! {
+    #[cfg(feature = "jemalloc")]
+    {
+        use jemallocator::Jemalloc;
+
+        #[global_allocator]
+        static GLOBAL: Jemalloc = Jemalloc;
+    }
+
     let start_time = Instant::now();
     let start_rss = get_resident_set_size();
 

src/tools/tidy/src/deps.rs

@@ -318,6 +318,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "itertools",
     "itoa",
     "jemalloc-sys",
+    "jemallocator",
     "jobserver",
     "lazy_static",
     "leb128",