Auto merge of #155726 - Zoxc:global-jemalloc-only, r=<try>

[TEST] Use only global Rust jemalloc

Cargo.lock

@@ -756,7 +756,7 @@ checksum = "af491d569909a7e4dee0ad7db7f5341fef5c614d5b8ec8cf765732aba3cff681"
 dependencies = [
  "serde",
  "termcolor",
- "unicode-width 0.1.14",
+ "unicode-width 0.2.2",
 ]
 
 [[package]]
@@ -3429,7 +3429,6 @@ dependencies = [
  "rustc_public",
  "rustc_public_bridge",
  "rustc_windows_rc",
- "tikv-jemalloc-sys",
  "wasi 0.14.2+wasi-0.2.4",
 ]
 
@@ -3837,6 +3836,7 @@ dependencies = [
  "rustc_target",
  "serde_json",
  "shlex",
+ "tikv-jemallocator",
  "tracing",
  "windows 0.61.3",
 ]
@@ -5551,6 +5551,16 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "tikv-jemallocator"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0359b4327f954e0567e69fb191cf1436617748813819c94b8cd4a431422d053a"
+dependencies = [
+ "libc",
+ "tikv-jemalloc-sys",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.2"

compiler/rustc/Cargo.toml

@@ -26,16 +26,10 @@ rustc_public_bridge = { path = "../rustc_public_bridge" }
 getrandom = "=0.3.3"
 wasi = "=0.14.2"
 
-
-[dependencies.tikv-jemalloc-sys]
-version = "0.6.1"
-optional = true
-features = ['override_allocator_on_supported_platforms']
-
 [features]
 # tidy-alphabetical-start
 check_only = ['rustc_driver_impl/check_only']
-jemalloc = ['dep:tikv-jemalloc-sys']
+jemalloc = ['rustc_driver_impl/jemalloc']
 llvm = ['rustc_driver_impl/llvm']
 llvm_enzyme = ['rustc_driver_impl/llvm_enzyme']
 llvm_offload = ['rustc_driver_impl/llvm_offload']

compiler/rustc/src/main.rs

@@ -5,41 +5,6 @@
 
 use std::process::ExitCode;
 
-// A note about jemalloc: rustc uses jemalloc when built for CI and
-// distribution. The obvious way to do this is with the `#[global_allocator]`
-// mechanism. However, for complicated reasons (see
-// https://github.com/rust-lang/rust/pull/81782#issuecomment-784438001 for some
-// details) that mechanism doesn't work here. Also, we'd like to use a
-// consistent allocator across the rustc <-> llvm boundary, and
-// `#[global_allocator]` wouldn't provide that.
-//
-// Instead, we use a lower-level mechanism, namely the
-// `"override_allocator_on_supported_platforms"` Cargo feature of jemalloc-sys.
-//
-// This makes jemalloc-sys override the libc/system allocator's implementation
-// of `malloc`, `free`, etc.. This means that Rust's `System` allocator, which
-// calls `libc::malloc()` et al., is actually calling into jemalloc.
-//
-// A consequence of not using `GlobalAlloc` (and the `tikv-jemallocator` crate
-// provides an impl of that trait, which is called `Jemalloc`) is that we
-// cannot use the sized deallocation APIs (`sdallocx`) that jemalloc provides.
-// It's unclear how much performance is lost because of this.
-//
-// NOTE: Even though Cargo passes `--extern` with `tikv_jemalloc_sys`, we still need to `use` the
-// crate for the compiler to see the `#[used]`, see https://github.com/rust-lang/rust/issues/64402.
-// This is similarly required if we used a crate with `#[global_allocator]`.
-//
-// NOTE: if you are reading this comment because you want to set a custom `global_allocator` for
-// benchmarking, consider using the benchmarks in the `rustc-perf` collector suite instead:
-// https://github.com/rust-lang/rustc-perf/blob/master/collector/README.md#profiling
-//
-// NOTE: if you are reading this comment because you want to replace jemalloc with another allocator
-// to compare their performance, see
-// https://github.com/rust-lang/rust/commit/b90cfc887c31c3e7a9e6d462e2464db1fe506175#diff-43914724af6e464c1da2171e4a9b6c7e607d5bc1203fa95c0ab85be4122605ef
-// for an example of how to do so.
-#[cfg(feature = "jemalloc")]
-use tikv_jemalloc_sys as _;
-
 fn main() -> ExitCode {
     rustc_driver::main()
 }

compiler/rustc_driver_impl/Cargo.toml

@@ -55,9 +55,14 @@ features = [
 ctrlc = "3.4.4"
 # tidy-alphabetical-end
 
+[dependencies.tikv-jemallocator]
+version = "0.6.1"
+optional = true
+
 [features]
 # tidy-alphabetical-start
 check_only = ['rustc_interface/check_only']
+jemalloc = ['dep:tikv-jemallocator']
 llvm = ['rustc_interface/llvm']
 llvm_enzyme = ['rustc_interface/llvm_enzyme']
 llvm_offload = ['rustc_interface/llvm_offload']

compiler/rustc_driver_impl/src/lib.rs

@@ -63,6 +63,10 @@ use rustc_target::json::ToJson;
 use rustc_target::spec::{Target, TargetTuple};
 use tracing::trace;
 
+#[cfg(feature = "jemalloc")]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 #[allow(unused_macros)]
 macro do_not_use_print($($t:tt)*) {
     std::compile_error!(

src/librustdoc/lib.rs

@@ -56,15 +56,6 @@ extern crate rustc_target;
 extern crate rustc_trait_selection;
 extern crate test;
 
-/// 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.
-///
-/// FIXME(madsmtm): This is loaded from the sysroot that was built with the other `rustc` crates
-/// above, instead of via Cargo as you'd normally do. This is currently needed for LTO due to
-/// https://github.com/rust-lang/cc-rs/issues/1613.
-#[cfg(feature = "jemalloc")]
-extern crate tikv_jemalloc_sys as _;
-
 use std::env::{self, VarError};
 use std::io::{self, IsTerminal};
 use std::path::Path;

src/tools/clippy/src/driver.rs

@@ -11,15 +11,6 @@ extern crate rustc_interface;
 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.
-///
-/// FIXME(madsmtm): This is loaded from the sysroot that was built with the other `rustc` crates
-/// above, instead of via Cargo as you'd normally do. This is currently needed for LTO due to
-/// <https://github.com/rust-lang/cc-rs/issues/1613>.
-#[cfg(feature = "jemalloc")]
-extern crate tikv_jemalloc_sys as _;
-
 use clippy_utils::sym;
 use declare_clippy_lint::LintListBuilder;
 use rustc_interface::interface;

src/tools/miri/src/bin/miri.rs

@@ -18,20 +18,6 @@ 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.
-///
-/// FIXME(madsmtm): This is loaded from the sysroot that was built with the other `rustc` crates
-/// above, instead of via Cargo as you'd normally do. This is currently needed for LTO due to
-/// https://github.com/rust-lang/cc-rs/issues/1613.
-#[cfg(feature = "jemalloc")]
-// Make sure `--all-features` works: only Linux and macOS actually use jemalloc, and not on arm32.
-#[cfg(all(
-    any(target_os = "linux", target_os = "macos"),
-    any(target_arch = "x86_64", target_arch = "x86", target_arch = "aarch64"),
-))]
-extern crate tikv_jemalloc_sys as _;
-
 mod log;
 
 use std::env;

src/tools/tidy/src/deps.rs

@@ -442,6 +442,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "thorin-dwp",
     "thread_local",
     "tikv-jemalloc-sys",
+    "tikv-jemallocator",
     "tinystr",
     "tinyvec",
     "tinyvec_macros",