rustc: Move jemalloc from rustc_driver to rustc

This commit moves jemalloc to just the rustc binary rather than the
rustc_driver shared library, enusring that it's only used for binaries
that opt-in to it like rustc rather than other binaries using
librustc_driver like rustdoc/rls/etc. This will hopefully address #56980

2 files changed, 14 insertions, 1 deletions

diff --git a/src/rustc/Cargo.toml b/src/rustc/Cargo.toml
index 32969d09e85..164a3c6ad0d 100644
--- a/src/rustc/Cargo.toml
+++ b/src/rustc/Cargo.toml
@@ -15,5 +15,10 @@ rustc_driver = { path = "../librustc_driver" }
 # crate is intended to be used by codegen backends, which may not be in-tree.
 rustc_codegen_ssa = { path = "../librustc_codegen_ssa" }
 
+[dependencies.jemalloc-sys]
+version = '0.1.8'
+optional = true
+features = ['unprefixed_malloc_on_supported_platforms']
+
 [features]
-jemalloc = ['rustc_driver/jemalloc-sys']
+jemalloc = ['jemalloc-sys']
diff --git a/src/rustc/rustc.rs b/src/rustc/rustc.rs
index ab5a7c3f747..1c1c7b4bb8e 100644
--- a/src/rustc/rustc.rs
+++ b/src/rustc/rustc.rs
@@ -23,6 +23,14 @@ extern {}
 
 extern crate rustc_driver;
 
+// Note that the linkage here should be all that we need, on Linux we're not
+// prefixing the symbols here so this should naturally override our default
+// allocator. On OSX it should override via the zone allocator. We shouldn't
+// enable this by default on other platforms, so other platforms aren't handled
+// here yet.
+#[cfg(feature = "jemalloc-sys")]
+extern crate jemalloc_sys;
+
 fn main() {
     rustc_driver::set_sigpipe_handler();
     rustc_driver::main()