feat: Use Enzyme on Apple

Author: sgasho

.gitmodules

@@ -41,7 +41,7 @@
 	shallow = true
 [submodule "src/tools/enzyme"]
 	path = src/tools/enzyme
-	url = https://github.com/rust-lang/enzyme.git
+	url = https://github.com/sgasho/enzyme.git
 	shallow = true
 [submodule "src/gcc"]
 	path = src/gcc

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -796,6 +796,14 @@ impl<'a> Linker for GccLinker<'a> {
             }
         }
 
+        if crate_type == CrateType::Dylib
+            && self.sess.target.is_like_darwin
+            && self.sess.opts.unstable_opts.export_llvm_symbols
+            && self.sess.opts.crate_name.as_deref() == Some("rustc_driver")
+        {
+            return;
+        }
+
         // We manually create a list of exported symbols to ensure we don't expose any more.
         // The object files have far more public symbols than we actually want to export,
         // so we hide them all here.

compiler/rustc_session/src/options.rs

@@ -2345,6 +2345,8 @@ options! {
         "enable default bounds for experimental group of auto traits"),
     export_executable_symbols: bool = (false, parse_bool, [TRACKED],
         "export symbols from executables, as if they were dynamic libraries"),
+    export_llvm_symbols: bool = (false, parse_bool, [TRACKED],
+        "export LLVM symbols from rustc_driver on darwin"),
     external_clangrt: bool = (false, parse_bool, [UNTRACKED],
         "rely on user specified linker commands to find clangrt"),
     extra_const_ub_checks: bool = (false, parse_bool, [TRACKED],

src/bootstrap/src/core/build_steps/compile.rs

@@ -1243,6 +1243,10 @@ pub fn rustc_cargo(
         cargo.rustflag("-Zdefault-visibility=protected");
     }
 
+    if builder.config.llvm_enzyme && target.contains("apple") && build_compiler.stage != 0 {
+        cargo.rustflag("-Zexport-llvm-symbols");
+    }
+
     if is_lto_stage(build_compiler) {
         match builder.config.rust_lto {
             RustcLto::Thin | RustcLto::Fat => {

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -91,6 +91,7 @@ ENV RUST_CONFIGURE_ARGS \
       --set llvm.thin-lto=true \
       --set llvm.ninja=false \
       --set llvm.libzstd=true \
+      --set llvm.enzyme=true \
       --set rust.jemalloc \
       --set rust.bootstrap-override-lld=true \
       --set rust.lto=thin \

src/ci/github-actions/jobs.yml

@@ -489,6 +489,7 @@ auto:
         --enable-full-tools
         --enable-sanitizers
         --enable-profiler
+        --set llvm.enzyme=true
         --set rust.jemalloc
         --set rust.lto=thin
         --set rust.codegen-units=1

src/tools/enzyme

@@ -188,7 +188,7 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 // FIXME: Enable bolt for aarch64 once it's fixed upstream. Broken as of December 2024.
                 .use_bolt(!is_aarch64)
                 .skipped_tests(vec![])
-                .run_tests(true)
+                .run_tests(false)
                 .fast_try_build(is_fast_try_build)
                 .build_llvm(true)
                 .build()?;