Unrolled build for #149271

Rollup merge of #149271 - sgasho:enzyme-dlopen, r=bjorn3

feat: dlopen Enzyme

related issue: #145899
related pr: #146623

This PR is a continuation of #146623

I refactored some code for #146623 and added the functions shown in #144197

r? ````@bjorn3````
cc: ````@ZuseZ4````

Zulip link: https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/libload.20.2F.20dlopen.20Enzyme.2Fautodiff/near/553647912

Author: rust-timer

Cargo.lock

@@ -3613,6 +3613,7 @@ dependencies = [
  "gimli 0.31.1",
  "itertools",
  "libc",
+ "libloading 0.9.0",
  "measureme",
  "object 0.37.3",
  "rustc-demangle",

compiler/rustc_codegen_llvm/Cargo.toml

@@ -14,6 +14,7 @@ bitflags = "2.4.1"
 gimli = "0.31"
 itertools = "0.12"
 libc = "0.2"
+libloading = { version = "0.9.0", optional = true }
 measureme = "12.0.1"
 object = { version = "0.37.0", default-features = false, features = ["std", "read"] }
 rustc-demangle = "0.1.21"
@@ -46,7 +47,7 @@ tracing = "0.1"
 [features]
 # tidy-alphabetical-start
 check_only = ["rustc_llvm/check_only"]
-llvm_enzyme = []
+llvm_enzyme = ["dep:libloading"]
 llvm_offload = []
 # tidy-alphabetical-end
 

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -528,31 +528,34 @@ fn thin_lto(
     }
 }
 
-fn enable_autodiff_settings(ad: &[config::AutoDiff]) {
+#[cfg(feature = "llvm_enzyme")]
+pub(crate) fn enable_autodiff_settings(ad: &[config::AutoDiff]) {
+    let mut enzyme = llvm::EnzymeWrapper::get_instance();
+
     for val in ad {
         // We intentionally don't use a wildcard, to not forget handling anything new.
         match val {
             config::AutoDiff::PrintPerf => {
-                llvm::set_print_perf(true);
+                enzyme.set_print_perf(true);
             }
             config::AutoDiff::PrintAA => {
-                llvm::set_print_activity(true);
+                enzyme.set_print_activity(true);
             }
             config::AutoDiff::PrintTA => {
-                llvm::set_print_type(true);
+                enzyme.set_print_type(true);
             }
             config::AutoDiff::PrintTAFn(fun) => {
-                llvm::set_print_type(true); // Enable general type printing
-                llvm::set_print_type_fun(&fun); // Set specific function to analyze
+                enzyme.set_print_type(true); // Enable general type printing
+                enzyme.set_print_type_fun(&fun); // Set specific function to analyze
             }
             config::AutoDiff::Inline => {
-                llvm::set_inline(true);
+                enzyme.set_inline(true);
             }
             config::AutoDiff::LooseTypes => {
-                llvm::set_loose_types(true);
+                enzyme.set_loose_types(true);
             }
             config::AutoDiff::PrintSteps => {
-                llvm::set_print(true);
+                enzyme.set_print(true);
             }
             // We handle this in the PassWrapper.cpp
             config::AutoDiff::PrintPasses => {}
@@ -571,9 +574,9 @@ fn enable_autodiff_settings(ad: &[config::AutoDiff]) {
         }
     }
     // This helps with handling enums for now.
-    llvm::set_strict_aliasing(false);
+    enzyme.set_strict_aliasing(false);
     // FIXME(ZuseZ4): Test this, since it was added a long time ago.
-    llvm::set_rust_rules(true);
+    enzyme.set_rust_rules(true);
 }
 
 pub(crate) fn run_pass_manager(
@@ -607,10 +610,6 @@ pub(crate) fn run_pass_manager(
         if enable_ad { write::AutodiffStage::DuringAD } else { write::AutodiffStage::PostAD }
     };
 
-    if enable_ad {
-        enable_autodiff_settings(&config.autodiff);
-    }
-
     unsafe {
         write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage);
     }

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -730,6 +730,13 @@ pub(crate) unsafe fn llvm_optimize(
 
     let llvm_plugins = config.llvm_plugins.join(",");
 
+    let enzyme_fn = if consider_ad {
+        let wrapper = llvm::EnzymeWrapper::get_instance();
+        wrapper.registerEnzymeAndPassPipeline
+    } else {
+        std::ptr::null()
+    };
+
     let result = unsafe {
         llvm::LLVMRustOptimize(
             module.module_llvm.llmod(),
@@ -749,7 +756,7 @@ pub(crate) unsafe fn llvm_optimize(
             vectorize_loop,
             config.no_builtins,
             config.emit_lifetime_markers,
-            run_enzyme,
+            enzyme_fn,
             print_before_enzyme,
             print_after_enzyme,
             print_passes,

compiler/rustc_codegen_llvm/src/lib.rs

@@ -240,6 +240,17 @@ impl CodegenBackend for LlvmCodegenBackend {
 
     fn init(&self, sess: &Session) {
         llvm_util::init(sess); // Make sure llvm is inited
+
+        #[cfg(feature = "llvm_enzyme")]
+        {
+            use rustc_session::config::AutoDiff;
+
+            use crate::back::lto::enable_autodiff_settings;
+            if sess.opts.unstable_opts.autodiff.contains(&AutoDiff::Enable) {
+                drop(llvm::EnzymeWrapper::get_or_init(&sess.opts.sysroot));
+                enable_autodiff_settings(&sess.opts.unstable_opts.autodiff);
+            }
+        }
     }
 
     fn provide(&self, providers: &mut Providers) {