Auto merge of #136428 - EnzymeAD:enable-autodiff, r=oli-obk

test building enzyme in CI

1) This PR fixes a significant compile-time regression, by only running the expensive autodiff pipeline, if the users pass the newly introduced Enable value to the `-Zautodiff=` flag. It updates the test(s) accordingly. It gives a nice error if users forget that.
2) It fixes macos support by explicitly linking against the Enzyme build folder. This doesn't cover CI macos yet.
3) It fixes the issue that setting ENZYME_RUNPASS was ignored by enzyme and in fact did not schedule enzyme's opt pass.
4) It also re-enables support for various other values for the autodiff flag, which were ignored since the refactor.
5) I merged some improvements to Enzyme core, which means we do not longer depend on LLVM being build with the Plugin Interface enabled.
6) Unrelated to other fixes, this changes `rustc_autodiff` to `EncodeCrossCrate::Yes`. It is not enough on it's own to enable usage of Enzyme in libraries, but it is for sure a piece of the fixes needed to get this to work.

try-job: x86_64-gnu

r? `@oli-obk`

Tracking:

- https://github.com/rust-lang/rust/issues/124509

compiler/rustc_ast/src/expand/autodiff_attrs.rs

@@ -17,7 +17,6 @@ use crate::{Ty, TyKind};
 /// functions. The proper solution is to recognize and resolve this DAG of autodiff invocations,
 /// as it's already done in the C++ and Julia frontend of Enzyme.
 ///
-/// (FIXME) remove *First variants.
 /// Documentation for using [reverse](https://enzyme.mit.edu/rust/rev.html) and
 /// [forward](https://enzyme.mit.edu/rust/fwd.html) mode is available online.
 #[derive(Clone, Copy, Eq, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]

compiler/rustc_builtin_macros/src/autodiff.rs

@@ -242,6 +242,7 @@ mod llvm_enzyme {
             defaultness: ast::Defaultness::Final,
             sig: d_sig,
             generics: Generics::default(),
+            contract: None,
             body: Some(d_body),
         });
         let mut rustc_ad_attr =

compiler/rustc_codegen_llvm/messages.ftl

@@ -1,3 +1,4 @@
+codegen_llvm_autodiff_without_enable = using the autodiff feature requires -Z autodiff=Enable
 codegen_llvm_autodiff_without_lto = using the autodiff feature requires using fat-lto
 
 codegen_llvm_copy_bitcode = failed to copy bitcode to object file: {$err}

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -586,6 +586,42 @@ fn thin_lto(
     }
 }
 
+fn enable_autodiff_settings(ad: &[config::AutoDiff], module: &mut ModuleCodegen<ModuleLlvm>) {
+    for &val in ad {
+        match val {
+            config::AutoDiff::PrintModBefore => {
+                unsafe { llvm::LLVMDumpModule(module.module_llvm.llmod()) };
+            }
+            config::AutoDiff::PrintPerf => {
+                llvm::set_print_perf(true);
+            }
+            config::AutoDiff::PrintAA => {
+                llvm::set_print_activity(true);
+            }
+            config::AutoDiff::PrintTA => {
+                llvm::set_print_type(true);
+            }
+            config::AutoDiff::Inline => {
+                llvm::set_inline(true);
+            }
+            config::AutoDiff::LooseTypes => {
+                llvm::set_loose_types(false);
+            }
+            config::AutoDiff::PrintSteps => {
+                llvm::set_print(true);
+            }
+            // We handle this below
+            config::AutoDiff::PrintModAfter => {}
+            // This is required and already checked
+            config::AutoDiff::Enable => {}
+        }
+    }
+    // This helps with handling enums for now.
+    llvm::set_strict_aliasing(false);
+    // FIXME(ZuseZ4): Test this, since it was added a long time ago.
+    llvm::set_rust_rules(true);
+}
+
 pub(crate) fn run_pass_manager(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     dcx: DiagCtxtHandle<'_>,
@@ -604,34 +640,37 @@ pub(crate) fn run_pass_manager(
     let opt_stage = if thin { llvm::OptStage::ThinLTO } else { llvm::OptStage::FatLTO };
     let opt_level = config.opt_level.unwrap_or(config::OptLevel::No);
 
-    // If this rustc version was build with enzyme/autodiff enabled, and if users applied the
-    // `#[autodiff]` macro at least once, then we will later call llvm_optimize a second time.
-    debug!("running llvm pm opt pipeline");
+    // The PostAD behavior is the same that we would have if no autodiff was used.
+    // It will run the default optimization pipeline. If AD is enabled we select
+    // the DuringAD stage, which will disable vectorization and loop unrolling, and
+    // schedule two autodiff optimization + differentiation passes.
+    // We then run the llvm_optimize function a second time, to optimize the code which we generated
+    // in the enzyme differentiation pass.
+    let enable_ad = config.autodiff.contains(&config::AutoDiff::Enable);
+    let stage =
+        if enable_ad { write::AutodiffStage::DuringAD } else { write::AutodiffStage::PostAD };
+
+    if enable_ad {
+        enable_autodiff_settings(&config.autodiff, module);
+    }
+
     unsafe {
-        write::llvm_optimize(
-            cgcx,
-            dcx,
-            module,
-            config,
-            opt_level,
-            opt_stage,
-            write::AutodiffStage::DuringAD,
-        )?;
+        write::llvm_optimize(cgcx, dcx, module, config, opt_level, opt_stage, stage)?;
     }
-    // FIXME(ZuseZ4): Make this more granular
-    if cfg!(llvm_enzyme) && !thin {
+
+    if cfg!(llvm_enzyme) && enable_ad {
+        let opt_stage = llvm::OptStage::FatLTO;
+        let stage = write::AutodiffStage::PostAD;
         unsafe {
-            write::llvm_optimize(
-                cgcx,
-                dcx,
-                module,
-                config,
-                opt_level,
-                llvm::OptStage::FatLTO,
-                write::AutodiffStage::PostAD,
-            )?;
+            write::llvm_optimize(cgcx, dcx, module, config, opt_level, opt_stage, stage)?;
+        }
+
+        // This is the final IR, so people should be able to inspect the optimized autodiff output.
+        if config.autodiff.contains(&config::AutoDiff::PrintModAfter) {
+            unsafe { llvm::LLVMDumpModule(module.module_llvm.llmod()) };
         }
     }
+
     debug!("lto done");
     Ok(())
 }

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -564,19 +564,16 @@ pub(crate) unsafe fn llvm_optimize(
     // FIXME(ZuseZ4): In a future update we could figure out how to only optimize individual functions getting
     // differentiated.
 
+    let consider_ad = cfg!(llvm_enzyme) && config.autodiff.contains(&config::AutoDiff::Enable);
+    let run_enzyme = autodiff_stage == AutodiffStage::DuringAD;
     let unroll_loops;
     let vectorize_slp;
     let vectorize_loop;
-    let run_enzyme = cfg!(llvm_enzyme) && autodiff_stage == AutodiffStage::DuringAD;
 
     // When we build rustc with enzyme/autodiff support, we want to postpone size-increasing
     // optimizations until after differentiation. Our pipeline is thus: (opt + enzyme), (full opt).
     // We therefore have two calls to llvm_optimize, if autodiff is used.
-    //
-    // FIXME(ZuseZ4): Before shipping on nightly,
-    // we should make this more granular, or at least check that the user has at least one autodiff
-    // call in their code, to justify altering the compilation pipeline.
-    if cfg!(llvm_enzyme) && autodiff_stage != AutodiffStage::PostAD {
+    if consider_ad && autodiff_stage != AutodiffStage::PostAD {
         unroll_loops = false;
         vectorize_slp = false;
         vectorize_loop = false;
@@ -706,10 +703,8 @@ pub(crate) unsafe fn optimize(
 
         // If we know that we will later run AD, then we disable vectorization and loop unrolling.
         // Otherwise we pretend AD is already done and run the normal opt pipeline (=PostAD).
-        // FIXME(ZuseZ4): Make this more granular, only set PreAD if we actually have autodiff
-        // usages, not just if we build rustc with autodiff support.
-        let autodiff_stage =
-            if cfg!(llvm_enzyme) { AutodiffStage::PreAD } else { AutodiffStage::PostAD };
+        let consider_ad = cfg!(llvm_enzyme) && config.autodiff.contains(&config::AutoDiff::Enable);
+        let autodiff_stage = if consider_ad { AutodiffStage::PreAD } else { AutodiffStage::PostAD };
         return unsafe {
             llvm_optimize(cgcx, dcx, module, config, opt_level, opt_stage, autodiff_stage)
         };

compiler/rustc_codegen_llvm/src/builder/autodiff.rs

@@ -10,7 +10,7 @@ use crate::back::write::llvm_err;
 use crate::builder::SBuilder;
 use crate::context::SimpleCx;
 use crate::declare::declare_simple_fn;
-use crate::errors::LlvmError;
+use crate::errors::{AutoDiffWithoutEnable, LlvmError};
 use crate::llvm::AttributePlace::Function;
 use crate::llvm::{Metadata, True};
 use crate::value::Value;
@@ -46,9 +46,6 @@ fn generate_enzyme_call<'ll>(
     let output = attrs.ret_activity;
 
     // We have to pick the name depending on whether we want forward or reverse mode autodiff.
-    // FIXME(ZuseZ4): The new pass based approach should not need the {Forward/Reverse}First method anymore, since
-    // it will handle higher-order derivatives correctly automatically (in theory). Currently
-    // higher-order derivatives fail, so we should debug that before adjusting this code.
     let mut ad_name: String = match attrs.mode {
         DiffMode::Forward => "__enzyme_fwddiff",
         DiffMode::Reverse => "__enzyme_autodiff",
@@ -291,6 +288,14 @@ pub(crate) fn differentiate<'ll>(
     let diag_handler = cgcx.create_dcx();
     let cx = SimpleCx { llmod: module.module_llvm.llmod(), llcx: module.module_llvm.llcx };
 
+    // First of all, did the user try to use autodiff without using the -Zautodiff=Enable flag?
+    if !diff_items.is_empty()
+        && !cgcx.opts.unstable_opts.autodiff.contains(&rustc_session::config::AutoDiff::Enable)
+    {
+        let dcx = cgcx.create_dcx();
+        return Err(dcx.handle().emit_almost_fatal(AutoDiffWithoutEnable));
+    }
+
     // Before dumping the module, we want all the TypeTrees to become part of the module.
     for item in diff_items.iter() {
         let name = item.source.clone();

compiler/rustc_codegen_llvm/src/errors.rs

@@ -92,9 +92,12 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for ParseTargetMachineConfig<'_> {
 
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_autodiff_without_lto)]
-#[note]
 pub(crate) struct AutoDiffWithoutLTO;
 
+#[derive(Diagnostic)]
+#[diag(codegen_llvm_autodiff_without_enable)]
+pub(crate) struct AutoDiffWithoutEnable;
+
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_lto_disallowed)]
 pub(crate) struct LtoDisallowed;

compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs

@@ -35,3 +35,97 @@ pub enum LLVMRustVerifierFailureAction {
     LLVMPrintMessageAction = 1,
     LLVMReturnStatusAction = 2,
 }
+
+#[cfg(llvm_enzyme)]
+pub use self::Enzyme_AD::*;
+
+#[cfg(llvm_enzyme)]
+pub mod Enzyme_AD {
+    use libc::c_void;
+    extern "C" {
+        pub fn EnzymeSetCLBool(arg1: *mut ::std::os::raw::c_void, arg2: u8);
+    }
+    extern "C" {
+        static mut EnzymePrintPerf: c_void;
+        static mut EnzymePrintActivity: c_void;
+        static mut EnzymePrintType: c_void;
+        static mut EnzymePrint: c_void;
+        static mut EnzymeStrictAliasing: c_void;
+        static mut looseTypeAnalysis: c_void;
+        static mut EnzymeInline: c_void;
+        static mut RustTypeRules: c_void;
+    }
+    pub fn set_print_perf(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintPerf), print as u8);
+        }
+    }
+    pub fn set_print_activity(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintActivity), print as u8);
+        }
+    }
+    pub fn set_print_type(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrintType), print as u8);
+        }
+    }
+    pub fn set_print(print: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymePrint), print as u8);
+        }
+    }
+    pub fn set_strict_aliasing(strict: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymeStrictAliasing), strict as u8);
+        }
+    }
+    pub fn set_loose_types(loose: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(looseTypeAnalysis), loose as u8);
+        }
+    }
+    pub fn set_inline(val: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(EnzymeInline), val as u8);
+        }
+    }
+    pub fn set_rust_rules(val: bool) {
+        unsafe {
+            EnzymeSetCLBool(std::ptr::addr_of_mut!(RustTypeRules), val as u8);
+        }
+    }
+}
+
+#[cfg(not(llvm_enzyme))]
+pub use self::Fallback_AD::*;
+
+#[cfg(not(llvm_enzyme))]
+pub mod Fallback_AD {
+    #![allow(unused_variables)]
+
+    pub fn set_inline(val: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_perf(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_activity(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print_type(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_print(print: bool) {
+        unimplemented!()
+    }
+    pub fn set_strict_aliasing(strict: bool) {
+        unimplemented!()
+    }
+    pub fn set_loose_types(loose: bool) {
+        unimplemented!()
+    }
+    pub fn set_rust_rules(val: bool) {
+        unimplemented!()
+    }
+}

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -405,7 +405,8 @@ fn generate_lto_work<B: ExtraBackendMethods>(
             B::run_fat_lto(cgcx, needs_fat_lto, import_only_modules).unwrap_or_else(|e| e.raise());
         if cgcx.lto == Lto::Fat && !autodiff.is_empty() {
             let config = cgcx.config(ModuleKind::Regular);
-            module = unsafe { module.autodiff(cgcx, autodiff, config).unwrap() };
+            module =
+                unsafe { module.autodiff(cgcx, autodiff, config).unwrap_or_else(|e| e.raise()) };
         }
         // We are adding a single work item, so the cost doesn't matter.
         vec![(WorkItem::LTO(module), 0)]

compiler/rustc_feature/src/builtin_attrs.rs

@@ -743,7 +743,7 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     rustc_attr!(
         rustc_autodiff, Normal,
         template!(Word, List: r#""...""#), DuplicatesOk,
-        EncodeCrossCrate::No, INTERNAL_UNSTABLE
+        EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
     ),
 
     // ==========================================================================

compiler/rustc_interface/src/tests.rs

@@ -759,7 +759,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(allow_features, Some(vec![String::from("lang_items")]));
     tracked!(always_encode_mir, true);
     tracked!(assume_incomplete_release, true);
-    tracked!(autodiff, vec![AutoDiff::Print]);
+    tracked!(autodiff, vec![AutoDiff::Enable]);
     tracked!(binary_dep_depinfo, true);
     tracked!(box_noalias, false);
     tracked!(

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -692,9 +692,12 @@ struct LLVMRustSanitizerOptions {
   bool SanitizeKernelAddressRecover;
 };
 
-// This symbol won't be available or used when Enzyme is not enabled
+// This symbol won't be available or used when Enzyme is not enabled.
+// Always set AugmentPassBuilder to true, since it registers optimizations which
+// will improve the performance for Enzyme.
 #ifdef ENZYME
-extern "C" void registerEnzyme(llvm::PassBuilder &PB);
+extern "C" void registerEnzymeAndPassPipeline(llvm::PassBuilder &PB,
+                                              /* augmentPassBuilder */ bool);
 #endif
 
 extern "C" LLVMRustResult LLVMRustOptimize(
@@ -1023,7 +1026,7 @@ extern "C" LLVMRustResult LLVMRustOptimize(
   // now load "-enzyme" pass:
 #ifdef ENZYME
   if (RunEnzyme) {
-    registerEnzyme(PB);
+    registerEnzymeAndPassPipeline(PB, true);
     if (auto Err = PB.parsePassPipeline(MPM, "enzyme")) {
       std::string ErrMsg = toString(std::move(Err));
       LLVMRustSetLastError(ErrMsg.c_str());

compiler/rustc_monomorphize/src/partitioning/autodiff.rs

@@ -66,7 +66,7 @@ pub(crate) fn find_autodiff_source_functions<'tcx>(
     let mut autodiff_items: Vec<AutoDiffItem> = vec![];
     for (item, instance) in autodiff_mono_items {
         let target_id = instance.def_id();
-        let cg_fn_attr = tcx.codegen_fn_attrs(target_id).autodiff_item.clone();
+        let cg_fn_attr = &tcx.codegen_fn_attrs(target_id).autodiff_item;
         let Some(target_attrs) = cg_fn_attr else {
             continue;
         };

compiler/rustc_session/src/config.rs

@@ -198,33 +198,26 @@ pub enum CoverageLevel {
 /// The different settings that the `-Z autodiff` flag can have.
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum AutoDiff {
+    /// Enable the autodiff opt pipeline
+    Enable,
+
     /// Print TypeAnalysis information
     PrintTA,
     /// Print ActivityAnalysis Information
     PrintAA,
     /// Print Performance Warnings from Enzyme
     PrintPerf,
-    /// Combines the three print flags above.
-    Print,
+    /// Print intermediate IR generation steps
+    PrintSteps,
     /// Print the whole module, before running opts.
     PrintModBefore,
-    /// Print the whole module just before we pass it to Enzyme.
-    /// For Debug purpose, prefer the OPT flag below
-    PrintModAfterOpts,
     /// Print the module after Enzyme differentiated everything.
-    PrintModAfterEnzyme,
+    PrintModAfter,
 
-    /// Enzyme's loose type debug helper (can cause incorrect gradients)
+    /// Enzyme's loose type debug helper (can cause incorrect gradients!!)
+    /// Usable in cases where Enzyme errors with `can not deduce type of X`.
     LooseTypes,
-
-    /// More flags
-    NoModOptAfter,
-    /// Tell Enzyme to run LLVM Opts on each function it generated. By default off,
-    /// since we already optimize the whole module after Enzyme is done.
-    EnableFncOpt,
-    NoVecUnroll,
-    RuntimeActivity,
-    /// Runs Enzyme specific Inlining
+    /// Runs Enzyme's aggressive inlining
     Inline,
 }
 

compiler/rustc_session/src/options.rs

@@ -707,7 +707,7 @@ mod desc {
     pub(crate) const parse_list: &str = "a space-separated list of strings";
     pub(crate) const parse_list_with_polarity: &str =
         "a comma-separated list of strings, with elements beginning with + or -";
-    pub(crate) const parse_autodiff: &str = "a comma separated list of settings: `Print`, `PrintTA`, `PrintAA`, `PrintPerf`, `PrintModBefore`, `PrintModAfterOpts`, `PrintModAfterEnzyme`, `LooseTypes`, `NoModOptAfter`, `EnableFncOpt`, `NoVecUnroll`, `Inline`";
+    pub(crate) const parse_autodiff: &str = "a comma separated list of settings: `Enable`, `PrintSteps`, `PrintTA`, `PrintAA`, `PrintPerf`, `PrintModBefore`, `PrintModAfter`, `LooseTypes`, `Inline`";
     pub(crate) const parse_comma_list: &str = "a comma-separated list of strings";
     pub(crate) const parse_opt_comma_list: &str = parse_comma_list;
     pub(crate) const parse_number: &str = "a number";
@@ -1348,17 +1348,14 @@ pub mod parse {
         v.sort_unstable();
         for &val in v.iter() {
             let variant = match val {
+                "Enable" => AutoDiff::Enable,
                 "PrintTA" => AutoDiff::PrintTA,
                 "PrintAA" => AutoDiff::PrintAA,
                 "PrintPerf" => AutoDiff::PrintPerf,
-                "Print" => AutoDiff::Print,
+                "PrintSteps" => AutoDiff::PrintSteps,
                 "PrintModBefore" => AutoDiff::PrintModBefore,
-                "PrintModAfterOpts" => AutoDiff::PrintModAfterOpts,
-                "PrintModAfterEnzyme" => AutoDiff::PrintModAfterEnzyme,
+                "PrintModAfter" => AutoDiff::PrintModAfter,
                 "LooseTypes" => AutoDiff::LooseTypes,
-                "NoModOptAfter" => AutoDiff::NoModOptAfter,
-                "EnableFncOpt" => AutoDiff::EnableFncOpt,
-                "NoVecUnroll" => AutoDiff::NoVecUnroll,
                 "Inline" => AutoDiff::Inline,
                 _ => {
                     // FIXME(ZuseZ4): print an error saying which value is not recognized
@@ -2081,19 +2078,17 @@ options! {
     assume_incomplete_release: bool = (false, parse_bool, [TRACKED],
         "make cfg(version) treat the current version as incomplete (default: no)"),
     autodiff: Vec<crate::config::AutoDiff> = (Vec::new(), parse_autodiff, [TRACKED],
-        "a list of optional autodiff flags to enable
+        "a list of autodiff flags to enable
+        Mandatory setting:
+        `=Enable`
         Optional extra settings:
         `=PrintTA`
         `=PrintAA`
         `=PrintPerf`
-         `=Print`
+        `=PrintSteps`
         `=PrintModBefore`
-         `=PrintModAfterOpts`
-         `=PrintModAfterEnzyme`
+        `=PrintModAfter`
         `=LooseTypes`
-         `=NoModOptAfter`
-         `=EnableFncOpt`
-         `=NoVecUnroll`
         `=Inline`
         Multiple options can be combined with commas."),
     #[rustc_lint_opt_deny_field_access("use `Session::binary_dep_depinfo` instead of this field")]

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

@@ -1174,10 +1174,16 @@ pub fn rustc_cargo(
     // We want to link against registerEnzyme and in the future we want to use additional
     // functionality from Enzyme core. For that we need to link against Enzyme.
     if builder.config.llvm_enzyme {
+        let arch = builder.build.build;
+        let enzyme_dir = builder.build.out.join(arch).join("enzyme").join("lib");
+        cargo.rustflag("-L").rustflag(enzyme_dir.to_str().expect("Invalid path"));
+
+        if !builder.config.dry_run() {
             let llvm_config = builder.llvm_config(builder.config.build).unwrap();
             let llvm_version_major = llvm::get_llvm_version_major(builder, &llvm_config);
             cargo.rustflag("-l").rustflag(&format!("Enzyme-{llvm_version_major}"));
         }
+    }
 
     // Building with protected visibility reduces the number of dynamic relocations needed, giving
     // us a faster startup time. However GNU ld < 2.40 will error if we try to link a shared object
@@ -2028,16 +2034,20 @@ impl Step for Assemble {
         let mut build_compiler = builder.compiler(target_compiler.stage - 1, builder.config.build);
 
         // Build enzyme
-        if builder.config.llvm_enzyme {
+        if builder.config.llvm_enzyme && !builder.config.dry_run() {
             debug!("`llvm_enzyme` requested");
             let enzyme_install = builder.ensure(llvm::Enzyme { target: build_compiler.host });
+            let llvm_config = builder.llvm_config(builder.config.build).unwrap();
+            let llvm_version_major = llvm::get_llvm_version_major(builder, &llvm_config);
             let lib_ext = std::env::consts::DLL_EXTENSION;
-            let src_lib = enzyme_install.join("build/Enzyme/libEnzyme-19").with_extension(lib_ext);
+            let libenzyme = format!("libEnzyme-{llvm_version_major}");
+            let src_lib =
+                enzyme_install.join("build/Enzyme").join(&libenzyme).with_extension(lib_ext);
             let libdir = builder.sysroot_target_libdir(build_compiler, build_compiler.host);
             let target_libdir =
                 builder.sysroot_target_libdir(target_compiler, target_compiler.host);
-            let dst_lib = libdir.join("libEnzyme-19").with_extension(lib_ext);
-            let target_dst_lib = target_libdir.join("libEnzyme-19").with_extension(lib_ext);
+            let dst_lib = libdir.join(&libenzyme).with_extension(lib_ext);
+            let target_dst_lib = target_libdir.join(&libenzyme).with_extension(lib_ext);
             builder.copy_link(&src_lib, &dst_lib);
             builder.copy_link(&src_lib, &target_dst_lib);
         }

src/bootstrap/src/core/build_steps/llvm.rs

@@ -996,13 +996,11 @@ impl Step for Enzyme {
             .config
             .update_submodule(Path::new("src").join("tools").join("enzyme").to_str().unwrap());
         let mut cfg = cmake::Config::new(builder.src.join("src/tools/enzyme/enzyme/"));
-        // FIXME(ZuseZ4): Find a nicer way to use Enzyme Debug builds
-        //cfg.profile("Debug");
-        //cfg.define("CMAKE_BUILD_TYPE", "Debug");
         configure_cmake(builder, target, &mut cfg, true, LdFlags::default(), &[]);
 
         // Re-use the same flags as llvm to control the level of debug information
-        // generated for lld.
+        // generated by Enzyme.
+        // FIXME(ZuseZ4): Find a nicer way to use Enzyme Debug builds.
         let profile = match (builder.config.llvm_optimize, builder.config.llvm_release_debuginfo) {
             (false, _) => "Debug",
             (true, false) => "Release",
@@ -1015,7 +1013,6 @@ impl Step for Enzyme {
             .env("LLVM_CONFIG_REAL", &llvm_config)
             .define("LLVM_ENABLE_ASSERTIONS", "ON")
             .define("ENZYME_EXTERNAL_SHARED_LIB", "ON")
-            .define("ENZYME_RUNPASS", "ON")
             .define("LLVM_DIR", builder.llvm_out(target));
 
         cfg.build();

src/doc/unstable-book/src/compiler-flags/autodiff.md

@@ -8,16 +8,13 @@ This feature allows you to differentiate functions using automatic differentiati
 Set the `-Zautodiff=<options>` compiler flag to adjust the behaviour of the autodiff feature.
 Multiple options can be separated with a comma. Valid options are:
 
+`Enable` - Required flag to enable autodiff
 `PrintTA` - print Type Analysis Information
 `PrintAA` - print Activity Analysis Information
 `PrintPerf` - print Performance Warnings from Enzyme
-`Print` - prints all intermediate transformations
+`PrintSteps` - prints all intermediate transformations
 `PrintModBefore` - print the whole module, before running opts
-`PrintModAfterOpts` - print the whole module just before we pass it to Enzyme
-`PrintModAfterEnzyme` - print the module after Enzyme differentiated everything
+`PrintModAfter` - print the module after Enzyme differentiated everything
 `LooseTypes` - Enzyme's loose type debug helper (can cause incorrect gradients)
 `Inline` - runs Enzyme specific Inlining
-`NoModOptAfter` - do not optimize the module after Enzyme is done
-`EnableFncOpt` - tell Enzyme to run LLVM Opts on each function it generated
-`NoVecUnroll` - do not unroll vectorized loops
 `RuntimeActivity` - allow specifying activity at runtime

src/tools/enzyme

@@ -1 +1 @@
-Subproject commit 7f3b207c4413c9d715fd54b36b8a8fd3179e0b67
+Subproject commit 5004a8f6f5d8468b64fae457afb7d96e1784c783

tests/codegen/autodiff.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: -C opt-level=3  -Clto=fat
+//@ compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme
 #![feature(autodiff)]