Remove llvm_enzyme feature outside of bootstrap

compiler/rustc/Cargo.toml

@@ -37,7 +37,6 @@ features = ['override_allocator_on_supported_platforms']
 check_only = ['rustc_driver_impl/check_only']
 jemalloc = ['dep:tikv-jemalloc-sys']
 llvm = ['rustc_driver_impl/llvm']
-llvm_enzyme = ['rustc_driver_impl/llvm_enzyme']
 llvm_offload = ['rustc_driver_impl/llvm_offload']
 max_level_info = ['rustc_driver_impl/max_level_info']
 rustc_randomized_layouts = ['rustc_driver_impl/rustc_randomized_layouts']

compiler/rustc_builtin_macros/Cargo.toml

@@ -35,5 +35,4 @@ tracing = "0.1"
 
 [features]
 # tidy-alphabetical-start
-llvm_enzyme = []
 # tidy-alphabetical-end

compiler/rustc_codegen_llvm/Cargo.toml

@@ -43,7 +43,6 @@ tracing = "0.1"
 [features]
 # tidy-alphabetical-start
 check_only = ["rustc_llvm/check_only"]
-llvm_enzyme = []
 llvm_offload = []
 # tidy-alphabetical-end
 

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -617,7 +617,7 @@ pub(crate) fn run_pass_manager(
         );
     }
 
-    if cfg!(feature = "llvm_enzyme") && enable_ad && !thin {
+    if enable_ad && !thin {
         let opt_stage = llvm::OptStage::FatLTO;
         let stage = write::AutodiffStage::PostAD;
         if !config.autodiff.contains(&config::AutoDiff::NoPostopt) {

compiler/rustc_codegen_llvm/src/typetree.rs

@@ -51,21 +51,12 @@ fn process_typetree_recursive(
     }
 }
 
-#[cfg_attr(not(feature = "llvm_enzyme"), allow(unused))]
 pub(crate) fn add_tt<'ll>(
     llmod: &'ll llvm::Module,
     llcx: &'ll llvm::Context,
     fn_def: &'ll Value,
     tt: FncTree,
 ) {
-    // TypeTree processing uses functions from Enzyme, which we might not have available if we did
-    // not build this compiler with `llvm_enzyme`. This feature is not strictly necessary, but
-    // skipping this function increases the chance that Enzyme fails to compile some code.
-    // FIXME(autodiff): In the future we should conditionally run this function even without the
-    // `llvm_enzyme` feature, in case that libEnzyme was provided via rustup.
-    #[cfg(not(feature = "llvm_enzyme"))]
-    return;
-
     let inputs = tt.args;
     let ret_tt: RustTypeTree = tt.ret;
 

compiler/rustc_driver_impl/Cargo.toml

@@ -58,7 +58,6 @@ ctrlc = "3.4.4"
 # tidy-alphabetical-start
 check_only = ['rustc_interface/check_only']
 llvm = ['rustc_interface/llvm']
-llvm_enzyme = ['rustc_interface/llvm_enzyme']
 llvm_offload = ['rustc_interface/llvm_offload']
 max_level_info = ['rustc_log/max_level_info']
 rustc_randomized_layouts = [

compiler/rustc_interface/Cargo.toml

@@ -57,6 +57,5 @@ rustc_abi = { path = "../rustc_abi" }
 # tidy-alphabetical-start
 check_only = ['rustc_codegen_llvm?/check_only']
 llvm = ['dep:rustc_codegen_llvm']
-llvm_enzyme = ['rustc_builtin_macros/llvm_enzyme', 'rustc_codegen_llvm/llvm_enzyme']
 llvm_offload = ['rustc_codegen_llvm/llvm_offload']
 # tidy-alphabetical-end

library/core/Cargo.toml

@@ -23,7 +23,6 @@ optimize_for_size = []
 # Make `RefCell` store additional debugging information, which is printed out when
 # a borrow error occurs
 debug_refcell = []
-llvm_enzyme = []
 
 [lints.rust.unexpected_cfgs]
 level = "warn"
@@ -39,6 +38,5 @@ check-cfg = [
     'cfg(target_has_reliable_f16_math)',
     'cfg(target_has_reliable_f128)',
     'cfg(target_has_reliable_f128_math)',
-    'cfg(llvm_enzyme)',
 
 ]

library/std/Cargo.toml

@@ -125,8 +125,6 @@ optimize_for_size = ["core/optimize_for_size", "alloc/optimize_for_size"]
 # a borrow error occurs
 debug_refcell = ["core/debug_refcell"]
 
-llvm_enzyme = ["core/llvm_enzyme"]
-
 # Enable using raw-dylib for Windows imports.
 # This will eventually be the default.
 windows_raw_dylib = ["windows-link/windows_raw_dylib"]

library/sysroot/Cargo.toml

@@ -32,4 +32,3 @@ optimize_for_size = ["std/optimize_for_size"]
 panic-unwind = ["std/panic-unwind"]
 profiler = ["dep:profiler_builtins"]
 windows_raw_dylib = ["std/windows_raw_dylib"]
-llvm_enzyme = ["std/llvm_enzyme"]