Remove unused code

Sa4dUs · Sa4dUs · commit e58ebacf3b20 · 2025-07-12T10:28:06.000Z
diff --git a/compiler/rustc_builtin_macros/src/autodiff.rs b/compiler/rustc_builtin_macros/src/autodiff.rs
@@ -262,7 +262,6 @@ mod llvm_enzyme {
         };
 
         let has_ret = has_ret(&sig.decl.output);
-        let sig_span = ecx.with_call_site_ctxt(sig.span);
 
         // create TokenStream from vec elemtents:
         // meta_item doesn't have a .tokens field
@@ -331,24 +330,13 @@ mod llvm_enzyme {
         }
         let span = ecx.with_def_site_ctxt(expand_span);
 
-        let n_active: u32 = x
-            .input_activity
-            .iter()
-            .filter(|a| **a == DiffActivity::Active || **a == DiffActivity::ActiveOnly)
-            .count() as u32;
-        let (d_sig, new_args, idents, errored) = gen_enzyme_decl(ecx, &sig, &x, span);
+        let (d_sig, idents, errored) = gen_enzyme_decl(ecx, &sig, &x, span);
 
-        // TODO(Sa4dUs): Remove this and all the related logic
         let d_body = gen_enzyme_body(
             ecx,
-            &x,
-            n_active,
-            &sig,
             &d_sig,
             primal,
-            &new_args,
             span,
-            sig_span,
             idents,
             errored,
             first_ident(&meta_item_vec[0]),
@@ -361,7 +349,7 @@ mod llvm_enzyme {
             defaultness: ast::Defaultness::Final,
             sig: d_sig,
             ident: first_ident(&meta_item_vec[0]),
-            generics: generics.clone(),
+            generics,
             contract: None,
             body: Some(d_body),
             define_opaque: None,
@@ -542,7 +530,7 @@ mod llvm_enzyme {
             vec![
                 Ident::from_str("std"),
                 Ident::from_str("intrinsics"),
-                Ident::from_str("enzyme_autodiff"),
+                Ident::with_dummy_span(sym::enzyme_autodiff),
             ],
         );
         let call_expr = ecx.expr_call(
@@ -555,7 +543,7 @@ mod llvm_enzyme {
     }
 
     // Generate turbofish expression from fn name and generics
-    // Given `foo` and `<A, B, C>`, gen `foo::<A, B, C>`
+    // Given `foo` and `<A, B, C>` params, gen `foo::<A, B, C>`
     fn gen_turbofish_expr(
         ecx: &ExtCtxt<'_>,
         ident: Ident,
@@ -597,43 +585,27 @@ mod llvm_enzyme {
 
     // Will generate a body of the type:
     // ```
-    // {
-    //   unsafe {
-    //   asm!("NOP");
-    //   }
-    //   ::core::hint::black_box(primal(args));
-    //   ::core::hint::black_box((args, ret));
-    //   <This part remains to be done by following function>
+    //   primal(args);
+    //   std::intrinsics::enzyme_autodiff(primal, diff, (args))
     // }
     // ```
     fn init_body_helper(
         ecx: &ExtCtxt<'_>,
         span: Span,
         primal: Ident,
-        _new_names: &[String],
-        _sig_span: Span,
-        new_decl_span: Span,
         idents: &[Ident],
         errored: bool,
         generics: &Generics,
-    ) -> (P<ast::Block>, P<ast::Expr>, P<ast::Expr>, P<ast::Expr>) {
-        let blackbox_path = ecx.std_path(&[sym::hint, sym::black_box]);
-        let blackbox_call_expr = ecx.expr_path(ecx.path(span, blackbox_path));
+    ) -> P<ast::Block> {
         let primal_call = gen_primal_call(ecx, span, primal, idents, generics);
-        let black_box_primal_call = ecx.expr_call(
-            new_decl_span,
-            blackbox_call_expr.clone(),
-            thin_vec![primal_call.clone()],
-        );
-
         let mut body = ecx.block(span, ThinVec::new());
 
         // This uses primal args which won't be available if we errored before
         if !errored {
             body.stmts.push(ecx.stmt_semi(primal_call.clone()));
         }
 
-        (body, primal_call, black_box_primal_call, blackbox_call_expr)
+        body
     }
 
     /// We only want this function to type-check, since we will replace the body
@@ -646,14 +618,9 @@ mod llvm_enzyme {
     /// from optimizing any arguments away.
     fn gen_enzyme_body(
         ecx: &ExtCtxt<'_>,
-        _x: &AutoDiffAttrs,
-        _n_active: u32,
-        _sig: &ast::FnSig,
         d_sig: &ast::FnSig,
         primal: Ident,
-        new_names: &[String],
         span: Span,
-        sig_span: Span,
         idents: Vec<Ident>,
         errored: bool,
         diff_ident: Ident,
@@ -664,17 +631,7 @@ mod llvm_enzyme {
 
         // Add a call to the primal function to prevent it from being inlined
         // and call `enzyme_autodiff` intrinsic (this also covers the return type)
-        let (mut body, _primal_call, _bb_primal_call, _bb_call_expr) = init_body_helper(
-            ecx,
-            span,
-            primal,
-            new_names,
-            sig_span,
-            new_decl_span,
-            &idents,
-            errored,
-            generics,
-        );
+        let mut body = init_body_helper(ecx, span, primal, &idents, errored, generics);
 
         body.stmts.push(call_enzyme_autodiff(
             ecx,
@@ -771,7 +728,7 @@ mod llvm_enzyme {
         sig: &ast::FnSig,
         x: &AutoDiffAttrs,
         span: Span,
-    ) -> (ast::FnSig, Vec<String>, Vec<Ident>, bool) {
+    ) -> (ast::FnSig, Vec<Ident>, bool) {
         let dcx = ecx.sess.dcx();
         let has_ret = has_ret(&sig.decl.output);
         let sig_args = sig.decl.inputs.len() + if has_ret { 1 } else { 0 };
@@ -783,7 +740,7 @@ mod llvm_enzyme {
                 found: num_activities,
             });
             // This is not the right signature, but we can continue parsing.
-            return (sig.clone(), vec![], vec![], true);
+            return (sig.clone(), vec![], true);
         }
         assert!(sig.decl.inputs.len() == x.input_activity.len());
         assert!(has_ret == x.has_ret_activity());
@@ -826,7 +783,7 @@ mod llvm_enzyme {
 
         if errors {
             // This is not the right signature, but we can continue parsing.
-            return (sig.clone(), new_inputs, idents, true);
+            return (sig.clone(), idents, true);
         }
 
         let unsafe_activities = x
@@ -1034,7 +991,7 @@ mod llvm_enzyme {
         }
         let d_sig = FnSig { header: d_header, decl: d_decl, span };
         trace!("Generated signature: {:?}", d_sig);
-        (d_sig, new_inputs, idents, false)
+        (d_sig, idents, false)
     }
 }
 
diff --git a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
@@ -1,43 +1,18 @@
 use std::ptr;
 
-use rustc_ast::expand::autodiff_attrs::{AutoDiffAttrs, AutoDiffItem, DiffActivity, DiffMode};
-use rustc_codegen_ssa::ModuleCodegen;
-use rustc_codegen_ssa::back::write::ModuleConfig;
+use rustc_ast::expand::autodiff_attrs::{AutoDiffAttrs, DiffActivity, DiffMode};
 use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::traits::{BaseTypeCodegenMethods, BuilderMethods};
-use rustc_errors::FatalError;
 use rustc_middle::bug;
-use tracing::{debug, trace};
+use tracing::debug;
 
-use crate::back::write::llvm_err;
 use crate::builder::{Builder, PlaceRef, UNNAMED};
 use crate::context::SimpleCx;
 use crate::declare::declare_simple_fn;
-use crate::errors::{AutoDiffWithoutEnable, LlvmError};
 use crate::llvm::AttributePlace::Function;
 use crate::llvm::{Metadata, True, Type};
 use crate::value::Value;
-use crate::{CodegenContext, LlvmCodegenBackend, ModuleLlvm, attributes, llvm};
-
-fn _get_params(fnc: &Value) -> Vec<&Value> {
-    let param_num = llvm::LLVMCountParams(fnc) as usize;
-    let mut fnc_args: Vec<&Value> = vec![];
-    fnc_args.reserve(param_num);
-    unsafe {
-        llvm::LLVMGetParams(fnc, fnc_args.as_mut_ptr());
-        fnc_args.set_len(param_num);
-    }
-    fnc_args
-}
-
-fn _has_sret(fnc: &Value) -> bool {
-    let num_args = llvm::LLVMCountParams(fnc) as usize;
-    if num_args == 0 {
-        false
-    } else {
-        unsafe { llvm::LLVMRustHasAttributeAtIndex(fnc, 0, llvm::AttributeKind::StructRet) }
-    }
-}
+use crate::{attributes, llvm};
 
 // When we call the `__enzyme_autodiff` or `__enzyme_fwddiff` function, we need to pass all the
 // original inputs, as well as metadata and the additional shadow arguments.
@@ -294,62 +269,3 @@ pub(crate) fn generate_enzyme_call<'ll, 'tcx>(
 
     builder.store_to_place(call, dest.val);
 }
-
-pub(crate) fn differentiate<'ll>(
-    module: &'ll ModuleCodegen<ModuleLlvm>,
-    cgcx: &CodegenContext<LlvmCodegenBackend>,
-    diff_items: Vec<AutoDiffItem>,
-    _config: &ModuleConfig,
-) -> Result<(), FatalError> {
-    // TODO(Sa4dUs): delete all this logic
-    for item in &diff_items {
-        trace!("{}", item);
-    }
-
-    let diag_handler = cgcx.create_dcx();
-
-    let cx = SimpleCx::new(module.module_llvm.llmod(), module.module_llvm.llcx, cgcx.pointer_size);
-
-    // 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)
-    {
-        return Err(diag_handler.handle().emit_almost_fatal(AutoDiffWithoutEnable));
-    }
-
-    // Here we replace the placeholder code with the actual autodiff code, which calls Enzyme.
-    for item in diff_items.iter() {
-        let name = item.source.clone();
-        let fn_def: Option<&llvm::Value> = cx.get_function(&name);
-        let Some(_fn_def) = fn_def else {
-            return Err(llvm_err(
-                diag_handler.handle(),
-                LlvmError::PrepareAutoDiff {
-                    src: item.source.clone(),
-                    target: item.target.clone(),
-                    error: "could not find source function".to_owned(),
-                },
-            ));
-        };
-        debug!(?item.target);
-        let fn_target: Option<&llvm::Value> = cx.get_function(&item.target);
-        let Some(_fn_target) = fn_target else {
-            return Err(llvm_err(
-                diag_handler.handle(),
-                LlvmError::PrepareAutoDiff {
-                    src: item.source.clone(),
-                    target: item.target.clone(),
-                    error: "could not find target function".to_owned(),
-                },
-            ));
-        };
-
-        // generate_enzyme_call(&cx, fn_def, fn_target, item.attrs.clone());
-    }
-
-    // FIXME(ZuseZ4): support SanitizeHWAddress and prevent illegal/unsupported opts
-
-    trace!("done with differentiate()");
-
-    Ok(())
-}
diff --git a/compiler/rustc_codegen_llvm/src/errors.rs b/compiler/rustc_codegen_llvm/src/errors.rs
@@ -37,13 +37,16 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for ParseTargetMachineConfig<'_> {
     }
 }
 
+// TODO(Sa4dUs): we will need to reintroduce these errors somewhere
+/*
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_autodiff_without_lto)]
 pub(crate) struct AutoDiffWithoutLTO;
 
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_autodiff_without_enable)]
 pub(crate) struct AutoDiffWithoutEnable;
+*/
 
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_lto_disallowed)]
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -26,10 +26,9 @@ use std::mem::ManuallyDrop;
 use back::owned_target_machine::OwnedTargetMachine;
 use back::write::{create_informational_target_machine, create_target_machine};
 use context::SimpleCx;
-use errors::{AutoDiffWithoutLTO, ParseTargetMachineConfig};
+use errors::ParseTargetMachineConfig;
 use llvm_util::target_config;
 use rustc_ast::expand::allocator::AllocatorKind;
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{
     CodegenContext, FatLtoInput, ModuleConfig, TargetMachineFactoryConfig, TargetMachineFactoryFn,
@@ -43,7 +42,7 @@ use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::TyCtxt;
 use rustc_middle::util::Providers;
 use rustc_session::Session;
-use rustc_session::config::{Lto, OptLevel, OutputFilenames, PrintKind, PrintRequest};
+use rustc_session::config::{OptLevel, OutputFilenames, PrintKind, PrintRequest};
 use rustc_span::Symbol;
 
 mod back {
@@ -227,19 +226,6 @@ impl WriteBackendMethods for LlvmCodegenBackend {
     fn serialize_module(module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer) {
         (module.name, back::lto::ModuleBuffer::new(module.module_llvm.llmod()))
     }
-    /// Generate autodiff rules
-    fn autodiff(
-        cgcx: &CodegenContext<Self>,
-        module: &ModuleCodegen<Self::Module>,
-        diff_fncs: Vec<AutoDiffItem>,
-        config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
-        if cgcx.lto != Lto::Fat {
-            let dcx = cgcx.create_dcx();
-            return Err(dcx.handle().emit_almost_fatal(AutoDiffWithoutLTO));
-        }
-        builder::autodiff::differentiate(module, cgcx, diff_fncs, config)
-    }
 }
 
 impl LlvmCodegenBackend {
diff --git a/compiler/rustc_codegen_ssa/src/back/lto.rs b/compiler/rustc_codegen_ssa/src/back/lto.rs
@@ -1,13 +1,11 @@
 use std::ffi::CString;
 use std::sync::Arc;
 
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_data_structures::memmap::Mmap;
 use rustc_errors::FatalError;
 
 use super::write::CodegenContext;
 use crate::ModuleCodegen;
-use crate::back::write::ModuleConfig;
 use crate::traits::*;
 
 pub struct ThinModule<B: WriteBackendMethods> {
@@ -78,23 +76,6 @@ impl<B: WriteBackendMethods> LtoModuleCodegen<B> {
             LtoModuleCodegen::Thin(ref m) => m.cost(),
         }
     }
-
-    /// Run autodiff on Fat LTO module
-    pub fn autodiff(
-        self,
-        cgcx: &CodegenContext<B>,
-        diff_fncs: Vec<AutoDiffItem>,
-        config: &ModuleConfig,
-    ) -> Result<LtoModuleCodegen<B>, FatalError> {
-        match &self {
-            LtoModuleCodegen::Fat(module) => {
-                B::autodiff(cgcx, &module, diff_fncs, config)?;
-            }
-            _ => panic!("autodiff called with non-fat LTO module"),
-        }
-
-        Ok(self)
-    }
 }
 
 pub enum SerializedModule<M: ModuleBufferMethods> {
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -408,12 +408,8 @@ fn generate_lto_work<B: ExtraBackendMethods>(
 
     if !needs_fat_lto.is_empty() {
         assert!(needs_thin_lto.is_empty());
-        let mut module =
+        let module =
             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 = 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)]
     } else {
diff --git a/compiler/rustc_codegen_ssa/src/traits/write.rs b/compiler/rustc_codegen_ssa/src/traits/write.rs

Original file line number	Diff line number	Diff line change
`@@ -37,13 +37,16 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for ParseTargetMachineConfig<'_> {`
`37`	`37`	`}`
`38`	`38`	`}`
`39`	`39`
	`40`	`+// TODO(Sa4dUs): we will need to reintroduce these errors somewhere`
	`41`	`+/*`
`40`	`42`	`#[derive(Diagnostic)]`
`41`	`43`	`#[diag(codegen_llvm_autodiff_without_lto)]`
`42`	`44`	`pub(crate) struct AutoDiffWithoutLTO;`
`43`	`45`
`44`	`46`	`#[derive(Diagnostic)]`
`45`	`47`	`#[diag(codegen_llvm_autodiff_without_enable)]`
`46`	`48`	`pub(crate) struct AutoDiffWithoutEnable;`
	`49`	`+*/`
`47`	`50`
`48`	`51`	`#[derive(Diagnostic)]`
`49`	`52`	`#[diag(codegen_llvm_lto_disallowed)]`