Auto merge of #146685 - jdonszelmann:rollup-kwuih4z, r=jdonszelmann

Rollup of 7 pull requests

Successful merges:

 - rust-lang/rust#146458 (Add parallel-frontend-threads to bootstrap.toml and enable multi-threaded parallel compilation)
 - rust-lang/rust#146485 (Remove unsized arg handling in `ArgAbiBuilderMethods::store_fn_arg` implementations)
 - rust-lang/rust#146536 (clean up several trait related UI tests)
 - rust-lang/rust#146598 (Make llvm_enzyme a regular cargo feature)
 - rust-lang/rust#146647 (Move `#[rustc_coherence_is_core]` to the `crate_level` file)
 - rust-lang/rust#146654 (Do not use `git -C dir`)
 - rust-lang/rust#146681 (Add space after brace in `Box<[T]>::new_uninit_slice` example)

r? `@ghost`
`@rustbot` modify labels: rollup

5 files changed, 13 insertions, 15 deletions

diff --git a/compiler/rustc_codegen_llvm/Cargo.toml b/compiler/rustc_codegen_llvm/Cargo.toml
index 2d11628250c..67bd1e59bb0 100644
--- a/compiler/rustc_codegen_llvm/Cargo.toml
+++ b/compiler/rustc_codegen_llvm/Cargo.toml
@@ -46,5 +46,6 @@ tracing = "0.1"
 [features]
 # tidy-alphabetical-start
 check_only = ["rustc_llvm/check_only"]
+llvm_enzyme = []
 # tidy-alphabetical-end
 
diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index ac7583f5666..11be7041167 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -215,9 +215,9 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 let align = attrs.pointee_align.unwrap_or(self.layout.align.abi);
                 OperandValue::Ref(PlaceValue::new_sized(val, align)).store(bx, dst);
             }
-            // Unsized indirect qrguments
+            // Unsized indirect arguments cannot be stored
             PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
-                bug!("unsized `ArgAbi` must be handled through `store_fn_arg`");
+                bug!("unsized `ArgAbi` cannot be stored");
             }
             PassMode::Cast { cast, pad_i32: _ } => {
                 // The ABI mandates that the value is passed as a different struct representation.
@@ -272,12 +272,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 OperandValue::Pair(next(), next()).store(bx, dst);
             }
             PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
-                let place_val = PlaceValue {
-                    llval: next(),
-                    llextra: Some(next()),
-                    align: self.layout.align.abi,
-                };
-                OperandValue::Ref(place_val).store(bx, dst);
+                bug!("unsized `ArgAbi` cannot be stored");
             }
             PassMode::Direct(_)
             | PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ }
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index f571716d9dd..78107d95e5a 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -617,7 +617,7 @@ pub(crate) fn run_pass_manager(
         crate::builder::gpu_offload::handle_gpu_code(cgcx, &cx);
     }
 
-    if cfg!(llvm_enzyme) && enable_ad && !thin {
+    if cfg!(feature = "llvm_enzyme") && enable_ad && !thin {
         let opt_stage = llvm::OptStage::FatLTO;
         let stage = write::AutodiffStage::PostAD;
         if !config.autodiff.contains(&config::AutoDiff::NoPostopt) {
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 423f0da4878..bda81fbd19e 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -574,7 +574,8 @@ 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 consider_ad =
+        cfg!(feature = "llvm_enzyme") && config.autodiff.contains(&config::AutoDiff::Enable);
     let run_enzyme = autodiff_stage == AutodiffStage::DuringAD;
     let print_before_enzyme = config.autodiff.contains(&config::AutoDiff::PrintModBefore);
     let print_after_enzyme = config.autodiff.contains(&config::AutoDiff::PrintModAfter);
@@ -740,7 +741,8 @@ pub(crate) 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).
-        let consider_ad = cfg!(llvm_enzyme) && config.autodiff.contains(&config::AutoDiff::Enable);
+        let consider_ad =
+            cfg!(feature = "llvm_enzyme") && config.autodiff.contains(&config::AutoDiff::Enable);
         let autodiff_stage = if consider_ad { AutodiffStage::PreAD } else { AutodiffStage::PostAD };
         // The embedded bitcode is used to run LTO/ThinLTO.
         // The bitcode obtained during the `codegen` phase is no longer suitable for performing LTO.
diff --git a/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
index 56d756e52cc..695435eb6da 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
@@ -59,10 +59,10 @@ pub(crate) enum LLVMRustVerifierFailureAction {
     LLVMReturnStatusAction = 2,
 }
 
-#[cfg(llvm_enzyme)]
+#[cfg(feature = "llvm_enzyme")]
 pub(crate) use self::Enzyme_AD::*;
 
-#[cfg(llvm_enzyme)]
+#[cfg(feature = "llvm_enzyme")]
 pub(crate) mod Enzyme_AD {
     use std::ffi::{CString, c_char};
 
@@ -134,10 +134,10 @@ pub(crate) mod Enzyme_AD {
     }
 }
 
-#[cfg(not(llvm_enzyme))]
+#[cfg(not(feature = "llvm_enzyme"))]
 pub(crate) use self::Fallback_AD::*;
 
-#[cfg(not(llvm_enzyme))]
+#[cfg(not(feature = "llvm_enzyme"))]
 pub(crate) mod Fallback_AD {
     #![allow(unused_variables)]