move offload checks into the step, still copy files

Author: ZuseZ4

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

@@ -1428,10 +1428,7 @@ fn rustc_llvm_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelect
         cargo.env("LLVM_ENZYME", "1");
     }
     let llvm::LlvmResult { host_llvm_config, .. } = builder.ensure(llvm::Llvm { target });
-    if builder.config.llvm_offload
-        && !builder.config.llvm_profile_generate
-        && builder.config.llvm_profile_use.is_none()
-    {
+    if builder.config.llvm_offload {
         builder.ensure(llvm::OmpOffload { target });
         cargo.env("LLVM_OFFLOAD", "1");
     }
@@ -2298,11 +2295,7 @@ impl Step for Assemble {
             }
         }
 
-        if builder.config.llvm_offload
-            && !builder.config.dry_run()
-            && !builder.config.llvm_profile_generate
-            && builder.config.llvm_profile_use.is_none()
-        {
+        if builder.config.llvm_offload && !builder.config.dry_run() {
             debug!("`llvm_offload` requested");
             let offload_install = builder.ensure(llvm::OmpOffload { target: build_compiler.host });
             if let Some(_llvm_config) = builder.llvm_config(builder.config.host_target) {

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

@@ -935,9 +935,10 @@ impl Step for OmpOffload {
         if builder.config.dry_run() {
             return builder.config.tempdir().join("llvm-offload-dry-run");
         }
+
         let target = self.target;
 
-        let LlvmResult { host_llvm_config, .. } = builder.ensure(Llvm { target: self.target });
+        let LlvmResult { host_llvm_config, .. } = builder.ensure(Llvm { target });
 
         // Running cmake twice in the same folder is known to cause issues, like deleting existing
         // binaries. We therefore write our offload artifacts into it's own subfolder. We use a
@@ -948,6 +949,14 @@ impl Step for OmpOffload {
             std::fs::DirBuilder::new().create(&out_dir).unwrap();
         }
 
+        if !builder.config.llvm_offload
+            || builder.config.dry_run()
+            || builder.config.llvm_profile_generate
+            || builder.config.llvm_profile_use.is_some()
+        {
+            return out_dir;
+        }
+
         // Offload/OpenMP are just subfolders of LLVM, so we can use the LLVM sha.
         static STAMP_HASH_MEMO: OnceLock<String> = OnceLock::new();
         let smart_stamp_hash = STAMP_HASH_MEMO.get_or_init(|| {