reduce compiler Assemble complexity

`compile::Assemble` is already complicated by its nature (as it handles core
internals like recursive building logic, etc.) and also handles half of `LldWrapper`
tool logic for no good reason since it should be done in the build step directly.

This change moves it there to reduce complexity of `compile::Assemble` logic.

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

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

@@ -1892,12 +1892,6 @@ impl Step for Assemble {
             });
         }
 
-        let lld_install = if builder.config.lld_enabled {
-            Some(builder.ensure(llvm::Lld { target: target_compiler.host }))
-        } else {
-            None
-        };
-
         let stage = target_compiler.stage;
         let host = target_compiler.host;
         let (host_info, dir_name) = if build_compiler.host == host {
@@ -1958,22 +1952,11 @@ impl Step for Assemble {
 
         copy_codegen_backends_to_sysroot(builder, build_compiler, target_compiler);
 
-        if let Some(lld_install) = lld_install {
-            let src_exe = exe("lld", target_compiler.host);
-            let dst_exe = exe("rust-lld", target_compiler.host);
-            builder.copy_link(&lld_install.join("bin").join(src_exe), &libdir_bin.join(dst_exe));
-            let self_contained_lld_dir = libdir_bin.join("gcc-ld");
-            t!(fs::create_dir_all(&self_contained_lld_dir));
-            let lld_wrapper_exe = builder.ensure(crate::core::build_steps::tool::LldWrapper {
-                compiler: build_compiler,
-                target: target_compiler.host,
+        if builder.config.lld_enabled {
+            builder.ensure(crate::core::build_steps::tool::LldWrapper {
+                build_compiler,
+                target_compiler,
             });
-            for name in crate::LLD_FILE_NAMES {
-                builder.copy_link(
-                    &lld_wrapper_exe,
-                    &self_contained_lld_dir.join(exe(name, target_compiler.host)),
-                );
-            }
         }
 
         if builder.config.llvm_enabled(target_compiler.host) && builder.config.llvm_tools_enabled {

src/bootstrap/src/core/build_steps/tool.rs

@@ -1,8 +1,8 @@
 use std::path::PathBuf;
 use std::{env, fs};
 
-use crate::core::build_steps::compile;
 use crate::core::build_steps::toolstate::ToolState;
+use crate::core::build_steps::{compile, llvm};
 use crate::core::builder;
 use crate::core::builder::{Builder, Cargo as CargoCommand, RunConfig, ShouldRun, Step};
 use crate::core::config::TargetSelection;
@@ -722,29 +722,50 @@ impl Step for Cargo {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct LldWrapper {
-    pub compiler: Compiler,
-    pub target: TargetSelection,
+    pub build_compiler: Compiler,
+    pub target_compiler: Compiler,
 }
 
 impl Step for LldWrapper {
-    type Output = PathBuf;
+    type Output = ();
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
         run.never()
     }
 
-    fn run(self, builder: &Builder<'_>) -> PathBuf {
-        builder.ensure(ToolBuild {
-            compiler: self.compiler,
-            target: self.target,
+    fn run(self, builder: &Builder<'_>) {
+        if builder.config.dry_run() {
+            return;
+        }
+
+        let target = self.target_compiler.host;
+
+        let executable = builder.ensure(ToolBuild {
+            compiler: self.build_compiler,
+            target,
             tool: "lld-wrapper",
             mode: Mode::ToolStd,
             path: "src/tools/lld-wrapper",
             source_type: SourceType::InTree,
             extra_features: Vec::new(),
             allow_features: "",
             cargo_args: Vec::new(),
-        })
+        });
+
+        let libdir_bin = builder.sysroot_target_bindir(self.target_compiler, target);
+        t!(fs::create_dir_all(&libdir_bin));
+
+        let lld_install = builder.ensure(llvm::Lld { target });
+        let src_exe = exe("lld", target);
+        let dst_exe = exe("rust-lld", target);
+
+        builder.copy_link(&lld_install.join("bin").join(src_exe), &libdir_bin.join(dst_exe));
+        let self_contained_lld_dir = libdir_bin.join("gcc-ld");
+        t!(fs::create_dir_all(&self_contained_lld_dir));
+
+        for name in crate::LLD_FILE_NAMES {
+            builder.copy_link(&executable, &self_contained_lld_dir.join(exe(name, target)));
+        }
     }
 }