Unrolled build for #165275 in rollup 165510

Rollup merge of #165275 - TechnoPorg:push-wrpxssqqoxqw, r=ZuseZ4

Build TPDE with local Clang when available

As noted in #164108 (review), TPDE requires a clang with a major version <= the LLVM major version, and performance tends to be better when built with clang. This PR makes TPDE compilation and encodegen use the locally built clang if it's available.

I haven't added any sort of warning if `llvm.clang` is _not_ set as TPDE will throw its own error if the major version is too high. Maybe it's worth doing so, though?

This also includes the TPDE compilation fix commit from #164108. We will see which ones makes it in first.

r? @ZuseZ4

Author: bors

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

@@ -2333,13 +2333,14 @@ fn get_locally_built_tpde_build_status(
         tpde_root_dir: out_dir,
     };
 
+    // TPDE links against LLVM.
+    // By including the LLVM hash as well as the TPDE hash we force a rebuild of TPDE when updating LLVM.
+    let tpde_hash_input = builder.in_tree_llvm_info.sha().unwrap_or_default().to_owned()
+        + builder.in_tree_tpde_info.sha().unwrap_or_default();
+
     static STAMP_HASH_MEMO: OnceLock<String> = OnceLock::new();
     let smart_stamp_hash = STAMP_HASH_MEMO.get_or_init(|| {
-        generate_smart_stamp_hash(
-            builder,
-            &builder.config.src.join("src/tpde"),
-            builder.in_tree_tpde_info.sha().unwrap_or_default(),
-        )
+        generate_smart_stamp_hash(builder, &builder.config.src.join("src/tpde"), &tpde_hash_input)
     });
 
     // Rebuild if build options change
@@ -2348,7 +2349,8 @@ fn get_locally_built_tpde_build_status(
         .add_stamp(smart_stamp_hash)
         .add_stamp(builder.config.llvm_assertions)
         .add_stamp(builder.config.llvm_optimize)
-        .add_stamp(builder.config.llvm_release_debuginfo);
+        .add_stamp(builder.config.llvm_release_debuginfo)
+        .add_stamp(builder.config.llvm_clang);
 
     if stamp.is_up_to_date() {
         if smart_stamp_hash.is_empty() {
@@ -2436,17 +2438,29 @@ impl CommandLineStep for Tpde {
             .define("TPDE_ENABLE_COVERAGE", "OFF")
             .define("TPDE_BUILD_DOCS", "OFF")
             .define("TPDE_ENABLE_EH", "OFF")
+            .define("CMAKE_INSTALL_LIBDIR", "lib")
             .define("LLVM_DIR", llvm.cmake_dir());
 
         let mut ldflags = LdFlags::default();
         try_link_with_in_tree_lld(builder, target, &llvm, &mut cfg, &mut ldflags);
         configure_cmake(builder, target, &mut cfg, true, ldflags, CcFlags::default(), &[]);
 
+        if builder.config.llvm_clang {
+            let clang_bin_dir = llvm.llvm_config().parent().map(Path::to_path_buf).unwrap();
+            let clang = clang_bin_dir.join(exe("clang", target));
+            let clangxx = clang_bin_dir.join(exe("clang++", target));
+
+            cfg.define("CMAKE_C_COMPILER", &clang)
+                .define("CMAKE_CXX_COMPILER", &clangxx)
+                .define("CMAKE_ASM_COMPILER", &clang);
+        }
+
         if builder.config.dry_run() {
             return output;
         }
 
         cfg.build_target("tpde-plugin.so");
+        cfg.build();
 
         // When building TPDE as a shared library on linux, it can contain unexpected debuginfo:
         // some can come from the C++ standard library. Unless we're explicitly requesting TPDE to