allow specifying cc/cxx for llvm_offload subproject build

Author: ZuseZ4

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

@@ -939,34 +939,34 @@ impl Step for OmpOffload {
 
         let out_dir = builder.llvm_out(target);
         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/llvm-project/offload"),
-        //        builder.offload_info.sha().unwrap_or_default(),
-        //    )
-        //});
-        //let stamp = BuildStamp::new(&out_dir).with_prefix("enzyme").add_stamp(smart_stamp_hash);
+        let smart_stamp_hash = STAMP_HASH_MEMO.get_or_init(|| {
+            generate_smart_stamp_hash(
+                builder,
+                &builder.config.src.join("src/llvm-project/offload"),
+                builder.offload_info.sha().unwrap_or_default(),
+            )
+        });
+        let stamp = BuildStamp::new(&out_dir).with_prefix("offload").add_stamp(smart_stamp_hash);
 
         trace!("checking build stamp to see if we need to rebuild offload/openmp artifacts");
-        //if stamp.is_up_to_date() {
-        //    trace!(?out_dir, "offload/openmp build artifacts are up to date");
-        //    if stamp.stamp().is_empty() {
-        //        builder.info(
-        //            "Could not determine the Offload submodule commit hash. \
-        //             Assuming that an Offload rebuild is not necessary.",
-        //        );
-        //        builder.info(&format!(
-        //            "To force Offload to rebuild, remove the file `{}`",
-        //            stamp.path().display()
-        //        ));
-        //    }
-        //    return out_dir;
-        //}
-
-        trace!(?target, "(re)building offload artifacts");
-        builder.info(&format!("Building Omp/Offload for {target}"));
-        //t!(stamp.remove());
+        if stamp.is_up_to_date() {
+            trace!(?out_dir, "offload/openmp build artifacts are up to date");
+            if stamp.stamp().is_empty() {
+                builder.info(
+                    "Could not determine the Offload submodule commit hash. \
+                     Assuming that an Offload rebuild is not necessary.",
+                );
+                builder.info(&format!(
+                    "To force Offload/OpenMP to rebuild, remove the file `{}`",
+                    stamp.path().display()
+                ));
+            }
+            return out_dir;
+        }
+
+        trace!(?target, "(re)building offload/openmp artifacts");
+        builder.info(&format!("Building OpenMP/Offload for {target}"));
+        t!(stamp.remove());
         let _time = helpers::timeit(builder);
         t!(fs::create_dir_all(&out_dir));
 
@@ -984,6 +984,17 @@ impl Step for OmpOffload {
         };
         trace!(?profile);
 
+        let cc = if let Some(p) = &builder.build.config.llvm_offload_cc {
+            p.clone()
+        } else {
+            builder.cc(target)
+        };
+        let cxx = if let Some(p) = &builder.build.config.llvm_offload_cxx {
+            p.clone()
+        } else {
+            builder.cxx(target).unwrap()
+        };
+
         cfg.out_dir(&out_dir)
             .profile(profile)
             .env("LLVM_CONFIG_REAL", &host_llvm_config)
@@ -997,9 +1008,8 @@ impl Step for OmpOffload {
             //    "CMAKE_CXX_COMPILER",
             //    "/tmp/drehwald1/prog/rust/build/x86_64-unknown-linux-gnu/llvm/bin/clang++",
             //)
-            .define("CMAKE_C_COMPILER", builder.cc(target))
-            .define("CMAKE_CXX_COMPILER", builder.cxx(target).unwrap())
-            //.define("LLVM_DEFAULT_TARGET_TRIPLE", &target.triple)
+            .define("CMAKE_C_COMPILER", cc)
+            .define("CMAKE_CXX_COMPILER", cxx)
             .define("OPENMP_STANDALONE_BUILD", "ON")
             .define("LLVM_ROOT", builder.llvm_out(target).join("build"))
             //.define(

src/bootstrap/src/core/config/config.rs

@@ -169,6 +169,8 @@ pub struct Config {
     pub llvm_link_jobs: Option<u32>,
     pub llvm_version_suffix: Option<String>,
     pub llvm_use_linker: Option<String>,
+    pub llvm_offload_cc: Option<PathBuf>,
+    pub llvm_offload_cxx: Option<PathBuf>,
     pub llvm_allow_old_toolchain: bool,
     pub llvm_polly: bool,
     pub llvm_clang: bool,
@@ -290,6 +292,7 @@ pub struct Config {
     pub miri_info: channel::GitInfo,
     pub rustfmt_info: channel::GitInfo,
     pub enzyme_info: channel::GitInfo,
+    pub offload_info: channel::GitInfo,
     pub in_tree_llvm_info: channel::GitInfo,
     pub in_tree_gcc_info: channel::GitInfo,
 
@@ -601,6 +604,8 @@ impl Config {
             ldflags: llvm_ldflags,
             use_libcxx: llvm_use_libcxx,
             use_linker: llvm_use_linker,
+            offload_cc: llvm_offload_cc,
+            offload_cxx: llvm_offload_cxx,
             allow_old_toolchain: llvm_allow_old_toolchain,
             offload: llvm_offload,
             polly: llvm_polly,
@@ -1257,6 +1262,8 @@ impl Config {
         let in_tree_gcc_info = git_info(&exec_ctx, false, &src.join("src/gcc"));
         let in_tree_llvm_info = git_info(&exec_ctx, false, &src.join("src/llvm-project"));
         let enzyme_info = git_info(&exec_ctx, omit_git_hash, &src.join("src/tools/enzyme"));
+        let offload_info =
+            git_info(&exec_ctx, omit_git_hash, &src.join("src/llvm-project/offload"));
         let miri_info = git_info(&exec_ctx, omit_git_hash, &src.join("src/tools/miri"));
         let rust_analyzer_info =
             git_info(&exec_ctx, omit_git_hash, &src.join("src/tools/rust-analyzer"));
@@ -1320,6 +1327,7 @@ impl Config {
             ehcont_guard: rust_ehcont_guard.unwrap_or(false),
             enable_bolt_settings: flags_enable_bolt_settings,
             enzyme_info,
+            offload_info,
             exec_ctx,
             explicit_stage_from_cli: flags_stage.is_some(),
             explicit_stage_from_config,
@@ -1360,6 +1368,8 @@ impl Config {
             llvm_enable_warnings: llvm_enable_warnings.unwrap_or(false),
             llvm_enzyme: llvm_enzyme.unwrap_or(false),
             llvm_experimental_targets,
+            llvm_offload_cc: llvm_offload_cc.map(PathBuf::from),
+            llvm_offload_cxx: llvm_offload_cxx.map(PathBuf::from),
             llvm_from_ci,
             llvm_ldflags,
             llvm_libunwind_default: rust_llvm_libunwind

src/bootstrap/src/core/config/toml/llvm.rs

@@ -32,6 +32,8 @@ define_config! {
         ldflags: Option<String> = "ldflags",
         use_libcxx: Option<bool> = "use-libcxx",
         use_linker: Option<String> = "use-linker",
+        offload_cc: Option<String> = "offload-cc",
+        offload_cxx: Option<String> = "offload-cxx",
         allow_old_toolchain: Option<bool> = "allow-old-toolchain",
         offload: Option<bool> = "offload",
         polly: Option<bool> = "polly",
@@ -110,6 +112,8 @@ pub fn check_incompatible_options_for_ci_llvm(
         ldflags,
         use_libcxx,
         use_linker,
+        offload_cc,
+        offload_cxx,
         allow_old_toolchain,
         offload,
         polly,

src/bootstrap/src/lib.rs

@@ -212,12 +212,15 @@ pub struct Build {
     src: PathBuf,
     out: PathBuf,
     bootstrap_out: PathBuf,
+    //offload_cc: PathBuf,
+    //offload_cxx: PathBuf,
     cargo_info: GitInfo,
     rust_analyzer_info: GitInfo,
     clippy_info: GitInfo,
     miri_info: GitInfo,
     rustfmt_info: GitInfo,
     enzyme_info: GitInfo,
+    offload_info: GitInfo,
     in_tree_llvm_info: GitInfo,
     in_tree_gcc_info: GitInfo,
     local_rebuild: bool,
@@ -476,6 +479,7 @@ impl Build {
         let miri_info = config.miri_info.clone();
         let rustfmt_info = config.rustfmt_info.clone();
         let enzyme_info = config.enzyme_info.clone();
+        let offload_info = config.offload_info.clone();
         let in_tree_llvm_info = config.in_tree_llvm_info.clone();
         let in_tree_gcc_info = config.in_tree_gcc_info.clone();
 
@@ -568,6 +572,7 @@ impl Build {
             miri_info,
             rustfmt_info,
             enzyme_info,
+            offload_info,
             in_tree_llvm_info,
             in_tree_gcc_info,
             cc: HashMap::new(),