ci: ensure nightly and rustup are available

.github/workflows/enzyme-ci.yml

@@ -21,18 +21,35 @@ jobs:
 
     timeout-minutes: 600
     steps:
-      - name: checkout the source code
-        uses: actions/checkout@v3
+      - name: Checkout Rust source
+        uses: actions/checkout@v4
         with:
           fetch-depth: 2
-      - name: build
+      - uses: dtolnay/rust-toolchain@nightly
+      - name: Get LLVM commit hash
+        id: llvm-commit
+        run: echo "HEAD=$(git -C src/llvm-project rev-parse HEAD)" >> $GITHUB_OUTPUT
+      - name: Cache LLVM
+        id: cache-llvm
+        uses: actions/cache@v4
+        with:
+          path: build/build/x86_64-unknown-linux-gnu/llvm
+          key: ${{ matrix.os }}-llvm-${{ steps.llvm-commit.outputs.HEAD }}
+      - name: Build
         run: |
-          mkdir build
+          mkdir -p build
           cd build
+          rm -f config.toml
           ../configure --enable-llvm-link-shared --enable-llvm-plugins --enable-llvm-enzyme --release-channel=nightly --enable-llvm-assertions --enable-lld --enable-option-checking --enable-ninja --disable-docs
           ../x.py build --stage 1 library/std library/proc_macro library/test tools/rustdoc
-          rustup toolchain link enzyme `pwd`/build/`rustup target list --installed`/stage1
-          rustup toolchain install nightly # enables -Z unstable-options
-      - name: test
+          rustup toolchain link enzyme build/host/stage1
+      - name: checkout Enzyme/rustbook
+        uses: actions/checkout@v4
+        with:
+          repository: EnzymeAD/rustbook
+          ref: mdbook-test
+          path: rustbook
+      - name: test Enzyme/rustbook
+        working-directory: rustbook
         run: |
-          cargo +enzyme test --examples
+          cargo +enzyme test --workspace

README.md

@@ -21,7 +21,7 @@ Afterwards you can build rustc using:
 
 Afterwards rustc toolchain link will allow you to use it through cargo:
 ```
-rustup toolchain link enzyme `pwd`/build/`rustup target list --installed`/stage1
+rustup toolchain link enzyme build/host/stage1
 rustup toolchain install nightly # enables -Z unstable-options
 ```
 

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

@@ -844,13 +844,34 @@ impl Step for Enzyme {
 
         let LlvmResult { llvm_config, llvm_cmake_dir } = builder.ensure(Llvm { target });
 
+        static STAMP_HASH_MEMO: OnceLock<String> = OnceLock::new();
+        let smart_stamp_hash = STAMP_HASH_MEMO.get_or_init(|| {
+            generate_smart_stamp_hash(
+                &builder.config.src.join("src/tools/enzyme"),
+                &builder.enzyme_info.sha().unwrap_or_default(),
+            )
+        });
+
         let out_dir = builder.enzyme_out(target);
-        let done_stamp = out_dir.join("enzyme-finished-building");
-        if done_stamp.exists() {
+        let stamp = out_dir.join("enzyme-finished-building");
+        let stamp = HashStamp::new(stamp, Some(smart_stamp_hash));
+
+        if stamp.is_done() {
+            if stamp.hash.is_none() {
+                builder.info(
+                    "Could not determine the Enzyme submodule commit hash. \
+                     Assuming that an Enzyme rebuild is not necessary.",
+                );
+                builder.info(&format!(
+                    "To force Enzyme to rebuild, remove the file `{}`",
+                    stamp.path.display()
+                ));
+            }
             return out_dir;
         }
 
         builder.info(&format!("Building Enzyme for {}", target));
+        t!(stamp.remove());
         let _time = helpers::timeit(&builder);
         t!(fs::create_dir_all(&out_dir));
 
@@ -878,7 +899,8 @@ impl Step for Enzyme {
 
         cfg.build();
 
-        t!(File::create(&done_stamp));
+        t!(stamp.write());
+
         out_dir
     }
 }

src/bootstrap/src/lib.rs

@@ -168,6 +168,7 @@ pub struct Build {
     clippy_info: GitInfo,
     miri_info: GitInfo,
     rustfmt_info: GitInfo,
+    enzyme_info: GitInfo,
     in_tree_llvm_info: GitInfo,
     local_rebuild: bool,
     fail_fast: bool,
@@ -331,6 +332,7 @@ impl Build {
         let clippy_info = GitInfo::new(omit_git_hash, &src.join("src/tools/clippy"));
         let miri_info = GitInfo::new(omit_git_hash, &src.join("src/tools/miri"));
         let rustfmt_info = GitInfo::new(omit_git_hash, &src.join("src/tools/rustfmt"));
+        let enzyme_info = GitInfo::new(omit_git_hash, &src.join("src/tools/enzyme"));
 
         // we always try to use git for LLVM builds
         let in_tree_llvm_info = GitInfo::new(false, &src.join("src/llvm-project"));
@@ -413,6 +415,7 @@ impl Build {
             clippy_info,
             miri_info,
             rustfmt_info,
+            enzyme_info,
             in_tree_llvm_info,
             cc: RefCell::new(HashMap::new()),
             cxx: RefCell::new(HashMap::new()),