Replace CG_CLIF_JIT with --jit

Author: bjorn3

Readme.md

@@ -36,7 +36,24 @@ If you compiled cg_clif in debug mode (aka you didn't pass `--release` to `./tes
 > You should prefer using the Cargo method.
 
 ```bash
-$ rustc +$(cat $cg_clif_dir/rust-toolchain) -Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/release/librustc_codegen_cranelift.so --sysroot $cg_clif_dir/build_sysroot/sysroot my_crate.rs
+$ $cg_clif_dir/target/release/cg_clif my_crate.rs
+```
+
+### Jit mode
+
+In jit mode cg_clif will immediately execute your code without creating an executable file.
+This requires all dependencies to be available as dynamic library.
+The easiest way to achieve this is by creating a new dylib crate that has all your dependencies as dependencies of itself.
+Rustc will then link all your rlib dependencies into the dylib.
+
+```bash
+$ $cg_clif_dir/cargo.sh jit
+```
+
+or
+
+```bash
+$ $cg_clif_dir/target/release/cg_clif --jit my_crate.rs
 ```
 
 ### Shell
@@ -45,7 +62,7 @@ These are a few functions that allow you to easily run rust code from the shell
 
 ```bash
 function jit_naked() {
-    echo "$@" | CG_CLIF_JIT=1 rustc -Zcodegen-backend=$cg_clif_dir/target/release/librustc_codegen_cranelift.so --sysroot $cg_clif_dir/build_sysroot/sysroot - -Cprefer-dynamic
+    echo "$@" | $cg_clif_dir/target/release/cg_clif - --jit
 }
 
 function jit() {

cargo.sh

@@ -12,12 +12,11 @@ TOOLCHAIN=$(cat rust-toolchain)
 
 popd >/dev/null
 
-if [[ $(rustc -V) != $(rustc +${TOOLCHAIN} -V) ]]; then
-    echo "rustc_codegen_cranelift is build for $(rustc +${TOOLCHAIN} -V) but the default rustc version is $(rustc -V)."
-    echo "Using $(rustc +${TOOLCHAIN} -V)."
-fi
-
 cmd=$1
 shift
 
+if [[ "$cmd" = "jit" ]]; then
+cargo +${TOOLCHAIN} rustc $@ -- --jit
+else
 cargo +${TOOLCHAIN} $cmd $@
+fi

docs/env_vars.md

@@ -1,8 +1,6 @@
 # List of env vars recognized by cg_clif
 
 <dl>
-    <dt>CG_CLIF_JIT</dt>
-    <dd>Enable JIT mode to immediately run a program instead of writing an executable file.</dd>
     <dt>CG_CLIF_JIT_ARGS</dt>
     <dd>When JIT mode is enable pass these arguments to the program.</dd>
     <dt>CG_CLIF_INCR_CACHE_DISABLED</dt>

scripts/filter_profile.rs

@@ -5,7 +5,7 @@ CHANNEL="release"
 pushd $(dirname "$0")/../
 source scripts/config.sh
 popd
-CG_CLIF_JIT=1 PROFILE=$1 OUTPUT=$2 exec rustc $RUSTFLAGS $0 --crate-type bin -Cprefer-dynamic
+PROFILE=$1 OUTPUT=$2 exec $RUSTC $RUSTFLAGS --jit $0
 #*/
 
 //! This program filters away uninteresting samples and trims uninteresting frames for stackcollapse

src/bin/cg_clif.rs

@@ -50,7 +50,9 @@ fn main() {
     let mut callbacks = TimePassesCallbacks::default();
     rustc_driver::install_ice_hook();
     let exit_code = rustc_driver::catch_with_exit_code(|| {
-        let args = std::env::args_os()
+        let mut use_jit = false;
+
+        let mut args = std::env::args_os()
             .enumerate()
             .map(|(i, arg)| {
                 arg.into_string().unwrap_or_else(|arg| {
@@ -60,14 +62,29 @@ fn main() {
                     )
                 })
             })
+            .filter(|arg| {
+                if arg == "--jit" {
+                    use_jit = true;
+                    false
+                } else {
+                    true
+                }
+            })
             .collect::<Vec<_>>();
+        if use_jit {
+            args.push("-Cprefer-dynamic".to_string());
+        }
         rustc_driver::run_compiler(
             &args,
             &mut callbacks,
             None,
             None,
-            Some(Box::new(|_| {
-                rustc_codegen_cranelift::__rustc_codegen_backend()
+            Some(Box::new(move |_| {
+                Box::new(rustc_codegen_cranelift::CraneliftCodegenBackend {
+                    config: rustc_codegen_cranelift::BackendConfig {
+                        use_jit,
+                    }
+                })
             })),
         )
     });

src/driver/jit.rs

@@ -87,7 +87,7 @@ pub(super) fn run_jit(tcx: TyCtxt<'_>) -> ! {
 
     let finalized_main: *const u8 = jit_module.get_finalized_function(main_func_id);
 
-    println!("Rustc codegen cranelift will JIT run the executable, because the CG_CLIF_JIT env var is set");
+    println!("Rustc codegen cranelift will JIT run the executable, because --jit was passed");
 
     let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
         unsafe { ::std::mem::transmute(finalized_main) };

src/driver/mod.rs

@@ -16,15 +16,19 @@ pub(crate) fn codegen_crate(
     tcx: TyCtxt<'_>,
     metadata: EncodedMetadata,
     need_metadata_module: bool,
+    config: crate::BackendConfig,
 ) -> Box<dyn Any> {
     tcx.sess.abort_if_errors();
 
-    if std::env::var("CG_CLIF_JIT").is_ok()
-        && tcx
+    if config.use_jit {
+        let is_executable = tcx
             .sess
             .crate_types()
-            .contains(&rustc_session::config::CrateType::Executable)
-    {
+            .contains(&rustc_session::config::CrateType::Executable);
+        if !is_executable {
+            tcx.sess.fatal("can't jit non-executable crate");
+        }
+
         #[cfg(feature = "jit")]
         let _: ! = jit::run_jit(tcx);
 

src/lib.rs

@@ -181,7 +181,14 @@ impl<'tcx, B: Backend + 'static> CodegenCx<'tcx, B> {
     }
 }
 
-struct CraneliftCodegenBackend;
+#[derive(Copy, Clone, Debug)]
+pub struct BackendConfig {
+    pub use_jit: bool,
+}
+
+pub struct CraneliftCodegenBackend {
+    pub config: BackendConfig,
+}
 
 impl CodegenBackend for CraneliftCodegenBackend {
     fn init(&self, sess: &Session) {
@@ -223,7 +230,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
         metadata: EncodedMetadata,
         need_metadata_module: bool,
     ) -> Box<dyn Any> {
-        let res = driver::codegen_crate(tcx, metadata, need_metadata_module);
+        let res = driver::codegen_crate(tcx, metadata, need_metadata_module, self.config);
 
         rustc_symbol_mangling::test::report_symbol_names(tcx);
 
@@ -345,5 +352,9 @@ fn build_isa(sess: &Session, enable_pic: bool) -> Box<dyn isa::TargetIsa + 'stat
 /// This is the entrypoint for a hot plugged rustc_codegen_cranelift
 #[no_mangle]
 pub fn __rustc_codegen_backend() -> Box<dyn CodegenBackend> {
-    Box::new(CraneliftCodegenBackend)
+    Box::new(CraneliftCodegenBackend {
+        config: BackendConfig {
+            use_jit: false,
+        }
+    })
 }

test.sh

@@ -29,7 +29,7 @@ $RUSTC example/example.rs --crate-type lib --target $TARGET_TRIPLE
 
 if [[ "$JIT_SUPPORTED" = "1" ]]; then
     echo "[JIT] mini_core_hello_world"
-    CG_CLIF_JIT=1 CG_CLIF_JIT_ARGS="abc bcd" $RUSTC --crate-type bin -Cprefer-dynamic example/mini_core_hello_world.rs --cfg jit --target $HOST_TRIPLE
+    CG_CLIF_JIT_ARGS="abc bcd" $RUSTC --jit example/mini_core_hello_world.rs --cfg jit --target $HOST_TRIPLE
 else
     echo "[JIT] mini_core_hello_world (skipped)"
 fi
@@ -52,7 +52,7 @@ $RUN_WRAPPER ./target/out/alloc_example
 
 if [[ "$JIT_SUPPORTED" = "1" ]]; then
     echo "[JIT] std_example"
-    CG_CLIF_JIT=1 $RUSTC --crate-type bin -Cprefer-dynamic example/std_example.rs --target $HOST_TRIPLE
+    $RUSTC --jit example/std_example.rs --target $HOST_TRIPLE
 else
     echo "[JIT] std_example (skipped)"
 fi