Merge pull request #1120 from bjorn3/lazy_jit

Lazy compilation in jit mode

Author: bjorn3

Readme.md

@@ -68,7 +68,15 @@ $ $cg_clif_dir/build/cargo.sh jit
 or
 
 ```bash
-$ $cg_clif_dir/build/bin/cg_clif --jit my_crate.rs
+$ $cg_clif_dir/build/bin/cg_clif -Cllvm-args=mode=jit -Cprefer-dynamic my_crate.rs
+```
+
+There is also an experimental lazy jit mode. In this mode functions are only compiled once they are
+first called. It currently does not work with multi-threaded programs. When a not yet compiled
+function is called from another thread than the main thread, you will get an ICE.
+
+```bash
+$ $cg_clif_dir/build/cargo.sh lazy-jit
 ```
 
 ### Shell
@@ -77,7 +85,7 @@ These are a few functions that allow you to easily run rust code from the shell
 
 ```bash
 function jit_naked() {
-    echo "$@" | $cg_clif_dir/build/bin/cg_clif - --jit
+    echo "$@" | $cg_clif_dir/build/bin/cg_clif - -Cllvm-args=mode=jit -Cprefer-dynamic
 }
 
 function jit() {

example/std_example.rs

@@ -15,6 +15,8 @@ fn main() {
     let stderr = ::std::io::stderr();
     let mut stderr = stderr.lock();
 
+    // FIXME support lazy jit when multi threading
+    #[cfg(not(lazy_jit))]
     std::thread::spawn(move || {
         println!("Hello from another thread!");
     });

scripts/cargo.sh

@@ -10,7 +10,9 @@ cmd=$1
 shift || true
 
 if [[ "$cmd" = "jit" ]]; then
-cargo "+${TOOLCHAIN}" rustc "$@" -- --jit
+cargo "+${TOOLCHAIN}" rustc "$@" -- -Cllvm-args=mode=jit -Cprefer-dynamic
+elif [[ "$cmd" = "lazy-jit" ]]; then
+cargo "+${TOOLCHAIN}" rustc "$@" -- -Cllvm-args=mode=jit-lazy -Cprefer-dynamic
 else
 cargo "+${TOOLCHAIN}" "$cmd" "$@"
 fi

scripts/filter_profile.rs

@@ -4,7 +4,7 @@
 pushd $(dirname "$0")/../
 source build/config.sh
 popd
-PROFILE=$1 OUTPUT=$2 exec $RUSTC $RUSTFLAGS --jit $0
+PROFILE=$1 OUTPUT=$2 exec $RUSTC $RUSTFLAGS -Cllvm-args=mode=jit -Cprefer-dynamic $0
 #*/
 
 //! This program filters away uninteresting samples and trims uninteresting frames for stackcollapse

scripts/tests.sh

@@ -15,7 +15,10 @@ function no_sysroot_tests() {
 
     if [[ "$JIT_SUPPORTED" = "1" ]]; then
         echo "[JIT] mini_core_hello_world"
-        CG_CLIF_JIT_ARGS="abc bcd" $MY_RUSTC --jit example/mini_core_hello_world.rs --cfg jit --target "$HOST_TRIPLE"
+        CG_CLIF_JIT_ARGS="abc bcd" $MY_RUSTC -Cllvm-args=mode=jit -Cprefer-dynamic example/mini_core_hello_world.rs --cfg jit --target "$HOST_TRIPLE"
+
+        echo "[JIT-lazy] mini_core_hello_world"
+        CG_CLIF_JIT_ARGS="abc bcd" $MY_RUSTC -Cllvm-args=mode=jit-lazy -Cprefer-dynamic example/mini_core_hello_world.rs --cfg jit --target "$HOST_TRIPLE"
     else
         echo "[JIT] mini_core_hello_world (skipped)"
     fi
@@ -37,7 +40,10 @@ function base_sysroot_tests() {
 
     if [[ "$JIT_SUPPORTED" = "1" ]]; then
         echo "[JIT] std_example"
-        $MY_RUSTC --jit example/std_example.rs --target "$HOST_TRIPLE"
+        $MY_RUSTC -Cllvm-args=mode=jit -Cprefer-dynamic example/std_example.rs --target "$HOST_TRIPLE"
+
+        echo "[JIT-lazy] std_example"
+        $MY_RUSTC -Cllvm-args=mode=jit-lazy -Cprefer-dynamic example/std_example.rs --cfg lazy_jit --target "$HOST_TRIPLE"
     else
         echo "[JIT] std_example (skipped)"
     fi

src/backend.rs

@@ -162,7 +162,7 @@ impl AddConstructor for ObjectProduct {
 }
 
 pub(crate) fn with_object(sess: &Session, name: &str, f: impl FnOnce(&mut Object)) -> Vec<u8> {
-    let triple = crate::build_isa(sess, true).triple().clone();
+    let triple = crate::build_isa(sess).triple().clone();
 
     let binary_format = match triple.binary_format {
         target_lexicon::BinaryFormat::Elf => object::BinaryFormat::Elf,
@@ -193,7 +193,7 @@ pub(crate) fn with_object(sess: &Session, name: &str, f: impl FnOnce(&mut Object
 
 pub(crate) fn make_module(sess: &Session, name: String) -> ObjectModule {
     let mut builder = ObjectBuilder::new(
-        crate::build_isa(sess, true),
+        crate::build_isa(sess),
         name + ".o",
         cranelift_module::default_libcall_names(),
     )

src/bin/cg_clif.rs

@@ -44,9 +44,7 @@ fn main() {
     let mut callbacks = CraneliftPassesCallbacks::default();
     rustc_driver::install_ice_hook();
     let exit_code = rustc_driver::catch_with_exit_code(|| {
-        let mut use_jit = false;
-
-        let mut args = std::env::args_os()
+        let args = std::env::args_os()
             .enumerate()
             .map(|(i, arg)| {
                 arg.into_string().unwrap_or_else(|arg| {
@@ -56,23 +54,10 @@ fn main() {
                     )
                 })
             })
-            .filter(|arg| {
-                if arg == "--jit" {
-                    use_jit = true;
-                    false
-                } else {
-                    true
-                }
-            })
             .collect::<Vec<_>>();
-        if use_jit {
-            args.push("-Cprefer-dynamic".to_string());
-        }
         let mut run_compiler = rustc_driver::RunCompiler::new(&args, &mut callbacks);
         run_compiler.set_make_codegen_backend(Some(Box::new(move |_| {
-            Box::new(rustc_codegen_cranelift::CraneliftCodegenBackend {
-                config: rustc_codegen_cranelift::BackendConfig { use_jit },
-            })
+            Box::new(rustc_codegen_cranelift::CraneliftCodegenBackend { config: None })
         })));
         run_compiler.run()
     });

src/bin/cg_clif_build_sysroot.rs

@@ -92,9 +92,7 @@ fn main() {
         let mut run_compiler = rustc_driver::RunCompiler::new(&args, &mut callbacks);
         if use_clif {
             run_compiler.set_make_codegen_backend(Some(Box::new(move |_| {
-                Box::new(rustc_codegen_cranelift::CraneliftCodegenBackend {
-                    config: rustc_codegen_cranelift::BackendConfig { use_jit: false },
-                })
+                Box::new(rustc_codegen_cranelift::CraneliftCodegenBackend { config: None })
             })));
         }
         run_compiler.run()

src/constant.rs

@@ -447,7 +447,8 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut impl Module, cx: &mut Constan
             data_ctx.write_data_addr(offset.bytes() as u32, global_value, addend as i64);
         }
 
-        module.define_data(data_id, &data_ctx).unwrap();
+        // FIXME don't duplicate definitions in lazy jit mode
+        let _ = module.define_data(data_id, &data_ctx);
         cx.done.insert(data_id);
     }
 

src/debuginfo/unwind.rs

@@ -15,11 +15,11 @@ pub(crate) struct UnwindContext<'tcx> {
 }
 
 impl<'tcx> UnwindContext<'tcx> {
-    pub(crate) fn new(tcx: TyCtxt<'tcx>, isa: &dyn TargetIsa) -> Self {
+    pub(crate) fn new(tcx: TyCtxt<'tcx>, isa: &dyn TargetIsa, pic_eh_frame: bool) -> Self {
         let mut frame_table = FrameTable::default();
 
         let cie_id = if let Some(mut cie) = isa.create_systemv_cie() {
-            if isa.flags().is_pic() {
+            if pic_eh_frame {
                 cie.fde_address_encoding =
                     gimli::DwEhPe(gimli::DW_EH_PE_pcrel.0 | gimli::DW_EH_PE_sdata4.0);
             }

src/driver/aot.rs

@@ -146,7 +146,12 @@ fn module_codegen(tcx: TyCtxt<'_>, cgu_name: rustc_span::Symbol) -> ModuleCodege
         }
     }
 
-    let mut cx = crate::CodegenCx::new(tcx, module, tcx.sess.opts.debuginfo != DebugInfo::None);
+    let mut cx = crate::CodegenCx::new(
+        tcx,
+        module,
+        tcx.sess.opts.debuginfo != DebugInfo::None,
+        true,
+    );
     super::predefine_mono_items(&mut cx, &mono_items);
     for (mono_item, (linkage, visibility)) in mono_items {
         let linkage = crate::linkage::get_clif_linkage(mono_item, linkage, visibility);
@@ -254,7 +259,7 @@ pub(super) fn run_aot(
     tcx.sess.abort_if_errors();
 
     let mut allocator_module = new_module(tcx, "allocator_shim".to_string());
-    let mut allocator_unwind_context = UnwindContext::new(tcx, allocator_module.isa());
+    let mut allocator_unwind_context = UnwindContext::new(tcx, allocator_module.isa(), true);
     let created_alloc_shim =
         crate::allocator::codegen(tcx, &mut allocator_module, &mut allocator_unwind_context);