Better use of env vars

Readme.md

@@ -18,7 +18,6 @@ $ ./test.sh --release
 ### Cargo
 
 ```bash
-$ export CG_CLIF_INCR_CACHE=1 # Enable caching of object files in the incremental cache
 $ CHANNEL="release" $cg_clif_dir/cargo.sh run
 ```
 
@@ -27,10 +26,23 @@ If you compiled cg_clif in debug mode you should use `CHANNEL="debug"` instead o
 ### Rustc
 
 ```bash
-$ export CG_CLIF_INCR_CACHE=1 # Enable caching of object files in the incremental cache
 $ rustc -Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/release/librustc_codegen_cranelift.so --sysroot $cg_clif_dir/build_sysroot/sysroot my_crate.rs
 ```
 
+## Env vars
+
+<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_DISABLE</dt>
+    <dd>Don't cache object files in the incremental cache. Useful during development of cg_clif
+    to make it possible to use incremental mode for all analyses performed by rustc without caching
+    object files when their content should have been changed by a change to cg_clif.</dd>
+    <dt>CG_CLIF_DISPLAY_CG_TIME</dt>
+    <dd>Display the time it took to perform codegen for a crate</dd>
+</dl>
 
 ## Not yet supported
 

config.sh

@@ -24,3 +24,6 @@ export RUSTC_LOG=warn # display metadata load errors
 
 export LD_LIBRARY_PATH="$(pwd)/target/out:$(pwd)/build_sysroot/sysroot/lib/rustlib/$TARGET_TRIPLE/lib"
 export DYLD_LIBRARY_PATH=$LD_LIBRARY_PATH
+
+export CG_CLIF_DISPLAY_CG_TIME=1
+export CG_CLIF_INCR_CACHE_DISABLED=1

src/atomic_shim.rs

@@ -9,7 +9,7 @@ use crate::prelude::*;
 pub static mut __cg_clif_global_atomic_mutex: libc::pthread_mutex_t = libc::PTHREAD_MUTEX_INITIALIZER;
 
 pub fn init_global_lock(module: &mut Module<impl Backend>, bcx: &mut FunctionBuilder<'_>) {
-    if std::env::var("SHOULD_RUN").is_ok () {
+    if std::env::var("CG_CLIF_JIT").is_ok () {
         // When using JIT, dylibs won't find the __cg_clif_global_atomic_mutex data object defined here,
         // so instead define it in the cg_clif dylib.
 

src/driver.rs

@@ -21,7 +21,7 @@ pub fn codegen_crate(
 ) -> Box<dyn Any> {
     tcx.sess.abort_if_errors();
 
-    if std::env::var("SHOULD_RUN").is_ok()
+    if std::env::var("CG_CLIF_JIT").is_ok()
         && tcx.sess.crate_types.get().contains(&CrateType::Executable)
     {
         #[cfg(not(target_arch = "wasm32"))]
@@ -90,12 +90,12 @@ 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 SHOULD_RUN env var is set");
+    println!("Rustc codegen cranelift will JIT run the executable, because the CG_CLIF_JIT env var is set");
 
     let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
         unsafe { ::std::mem::transmute(finalized_main) };
 
-    let args = ::std::env::var("JIT_ARGS").unwrap_or_else(|_| String::new());
+    let args = ::std::env::var("CG_CLIF_JIT_ARGS").unwrap_or_else(|_| String::new());
     let args = args
         .split(" ")
         .chain(Some(&*tcx.crate_name(LOCAL_CRATE).as_str().to_string()))
@@ -215,14 +215,14 @@ fn run_aot(
             let obj = product.emit();
             std::fs::write(&tmp_file, obj).unwrap();
 
-            let work_product = if std::env::var("CG_CLIF_INCR_CACHE").is_ok() {
+            let work_product = if std::env::var("CG_CLIF_INCR_CACHE_DISABLED").is_ok() {
+                None
+            } else {
                 rustc_incremental::copy_cgu_workproducts_to_incr_comp_cache_dir(
                     tcx.sess,
                     &name,
                     &[(WorkProductFileKind::Object, tmp_file.clone())],
                 )
-            } else {
-                None
             };
 
             ModuleCodegenResult(
@@ -251,6 +251,7 @@ fn run_aot(
             tcx.sess.cgu_reuse_tracker.set_actual_reuse(&cgu.name().as_str(), cgu_reuse);
 
             match cgu_reuse {
+                _ if std::env::var("CG_CLIF_INCR_CACHE_DISABLED").is_ok() => {}
                 CguReuse::No => {}
                 CguReuse::PreLto => {
                     let incr_comp_session_dir = tcx.sess.incr_comp_session_dir();
@@ -491,12 +492,16 @@ fn trans_mono_item<'clif, 'tcx, B: Backend + 'static>(
 }
 
 fn time<R>(sess: &Session, name: &'static str, f: impl FnOnce() -> R) -> R {
+    if std::env::var("CG_CLIF_DISPLAY_CG_TIME").is_ok() {
         println!("[{}] start", name);
         let before = std::time::Instant::now();
         let res = sess.time(name, f);
         let after = std::time::Instant::now();
         println!("[{}] end time: {:?}", name, after - before);
         res
+    } else {
+        sess.time(name, f)
+    }
 }
 
 // Adapted from https://github.com/rust-lang/rust/blob/303d8aff6092709edd4dbd35b1c88e9aa40bf6d8/src/librustc_codegen_ssa/base.rs#L922-L953

test.sh

@@ -22,7 +22,7 @@ echo "[BUILD] example"
 $RUSTC example/example.rs --crate-type lib
 
 echo "[JIT] mini_core_hello_world"
-JIT_ARGS="abc bcd" SHOULD_RUN=1 $RUSTC --crate-type bin -Cprefer-dynamic example/mini_core_hello_world.rs --cfg jit
+CG_CLIF_JIT=1 CG_CLIF_JIT_ARGS="abc bcd" $RUSTC --crate-type bin -Cprefer-dynamic example/mini_core_hello_world.rs --cfg jit
 
 echo "[AOT] mini_core_hello_world"
 $RUSTC example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g
@@ -41,7 +41,7 @@ $RUSTC example/alloc_example.rs --crate-type bin
 ./target/out/alloc_example
 
 echo "[JIT] std_example"
-SHOULD_RUN=1 $RUSTC --crate-type bin -Cprefer-dynamic example/std_example.rs
+CG_CLIF_JIT=1 $RUSTC --crate-type bin -Cprefer-dynamic example/std_example.rs
 
 echo "[AOT] dst_field_align"
 # FIXME Re-add -Zmir-opt-level=2 once rust-lang/rust#67529 is fixed.