Add -Z dump-mir-dataflow flag for dumping dataflow results visualization

src/librustc_interface/tests.rs

@@ -566,6 +566,8 @@ fn test_debugging_options_tracking_hash() {
     assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
     opts.debugging_opts.dump_mir_graphviz = true;
     assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
+    opts.debugging_opts.dump_mir_dataflow = true;
+    assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
 
     // Make sure changing a [TRACKED] option changes the hash
     opts = reference.clone();

src/librustc_mir/borrow_check/nll.rs

@@ -317,7 +317,7 @@ pub(super) fn dump_mir_results<'a, 'tcx>(
     regioncx: &RegionInferenceContext<'_>,
     closure_region_requirements: &Option<ClosureRegionRequirements<'_>>,
 ) {
-    if !mir_util::dump_enabled(infcx.tcx, "nll", source) {
+    if !mir_util::dump_enabled(infcx.tcx, "nll", source.def_id()) {
         return;
     }
 

src/librustc_mir/dataflow/framework/engine.rs

@@ -15,6 +15,7 @@ use rustc_span::symbol::{sym, Symbol};
 
 use super::graphviz;
 use super::{Analysis, GenKillAnalysis, GenKillSet, Results};
+use crate::util::pretty::dump_enabled;
 
 /// A solver for dataflow problems.
 pub struct Engine<'a, 'tcx, A>
@@ -400,12 +401,25 @@ where
     let attrs = match RustcMirAttrs::parse(tcx, def_id) {
         Ok(attrs) => attrs,
 
-        // Invalid `rustc_mir` attrs will be reported using `span_err`.
+        // Invalid `rustc_mir` attrs are reported in `RustcMirAttrs::parse`
         Err(()) => return Ok(()),
     };
 
     let path = match attrs.output_path(A::NAME) {
         Some(path) => path,
+
+        None if tcx.sess.opts.debugging_opts.dump_mir_dataflow
+            && dump_enabled(tcx, A::NAME, def_id) =>
+        {
+            let mut path = PathBuf::from(&tcx.sess.opts.debugging_opts.dump_mir_dir);
+
+            let item_name = ty::print::with_forced_impl_filename_line(|| {
+                tcx.def_path(def_id).to_filename_friendly_no_crate()
+            });
+            path.push(format!("rustc.{}.{}.dot", item_name, A::NAME));
+            path
+        }
+
         None => return Ok(()),
     };
 
@@ -430,7 +444,12 @@ where
 
     let graphviz = graphviz::Formatter::new(body, def_id, results, &mut *formatter);
     dot::render_opts(&graphviz, &mut buf, &[dot::RenderOption::Monospace])?;
+
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)?;
+    }
     fs::write(&path, buf)?;
+
     Ok(())
 }
 

src/librustc_mir/transform/dump_mir.rs

@@ -46,7 +46,7 @@ pub fn on_mir_pass<'tcx>(
     body: &Body<'tcx>,
     is_after: bool,
 ) {
-    if mir_util::dump_enabled(tcx, pass_name, source) {
+    if mir_util::dump_enabled(tcx, pass_name, source.def_id()) {
         mir_util::dump_mir(
             tcx,
             Some(pass_num),

src/librustc_mir/util/liveness.rs

@@ -265,7 +265,7 @@ pub fn dump_mir<'tcx>(
     body: &Body<'tcx>,
     result: &LivenessResult,
 ) {
-    if !dump_enabled(tcx, pass_name, source) {
+    if !dump_enabled(tcx, pass_name, source.def_id()) {
         return;
     }
     let node_path = ty::print::with_forced_impl_filename_line(|| {

src/librustc_mir/util/pretty.rs

@@ -76,21 +76,21 @@ pub fn dump_mir<'tcx, F>(
 ) where
     F: FnMut(PassWhere, &mut dyn Write) -> io::Result<()>,
 {
-    if !dump_enabled(tcx, pass_name, source) {
+    if !dump_enabled(tcx, pass_name, source.def_id()) {
         return;
     }
 
     dump_matched_mir_node(tcx, pass_num, pass_name, disambiguator, source, body, extra_data);
 }
 
-pub fn dump_enabled<'tcx>(tcx: TyCtxt<'tcx>, pass_name: &str, source: MirSource<'tcx>) -> bool {
+pub fn dump_enabled<'tcx>(tcx: TyCtxt<'tcx>, pass_name: &str, def_id: DefId) -> bool {
     let filters = match tcx.sess.opts.debugging_opts.dump_mir {
         None => return false,
         Some(ref filters) => filters,
     };
     let node_path = ty::print::with_forced_impl_filename_line(|| {
         // see notes on #41697 below
-        tcx.def_path_str(source.def_id())
+        tcx.def_path_str(def_id)
     });
     filters.split('|').any(|or_filter| {
         or_filter.split('&').all(|and_filter| {

src/librustc_session/options.rs

@@ -837,6 +837,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "the directory the MIR is dumped into"),
     dump_mir_graphviz: bool = (false, parse_bool, [UNTRACKED],
         "in addition to `.mir` files, create graphviz `.dot` files"),
+    dump_mir_dataflow: bool = (false, parse_bool, [UNTRACKED],
+        "in addition to `.mir` files, create graphviz `.dot` files with dataflow results"),
     dump_mir_exclude_pass_number: bool = (false, parse_bool, [UNTRACKED],
         "if set, exclude the pass number when dumping MIR (used in tests)"),
     mir_emit_retag: bool = (false, parse_bool, [TRACKED],