Add -Z dump-mir-dataflow

Author: ecstatic-morse

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_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],