Tentatively revert "remove mir optimization count from session"

This reverts commit f9621f3.

Author: sgasho

compiler/rustc_mir_transform/src/pass_manager.rs

@@ -1,6 +1,6 @@
 use std::cell::RefCell;
 use std::collections::hash_map::Entry;
-use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::atomic::Ordering;
 
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_middle::mir::{Body, MirDumper, MirPhase, RuntimePhase};
@@ -290,6 +290,7 @@ fn run_passes_inner<'tcx>(
                 && let Some(limit) = &tcx.sess.opts.unstable_opts.mir_opt_bisect_limit
             {
                 if limited_by_opt_bisect(
+                    tcx,
                     tcx.def_path_debug_str(body.source.def_id()),
                     *limit,
                     *pass,
@@ -380,13 +381,17 @@ fn is_optimization_stage(
         && phase_change == Some(MirPhase::Runtime(RuntimePhase::Optimized))
 }
 
-static MIR_OPT_BISECT_COUNT: AtomicUsize = AtomicUsize::new(0);
-
-fn limited_by_opt_bisect<'tcx, P>(def_path: String, limit: usize, pass: &P) -> bool
+fn limited_by_opt_bisect<'tcx, P>(
+    tcx: TyCtxt<'tcx>,
+    def_path: String,
+    limit: usize,
+    pass: &P,
+) -> bool
 where
     P: MirPass<'tcx> + ?Sized,
 {
-    let current_opt_bisect_count = MIR_OPT_BISECT_COUNT.fetch_add(1, Ordering::Relaxed);
+    let current_opt_bisect_count =
+        tcx.sess.mir_opt_bisect_eval_count.fetch_add(1, Ordering::Relaxed);
 
     let can_run = current_opt_bisect_count < limit;
 

compiler/rustc_session/src/session.rs

@@ -2,7 +2,7 @@ use std::any::Any;
 use std::path::PathBuf;
 use std::str::FromStr;
 use std::sync::Arc;
-use std::sync::atomic::AtomicBool;
+use std::sync::atomic::{AtomicBool, AtomicUsize};
 use std::{env, io};
 
 use rand::{RngCore, rng};
@@ -158,6 +158,12 @@ pub struct Session {
     /// The names of intrinsics that the current codegen backend replaces
     /// with its own implementations.
     pub replaced_intrinsics: FxHashSet<Symbol>,
+
+    /// Global per-session counter for MIR optimization pass applications.
+    ///
+    /// Used by `-Zmir-opt-bisect-limit` to assign an index to each
+    /// optimization-pass execution candidate during this compilation.
+    pub mir_opt_bisect_eval_count: AtomicUsize,
 }
 
 #[derive(Clone, Copy)]
@@ -1097,6 +1103,7 @@ pub fn build_session(
         host_filesearch,
         invocation_temp,
         replaced_intrinsics: FxHashSet::default(), // filled by `run_compiler`
+        mir_opt_bisect_eval_count: AtomicUsize::new(0),
     };
 
     validate_commandline_args_with_session_available(&sess);