revert last commit; instead use max_level_trace and downgrade logging

there is a *lot* of logging in some very hot paths of the compiler.
downgrade a lot of it.

this uses the very stupid heuristic of "did the logging add more than 10 milliseconds to cargo's compile time"?

Author: jyn514

compiler/rustc/Cargo.toml

@@ -22,5 +22,5 @@ features = ['unprefixed_malloc_on_supported_platforms']
 [features]
 jemalloc = ['jemalloc-sys']
 llvm = ['rustc_driver_impl/llvm']
-max_level_info = ['rustc_driver_impl/max_level_info']
+max_level_debug = ['rustc_driver_impl/max_level_debug']
 rustc_use_parallel_compiler = ['rustc_driver_impl/rustc_use_parallel_compiler']

compiler/rustc_borrowck/src/borrow_set.rs

@@ -199,7 +199,7 @@ impl<'a, 'tcx> Visitor<'tcx> for GatherBorrows<'a, 'tcx> {
     ) {
         if let &mir::Rvalue::Ref(region, kind, borrowed_place) = rvalue {
             if borrowed_place.ignore_borrow(self.tcx, self.body, &self.locals_state_at_exit) {
-                debug!("ignoring_borrow of {:?}", borrowed_place);
+                trace!("ignoring_borrow of {:?}", borrowed_place);
                 return;
             }
 
@@ -296,13 +296,15 @@ impl<'a, 'tcx> GatherBorrows<'a, 'tcx> {
         kind: mir::BorrowKind,
         borrow_index: BorrowIndex,
     ) {
-        debug!(
+        trace!(
             "Borrows::insert_as_pending_if_two_phase({:?}, {:?}, {:?})",
-            start_location, assigned_place, borrow_index,
+            start_location,
+            assigned_place,
+            borrow_index,
         );
 
         if !allow_two_phase_borrow(kind) {
-            debug!("  -> {:?}", start_location);
+            trace!("  -> {:?}", start_location);
             return;
         }
 

compiler/rustc_borrowck/src/constraint_generation.rs

@@ -167,7 +167,7 @@ impl<'cx, 'tcx> ConstraintGeneration<'cx, 'tcx> {
     where
         T: TypeVisitable<TyCtxt<'tcx>>,
     {
-        debug!("add_regular_live_constraint(live_ty={:?}, location={:?})", live_ty, location);
+        trace!("add_regular_live_constraint(live_ty={:?}, location={:?})", live_ty, location);
 
         self.infcx.tcx.for_each_free_region(&live_ty, |live_region| {
             let vid = live_region.as_var();
@@ -190,9 +190,10 @@ impl<'cx, 'tcx> ConstraintGeneration<'cx, 'tcx> {
             match place.as_ref() {
                 PlaceRef { local, projection: &[] }
                 | PlaceRef { local, projection: &[ProjectionElem::Deref] } => {
-                    debug!(
+                    trace!(
                         "Recording `killed` facts for borrows of local={:?} at location={:?}",
-                        local, location
+                        local,
+                        location
                     );
 
                     record_killed_borrows_for_local(
@@ -206,10 +207,11 @@ impl<'cx, 'tcx> ConstraintGeneration<'cx, 'tcx> {
 
                 PlaceRef { local, projection: &[.., _] } => {
                     // Kill conflicting borrows of the innermost local.
-                    debug!(
+                    trace!(
                         "Recording `killed` facts for borrows of \
                             innermost projected local={:?} at location={:?}",
-                        local, location
+                        local,
+                        location
                     );
 
                     if let Some(borrow_indices) = self.borrow_set.local_map.get(&local) {

compiler/rustc_borrowck/src/constraints/mod.rs

@@ -24,7 +24,7 @@ pub(crate) struct OutlivesConstraintSet<'tcx> {
 
 impl<'tcx> OutlivesConstraintSet<'tcx> {
     pub(crate) fn push(&mut self, constraint: OutlivesConstraint<'tcx>) {
-        debug!("OutlivesConstraintSet::push({:?})", constraint);
+        trace!("OutlivesConstraintSet::push({:?})", constraint);
         if constraint.sup == constraint.sub {
             // 'a: 'a is pretty uninteresting
             return;

compiler/rustc_borrowck/src/dataflow.rs

@@ -183,7 +183,7 @@ impl<'tcx> OutOfScopePrecomputer<'_, 'tcx> {
                 let kill_location = Location { block: bb, statement_index: kill_stmt };
                 // If region does not contain a point at the location, then add to list and skip
                 // successor locations.
-                debug!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
+                trace!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
                 self.borrows_out_of_scope_at_location
                     .entry(kill_location)
                     .or_default()
@@ -285,7 +285,7 @@ impl<'a, 'tcx> Borrows<'a, 'tcx> {
 
     /// Kill any borrows that conflict with `place`.
     fn kill_borrows_on_place(&self, trans: &mut impl GenKill<BorrowIndex>, place: Place<'tcx>) {
-        debug!("kill_borrows_on_place: place={:?}", place);
+        trace!("kill_borrows_on_place: place={:?}", place);
 
         let other_borrows_of_local = self
             .borrow_set

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -171,7 +171,7 @@ trait TypeOpInfo<'tcx> {
     ) {
         let tcx = mbcx.infcx.tcx;
         let base_universe = self.base_universe();
-        debug!(?base_universe);
+        trace!(?base_universe);
 
         let Some(adjusted_universe) =
             placeholder.universe.as_u32().checked_sub(base_universe.as_u32())
@@ -200,7 +200,7 @@ trait TypeOpInfo<'tcx> {
             None
         };
 
-        debug!(?placeholder_region);
+        trace!(?placeholder_region);
 
         let span = cause.span;
         let nice_error = self.nice_error(mbcx, cause, placeholder_region, error_region);
@@ -418,7 +418,7 @@ fn try_extract_error_from_region_constraints<'tcx>(
             }
         })?;
 
-    debug!(?sub_region, "cause = {:#?}", cause);
+    trace!(?sub_region, "cause = {:#?}", cause);
     let error = match (error_region, *sub_region) {
         (Some(error_region), ty::ReVar(vid)) => RegionResolutionError::SubSupConflict(
             vid,