Remove -Zperf-stats.

The included measurements have varied over the years. At one point there
were quite a few more, but #49558 deleted a lot that were no longer
used. Today there's just four, and it's a motley collection that doesn't
seem particularly valuable.

I think it has been well and truly subsumed by self-profiling, which
collects way more data.

compiler/rustc_driver_impl/src/lib.rs

@@ -496,10 +496,6 @@ fn run_compiler(
             linker.link()?
         }
 
-        if sess.opts.unstable_opts.perf_stats {
-            sess.print_perf_stats();
-        }
-
         if sess.opts.unstable_opts.print_fuel.is_some() {
             eprintln!(
                 "Fuel used by {}: {}",

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -13,7 +13,6 @@ use rustc_middle::ty::flags::FlagComputation;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::GenericArg;
 use rustc_middle::ty::{self, BoundVar, InferConst, List, Ty, TyCtxt, TypeFlags, TypeVisitableExt};
-use std::sync::atomic::Ordering;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::Idx;
@@ -43,8 +42,6 @@ impl<'tcx> InferCtxt<'tcx> {
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        self.tcx.sess.perf_stats.queries_canonicalized.fetch_add(1, Ordering::Relaxed);
-
         Canonicalizer::canonicalize(value, self, self.tcx, &CanonicalizeAllFreeRegions, query_state)
     }
 
@@ -62,8 +59,6 @@ impl<'tcx> InferCtxt<'tcx> {
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        self.tcx.sess.perf_stats.queries_canonicalized.fetch_add(1, Ordering::Relaxed);
-
         Canonicalizer::canonicalize(
             value,
             self,
@@ -138,8 +133,6 @@ impl<'tcx> InferCtxt<'tcx> {
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        self.tcx.sess.perf_stats.queries_canonicalized.fetch_add(1, Ordering::Relaxed);
-
         Canonicalizer::canonicalize(
             value,
             self,

compiler/rustc_interface/src/tests.rs

@@ -691,7 +691,6 @@ fn test_unstable_options_tracking_hash() {
     untracked!(no_leak_check, true);
     untracked!(no_parallel_llvm, true);
     untracked!(parse_only, true);
-    untracked!(perf_stats, true);
     // `pre_link_arg` is omitted because it just forwards to `pre_link_args`.
     untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);
     untracked!(print_codegen_stats, true);

compiler/rustc_session/src/options.rs

@@ -1710,8 +1710,6 @@ options! {
         "panic strategy for panics in drops"),
     parse_only: bool = (false, parse_bool, [UNTRACKED],
         "parse only; do not compile, assemble, or link (default: no)"),
-    perf_stats: bool = (false, parse_bool, [UNTRACKED],
-        "print some performance-related statistics (default: no)"),
     plt: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "whether to use the PLT when calling into shared libraries;
         only has effect for PIC code on systems with ELF binaries

compiler/rustc_session/src/session.rs

@@ -15,10 +15,8 @@ pub use rustc_ast::Attribute;
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_data_structures::jobserver::{self, Client};
-use rustc_data_structures::profiling::{duration_to_secs_str, SelfProfiler, SelfProfilerRef};
-use rustc_data_structures::sync::{
-    AtomicU64, AtomicUsize, Lock, Lrc, OneThread, Ordering, Ordering::SeqCst,
-};
+use rustc_data_structures::profiling::{SelfProfiler, SelfProfilerRef};
+use rustc_data_structures::sync::{AtomicU64, Lock, Lrc, OneThread, Ordering::SeqCst};
 use rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitterWriter;
 use rustc_errors::emitter::{DynEmitter, EmitterWriter, HumanReadableErrorType};
 use rustc_errors::json::JsonEmitter;
@@ -46,7 +44,6 @@ use std::ops::{Div, Mul};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::sync::{atomic::AtomicBool, Arc};
-use std::time::Duration;
 
 pub struct OptimizationFuel {
     /// If `-zfuel=crate=n` is specified, initially set to `n`, otherwise `0`.
@@ -157,9 +154,6 @@ pub struct Session {
     /// Used by `-Z self-profile`.
     pub prof: SelfProfilerRef,
 
-    /// Some measurements that are being gathered during compilation.
-    pub perf_stats: PerfStats,
-
     /// Data about code being compiled, gathered during compilation.
     pub code_stats: CodeStats,
 
@@ -215,17 +209,6 @@ pub struct Session {
     pub expanded_args: Vec<String>,
 }
 
-pub struct PerfStats {
-    /// The accumulated time spent on computing symbol hashes.
-    pub symbol_hash_time: Lock<Duration>,
-    /// Total number of values canonicalized queries constructed.
-    pub queries_canonicalized: AtomicUsize,
-    /// Number of times this query is invoked.
-    pub normalize_generic_arg_after_erasing_regions: AtomicUsize,
-    /// Number of times this query is invoked.
-    pub normalize_projection_ty: AtomicUsize,
-}
-
 #[derive(PartialEq, Eq, PartialOrd, Ord)]
 pub enum MetadataKind {
     None,
@@ -883,25 +866,6 @@ impl Session {
         self.opts.incremental.as_ref().map(|_| self.incr_comp_session_dir())
     }
 
-    pub fn print_perf_stats(&self) {
-        eprintln!(
-            "Total time spent computing symbol hashes:      {}",
-            duration_to_secs_str(*self.perf_stats.symbol_hash_time.lock())
-        );
-        eprintln!(
-            "Total queries canonicalized:                   {}",
-            self.perf_stats.queries_canonicalized.load(Ordering::Relaxed)
-        );
-        eprintln!(
-            "normalize_generic_arg_after_erasing_regions:   {}",
-            self.perf_stats.normalize_generic_arg_after_erasing_regions.load(Ordering::Relaxed)
-        );
-        eprintln!(
-            "normalize_projection_ty:                       {}",
-            self.perf_stats.normalize_projection_ty.load(Ordering::Relaxed)
-        );
-    }
-
     /// We want to know if we're allowed to do an optimization for crate foo from -z fuel=foo=n.
     /// This expends fuel if applicable, and records fuel if applicable.
     pub fn consider_optimizing(
@@ -1515,12 +1479,6 @@ pub fn build_session(
         io,
         incr_comp_session: OneThread::new(RefCell::new(IncrCompSession::NotInitialized)),
         prof,
-        perf_stats: PerfStats {
-            symbol_hash_time: Lock::new(Duration::from_secs(0)),
-            queries_canonicalized: AtomicUsize::new(0),
-            normalize_generic_arg_after_erasing_regions: AtomicUsize::new(0),
-            normalize_projection_ty: AtomicUsize::new(0),
-        },
         code_stats: Default::default(),
         optimization_fuel,
         print_fuel,

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -4,7 +4,6 @@ use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
 use rustc_middle::ty::print::{PrettyPrinter, Print, PrintError, Printer};
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeVisitableExt};
 use rustc_middle::ty::{GenericArg, GenericArgKind};
-use rustc_middle::util::common::record_time;
 
 use std::fmt::{self, Write};
 use std::mem::{self, discriminant};
@@ -101,7 +100,6 @@ fn get_symbol_hash<'tcx>(
     tcx.with_stable_hashing_context(|mut hcx| {
         let mut hasher = StableHasher::new();
 
-        record_time(&tcx.sess.perf_stats.symbol_hash_time, || {
         // the main symbol name is not necessarily unique; hash in the
         // compiler's internal def-path, guaranteeing each symbol has a
         // truly unique path
@@ -135,7 +133,6 @@ fn get_symbol_hash<'tcx>(
             // instances without this.
             discriminant(&instance.def).hash_stable(hcx, &mut hasher);
         });
-        });
 
         // 64 bits should be enough to avoid collisions.
         hasher.finish::<Hash64>()

compiler/rustc_traits/src/normalize_erasing_regions.rs

@@ -4,18 +4,12 @@ use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt, TypeFoldable, TypeVisitableExt};
 use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::{Normalized, ObligationCause};
-use std::sync::atomic::Ordering;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers {
         try_normalize_generic_arg_after_erasing_regions: |tcx, goal| {
             debug!("try_normalize_generic_arg_after_erasing_regions(goal={:#?}", goal);
 
-            tcx.sess
-                .perf_stats
-                .normalize_generic_arg_after_erasing_regions
-                .fetch_add(1, Ordering::Relaxed);
-
             try_normalize_after_erasing_regions(tcx, goal)
         },
         ..*p

compiler/rustc_traits/src/normalize_projection_ty.rs

@@ -10,7 +10,6 @@ use rustc_trait_selection::traits::query::{
 use rustc_trait_selection::traits::{
     self, FulfillmentErrorCode, ObligationCause, SelectionContext,
 };
-use std::sync::atomic::Ordering;
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers {
@@ -27,7 +26,6 @@ fn normalize_projection_ty<'tcx>(
 ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
     debug!("normalize_provider(goal={:#?})", goal);
 
-    tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed);
     tcx.infer_ctxt().enter_canonical_trait_query(
         &goal,
         |ocx, ParamEnvAnd { param_env, value: goal }| {
@@ -78,7 +76,6 @@ fn normalize_weak_ty<'tcx>(
 ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
     debug!("normalize_provider(goal={:#?})", goal);
 
-    tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed);
     tcx.infer_ctxt().enter_canonical_trait_query(
         &goal,
         |ocx, ParamEnvAnd { param_env, value: goal }| {