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_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,