[self-profiling] Include the estimated size of each cgu in the profile

This is helpful when looking for CGUs where the size estimate isn't a
good indicator of compilation time.

I verified that moving the profiling timer call doesn't affect the
results.

compiler/rustc_codegen_llvm/src/base.rs

@@ -97,21 +97,23 @@ pub fn compile_codegen_unit(
     tcx: TyCtxt<'tcx>,
     cgu_name: Symbol,
 ) -> (ModuleCodegen<ModuleLlvm>, u64) {
-    let prof_timer = tcx.prof.generic_activity_with_arg("codegen_module", cgu_name.to_string());
     let start_time = Instant::now();
 
     let dep_node = tcx.codegen_unit(cgu_name).codegen_dep_node(tcx);
     let (module, _) =
         tcx.dep_graph.with_task(dep_node, tcx, cgu_name, module_codegen, dep_graph::hash_result);
     let time_to_codegen = start_time.elapsed();
-    drop(prof_timer);
 
     // We assume that the cost to run LLVM on a CGU is proportional to
     // the time we needed for codegenning it.
     let cost = time_to_codegen.as_nanos() as u64;
 
     fn module_codegen(tcx: TyCtxt<'_>, cgu_name: Symbol) -> ModuleCodegen<ModuleLlvm> {
         let cgu = tcx.codegen_unit(cgu_name);
+        let _prof_timer = tcx.prof.generic_activity_with_args(
+            "codegen_module",
+            &[cgu_name.to_string(), cgu.size_estimate().to_string()],
+        );
         // Instantiate monomorphizations without filling out definitions yet...
         let llvm_module = ModuleLlvm::new(tcx, &cgu_name.as_str());
         {

compiler/rustc_data_structures/src/profiling.rs

@@ -272,6 +272,28 @@ impl SelfProfilerRef {
         })
     }
 
+    #[inline(always)]
+    pub fn generic_activity_with_args(
+        &self,
+        event_label: &'static str,
+        event_args: &[String],
+    ) -> TimingGuard<'_> {
+        self.exec(EventFilter::GENERIC_ACTIVITIES, |profiler| {
+            let builder = EventIdBuilder::new(&profiler.profiler);
+            let event_label = profiler.get_or_alloc_cached_string(event_label);
+            let event_id = if profiler.event_filter_mask.contains(EventFilter::FUNCTION_ARGS) {
+                let event_args: Vec<_> = event_args
+                    .iter()
+                    .map(|s| profiler.get_or_alloc_cached_string(&s[..]))
+                    .collect();
+                builder.from_label_and_args(event_label, &event_args)
+            } else {
+                builder.from_label(event_label)
+            };
+            TimingGuard::start(profiler, profiler.generic_activity_event_kind, event_id)
+        })
+    }
+
     /// Start profiling a query provider. Profiling continues until the
     /// TimingGuard returned from this call is dropped.
     #[inline(always)]