[baseline] Add max threads flags for CSP

Bug: v8:12054
Change-Id: I49238fe673858b60c2a2a935ed1f45f465269216
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3308707
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78187}

src/baseline/baseline-batch-compiler.cc

@@ -9,6 +9,8 @@
 #include "src/flags/flags.h"
 #if ENABLE_SPARKPLUG
 
+#include <algorithm>
+
 #include "src/baseline/baseline-compiler.h"
 #include "src/codegen/compiler.h"
 #include "src/execution/isolate.h"
@@ -181,6 +183,10 @@ class ConcurrentBaselineCompiler {
     }
 
     size_t GetMaxConcurrency(size_t worker_count) const override {
+      size_t max_threads = FLAG_concurrent_sparkplug_max_threads;
+      if (max_threads > 0) {
+        return std::min(max_threads, incoming_queue_->size());
+      }
       return incoming_queue_->size();
     }
 

src/flags/flag-definitions.h

@@ -709,6 +709,9 @@ DEFINE_BOOL_READONLY(concurrent_sparkplug, false,
 #else
 DEFINE_BOOL(concurrent_sparkplug, false,
             "compile Sparkplug code in a background thread")
+DEFINE_UINT(
+    concurrent_sparkplug_max_threads, 0,
+    "max number of threads that concurrent Sparkplug can use (0 for unbounded)")
 DEFINE_WEAK_IMPLICATION(future, concurrent_sparkplug)
 DEFINE_NEG_IMPLICATION(predictable, concurrent_sparkplug)
 DEFINE_NEG_IMPLICATION(single_threaded, concurrent_sparkplug)