From d8c48d68308f9b107d687517b1be99655f187439 Mon Sep 17 00:00:00 2001
From: ownedbywuigi <ownedbywuigi@gmail.com>
Date: Sat, 25 Apr 2026 09:49:36 +0100
Subject: [PATCH] Issue #451 part 2a - Enable OpenMP parallelization for
 CopyValues in SelfHosting.cpp

---
 js/src/moz.build          |  6 +++++-
 js/src/vm/SelfHosting.cpp | 19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/js/src/moz.build b/js/src/moz.build
index cf43ed2bbe..81825bae45 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -325,7 +325,6 @@ main_deunified_sources = [
     'vm/Runtime.cpp',
     'vm/SavedStacks.cpp',
     'vm/Scope.cpp',
-    'vm/SelfHosting.cpp',
     'vm/Shape.cpp',
     'vm/SharedArrayObject.cpp',
     'vm/SharedImmutableStringsCache.cpp',
@@ -400,8 +399,13 @@ SOURCES += [
     'jsutil.cpp',
     'vm/BigIntType.cpp',
     'vm/Initialization.cpp',
+    'vm/SelfHosting.cpp',
 ]
 
+if CONFIG['CC_TYPE'] == 'gcc':
+    SOURCES['vm/SelfHosting.cpp'].flags += ['-fopenmp']
+    OS_LIBS += ['gomp']
+
 if CONFIG['JS_POSIX_NSPR']:
     posix_nspr_deunified_sources = [
         'vm/PosixNSPR.cpp',
diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index c9f290463e..26fd6cc9e1 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -1492,9 +1492,22 @@ CopyValues(SharedMem<To*> dest, SharedMem<From*> src, uint32_t count)
 
     using namespace jit;
 
-    for (; count > 0; count--) {
-        AtomicOperations::storeSafeWhenRacy(dest++,
-                                            To(AtomicOperations::loadSafeWhenRacy(src++)));
+#if defined(_OPENMP)
+    const int64_t openMpCount = int64_t(count);
+    if (openMpCount >= (1 << 14)) {
+#pragma omp parallel for default(none) shared(dest, src, openMpCount) schedule(static)
+        for (int64_t i = 0; i < openMpCount; i++) {
+            uint32_t index = uint32_t(i);
+            AtomicOperations::storeSafeWhenRacy(dest + index,
+                                                To(AtomicOperations::loadSafeWhenRacy(src + index)));
+        }
+        return;
+    }
+#endif
+
+    for (uint32_t i = 0; i < count; i++) {
+        AtomicOperations::storeSafeWhenRacy(dest + i,
+                                            To(AtomicOperations::loadSafeWhenRacy(src + i)));
     }
 }