From 30d00ef817b549e888a9dc2a665dc005af958c1d Mon Sep 17 00:00:00 2001
From: Wenju He <wenju.he@intel.com>
Date: Wed, 29 Oct 2025 08:17:41 +0100
Subject: [PATCH] Remove compileMutex to enable parallel compilation on Windows

The issue observed in 76bc7f93d591 seems fixed on llvm-14 branch
based on new testing of a multi-threaded workload on Ice Lake server and
Alder Lake desktop.
The same workload still fails on llvm-9 branch on Alder Lake.
---
 common_clang.cpp    | 11 -----------
 options_compile.cpp |  6 ------
 2 files changed, 17 deletions(-)

diff --git a/common_clang.cpp b/common_clang.cpp
index 4b2579cc..43a41c1b 100644
--- a/common_clang.cpp
+++ b/common_clang.cpp
@@ -85,8 +85,6 @@ static volatile bool lazyCCInit =
     true; // the flag must be 'volatile' to prevent caching in a CPU register
 static llvm::sys::Mutex lazyCCInitMutex;
 
-llvm::ManagedStatic<llvm::sys::SmartMutex<true>> compileMutex;
-
 void CommonClangTerminate() { llvm::llvm_shutdown(); }
 
 // This function mustn't be invoked from a static object constructor,
@@ -212,9 +210,6 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
   CommonClangInitialize();
 
   try {
-#ifdef _WIN32
-    llvm::sys::SmartScopedLock<true> compileGuard{*compileMutex};
-#endif
     std::unique_ptr<OCLFEBinaryResult> pResult(new OCLFEBinaryResult());
 
     // Create the clang compiler
@@ -226,9 +221,6 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
     // Prepare error log
     llvm::raw_string_ostream err_ostream(pResult->getLogRef());
     {
-#ifndef _WIN32
-      llvm::sys::SmartScopedLock<true> compileGuard{*compileMutex};
-#endif
       // Parse options
       optionsParser.processOptions(pszOptions, pszOptionsEx);
 
@@ -347,9 +339,6 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
       err_ostream.flush();
     }
     {
-#ifndef _WIN32
-      llvm::sys::SmartScopedLock<true> compileGuard{*compileMutex};
-#endif
       if (pBinaryResult) {
         *pBinaryResult = pResult.release();
       }
diff --git a/options_compile.cpp b/options_compile.cpp
index 25cb1d66..5b922569 100644
--- a/options_compile.cpp
+++ b/options_compile.cpp
@@ -39,8 +39,6 @@ Copyright (c) Intel Corporation (2009-2017).
 
 using namespace llvm::opt;
 
-extern llvm::ManagedStatic<llvm::sys::SmartMutex<true>> compileMutex;
-
 static const OptTable::Info ClangOptionsInfoTable[] = {
 #define PREFIX(NAME, VALUE)
 #define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
@@ -442,10 +440,6 @@ std::string CompileOptionsParser::getEffectiveOptionsAsString() const {
 extern "C" CC_DLL_EXPORT bool CheckCompileOptions(const char *pszOptions,
                                                   char *pszUnknownOptions,
                                                   size_t uiUnknownOptionsSize) {
-  // LLVM doesn't guarantee thread safety,
-  // therefore we serialize execution of LLVM code.
-  llvm::sys::SmartScopedLock<true> compileOptionsGuard{*compileMutex};
-
   try {
     CompileOptionsParser optionsParser("200");
     return optionsParser.checkOptions(pszOptions, pszUnknownOptions,