[llvm-driver] Fix usage of InitLLVM on Windows (#76306)

Previously, some tools such as `clang` or `lld` which require strict
order for certain command-line options, such as `clang -cc1` or `lld
-flavor`, would not longer work on Windows, when these tools were linked
as part of `llvm-driver`. This was caused by `InitLLVM` which was part
of the `*_main()` function of these tools, which in turn calls
`windows::GetCommandLineArguments`. That function completly replaces
argc/argv by new UTF-8 contents, so any ajustements to argc/argv made by
`llvm-driver` prior to calling these tools was reset.

`InitLLVM` is now called by the `llvm-driver`. Any tool that
participates in (or is part of) the `llvm-driver` doesn't call
`InitLLVM` anymore.

Author: aganea

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -20,7 +20,6 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Format.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/Program.h"
@@ -699,7 +698,6 @@ static std::string getModuleCachePath(ArrayRef<std::string> Args) {
 // form specified command line after the positional parameter "--".
 static std::unique_ptr<tooling::CompilationDatabase>
 getCompilationDataBase(int argc, char **argv, std::string &ErrorMessage) {
-  llvm::InitLLVM X(argc, argv);
   ParseArgs(argc, argv);
 
   if (!CompilationDB.empty())

clang/tools/driver/driver.cpp

@@ -36,7 +36,6 @@
 #include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/PrettyStackTrace.h"
@@ -377,7 +376,6 @@ static int ExecuteCC1Tool(SmallVectorImpl<const char *> &ArgV,
 
 int clang_main(int Argc, char **Argv, const llvm::ToolContext &ToolContext) {
   noteBottomOfStack();
-  llvm::InitLLVM X(Argc, Argv);
   llvm::setBugReportMsg("PLEASE submit a bug report to " BUG_REPORT_URL
                         " and include the crash backtrace, preprocessed "
                         "source, and associated run script.\n");

lld/Common/DriverDispatcher.cpp

@@ -16,7 +16,6 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/CrashRecoveryContext.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include "llvm/TargetParser/Host.h"

lld/tools/lld/lld.cpp

@@ -33,7 +33,6 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/CrashRecoveryContext.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/PluginLoader.h"
@@ -74,7 +73,6 @@ LLD_HAS_DRIVER(macho)
 LLD_HAS_DRIVER(wasm)
 
 int lld_main(int argc, char **argv, const llvm::ToolContext &) {
-  InitLLVM x(argc, argv);
   sys::Process::UseANSIEscapeCodes(true);
 
   if (::getenv("FORCE_LLD_DIAGNOSTICS_CRASH")) {

llvm/cmake/modules/llvm-driver-template.cpp.in

@@ -8,9 +8,11 @@
 
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/InitLLVM.h"
 
 int @TOOL_NAME@_main(int argc, char **, const llvm::ToolContext &);
 
 int main(int argc, char **argv) {
+  llvm::InitLLVM X(argc, argv);
   return @TOOL_NAME@_main(argc, argv, {argv[0], nullptr, false});
 }

llvm/lib/Support/InitLLVM.cpp

@@ -38,6 +38,11 @@ using namespace llvm::sys;
 
 InitLLVM::InitLLVM(int &Argc, const char **&Argv,
                    bool InstallPipeSignalExitHandler) {
+#ifndef NDEBUG
+  static std::atomic<bool> Initialized{false};
+  assert(!Initialized && "InitLLVM was already initialized!");
+  Initialized = true;
+#endif
 #ifdef __MVS__
   // Bring stdin/stdout/stderr into a known state.
   sys::AddSignalHandler(CleanupStdHandles, nullptr);

llvm/tools/dsymutil/dsymutil.cpp

@@ -37,7 +37,6 @@
 #include "llvm/Support/FileCollector.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FormatVariadic.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TargetSelect.h"
@@ -608,8 +607,6 @@ getOutputFileName(StringRef InputFile, const DsymutilOptions &Options) {
 }
 
 int dsymutil_main(int argc, char **argv, const llvm::ToolContext &) {
-  InitLLVM X(argc, argv);
-
   // Parse arguments.
   DsymutilOptTable T;
   unsigned MAI;

llvm/tools/llvm-ar/llvm-ar.cpp

@@ -25,7 +25,6 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/FormatVariadic.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -1500,7 +1499,6 @@ static int ranlib_main(int argc, char **argv) {
 }
 
 int llvm_ar_main(int argc, char **argv, const llvm::ToolContext &) {
-  InitLLVM X(argc, argv);
   ToolName = argv[0];
 
   llvm::InitializeAllTargetInfos();

llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp

@@ -13,7 +13,6 @@
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/CommandLine.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
@@ -146,7 +145,6 @@ static void demangleLine(llvm::raw_ostream &OS, StringRef Mangled, bool Split) {
 }
 
 int llvm_cxxfilt_main(int argc, char **argv, const llvm::ToolContext &) {
-  InitLLVM X(argc, argv);
   BumpPtrAllocator A;
   StringSaver Saver(A);
   CxxfiltOptTable Tbl;

llvm/tools/llvm-debuginfod/llvm-debuginfod.cpp

@@ -22,7 +22,6 @@
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/CommandLine.h"
-#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/ThreadPool.h"
 
@@ -121,7 +120,6 @@ static void parseArgs(int argc, char **argv) {
 }
 
 int llvm_debuginfod_main(int argc, char **argv, const llvm::ToolContext &) {
-  InitLLVM X(argc, argv);
   HTTPClient::initialize();
   parseArgs(argc, argv);