Revert "[Support] Add a way to run a function on a detached thread"

This reverts commit 40668abca4d307e02b33345cfdb7271549ff48d0.
This causes clang tests to fail, as stacksize=0 is being explicitly passed and
is no longer a no-op.

3 files changed, 32 insertions, 33 deletions

diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index 3526e3dee6f..4b91f9f7fc6 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -439,6 +439,13 @@ const char *Process::ResetColor() {
   return 0;
 }
 
+// Include GetLastError() in a fatal error message.
+static void ReportLastErrorFatal(const char *Msg) {
+  std::string ErrMsg;
+  MakeErrMsg(&ErrMsg, Msg);
+  report_fatal_error(ErrMsg);
+}
+
 unsigned Process::GetRandomNumber() {
   HCRYPTPROV HCPC;
   if (!::CryptAcquireContextW(&HCPC, NULL, NULL, PROV_RSA_FULL,
diff --git a/llvm/lib/Support/Windows/Threading.inc b/llvm/lib/Support/Windows/Threading.inc
index 83b47ea1e3d..96649472cc9 100644
--- a/llvm/lib/Support/Windows/Threading.inc
+++ b/llvm/lib/Support/Windows/Threading.inc
@@ -21,36 +21,36 @@
 #undef MemoryFence
 #endif
 
-static unsigned __stdcall threadFuncSync(void *Arg) {
-  SyncThreadInfo *TI = static_cast<SyncThreadInfo *>(Arg);
-  TI->UserFn(TI->UserData);
-  return 0;
+namespace {
+  struct ThreadInfo {
+    void(*func)(void*);
+    void *param;
+  };
 }
 
-static unsigned __stdcall threadFuncAsync(void *Arg) {
-  std::unique_ptr<AsyncThreadInfo> Info(static_cast<AsyncThreadInfo *>(Arg));
-  (*Info)();
+static unsigned __stdcall ThreadCallback(void *param) {
+  struct ThreadInfo *info = reinterpret_cast<struct ThreadInfo *>(param);
+  info->func(info->param);
+
   return 0;
 }
 
-static void
-llvm_execute_on_thread_impl(_beginthreadex_proc_type ThreadFunc, void *Arg,
-                            llvm::Optional<unsigned> StackSizeInBytes,
-                            JoiningPolicy JP) {
-  HANDLE hThread = (HANDLE)::_beginthreadex(
-      NULL, StackSizeInBytes.getValueOr(0), ThreadFunc, Arg, 0, NULL);
-
-  if (!hThread) {
-    ReportLastErrorFatal("_beginthreadex failed");
-  }
-
-  if (JP == JoiningPolicy::Join) {
-    if (::WaitForSingleObject(hThread, INFINITE) == WAIT_FAILED) {
-      ReportLastErrorFatal("WaitForSingleObject failed");
-    }
-  }
-  if (::CloseHandle(hThread) == FALSE) {
-    ReportLastErrorFatal("CloseHandle failed");
+void llvm::llvm_execute_on_thread(void(*Fn)(void*), void *UserData,
+  unsigned RequestedStackSize) {
+  struct ThreadInfo param = { Fn, UserData };
+
+  HANDLE hThread = (HANDLE)::_beginthreadex(NULL,
+    RequestedStackSize, ThreadCallback,
+    &param, 0, NULL);
+
+  if (hThread) {
+    // We actually don't care whether the wait succeeds or fails, in
+    // the same way we don't care whether the pthread_join call succeeds
+    // or fails.  There's not much we could do if this were to fail. But
+    // on success, this call will wait until the thread finishes executing
+    // before returning.
+    (void)::WaitForSingleObject(hThread, INFINITE);
+    ::CloseHandle(hThread);
   }
 }
 
diff --git a/llvm/lib/Support/Windows/WindowsSupport.h b/llvm/lib/Support/Windows/WindowsSupport.h
index bb7e79b8601..2e2e97430b7 100644
--- a/llvm/lib/Support/Windows/WindowsSupport.h
+++ b/llvm/lib/Support/Windows/WindowsSupport.h
@@ -41,7 +41,6 @@
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/VersionTuple.h"
 #include <cassert>
 #include <string>
@@ -67,13 +66,6 @@ llvm::VersionTuple GetWindowsOSVersion();
 
 bool MakeErrMsg(std::string *ErrMsg, const std::string &prefix);
 
-// Include GetLastError() in a fatal error message.
-LLVM_ATTRIBUTE_NORETURN inline void ReportLastErrorFatal(const char *Msg) {
-  std::string ErrMsg;
-  MakeErrMsg(&ErrMsg, Msg);
-  llvm::report_fatal_error(ErrMsg);
-}
-
 template <typename HandleTraits>
 class ScopedHandle {
   typedef typename HandleTraits::handle_type handle_type;