[Concurrency] Add Win32 implementation for recursive mutex.

We're using `CRITICAL_SECTION` here, as that supports recursion.

rdar://113898653

Author: al45tair

include/swift/Threading/Impl/Win32.h

@@ -87,6 +87,26 @@ inline void lazy_mutex_unsafe_unlock(lazy_mutex_handle &handle) {
   ReleaseSRWLockExclusive(&handle);
 }
 
+// .. Recursive mutex support ................................................
+
+using recursive_mutex_handle = SWIFT_CRITICAL_SECTION;
+
+inline void recursive_mutex_init(recursive_mutex_handle &handle,
+                                 bool checked = false) {
+  InitializeCriticalSection(&handle);
+}
+
+inline void recursive_mutex_destroy(recursive_mutex_handle &handle) {
+  DeleteCriticalSection(&handle);
+}
+
+inline void recursive_mutex_lock(recursive_mutex_handle &handle) {
+  EnterCriticalSection(&handle);
+}
+inline void recursive_mutex_unlock(recursive_mutex_handle &handle) {
+  LeaveCriticalSection(&handle);
+}
+
 // .. ConditionVariable support ..............................................
 
 struct cond_handle {

include/swift/Threading/Impl/Win32/Win32Defs.h

@@ -36,7 +36,10 @@ typedef unsigned char BYTE;
 typedef BYTE BOOLEAN;
 typedef int BOOL;
 typedef unsigned long DWORD;
+typedef long LONG;
 typedef unsigned long ULONG;
+typedef unsigned long ULONG_PTR;
+typedef PVOID HANDLE;
 
 typedef VOID(NTAPI *PFLS_CALLBACK_FUNCTION)(PVOID lpFlsData);
 
@@ -46,6 +49,11 @@ typedef PRTL_SRWLOCK PSRWLOCK;
 typedef struct _RTL_CONDITION_VARIABLE *PRTL_CONDITION_VARIABLE;
 typedef PRTL_CONDITION_VARIABLE PCONDITION_VARIABLE;
 
+typedef struct _RTL_CRITICAL_SECTION_DEBUG *PRTL_CRITICAL_SECTION_DEBUG;
+typedef struct _RTL_CRITICAL_SECTION *PRTL_CRITICAL_SECTION;
+typedef PRTL_CRITICAL_SECTION PCRITICAL_SECTION;
+typedef PRTL_CRITICAL_SECTION LPCRITICAL_SECTION;
+
 // These have to be #defines, to avoid problems with <windows.h>
 #define RTL_SRWLOCK_INIT {0}
 #define SRWLOCK_INIT RTL_SRWLOCK_INIT
@@ -83,6 +91,19 @@ WINBASEAPI BOOL WINAPI SleepConditionVariableSRW(
   ULONG Flags
 );
 
+WINBASEAPI VOID WINAPI InitializeCriticalSection(
+  LPCRITICAL_SECTION lpCriticalSection
+);
+WINBASEAPI VOID WINAPI DeleteCriticalSection(
+  LPCRITICAL_SECTION lpCriticalSection
+);
+WINBASEAPI VOID WINAPI EnterCriticalSection(
+  LPCRITICAL_SECTION lpCriticalSection
+);
+WINBASEAPI VOID WINAPI LeaveCriticalSection(
+  LPCRITICAL_SECTION lpCriticalSection
+);
+
 WINBASEAPI DWORD WINAPI FlsAlloc(PFLS_CALLBACK_FUNCTION lpCallback);
 WINBASEAPI PVOID WINAPI FlsGetValue(DWORD dwFlsIndex);
 WINBASEAPI BOOL WINAPI FlsSetValue(DWORD dwFlsIndex, PVOID lpFlsData);
@@ -140,6 +161,34 @@ inline BOOL SleepConditionVariableSRW(PSWIFT_CONDITION_VARIABLE CondVar,
     Flags);
 }
 
+// And with CRITICAL_SECTION
+#pragma pack(push, 8)
+typedef struct SWIFT_CRITICAL_SECTION {
+  PRTL_CRITICAL_SECTION_DEBUG DebugInfo;
+  LONG LockCount;
+  LONG RecursionCount;
+  HANDLE OwningThread;
+  HANDLE LockSemaphore;
+  ULONG_PTR SpinCount;
+} SWIFT_CRITICAL_SECTION, *PSWIFT_CRITICAL_SECTION;
+#pragma pack(pop)
+
+inline VOID InitializeCriticalSection(PSWIFT_CRITICAL_SECTION CritSec) {
+  ::InitializeCriticalSection(reinterpret_cast<LPCRITICAL_SECTION>(CritSec));
+}
+
+inline VOID DeleteCriticalSection(PSWIFT_CRITICAL_SECTION CritSec) {
+  ::DeleteCriticalSection(reinterpret_cast<LPCRITICAL_SECTION>(CritSec));
+}
+
+inline VOID EnterCriticalSection(PSWIFT_CRITICAL_SECTION CritSec) {
+  ::EnterCriticalSection(reinterpret_cast<LPCRITICAL_SECTION>(CritSec));
+}
+
+inline VOID LeaveCriticalSection(PSWIFT_CRITICAL_SECTION CritSec) {
+  ::LeaveCriticalSection(reinterpret_cast<LPCRITICAL_SECTION>(CritSec));
+}
+
 } // namespace threading_impl
 } // namespace swift