[ABI] Removed OSUtils::getTickCount(), use 64-bit file API by default

OSUtils::getTickCount() is a legacy function that used to have some
magic to actually return correct values. However, since the function
was not used by any open-source project on GH it's better if it's just
removed so it doesn't have to be maintained. It had no tests and since
there is <chrono> in C++ it really has no purpose anymore.

In addition, use 64-bit file API by default on some platforms as this
is what most applications use anyway. This is just a little optimization
to avoid using both open() and open64() functions in an application if
it already uses 64-bit file API.

src/asmjit/core/api-build_p.h

@@ -27,6 +27,25 @@
     #define NOMINMAX
   #endif
   #include <windows.h>
+#else
+  // Most production code is compiled with large file support, so do the same.
+  #if !defined(_WIN32) && !defined(_LARGEFILE64_SOURCE)
+    #define _LARGEFILE64_SOURCE 1
+  #endif
+
+  // These OSes use 64-bit API by default.
+  #if defined(__APPLE__    ) || \
+      defined(__HAIKU__    ) || \
+      defined(__bsdi__     ) || \
+      defined(__DragonFly__) || \
+      defined(__FreeBSD__  ) || \
+      defined(__NetBSD__   ) || \
+      defined(__OpenBSD__  )
+    #define ASMJIT_FILE64_API(NAME) NAME
+  #else
+    #define ASMJIT_FILE64_API(NAME) NAME##64
+  #endif
+
 #endif
 
 #include "./api-config.h"

src/asmjit/core/osutils.cpp

@@ -7,90 +7,20 @@
 #include "../core/osutils_p.h"
 #include "../core/support.h"
 
-#if defined(_WIN32)
+#if !defined(_WIN32)
-  #include <atomic>
-#else
   #include <fcntl.h>
   #include <unistd.h>
-  #if defined(__APPLE__)
-    #include <mach/mach_time.h>
-  #else
-    #include <time.h>
-  #endif
 #endif
 
 ASMJIT_BEGIN_NAMESPACE
 
-uint32_t OSUtils::getTickCount() noexcept {
-#if defined(_WIN32)
-  enum HiResStatus : uint32_t {
-    kHiResUnknown      = 0,
-    kHiResAvailable    = 1,
-    kHiResNotAvailable = 2
-  };
-
-  static std::atomic<uint32_t> _hiResStatus(kHiResUnknown);
-  static volatile double _hiResFreq(0);
-
-  uint32_t status = _hiResStatus.load();
-  LARGE_INTEGER now, qpf;
-
-  if (status != kHiResNotAvailable && ::QueryPerformanceCounter(&now)) {
-    double freq = _hiResFreq;
-    if (status == kHiResUnknown) {
-      // Detects the availability of high resolution counter.
-      if (::QueryPerformanceFrequency(&qpf)) {
-        freq = double(qpf.QuadPart) / 1000.0;
-        _hiResFreq = freq;
-        _hiResStatus.compare_exchange_strong(status, kHiResAvailable);
-        status = kHiResAvailable;
-      }
-      else {
-        // High resolution not available.
-        _hiResStatus.compare_exchange_strong(status, kHiResNotAvailable);
-      }
-    }
-
-    if (status == kHiResAvailable)
-      return uint32_t(uint64_t(int64_t(double(now.QuadPart) / freq)) & 0xFFFFFFFFu);
-  }
-
-  // Bail to `GetTickCount()` if we cannot use high resolution.
-  return ::GetTickCount();
-#elif defined(__APPLE__)
-  // See Apple's QA1398.
-  static mach_timebase_info_data_t _machTime;
-
-  uint32_t denom = _machTime.denom;
-  if (ASMJIT_UNLIKELY(!denom)) {
-    if (mach_timebase_info(&_machTime) != KERN_SUCCESS || !(denom = _machTime.denom))
-      return 0;
-  }
-
-  // `mach_absolute_time()` returns nanoseconds, we want milliseconds.
-  uint64_t t = mach_absolute_time() / 1000000u;
-  t = (t * _machTime.numer) / _machTime.denom;
-  return uint32_t(t & 0xFFFFFFFFu);
-#elif defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0
-  struct timespec ts;
-  if (ASMJIT_UNLIKELY(clock_gettime(CLOCK_MONOTONIC, &ts) != 0))
-    return 0;
-
-  uint64_t t = (uint64_t(ts.tv_sec ) * 1000u) + (uint64_t(ts.tv_nsec) / 1000000u);
-  return uint32_t(t & 0xFFFFFFFFu);
-#else
-  #pragma message("[asmjit] OSUtils::getTickCount() doesn't have implementation for the target OS.")
-  return 0;
-#endif
-}
-
 #if !defined(_WIN32)
 Error OSUtils::readFile(const char* name, String& dst, size_t maxSize) noexcept {
   char* buffer = dst.prepare(String::ModifyOp::kAssign, maxSize);
   if (ASMJIT_UNLIKELY(!buffer))
     return DebugUtils::errored(kErrorOutOfMemory);
 
-  int fd = ::open(name, O_RDONLY);
+  int fd = ASMJIT_FILE64_API(::open)(name, O_RDONLY);
   if (fd < 0) {
     dst.clear();
     return DebugUtils::errored(kErrorFailedToOpenFile);

src/asmjit/core/osutils.h

@@ -13,14 +13,6 @@ ASMJIT_BEGIN_NAMESPACE
 //! \addtogroup asmjit_utilities
 //! \{
 
-//! Operating system utilities.
-namespace OSUtils {
-
-//! Gets the current CPU tick count, used for benchmarking (1ms resolution).
-ASMJIT_API uint32_t getTickCount() noexcept;
-
-} // {OSUtils}
-
 //! \cond INTERNAL
 //! Lock.
 //!

src/asmjit/core/virtmem.cpp

@@ -19,6 +19,10 @@
   #include <sys/types.h>
   #include <unistd.h>
 
+  #if !ASMJIT_ARCH_X86
+    #include <sys/time.h> // required by gettimeofday()
+  #endif
+
   // Linux has a `memfd_create` syscall that we would like to use, if available.
   #if defined(__linux__)
     #include <sys/syscall.h>
@@ -74,17 +78,17 @@
 
   #define ASMJIT_ANONYMOUS_MEMORY_USE_FD
 
-  #if defined(__APPLE__) || defined(__BIONIC__)
-    #define ASMJIT_VM_SHM_DETECT 0
-  #else
-    #define ASMJIT_VM_SHM_DETECT 1
-  #endif
-
   // Android NDK doesn't provide `shm_open()` and `shm_unlink()`.
   #if !defined(__BIONIC__) && !defined(ASMJIT_NO_SHM_OPEN)
     #define ASMJIT_HAS_SHM_OPEN
   #endif
 
+  #if defined(__APPLE__) || defined(__BIONIC__) || !defined(ASMJIT_HAS_SHM_OPEN)
+    #define ASMJIT_VM_SHM_DETECT 0
+  #else
+    #define ASMJIT_VM_SHM_DETECT 1
+  #endif
+
   #if defined(__APPLE__) && TARGET_OS_OSX && ASMJIT_ARCH_ARM >= 64
     #define ASMJIT_HAS_PTHREAD_JIT_WRITE_PROTECT_NP
   #endif
@@ -458,6 +462,28 @@ static uint32_t getMfdExecFlag() noexcept {
 }
 #endif // __linux__ && __NR_memfd_create
 
+
+// It's not fully random, just to avoid collisions when opening TMP or SHM file.
+ASMJIT_MAYBE_UNUSED
+static uint64_t generateRandomBits(uintptr_t stackPtr, uint32_t attempt) noexcept {
+  static std::atomic<uint32_t> internalCounter;
+
+#if defined(__GNUC__) && ASMJIT_ARCH_X86
+  // Use RDTSC instruction to avoid gettimeofday() as we just need some "random" bits.
+  uint64_t mix = __builtin_ia32_rdtsc();
+#else
+  struct timeval tm {};
+  uint64_t mix = 1; // only used when gettimeofday() fails, which is unlikely.
+  if (gettimeofday(&tm, nullptr) == 0) {
+    mix = uint64_t(tm.tv_usec) ^ uint64_t(tm.tv_sec);
+  }
+#endif
+
+  uint64_t bits = (uint64_t(stackPtr) & 0x1010505000055590u) - mix * 773703683;
+  bits = (bits >> 33) ^ (bits << 7) ^ (attempt * 87178291199);
+  return bits + uint64_t(++internalCounter) * 10619863;
+}
+
 class AnonymousMemory {
 public:
   enum FileType : uint32_t {
@@ -518,26 +544,20 @@ public:
     else
       return DebugUtils::errored(asmjitErrorFromErrno(errno));
 #else
-    // POSIX API. We have to generate somehow a unique name. This is nothing cryptographic, just using a bit from
+    // POSIX API. We have to generate somehow a unique name, so use `generateRandomBits()` helper. To prevent
-    // the stack address to always have a different base for different threads (as threads have their own stack)
+    // having file collisions we use `shm_open()` with flags that require creation of the file so we never open
-    // and retries for avoiding collisions. We use `shm_open()` with flags that require creation of the file so we
+    // an existing shared memory.
-    // never open an existing shared memory.
+    static const char kShmFormat[] = "/shm-id-%016llX";
-    static std::atomic<uint32_t> internalCounter;
-    const char* kShmFormat = "/shm-id-%016llX";
-
     uint32_t kRetryCount = 100;
-    uint64_t bits = ((uintptr_t)(void*)this) & 0x55555555u;
 
     for (uint32_t i = 0; i < kRetryCount; i++) {
-      bits -= uint64_t(OSUtils::getTickCount()) * 773703683;
-      bits = ((bits >> 14) ^ (bits << 6)) + uint64_t(++internalCounter) * 10619863;
-
       bool useTmp = !ASMJIT_VM_SHM_DETECT || preferTmpOverDevShm;
+      uint64_t bits = generateRandomBits((uintptr_t)this, i);
 
       if (useTmp) {
         _tmpName.assign(getTmpDir());
         _tmpName.appendFormat(kShmFormat, (unsigned long long)bits);
-        _fd = ::open(_tmpName.data(), O_RDWR | O_CREAT | O_EXCL, 0);
+        _fd = ASMJIT_FILE64_API(::open)(_tmpName.data(), O_RDWR | O_CREAT | O_EXCL, 0);
         if (ASMJIT_LIKELY(_fd >= 0)) {
           _fileType = kFileTypeTmp;
           return kErrorOk;
@@ -589,7 +609,7 @@ public:
 
   Error allocate(size_t size) noexcept {
     // TODO: Improve this by using `posix_fallocate()` when available.
-    if (ftruncate(_fd, off_t(size)) != 0)
+    if (ASMJIT_FILE64_API(ftruncate)(_fd, off_t(size)) != 0)
       return DebugUtils::errored(asmjitErrorFromErrno(errno));
 
     return kErrorOk;