1 files changed, 35 insertions, 25 deletions
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index 0d5cf821..a0930e97 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -17,7 +17,6 @@
 #include "absl/base/attributes.h"
 
 #ifdef _WIN32
-#include <shlwapi.h>
 #include <windows.h>
 #else
 #include <fcntl.h>
@@ -56,13 +55,9 @@
 #include "absl/base/internal/unscaledcycleclock.h"
 
 namespace absl {
-inline namespace lts_2019_08_08 {
+ABSL_NAMESPACE_BEGIN
 namespace base_internal {
 
-static once_flag init_system_info_once;
-static int num_cpus = 0;
-static double nominal_cpu_frequency = 1.0;  // 0.0 might be dangerous.
-
 static int GetNumCPUs() {
 #if defined(__myriad2__)
   return 1;
@@ -77,14 +72,23 @@ static int GetNumCPUs() {
 #if defined(_WIN32)
 
 static double GetNominalCPUFrequency() {
-  DWORD data;
-  DWORD data_size = sizeof(data);
-  #pragma comment(lib, "shlwapi.lib")  // For SHGetValue().
-  if (SUCCEEDED(
-          SHGetValueA(HKEY_LOCAL_MACHINE,
-                      "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0",
-                      "~MHz", nullptr, &data, &data_size))) {
-    return data * 1e6;  // Value is MHz.
+#pragma comment(lib, "advapi32.lib")  // For Reg* functions.
+  HKEY key;
+  // Use the Reg* functions rather than the SH functions because shlwapi.dll
+  // pulls in gdi32.dll which makes process destruction much more costly.
+  if (RegOpenKeyExA(HKEY_LOCAL_MACHINE,
+                    "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0", 0,
+                    KEY_READ, &key) == ERROR_SUCCESS) {
+    DWORD type = 0;
+    DWORD data = 0;
+    DWORD data_size = sizeof(data);
+    auto result = RegQueryValueExA(key, "~MHz", 0, &type,
+                                   reinterpret_cast<LPBYTE>(&data), &data_size);
+    RegCloseKey(key);
+    if (result == ERROR_SUCCESS && type == REG_DWORD &&
+        data_size == sizeof(data)) {
+      return data * 1e6;  // Value is MHz.
+    }
   }
   return 1.0;
 }
@@ -257,28 +261,34 @@ static double GetNominalCPUFrequency() {
 
 #endif
 
-// InitializeSystemInfo() may be called before main() and before
-// malloc is properly initialized, therefore this must not allocate
-// memory.
-static void InitializeSystemInfo() {
-  num_cpus = GetNumCPUs();
-  nominal_cpu_frequency = GetNominalCPUFrequency();
-}
+ABSL_CONST_INIT static once_flag init_num_cpus_once;
+ABSL_CONST_INIT static int num_cpus = 0;
 
+// NumCPUs() may be called before main() and before malloc is properly
+// initialized, therefore this must not allocate memory.
 int NumCPUs() {
-  base_internal::LowLevelCallOnce(&init_system_info_once, InitializeSystemInfo);
+  base_internal::LowLevelCallOnce(
+      &init_num_cpus_once, []() { num_cpus = GetNumCPUs(); });
   return num_cpus;
 }
 
+// A default frequency of 0.0 might be dangerous if it is used in division.
+ABSL_CONST_INIT static once_flag init_nominal_cpu_frequency_once;
+ABSL_CONST_INIT static double nominal_cpu_frequency = 1.0;
+
+// NominalCPUFrequency() may be called before main() and before malloc is
+// properly initialized, therefore this must not allocate memory.
 double NominalCPUFrequency() {
-  base_internal::LowLevelCallOnce(&init_system_info_once, InitializeSystemInfo);
+  base_internal::LowLevelCallOnce(
+      &init_nominal_cpu_frequency_once,
+      []() { nominal_cpu_frequency = GetNominalCPUFrequency(); });
   return nominal_cpu_frequency;
 }
 
 #if defined(_WIN32)
 
 pid_t GetTID() {
-  return GetCurrentThreadId();
+  return pid_t{GetCurrentThreadId()};
 }
 
 #elif defined(__linux__)
@@ -402,5 +412,5 @@ pid_t GetTID() {
 #endif
 
 }  // namespace base_internal
-}  // inline namespace lts_2019_08_08
+ABSL_NAMESPACE_END
 }  // namespace absl