Remove libstdc++ dependency from NativeAOT

src/coreclr/gc/gc.cpp

@@ -11488,6 +11488,8 @@ bool gc_heap::is_region_demoted (uint8_t* obj)
     return demoted_p;
 }
 
+static GCSpinLock write_barrier_spin_lock;
+
 inline
 void gc_heap::set_region_gen_num (heap_segment* region, int gen_num)
 {
@@ -11510,8 +11512,6 @@ void gc_heap::set_region_gen_num (heap_segment* region, int gen_num)
     {
         if ((region_start < ephemeral_low) || (ephemeral_high < region_end))
         {
-            static GCSpinLock write_barrier_spin_lock;
-
             while (true)
             {
                 if (Interlocked::CompareExchange(&write_barrier_spin_lock.lock, 0, -1) < 0)

src/coreclr/gc/gc.h

@@ -253,9 +253,9 @@ struct alloc_context : gc_alloc_context
 
 class IGCHeapInternal : public IGCHeap {
 public:
-    virtual int GetNumberOfHeaps () = 0;
-    virtual int GetHomeHeapNumber () = 0;
-    virtual size_t GetPromotedBytes(int heap_index) = 0;
+    virtual int GetNumberOfHeaps () PURE_VIRTUAL
+    virtual int GetHomeHeapNumber () PURE_VIRTUAL
+    virtual size_t GetPromotedBytes(int heap_index) PURE_VIRTUAL
 
     unsigned GetMaxGeneration()
     {

src/coreclr/gc/handletablecache.cpp

@@ -56,7 +56,7 @@ void SpinUntil(void *pCond, BOOL fNonZero)
 #endif //_DEBUG
 
     // on MP machines, allow ourselves some spin time before sleeping
-    static uint32_t uNonSleepSpins = 8 * (GCToEEInterface::GetCurrentProcessCpuCount() - 1);
+    uint32_t uNonSleepSpins = 8 * (GCToEEInterface::GetCurrentProcessCpuCount() - 1);
 
     // spin until the specified condition is met
     while ((*(uintptr_t *)pCond != 0) != (fNonZero != 0))

src/coreclr/gc/unix/events.cpp

@@ -1,11 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#include <cstdint>
-#include <cstddef>
-#include <cassert>
-#include <memory>
-#include <mutex>
 #include <pthread.h>
 #include <errno.h>
 #include "config.gc.h"
@@ -280,36 +275,37 @@ bool GCEvent::CreateManualEventNoThrow(bool initialState)
 bool GCEvent::CreateOSAutoEventNoThrow(bool initialState)
 {
     assert(m_impl == nullptr);
-    std::unique_ptr<GCEvent::Impl> event(new (std::nothrow) GCEvent::Impl(false, initialState));
+    GCEvent::Impl* event(new (nothrow) GCEvent::Impl(false, initialState));
     if (!event)
     {
         return false;
     }
 
     if (!event->Initialize())
     {
+        delete event;
         return false;
     }
 
-    m_impl = event.release();
+    m_impl = event;
     return true;
 }
 
 bool GCEvent::CreateOSManualEventNoThrow(bool initialState)
 {
     assert(m_impl == nullptr);
-    std::unique_ptr<GCEvent::Impl> event(new (std::nothrow) GCEvent::Impl(true, initialState));
+    GCEvent::Impl* event(new (nothrow) GCEvent::Impl(true, initialState));
     if (!event)
     {
         return false;
     }
 
     if (!event->Initialize())
     {
+        delete event;
         return false;
     }
 
-    m_impl = event.release();
+    m_impl = event;
     return true;
 }
-

src/coreclr/nativeaot/Bootstrap/base/CMakeLists.txt

@@ -12,4 +12,7 @@ if (CLR_CMAKE_TARGET_WIN32)
   add_library(bootstrapper.GuardCF STATIC ${SOURCES})
   install_static_library(bootstrapper.GuardCF aotsdk nativeaot)
   target_compile_options(bootstrapper.GuardCF PRIVATE $<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:/guard:cf>)
+else()
+  add_library(stdc++compat STATIC ../stdcppshim.cpp)
+  install_static_library(stdc++compat aotsdk nativeaot)
 endif()

src/coreclr/nativeaot/Bootstrap/stdcppshim.cpp

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#include <stdlib.h>
+
+namespace std
+{
+    struct nothrow_t {};
+    extern const nothrow_t nothrow = {};
+}
+
+void* operator new(size_t n, const std::nothrow_t&) noexcept
+{
+    return malloc(n);
+}
+
+void* operator new[](size_t n, const std::nothrow_t&) noexcept
+{
+    return malloc(n);
+}
+
+void operator delete(void *p) noexcept
+{
+    free(p);
+}
+
+void operator delete[](void *p) noexcept
+{
+    free(p);
+}

src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets

@@ -49,6 +49,7 @@ The .NET Foundation licenses this file to you under the MIT license.
       <NativeLibrary Condition="$(NativeLib) == ''" Include="$(IlcSdkPath)libbootstrapper.a" />
       <NativeLibrary Condition="$(NativeLib) != ''" Include="$(IlcSdkPath)libbootstrapperdll.a" />
       <NativeLibrary Include="$(IlcSdkPath)$(FullRuntimeName).a" />
+      <NativeLibrary Condition="'$(LinkStandardCPlusPlusLibrary)' != 'true'" Include="$(IlcSdkPath)libstdc++compat.a" />
     </ItemGroup>
 
     <ItemGroup>
@@ -96,7 +97,7 @@ The .NET Foundation licenses this file to you under the MIT license.
       <LinkerArg Include="-Wl,--as-needed" Condition="'$(TargetOS)' != 'OSX'" />
       <LinkerArg Include="-Wl,-e0x0" Condition="'$(NativeLib)' == 'Shared' and '$(TargetOS)' != 'OSX'" />
       <LinkerArg Include="-pthread" Condition="'$(TargetOS)' != 'OSX'" />
-      <LinkerArg Include="-lstdc++" />
+      <LinkerArg Include="-lstdc++" Condition="'$(LinkStandardCPlusPlusLibrary)' == 'true'" />
       <LinkerArg Include="-ldl" />
       <LinkerArg Include="-lm" />
       <LinkerArg Include="-lobjc" Condition="'$(TargetOS)' == 'OSX'" />

src/coreclr/nativeaot/CMakeLists.txt

@@ -30,6 +30,7 @@ if(CLR_CMAKE_HOST_UNIX)
 
   add_compile_options(-fno-rtti)          # Native AOT runtime doesn't use RTTI
   add_compile_options(-fno-exceptions)    # Native AOT runtime doesn't use C++ exception handling
+  add_compile_options(-nostdlib)
 
   if(CLR_CMAKE_TARGET_OSX)
     add_definitions(-D_XOPEN_SOURCE)

src/coreclr/nativeaot/Runtime/CMakeLists.txt

@@ -105,9 +105,6 @@ if (WIN32)
     ${GC_DIR}/handletablepriv.h
     ${GC_DIR}/objecthandle.h
     ${GC_DIR}/softwarewritewatch.h)
-endif(WIN32)
-
-if(WIN32)
 
   include_directories(windows)
 

src/coreclr/nativeaot/Runtime/ICodeManager.h

@@ -165,50 +165,50 @@ enum class AssociatedDataFlags : unsigned char
 class ICodeManager
 {
 public:
-    virtual bool IsSafePoint(PTR_VOID pvAddress) = 0;
+    virtual bool IsSafePoint(PTR_VOID pvAddress) PURE_VIRTUAL
 
     virtual bool FindMethodInfo(PTR_VOID        ControlPC,
-                                MethodInfo *    pMethodInfoOut) = 0;
+                                MethodInfo *    pMethodInfoOut) PURE_VIRTUAL
 
-    virtual bool IsFunclet(MethodInfo * pMethodInfo) = 0;
+    virtual bool IsFunclet(MethodInfo * pMethodInfo) PURE_VIRTUAL
 
     virtual PTR_VOID GetFramePointer(MethodInfo *   pMethodInfo,
-                                     REGDISPLAY *   pRegisterSet) = 0;
+                                     REGDISPLAY *   pRegisterSet) PURE_VIRTUAL
 
     virtual void EnumGcRefs(MethodInfo *    pMethodInfo,
                             PTR_VOID        safePointAddress,
                             REGDISPLAY *    pRegisterSet,
                             GCEnumContext * hCallback,
-                            bool            isActiveStackFrame) = 0;
+                            bool            isActiveStackFrame) PURE_VIRTUAL
 
     virtual bool UnwindStackFrame(MethodInfo *    pMethodInfo,
                                   REGDISPLAY *    pRegisterSet,                     // in/out
-                                  PInvokeTransitionFrame**      ppPreviousTransitionFrame) = 0;   // out
+                                  PInvokeTransitionFrame**      ppPreviousTransitionFrame) PURE_VIRTUAL   // out
 
     virtual uintptr_t GetConservativeUpperBoundForOutgoingArgs(MethodInfo *   pMethodInfo,
-                                                                REGDISPLAY *   pRegisterSet) = 0;
+                                                                REGDISPLAY *   pRegisterSet) PURE_VIRTUAL
 
-    virtual bool IsUnwindable(PTR_VOID pvAddress) = 0;
+    virtual bool IsUnwindable(PTR_VOID pvAddress) PURE_VIRTUAL
 
     virtual bool GetReturnAddressHijackInfo(MethodInfo *    pMethodInfo,
                                             REGDISPLAY *    pRegisterSet,           // in
                                             PTR_PTR_VOID *  ppvRetAddrLocation,     // out
-                                            GCRefKind *     pRetValueKind) = 0;     // out
+                                            GCRefKind *     pRetValueKind) PURE_VIRTUAL     // out
 
-    virtual PTR_VOID RemapHardwareFaultToGCSafePoint(MethodInfo * pMethodInfo, PTR_VOID controlPC) = 0;
+    virtual PTR_VOID RemapHardwareFaultToGCSafePoint(MethodInfo * pMethodInfo, PTR_VOID controlPC) PURE_VIRTUAL
 
-    virtual bool EHEnumInit(MethodInfo * pMethodInfo, PTR_VOID * pMethodStartAddress, EHEnumState * pEHEnumState) = 0;
+    virtual bool EHEnumInit(MethodInfo * pMethodInfo, PTR_VOID * pMethodStartAddress, EHEnumState * pEHEnumState) PURE_VIRTUAL
 
-    virtual bool EHEnumNext(EHEnumState * pEHEnumState, EHClause * pEHClause) = 0;
+    virtual bool EHEnumNext(EHEnumState * pEHEnumState, EHClause * pEHClause) PURE_VIRTUAL
 
-    virtual PTR_VOID GetMethodStartAddress(MethodInfo * pMethodInfo) = 0;
+    virtual PTR_VOID GetMethodStartAddress(MethodInfo * pMethodInfo) PURE_VIRTUAL
 
-    virtual PTR_VOID GetOsModuleHandle() = 0;
+    virtual PTR_VOID GetOsModuleHandle() PURE_VIRTUAL
 
-    virtual void * GetClasslibFunction(ClasslibFunctionId functionId) = 0;
+    virtual void * GetClasslibFunction(ClasslibFunctionId functionId) PURE_VIRTUAL
 
     // Returns any custom data attached to the method. Format:
     //      AssociatedDataFlags        // 1 byte. Flags describing the data stored
     //      Data (stream of bytes)     // Variable size (depending on flags). Custom data associated with method
-    virtual PTR_VOID GetAssociatedData(PTR_VOID ControlPC) = 0;
+    virtual PTR_VOID GetAssociatedData(PTR_VOID ControlPC) PURE_VIRTUAL
 };

src/coreclr/nativeaot/Runtime/inc/CommonTypes.h

@@ -6,9 +6,19 @@
 
 #include <cstddef>
 #include <cstdint>
-#include <cstdlib>
+#include <stdlib.h>
+#include <stdio.h>
 #include <new>
 
+// Implement pure virtual for Unix (for -p:LinkStandardCPlusPlusLibrary=false the default),
+// to avoid linker requiring __cxa_pure_virtual.
+#ifdef TARGET_WINDOWS
+#define PURE_VIRTUAL = 0;
+#else
+// `while(true);` is to satisfy the missing `return` statement. It will be optimized away by the compiler.
+#define PURE_VIRTUAL { assert(!"pure virtual function called"); while(true); }
+#endif
+
 using std::nothrow;
 using std::size_t;
 using std::uintptr_t;

src/coreclr/nativeaot/Runtime/unix/PalRedhawkUnix.cpp

@@ -20,6 +20,7 @@
 #include "UnixContext.h"
 #include "HardwareExceptions.h"
 #include "cgroupcpu.h"
+#include "threadstore.h"
 
 #define _T(s) s
 #include "RhConfig.h"
@@ -346,11 +347,6 @@ class EventUnixHandle : public UnixHandle<UnixHandleType::Event, UnixEvent>
 
 typedef UnixHandle<UnixHandleType::Thread, pthread_t> ThreadUnixHandle;
 
-#if !HAVE_THREAD_LOCAL
-extern "C" int __cxa_thread_atexit(void (*)(void*), void*, void *);
-extern "C" void *__dso_handle;
-#endif
-
 // This functions configures behavior of the signals that are not
 // related to hardware exception handling.
 void ConfigureSignals()
@@ -406,6 +402,10 @@ void InitializeCurrentProcessCpuCount()
     g_RhNumberOfProcessors = count;
 }
 
+#ifdef TARGET_LINUX
+static pthread_key_t key;
+#endif
+
 // The Redhawk PAL must be initialized before any of its exports can be called. Returns true for a successful
 // initialization and false on failure.
 REDHAWK_PALEXPORT bool REDHAWK_PALAPI PalInit()
@@ -430,11 +430,17 @@ REDHAWK_PALEXPORT bool REDHAWK_PALAPI PalInit()
 
     InitializeCurrentProcessCpuCount();
 
+#ifdef TARGET_LINUX
+    if (pthread_key_create(&key, RuntimeThreadShutdown) != 0)
+    {
+        return false;
+    }
+#endif
+
     return true;
 }
 
-#if HAVE_THREAD_LOCAL
-
+#ifndef TARGET_LINUX
 struct TlsDestructionMonitor
 {
     void* m_thread = nullptr;
@@ -456,8 +462,7 @@ struct TlsDestructionMonitor
 // This thread local object is used to detect thread shutdown. Its destructor
 // is called when a thread is being shut down.
 thread_local TlsDestructionMonitor tls_destructionMonitor;
-
-#endif // HAVE_THREAD_LOCAL
+#endif
 
 // This thread local variable is used for delegate marshalling
 DECLSPEC_THREAD intptr_t tls_thunkData;
@@ -481,10 +486,14 @@ EXTERN_C intptr_t RhGetCurrentThunkContext()
 //  thread        - thread to attach
 extern "C" void PalAttachThread(void* thread)
 {
-#if HAVE_THREAD_LOCAL
-    tls_destructionMonitor.SetThread(thread);
+#ifdef TARGET_LINUX
+    if (pthread_setspecific(key, thread) != 0)
+    {
+        _ASSERTE(!"pthread_setspecific failed");
+        RhFailFast();
+    }
 #else
-    __cxa_thread_atexit(RuntimeThreadShutdown, thread, &__dso_handle);
+    tls_destructionMonitor.SetThread(thread);
 #endif
 }
 
@@ -943,16 +952,13 @@ extern "C" UInt32_BOOL ResetEvent(HANDLE event)
 
 extern "C" uint32_t GetEnvironmentVariableA(const char * name, char * buffer, uint32_t size)
 {
-    // Using std::getenv instead of getenv since it is guaranteed to be thread safe w.r.t. other
-    // std::getenv calls in C++11
-    const char* value = std::getenv(name);
+    const char* value = getenv(name);
     if (value == NULL)
     {
         return 0;
     }
 
     size_t valueLen = strlen(value);
-
     if (valueLen < size)
     {
         strcpy(buffer, value);

src/coreclr/nativeaot/Runtime/unix/config.h.in

@@ -27,6 +27,4 @@
 #cmakedefine01 HAVE_CLOCK_GETTIME_NSEC_NP
 #cmakedefine01 HAVE_SCHED_GETAFFINITY
 
-#cmakedefine01 HAVE_THREAD_LOCAL
-
 #endif

src/coreclr/nativeaot/Runtime/unix/configure.cmake

@@ -105,13 +105,4 @@ check_symbol_exists(
 
 check_library_exists(c sched_getaffinity "" HAVE_SCHED_GETAFFINITY)
 
-check_cxx_source_compiles("
-thread_local int x;
-
-int main(int argc, char **argv)
-{
-    x = 1;
-    return 0;
-}" HAVE_THREAD_LOCAL)
-
 configure_file(${CMAKE_CURRENT_LIST_DIR}/config.h.in ${CMAKE_CURRENT_BINARY_DIR}/config.h)

src/tests/nativeaot/SmokeTests/Preinitialization/Preinitialization.csproj

@@ -11,6 +11,12 @@
       and this only works if presence of code implies presence of reflection metadata.
     -->
     <IlcTrimMetadata>false</IlcTrimMetadata>
+
+    <!--
+      By default, we link libstdc++compat.a, This property is set to exercise code
+      with system C++ runtime library (-lstdc++).
+    -->
+    <LinkStandardCPlusPlusLibrary>true</LinkStandardCPlusPlusLibrary>
   </PropertyGroup>
 
   <ItemGroup>