llvm · jhuber6 · Nov 10, 2023 · Nov 7, 2023
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
@@ -597,6 +597,9 @@ class LangOptions : public LangOptionsBase {
     return !requiresStrictPrototypes() && !OpenCL;
   }
 
+  /// Returns true if the language supports calling the 'atexit' function.
+  bool hasAtExit() const { return !(OpenMP && OpenMPIsTargetDevice); }
+
   /// Returns true if implicit int is part of the language requirements.
   bool isImplicitIntRequired() const { return !CPlusPlus && !C99; }
 

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -327,6 +327,15 @@ void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
   registerGlobalDtorWithAtExit(dtorStub);
 }
 
+/// Register a global destructor using the LLVM 'llvm.global_dtors' global.
+void CodeGenFunction::registerGlobalDtorWithLLVM(const VarDecl &VD,
+                                                 llvm::FunctionCallee Dtor,
+                                                 llvm::Constant *Addr) {
+  // Create a function which calls the destructor.
+  llvm::Function *dtorStub = createAtExitStub(VD, Dtor, Addr);
+  CGM.AddGlobalDtor(dtorStub);
+}
+
 void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtorStub) {
   // extern "C" int atexit(void (*f)(void));
   assert(dtorStub->getType() ==
@@ -519,10 +528,6 @@ CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
        D->hasAttr<CUDASharedAttr>()))
     return;
 
-  if (getLangOpts().OpenMP &&
-      getOpenMPRuntime().emitDeclareTargetVarDefinition(D, Addr, PerformInit))
-    return;
-
   // Check if we've already initialized this decl.
   auto I = DelayedCXXInitPosition.find(D);
   if (I != DelayedCXXInitPosition.end() && I->second == ~0U)

diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -1747,136 +1747,6 @@ llvm::Function *CGOpenMPRuntime::emitThreadPrivateVarDefinition(
   return nullptr;
 }
 
-bool CGOpenMPRuntime::emitDeclareTargetVarDefinition(const VarDecl *VD,
-                                                     llvm::GlobalVariable *Addr,
-                                                     bool PerformInit) {
-  if (CGM.getLangOpts().OMPTargetTriples.empty() &&
-      !CGM.getLangOpts().OpenMPIsTargetDevice)
-    return false;
-  std::optional<OMPDeclareTargetDeclAttr::MapTypeTy> Res =
-      OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(VD);
-  if (!Res || *Res == OMPDeclareTargetDeclAttr::MT_Link ||
-      ((*Res == OMPDeclareTargetDeclAttr::MT_To ||
-        *Res == OMPDeclareTargetDeclAttr::MT_Enter) &&
-       HasRequiresUnifiedSharedMemory))
-    return CGM.getLangOpts().OpenMPIsTargetDevice;
-  VD = VD->getDefinition(CGM.getContext());
-  assert(VD && "Unknown VarDecl");
-
-  if (!DeclareTargetWithDefinition.insert(CGM.getMangledName(VD)).second)
-    return CGM.getLangOpts().OpenMPIsTargetDevice;
-
-  QualType ASTTy = VD->getType();
-  SourceLocation Loc = VD->getCanonicalDecl()->getBeginLoc();
-
-  // Produce the unique prefix to identify the new target regions. We use
-  // the source location of the variable declaration which we know to not
-  // conflict with any target region.
-  llvm::TargetRegionEntryInfo EntryInfo =
-      getEntryInfoFromPresumedLoc(CGM, OMPBuilder, Loc, VD->getName());
-  SmallString<128> Buffer, Out;
-  OMPBuilder.OffloadInfoManager.getTargetRegionEntryFnName(Buffer, EntryInfo);
-
-  const Expr *Init = VD->getAnyInitializer();
-  if (CGM.getLangOpts().CPlusPlus && PerformInit) {
-    llvm::Constant *Ctor;
-    llvm::Constant *ID;
-    if (CGM.getLangOpts().OpenMPIsTargetDevice) {
-      // Generate function that re-emits the declaration's initializer into
-      // the threadprivate copy of the variable VD
-      CodeGenFunction CtorCGF(CGM);
-
-      const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
-      llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
-      llvm::Function *Fn = CGM.CreateGlobalInitOrCleanUpFunction(
-          FTy, Twine(Buffer, "_ctor"), FI, Loc, false,
-          llvm::GlobalValue::WeakODRLinkage);
-      Fn->setVisibility(llvm::GlobalValue::ProtectedVisibility);
-      if (CGM.getTriple().isAMDGCN())
-        Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
-      auto NL = ApplyDebugLocation::CreateEmpty(CtorCGF);
-      CtorCGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, Fn, FI,
-                            FunctionArgList(), Loc, Loc);
-      auto AL = ApplyDebugLocation::CreateArtificial(CtorCGF);
-      llvm::Constant *AddrInAS0 = Addr;
-      if (Addr->getAddressSpace() != 0)
-        AddrInAS0 = llvm::ConstantExpr::getAddrSpaceCast(
-            Addr, llvm::PointerType::get(CGM.getLLVMContext(), 0));
-      CtorCGF.EmitAnyExprToMem(Init,
-                               Address(AddrInAS0, Addr->getValueType(),
-                                       CGM.getContext().getDeclAlign(VD)),
-                               Init->getType().getQualifiers(),
-                               /*IsInitializer=*/true);
-      CtorCGF.FinishFunction();
-      Ctor = Fn;
-      ID = Fn;
-    } else {
-      Ctor = new llvm::GlobalVariable(
-          CGM.getModule(), CGM.Int8Ty, /*isConstant=*/true,
-          llvm::GlobalValue::PrivateLinkage,
-          llvm::Constant::getNullValue(CGM.Int8Ty), Twine(Buffer, "_ctor"));
-      ID = Ctor;
-    }
-
-    // Register the information for the entry associated with the constructor.
-    Out.clear();
-    auto CtorEntryInfo = EntryInfo;
-    CtorEntryInfo.ParentName = Twine(Buffer, "_ctor").toStringRef(Out);
-    OMPBuilder.OffloadInfoManager.registerTargetRegionEntryInfo(
-        CtorEntryInfo, Ctor, ID,
-        llvm::OffloadEntriesInfoManager::OMPTargetRegionEntryCtor);
-  }
-  if (VD->getType().isDestructedType() != QualType::DK_none) {
-    llvm::Constant *Dtor;
-    llvm::Constant *ID;
-    if (CGM.getLangOpts().OpenMPIsTargetDevice) {
-      // Generate function that emits destructor call for the threadprivate
-      // copy of the variable VD
-      CodeGenFunction DtorCGF(CGM);
-
-      const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
-      llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
-      llvm::Function *Fn = CGM.CreateGlobalInitOrCleanUpFunction(
-          FTy, Twine(Buffer, "_dtor"), FI, Loc, false,
-          llvm::GlobalValue::WeakODRLinkage);
-      Fn->setVisibility(llvm::GlobalValue::ProtectedVisibility);
-      if (CGM.getTriple().isAMDGCN())
-        Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
-      auto NL = ApplyDebugLocation::CreateEmpty(DtorCGF);
-      DtorCGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, Fn, FI,
-                            FunctionArgList(), Loc, Loc);
-      // Create a scope with an artificial location for the body of this
-      // function.
-      auto AL = ApplyDebugLocation::CreateArtificial(DtorCGF);
-      llvm::Constant *AddrInAS0 = Addr;
-      if (Addr->getAddressSpace() != 0)
-        AddrInAS0 = llvm::ConstantExpr::getAddrSpaceCast(
-            Addr, llvm::PointerType::get(CGM.getLLVMContext(), 0));
-      DtorCGF.emitDestroy(Address(AddrInAS0, Addr->getValueType(),
-                                  CGM.getContext().getDeclAlign(VD)),
-                          ASTTy, DtorCGF.getDestroyer(ASTTy.isDestructedType()),
-                          DtorCGF.needsEHCleanup(ASTTy.isDestructedType()));
-      DtorCGF.FinishFunction();
-      Dtor = Fn;
-      ID = Fn;
-    } else {
-      Dtor = new llvm::GlobalVariable(
-          CGM.getModule(), CGM.Int8Ty, /*isConstant=*/true,
-          llvm::GlobalValue::PrivateLinkage,
-          llvm::Constant::getNullValue(CGM.Int8Ty), Twine(Buffer, "_dtor"));
-      ID = Dtor;
-    }
-    // Register the information for the entry associated with the destructor.
-    Out.clear();
-    auto DtorEntryInfo = EntryInfo;
-    DtorEntryInfo.ParentName = Twine(Buffer, "_dtor").toStringRef(Out);
-    OMPBuilder.OffloadInfoManager.registerTargetRegionEntryInfo(
-        DtorEntryInfo, Dtor, ID,
-        llvm::OffloadEntriesInfoManager::OMPTargetRegionEntryDtor);
-  }
-  return CGM.getLangOpts().OpenMPIsTargetDevice;
-}
-
 void CGOpenMPRuntime::emitDeclareTargetFunction(const FunctionDecl *FD,
                                                 llvm::GlobalValue *GV) {
   std::optional<OMPDeclareTargetDeclAttr *> ActiveAttr =

diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.h b/clang/lib/CodeGen/CGOpenMPRuntime.h
@@ -1089,14 +1089,6 @@ class CGOpenMPRuntime {
                                  SourceLocation Loc, bool PerformInit,
                                  CodeGenFunction *CGF = nullptr);
 
-  /// Emit a code for initialization of declare target variable.
-  /// \param VD Declare target variable.
-  /// \param Addr Address of the global variable \a VD.
-  /// \param PerformInit true if initialization expression is not constant.
-  virtual bool emitDeclareTargetVarDefinition(const VarDecl *VD,
-                                              llvm::GlobalVariable *Addr,
-                                              bool PerformInit);
-
   /// Emit code for handling declare target functions in the runtime.
   /// \param FD Declare target function.
   /// \param Addr Address of the global \a FD.

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
@@ -4536,6 +4536,11 @@ class CodeGenFunction : public CodeGenTypeCache {
   void registerGlobalDtorWithAtExit(const VarDecl &D, llvm::FunctionCallee fn,
                                     llvm::Constant *addr);
 
+  /// Registers the dtor using 'llvm.global_dtors' for platforms that do not
+  /// support an 'atexit()' function.
+  void registerGlobalDtorWithLLVM(const VarDecl &D, llvm::FunctionCallee fn,
+                                  llvm::Constant *addr);
+
   /// Call atexit() with function dtorStub.
   void registerGlobalDtorWithAtExit(llvm::Constant *dtorStub);
 

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
@@ -1570,6 +1570,13 @@ class CodeGenModule : public CodeGenTypeCache {
                         const VarDecl *D,
                         ForDefinition_t IsForDefinition = NotForDefinition);
 
+  // FIXME: Hardcoding priority here is gross.
+  void AddGlobalCtor(llvm::Function *Ctor, int Priority = 65535,
+                     unsigned LexOrder = ~0U,
+                     llvm::Constant *AssociatedData = nullptr);
+  void AddGlobalDtor(llvm::Function *Dtor, int Priority = 65535,
+                     bool IsDtorAttrFunc = false);
+
 private:
   llvm::Constant *GetOrCreateLLVMFunction(
       StringRef MangledName, llvm::Type *Ty, GlobalDecl D, bool ForVTable,
@@ -1641,13 +1648,6 @@ class CodeGenModule : public CodeGenTypeCache {
   void EmitPointerToInitFunc(const VarDecl *VD, llvm::GlobalVariable *Addr,
                              llvm::Function *InitFunc, InitSegAttr *ISA);
 
-  // FIXME: Hardcoding priority here is gross.
-  void AddGlobalCtor(llvm::Function *Ctor, int Priority = 65535,
-                     unsigned LexOrder = ~0U,
-                     llvm::Constant *AssociatedData = nullptr);
-  void AddGlobalDtor(llvm::Function *Dtor, int Priority = 65535,
-                     bool IsDtorAttrFunc = false);
-
   /// EmitCtorList - Generates a global array of functions and priorities using
   /// the given list and name. This array will have appending linkage and is
   /// suitable for use as a LLVM constructor or destructor array. Clears Fns.

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -2794,6 +2794,14 @@ void ItaniumCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
   if (D.isNoDestroy(CGM.getContext()))
     return;
 
+  // OpenMP offloading supports C++ constructors and destructors but we do not
+  // always have 'atexit' available. Instead lower these to use the LLVM global
+  // destructors which we can handle directly in the runtime. Note that this is
+  // not strictly 1-to-1 with using `atexit` because we no longer tear down
+  // globals in reverse order of when they were constructed.
+  if (!CGM.getLangOpts().hasAtExit() && !D.isStaticLocal())
+    return CGF.registerGlobalDtorWithLLVM(D, dtor, addr);
+
   // emitGlobalDtorWithCXAAtExit will emit a call to either __cxa_thread_atexit
   // or __cxa_atexit depending on whether this VarDecl is a thread-local storage
   // or not. CXAAtExit controls only __cxa_atexit, so use it if it is enabled.

diff --git a/clang/test/Headers/amdgcn_openmp_device_math_constexpr.cpp b/clang/test/Headers/amdgcn_openmp_device_math_constexpr.cpp
@@ -35,7 +35,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 
 
 #pragma omp end declare target
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fabsf_f32_l14_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init
 // CHECK-SAME: () #[[ATTR0:[0-9]+]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -49,7 +49,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fabs_f32_l15_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.1
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -69,7 +69,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_sinf_f32_l17_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.2
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -83,7 +83,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_sin_f32_l18_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.3
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -103,7 +103,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_cosf_f32_l20_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.4
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -117,7 +117,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_cos_f32_l21_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.5
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -137,7 +137,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fmaf_f32_l23_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.6
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -159,7 +159,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fma_f32_l24_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.7
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -195,7 +195,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_min_f32_l27_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.8
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -213,7 +213,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_max_f32_l28_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.9
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -231,23 +231,23 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fmin_f32_l30_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.10
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[CALL:%.*]] = call noundef float @_Z4fminff(float noundef 2.000000e+00, float noundef -4.000000e+00) #[[ATTR4:[0-9]+]]
 // CHECK-NEXT:    store float [[CALL]], ptr addrspacecast (ptr addrspace(1) @_ZL18constexpr_fmin_f32 to ptr), align 4
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fmax_f32_l31_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.11
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[CALL:%.*]] = call noundef float @_Z4fmaxff(float noundef 2.000000e+00, float noundef -4.000000e+00) #[[ATTR4]]
 // CHECK-NEXT:    store float [[CALL]], ptr addrspacecast (ptr addrspace(1) @_ZL18constexpr_fmax_f32 to ptr), align 4
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fminf_f32_l33_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.12
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -265,7 +265,7 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    ret void
 //
 //
-// CHECK-LABEL: define {{[^@]+}}@{{__omp_offloading_[0-9a-z]+_[0-9a-z]+}}_constexpr_fmaxf_f32_l34_ctor
+// CHECK-LABEL: define {{[^@]+}}@__cxx_global_var_init.13
 // CHECK-SAME: () #[[ATTR0]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[RETVAL_I:%.*]] = alloca float, align 4, addrspace(5)
@@ -282,3 +282,23 @@ const float constexpr_fmaxf_f32 = fmaxf(2.0f, -4.0f);
 // CHECK-NEXT:    store float [[TMP2]], ptr addrspacecast (ptr addrspace(1) @_ZL19constexpr_fmaxf_f32 to ptr), align 4
 // CHECK-NEXT:    ret void
 //
+//
+// CHECK-LABEL: define {{[^@]+}}@_GLOBAL__sub_I_amdgcn_openmp_device_math_constexpr.cpp
+// CHECK-SAME: () #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @__cxx_global_var_init()
+// CHECK-NEXT:    call void @__cxx_global_var_init.1()
+// CHECK-NEXT:    call void @__cxx_global_var_init.2()
+// CHECK-NEXT:    call void @__cxx_global_var_init.3()
+// CHECK-NEXT:    call void @__cxx_global_var_init.4()
+// CHECK-NEXT:    call void @__cxx_global_var_init.5()
+// CHECK-NEXT:    call void @__cxx_global_var_init.6()
+// CHECK-NEXT:    call void @__cxx_global_var_init.7()
+// CHECK-NEXT:    call void @__cxx_global_var_init.8()
+// CHECK-NEXT:    call void @__cxx_global_var_init.9()
+// CHECK-NEXT:    call void @__cxx_global_var_init.10()
+// CHECK-NEXT:    call void @__cxx_global_var_init.11()
+// CHECK-NEXT:    call void @__cxx_global_var_init.12()
+// CHECK-NEXT:    call void @__cxx_global_var_init.13()
+// CHECK-NEXT:    ret void
+//