[SYCL] Do not emit unneeded static initializations in sycl device code (#1774)

Signed-off-by: Premanand M Rao <premanand.m.rao@intel.com>

Author: premanandrao

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1279,7 +1279,8 @@ void CodeGenModule::EmitCtorList(CtorList &Fns, const char *GlobalName) {
     ctor.addInt(Int32Ty, I.Priority);
     ctor.add(llvm::ConstantExpr::getBitCast(I.Initializer, CtorPFTy));
     if (I.AssociatedData)
-      ctor.add(llvm::ConstantExpr::getBitCast(I.AssociatedData, VoidPtrTy));
+      ctor.add(llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(
+          I.AssociatedData, VoidPtrTy));
     else
       ctor.addNullPointer(VoidPtrTy);
     ctor.finishAndAddTo(ctors);

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -5280,16 +5280,21 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
 
   // Make sure to pass the instantiated variable to the consumer at the end.
   struct PassToConsumerRAII {
+    Sema &SemaRef;
     ASTConsumer &Consumer;
     VarDecl *Var;
 
-    PassToConsumerRAII(ASTConsumer &Consumer, VarDecl *Var)
-      : Consumer(Consumer), Var(Var) { }
+    PassToConsumerRAII(Sema &SemaRef, ASTConsumer &Consumer, VarDecl *Var)
+        : SemaRef(SemaRef), Consumer(Consumer), Var(Var) {}
 
     ~PassToConsumerRAII() {
-      Consumer.HandleCXXStaticMemberVarInstantiation(Var);
+      // Do not explicitly emit non-const static data member definitions
+      // on SYCL device.
+      if (!SemaRef.getLangOpts().SYCLIsDevice || !Var->isStaticDataMember() ||
+          Var->isConstexpr() || Var->getType().isConstQualified())
+        Consumer.HandleCXXStaticMemberVarInstantiation(Var);
     }
-  } PassToConsumerRAII(Consumer, Var);
+  } PassToConsumerRAII(*this, Consumer, Var);
 
   // If we already have a definition, we're done.
   if (VarDecl *Def = Var->getDefinition()) {

clang/test/CodeGenSYCL/sycl-device-static-init.cpp

@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -fsycl -fsycl-is-device -triple spir64-unknown-unknown-sycldevice -disable-llvm-passes %s -emit-llvm -o -  | FileCheck %s
+// Test that static initializers do not force the emission of globals on sycl device
+
+// CHECK: %struct._ZTS16RegisterBaseInit.RegisterBaseInit = type { i8 }
+// CHECK-NOT: $_ZN8BaseInitI12TestBaseTypeE15s_regbase_ncsdmE = comdat any
+// CHECK: $_ZN8BaseInitI12TestBaseTypeE3varE = comdat any
+// CHECK: @_ZN8BaseInitI12TestBaseTypeE9s_regbaseE = {{.*}} global %struct._ZTS16RegisterBaseInit.RegisterBaseInit
+// CHECK-NOT: @_ZN8BaseInitI12TestBaseTypeE15s_regbase_ncsdmE = weak_odr addrspace(1) global %struct._ZTS16RegisterBaseInit.RegisterBaseInit zeroinitializer, comdat, align 1
+// CHECK: @_ZN8BaseInitI12TestBaseTypeE3varE = weak_odr addrspace(1) constant i32 9, comdat, align 4
+// CHECK: @llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @__cxx_global_var_init, i8* addrspacecast (i8 addrspace(1)* getelementptr inbounds (%struct._ZTS16RegisterBaseInit.RegisterBaseInit, %struct._ZTS16RegisterBaseInit.RegisterBaseInit addrspace(1)* @_ZN8BaseInitI12TestBaseTypeE9s_regbaseE, i32 0, i32 0) to i8*) }]
+// CHECK-NOT: @_ZGVN8BaseInitI12TestBaseTypeE15s_regbase_ncsdmE = weak_odr global i64 0, comdat($_ZN8BaseInitI12TestBaseTypeE9s_regbaseE), align 8
+// CHECK: define spir_kernel void @_ZTSZ4mainE11fake_kernel()
+// CHECK: call spir_func void @"_ZZ4mainENK3$_0clE16RegisterBaseInit
+// CHECK: declare spir_func void @_ZN16RegisterBaseInit3fooEv
+
+struct TestBaseType {};
+struct RegisterBaseInit {
+  __attribute__((sycl_device)) void foo();
+  RegisterBaseInit();
+};
+template <class T>
+struct BaseInit {
+  static const RegisterBaseInit s_regbase;
+  static RegisterBaseInit s_regbase_ncsdm;
+  static const int var;
+};
+template <class T>
+const RegisterBaseInit BaseInit<T>::s_regbase;
+template <class T>
+RegisterBaseInit BaseInit<T>::s_regbase_ncsdm;
+template <class T>
+const int BaseInit<T>::var = 9;
+template struct BaseInit<TestBaseType>;
+template <typename name, typename Func>
+__attribute__((sycl_kernel)) void kernel_single_task(Func kernelFunc) {
+  kernelFunc(BaseInit<TestBaseType>::s_regbase);
+}
+int main() {
+  kernel_single_task<class fake_kernel>([=](RegisterBaseInit s) {
+    s.foo();
+  });
+  return 0;
+}