[SYCL] Do not emit const sdm initializers

Const static variables need to be either zero-initialized or
constant-initialized.  We were emitting initializers for all const
static variables before, which needed invalid address space casts
from constant-space to private-space.  We now diagnose when they
are neither zero- nor constant-initialized and used in device code.

This change also reverts the address-space cast introduced in
intel#1774

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

Author: premanandrao

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10850,7 +10850,7 @@ def err_sycl_restrict : Error<
   "|call a dllimport function"
   "|call a variadic function"
   "|call an undefined function without SYCL_EXTERNAL attribute"
-  "|use a const static data variable that is neither zero-initialized "
+  "|use a const static variable that is neither zero-initialized "
   "nor constant-initialized"
   "}0">;
 def err_sycl_virtual_types : Error<

clang/include/clang/Sema/Sema.h

@@ -12662,7 +12662,7 @@ class Sema final {
     KernelCallDllimportFunction,
     KernelCallVariadicFunction,
     KernelCallUndefinedFunction,
-    KernelConstStaticDataVariable
+    KernelConstStaticVariable
   };
 
   bool isKnownGoodSYCLDecl(const Decl *D);

clang/lib/Sema/SemaExpr.cpp

@@ -223,13 +223,12 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
                VD->hasGlobalStorage() && !isa<ParmVarDecl>(VD))
         SYCLDiagIfDeviceCode(*Locs.begin(), diag::err_sycl_restrict)
             << Sema::KernelGlobalVariable;
-      // Disallow const static data members that are not zero-initialized
+      // Disallow const statics that are not zero-initialized
       // or constant-initialized
-      else if (IsConst && VD->isStaticDataMember() &&
-               !VD->isConstexpr() &&
-               !checkAllowedSYCLInitializer(VD, /*checkValueDependent =*/true))
+      else if (IsConst && VD->hasGlobalStorage() && !VD->isConstexpr() &&
+               !checkAllowedSYCLInitializer(VD, /*CheckValueDependent =*/true))
         SYCLDiagIfDeviceCode(*Locs.begin(), diag::err_sycl_restrict)
-            << Sema::KernelConstStaticDataVariable;
+            << Sema::KernelConstStaticVariable;
     }
   }
 

clang/lib/Sema/SemaSYCL.cpp

@@ -1854,13 +1854,9 @@ bool Sema::checkAllowedSYCLInitializer(VarDecl *VD, bool CheckValueDependent) {
 
   const Expr *Init = VD->getInit();
   bool ValueDependent = CheckValueDependent && Init->isValueDependent();
-  bool isZeroInit = Init && !ValueDependent &&
-                    Init->isIntegerConstantExpr(Context) &&
-                    Init->EvaluateKnownConstInt(Context) == 0;
   bool isConstantInit = Init && !ValueDependent &&
                         Init->isConstantInitializer(Context, false);
-  if (!VD->isConstexpr() && Init && !ValueDependent && !isZeroInit &&
-      !isConstantInit)
+  if (!VD->isConstexpr() && Init && !ValueDependent && !isConstantInit)
     return false;
 
   return true;

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -5104,7 +5104,7 @@ void Sema::InstantiateVariableInitializer(
 
   if (getLangOpts().SYCLIsDevice && !checkAllowedSYCLInitializer(Var))
     SYCLDiagIfDeviceCode(Var->getLocation(), diag::err_sycl_restrict)
-                         << Sema::KernelConstStaticDataVariable;
+                         << Sema::KernelConstStaticVariable;
 }
 
 /// Instantiate the definition of the given variable from its

clang/test/CodeGenSYCL/sycl-device-const-sdm.cpp

@@ -2,8 +2,8 @@
 
 struct Base {};
 struct S {
-  __attribute__((sycl_device)) void foo();
-  S();
+  void foo() {}
+  S() {}
 };
 
 struct T {
@@ -20,13 +20,20 @@ const S U<T>::s2;
 
 template struct U<Base>;
 
+const S s5;
+
 void usage() {
   // expected-error@+1{{SYCL kernel cannot use a non-const static data variable}}
   static int s1;
   const static int cs = 0;
   constexpr static int ces = 0;
-  // expected-error@+1{{SYCL kernel cannot use a const static data variable that is neither zero-initialized nor constant-initialized}}
+  static const S s6;
+  // expected-error@+1{{SYCL kernel cannot use a const static variable that is neither zero-initialized nor constant-initialized}}
   (void)T::s1;
+  // expected-error@+1{{SYCL kernel cannot use a const static variable that is neither zero-initialized nor constant-initialized}}
+  (void)s5;
+  // expected-error@+1{{SYCL kernel cannot use a const static variable that is neither zero-initialized nor constant-initialized}}
+  (void)s6;
 }
 
 
@@ -36,7 +43,7 @@ __attribute__((sycl_kernel)) void kernel_single_task(Func kernelFunc) {
   static int z;
   // expected-note-re@+3{{called by 'kernel_single_task<fake_kernel, (lambda at {{.*}})>}}
   // expected-note-re@+2{{called by 'kernel_single_task<fake_kernel, (lambda at {{.*}})>}}
-  // expected-error@+1{{SYCL kernel cannot use a const static data variable that is neither zero-initialized nor constant-initialized}}
+  // expected-error@+1{{SYCL kernel cannot use a const static variable that is neither zero-initialized nor constant-initialized}}
   kernelFunc(U<Base>::s2);
 }