[SYCL] Add option fsycl-allow-func-ptr which defaults to false

Signed-off-by: Vladimir Lazarev <vladimir.lazarev@intel.com>
Signed-off-by: Blower, Melanie <melanie.blower@intel.com>

Author: Blower, Melanie

clang/include/clang/Basic/LangOptions.def

@@ -219,6 +219,7 @@ LANGOPT(GPURelocatableDeviceCode, 1, 0, "generate relocatable device code")
 
 LANGOPT(SYCLIsDevice      , 1, 0, "Generate code for SYCL device")
 LANGOPT(SYCLUseBitcode    , 1, 0, "Generate bitcode for SYCL")
+LANGOPT(SYCLAllowFuncPtr  , 1, 0, "Allow function pointers in SYCL device code")
 
 LANGOPT(SizedDeallocation , 1, 0, "sized deallocation")
 LANGOPT(AlignedAllocation , 1, 0, "aligned allocation")

clang/include/clang/Driver/CC1Options.td

@@ -849,6 +849,9 @@ def fsycl_int_header : Separate<["-"], "fsycl-int-header">,
   HelpText<"Generate SYCL integration header into this file.">;
 def fsycl_int_header_EQ : Joined<["-"], "fsycl-int-header=">,
   Alias<fsycl_int_header>;
+def fsycl_allow_func_ptr : Flag<["-"], "fsycl-allow-func-ptr">,
+  HelpText<"Allow function pointers in SYCL device.">;
+def fno_sycl_allow_func_ptr : Flag<["-"], "fno-sycl-allow-func-ptr">;
 
 } // let Flags = [CC1Option]
 

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3550,6 +3550,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                      options::OPT_fno_sycl_use_bitcode, true)) {
       CmdArgs.push_back("-fsycl-use-bitcode");
     }
+    if (Args.hasFlag(options::OPT_fsycl_allow_func_ptr,
+                     options::OPT_fno_sycl_allow_func_ptr, false)) {
+      CmdArgs.push_back("-fsycl-allow-func-ptr");
+    }
   }
 
   if (IsOpenMPDevice) {

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2893,6 +2893,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.SYCLIsDevice   = Args.hasArg(options::OPT_fsycl_is_device);
   Opts.SYCLUseBitcode = Args.hasFlag(options::OPT_fsycl_use_bitcode,
                                      options::OPT_fno_sycl_use_bitcode, false);
+  Opts.SYCLAllowFuncPtr = Args.hasFlag(options::OPT_fsycl_allow_func_ptr,
+                                  options::OPT_fno_sycl_allow_func_ptr, false);
 
   // Set CUDA mode for OpenMP target NVPTX if specified in options
   Opts.OpenMPCUDAMode = Opts.OpenMPIsDevice && T.isNVPTX() &&

clang/lib/Sema/SemaSYCL.cpp

@@ -113,10 +113,9 @@ class MarkDeviceFunction : public RecursiveASTVisitor<MarkDeviceFunction> {
           SemaRef.AddSyclKernel(Def);
         }
       }
-    } else {
+    } else if (!SemaRef.getLangOpts().SYCLAllowFuncPtr)
       SemaRef.Diag(e->getExprLoc(), diag::err_sycl_restrict) <<
                    KernelCallFunctionPointer;
-    }
     return true;
   }
 

clang/test/SemaSYCL/sycl-restrict.cpp

@@ -1,4 +1,6 @@
 // RUN: %clang_cc1 -fcxx-exceptions -fsycl-is-device -Wno-return-type -verify -fsyntax-only -x c++ -emit-llvm-only -std=c++17 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsycl-is-device -fno-sycl-allow-func-ptr -Wno-return-type -verify -fsyntax-only -x c++ -emit-llvm-only -std=c++17 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsycl-is-device -DALLOW_FP=1 -fsycl-allow-func-ptr -Wno-return-type -verify -fsyntax-only -x c++ -emit-llvm-only -std=c++17 %s
 
 
 namespace std {
@@ -104,7 +106,11 @@ void usage(  myFuncDef functionPtr ) {
 
   eh_not_ok();
 
-  // expected-error@+1 {{SYCL kernel cannot call through a function pointer}}
+#if ALLOW_FP
+  // No error message for function pointer.
+#else
+  // expected-error@+2 {{SYCL kernel cannot call through a function pointer}}
+#endif
   if ((*functionPtr)(1,2))
   // expected-note@+3{{used here}}
   // expected-error@+2 {{SYCL kernel cannot use a global variable}}