[SYCL] Driver option to select SYCL version

clang/include/clang/Basic/LangOptions.def

@@ -199,6 +199,7 @@ LANGOPT(OpenCL            , 1, 0, "OpenCL")
 LANGOPT(OpenCLVersion     , 32, 0, "OpenCL C version")
 LANGOPT(OpenCLCPlusPlus   , 1, 0, "OpenCL C++")
 LANGOPT(OpenCLCPlusPlusVersion     , 32, 0, "OpenCL C++ version")
+ENUM_LANGOPT(SYCLVersion, SYCLVersionList, 4, SYCLVersionList::undefined, "Version of the SYCL standard used")
 LANGOPT(NativeHalfType    , 1, 0, "Native half type support")
 LANGOPT(NativeHalfArgsAndReturns, 1, 0, "Native half args and returns")
 LANGOPT(HalfArgsAndReturns, 1, 0, "half args and returns")

clang/include/clang/Basic/LangOptions.h

@@ -113,6 +113,11 @@ class LangOptions : public LangOptionsBase {
     MSVC2017_7 = 1914,
   };
 
+  enum class SYCLVersionList {
+    sycl_1_2_1,
+    undefined
+  };
+
   /// Clang versions with different platform ABI conformance.
   enum class ClangABI {
     /// Attempt to be ABI-compatible with code generated by Clang 3.8.x

clang/include/clang/Driver/Options.td

@@ -124,6 +124,9 @@ def pedantic_Group : OptionGroup<"<pedantic group>">, Group<f_Group>,
 def opencl_Group : OptionGroup<"<opencl group>">, Group<f_Group>,
                    DocName<"OpenCL flags">;
 
+def sycl_Group : OptionGroup<"<sycl group>">, Group<f_Group>, 
+                  DocName<"SYCL flags">;
+
 def m_Group : OptionGroup<"<m group>">, Group<CompileOnly_Group>,
               DocName<"Target-dependent compilation options">;
 
@@ -534,6 +537,8 @@ def cl_no_signed_zeros : Flag<["-"], "cl-no-signed-zeros">, Group<opencl_Group>,
   HelpText<"OpenCL only. Allow use of less precise no signed zeros computations in the generated binary.">;
 def cl_std_EQ : Joined<["-"], "cl-std=">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL language standard to compile for.">, Values<"cl,CL,cl1.1,CL1.1,cl1.2,CL1.2,cl2.0,CL2.0,c++">;
+def sycl_std_EQ : Joined<["-"], "sycl-std=">, Group<sycl_Group>, Flags<[CC1Option]>,
+  HelpText<"SYCL language standard to compile for.">, Values<"1.2.1">;
 def cl_denorms_are_zero : Flag<["-"], "cl-denorms-are-zero">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. Allow denormals to be flushed to zero.">;
 def cl_fp32_correctly_rounded_divide_sqrt : Flag<["-"], "cl-fp32-correctly-rounded-divide-sqrt">, Group<opencl_Group>, Flags<[CC1Option]>,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3565,6 +3565,13 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_sycl_std_EQ)) {
+    A->render(Args, CmdArgs);
+  } else if (IsSYCL) {
+    // Ensure the default version in SYCL mode is 1.2.1
+    CmdArgs.push_back("-sycl-std=1.2.1");
+  }
+
   if (IsOpenMPDevice) {
     // We have to pass the triple of the host if compiling for an OpenMP device.
     std::string NormalizedTriple =
@@ -4720,6 +4727,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Forward -cl options to -cc1
   RenderOpenCLOptions(Args, CmdArgs);
 
+  // Forward -sycl-std option to -cc1
+  Args.AddLastArg(CmdArgs, options::OPT_sycl_std_EQ);
+
   if (Arg *A = Args.getLastArg(options::OPT_fcf_protection_EQ)) {
     CmdArgs.push_back(
         Args.MakeArgString(Twine("-fcf-protection=") + A->getValue()));

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2421,6 +2421,24 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
       LangStd = OpenCLLangStd;
   }
 
+  // -sycl-std applies to any SYCL source, not only those containing kernels,
+  // but also those using the SYCL API
+  if(const Arg  *A = Args.getLastArg(OPT_sycl_std_EQ)) {
+    Opts.setSYCLVersion(llvm::StringSwitch<LangOptions::SYCLVersionList>(A->getValue())
+      .Cases("1.2.1",  "121", "sycl-1.2.1", LangOptions::SYCLVersionList::sycl_1_2_1)
+      .Default(LangOptions::SYCLVersionList::undefined));
+
+    if (Opts.getSYCLVersion() == LangOptions::SYCLVersionList::undefined) {
+      // User has passed an invalid value to the flag, this is an error
+      Diags.Report(diag::err_drv_invalid_value) 
+          << A->getAsString(Args) << A->getValue();
+    }
+  } else if (Args.hasArg(options::OPT_fsycl_is_device) 
+                         || Args.hasArg(options::OPT_fsycl_is_host)
+                         || Args.hasArg(options::OPT_fsycl)) {
+    Opts.setSYCLVersion(LangOptions::SYCLVersionList::sycl_1_2_1);
+  }
+
   Opts.IncludeDefaultHeader = Args.hasArg(OPT_finclude_default_header);
   Opts.DeclareOpenCLBuiltins = Args.hasArg(OPT_fdeclare_opencl_builtins);
 

clang/lib/Frontend/InitPreprocessor.cpp

@@ -449,6 +449,18 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
         Builder.defineMacro("__FAST_RELAXED_MATH__");
     }
   }
+
+  // SYCL Version is set to a value when building SYCL applications
+  switch (LangOpts.getSYCLVersion()) {
+    case LangOptions::SYCLVersionList::sycl_1_2_1:
+      Builder.defineMacro("CL_SYCL_LANGUAGE_VERSION", "121");
+      break;
+    case LangOptions::SYCLVersionList::undefined:
+    default:
+      // This is not a SYCL source, nothing to add
+      break;
+  }
+
   // Not "standard" per se, but available even with the -undef flag.
   if (LangOpts.AsmPreprocessor)
     Builder.defineMacro("__ASSEMBLER__");

clang/test/Preprocessor/sycl-macro.cpp

@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 %s -E -dM | FileCheck %s
 // RUN: %clang_cc1 %s -fsycl-is-device -E -dM | FileCheck --check-prefix=CHECK-SYCL %s
-
+// RUN: %clang_cc1 %s -fsycl -E -dM | FileCheck --check-prefix=CHECK-ANY-SYCL %s
 // CHECK-NOT:#define __SYCL_DEVICE_ONLY__ 1
-// CHECK-SYCL:#define __SYCL_DEVICE_ONLY__ 1
+// CHECK-NOT:#define CL_SYCL_LANGUAGE_VERSION 121
+// CHECK-ANY-SYCL-NOT:#define __SYCL_DEVICE_ONLY__ 1
+// CHECK-ANY-SYCL:#define CL_SYCL_LANGUAGE_VERSION 121
+// CHECK-SYCL:#define CL_SYCL_LANGUAGE_VERSION 121

sycl/doc/SYCL_compiler_and_runtime_design.md

@@ -152,7 +152,7 @@ targets like SPIR-V).
 
 #### Enable SYCL offload
 
-To enable compilation with SYCL specification conformance, a special option
+To enable compilation following the SYCL specification, a special option
 must be passed to the clang driver:
 
 `-fsycl`
@@ -162,6 +162,17 @@ number of device compilers for targets specified in the `-fsycl-targets`
 option.  If this option is not specified, then single SPIR-V target is assumed,
 and single device compiler for this target is invoked.
 
+In the driver, the following bools are defined to determine the compilation
+mode in SYCL:
+
+* IsSYCL : True if the user has passed `--sycl` to the compilation
+* IsSYCLOffloadDevice: True if calling clang to set up a device compilation
+* IsSYCLHost: True if setting up a call to clang to do a host compilation
+
+The option `-sycl-std` allows specifiying which version of
+the SYCL standard will be used for the compilation. 
+The default value for this option is `1.2.1`.
+
 #### Ahead of time (AOT) compilation
 
 Ahead-of-time compilation is the process of invoking the back-end at compile