[SYCL][Driver] Change default SYCL version to be 2020 (#2386)

Support _for_  `sycl-std=2020` was added in an earlier PR( #2259 ) but the default SYCL version was left alone.  Now we are changing the FE so that if not otherwise specified `sycl-std=2020` is elected as the default.

Signed-off-by: Chris Perkins <[email protected]>

Author: cperkinsintel

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4200,8 +4200,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       SYCLStdArg->render(Args, CmdArgs);
       CmdArgs.push_back("-fsycl-std-layout-kernel-params");
     } else {
-      // Ensure the default version in SYCL mode is 1.2.1 (aka 2017)
-      CmdArgs.push_back("-sycl-std=2017");
+      // Ensure the default version in SYCL mode is 2020
+      CmdArgs.push_back("-sycl-std=2020");
     }
   }
 

clang/test/Driver/sycl-device.cpp

@@ -21,4 +21,4 @@
 /// Check that -sycl-std=2017 is set if no std version is provided by user
 // RUN:   %clang -### -fsycl %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-SYCL-STD_VERSION %s
-// CHECK-SYCL-STD_VERSION: clang{{.*}} "-sycl-std=2017"
+// CHECK-SYCL-STD_VERSION: clang{{.*}} "-sycl-std=2020"

clang/test/Driver/sycl-offload-nvptx.cpp

@@ -8,9 +8,9 @@
 // RUN: -fsycl-targets=nvptx64-nvidia-nvcl-sycldevice --cuda-path=%S/Inputs/CUDA/usr/local/cuda \
 // RUN: -fsycl-libspirv-path=%S/Inputs/SYCL/libspirv.bc %s 2>&1 \
 // RUN: | FileCheck -check-prefix=CHK-ACTIONS %s
-// CHK-ACTIONS: "-cc1" "-triple" "nvptx64-nvidia-nvcl-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}} "-Wno-sycl-strict" "-sycl-std=2017" {{.*}} "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libspirv.bc"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libdevice{{.*}}.10.bc"{{.*}} "-target-feature" "+ptx42"{{.*}} "-target-sdk-version=[[CUDA_VERSION:[0-9.]+]]"{{.*}} "-target-cpu" "sm_50"{{.*}} "-std=c++11"{{.*}}
+// CHK-ACTIONS: "-cc1" "-triple" "nvptx64-nvidia-nvcl-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}} "-Wno-sycl-strict" "-sycl-std=2020" {{.*}} "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libspirv.bc"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libdevice{{.*}}.10.bc"{{.*}} "-target-feature" "+ptx42"{{.*}} "-target-sdk-version=[[CUDA_VERSION:[0-9.]+]]"{{.*}} "-target-cpu" "sm_50"{{.*}} "-std=c++11"{{.*}}
 // CHK-ACTIONS: clang-offload-wrapper"{{.*}} "-host=x86_64-unknown-linux-gnu" "-target=nvptx64" "-kind=sycl"{{.*}}
-// CHK-ACTIONS: "-cc1" "-triple" "nvptx64-nvidia-nvcl-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}} "-Wno-sycl-strict" "-sycl-std=2017" {{.*}} "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl"{{.*}}  "-mlink-builtin-bitcode" "{{.*}}libspirv.bc"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libdevice{{.*}}.10.bc"{{.*}} "-target-feature" "+ptx42"{{.*}} "-target-sdk-version=[[CUDA_VERSION]]"{{.*}} "-target-cpu" "sm_50"{{.*}} "-std=c++11"{{.*}}
+// CHK-ACTIONS: "-cc1" "-triple" "nvptx64-nvidia-nvcl-sycldevice"{{.*}} "-fsycl-is-device"{{.*}} "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}} "-Wno-sycl-strict" "-sycl-std=2020" {{.*}} "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl"{{.*}}  "-mlink-builtin-bitcode" "{{.*}}libspirv.bc"{{.*}} "-mlink-builtin-bitcode" "{{.*}}libdevice{{.*}}.10.bc"{{.*}} "-target-feature" "+ptx42"{{.*}} "-target-sdk-version=[[CUDA_VERSION]]"{{.*}} "-target-cpu" "sm_50"{{.*}} "-std=c++11"{{.*}}
 
 /// Check phases w/out specifying a compute capability.
 // RUN: %clangxx -ccc-print-phases -std=c++11 -target x86_64-unknown-linux-gnu -fsycl \