[Clang] Update of invoking SPIR-V Backend in Clang/Driver (#16602)

We introduce here SPIR-V Backend support in Clang/Driver

Author: VyacheslavLevytskyy

clang/lib/Driver/ToolChains/Clang.cpp

@@ -10706,38 +10706,21 @@ static void getSPIRVBackendOpts(const llvm::opt::ArgList &TCArgs,
                                 ArgStringList &BackendArgs) {
   BackendArgs.push_back(TCArgs.MakeArgString("-filetype=obj"));
   BackendArgs.push_back(
-      TCArgs.MakeArgString("-mtriple=spirv64-unknown-unknown"));
-  // TODO: Optimization level is currently forced to -O0 due to some testing
-  // issues. Update optimization level after testing issues are resolved.
-  BackendArgs.push_back(TCArgs.MakeArgString("-O0"));
+      TCArgs.MakeArgString("-mtriple=spirv64v1.6-unknown-unknown"));
   BackendArgs.push_back(
       TCArgs.MakeArgString("--avoid-spirv-capabilities=Shader"));
   BackendArgs.push_back(
       TCArgs.MakeArgString("--translator-compatibility-mode"));
-
-  // TODO: There is some overlap between the lists of extensions in SPIR-V
-  // backend and SPIR-V Trnaslator). We will try to combine them when SPIR-V
-  // backdn is ready.
-  std::string ExtArg("--spirv-ext=");
-  std::string DefaultExtArg =
-      "+SPV_EXT_shader_atomic_float_add,+SPV_EXT_shader_atomic_float_min_max"
-      ",+SPV_KHR_no_integer_wrap_decoration,+SPV_KHR_float_controls"
-      ",+SPV_KHR_expect_assume,+SPV_KHR_linkonce_odr";
-  std::string INTELExtArg = ",+SPV_INTEL_subgroups,+SPV_INTEL_function_pointers"
-                            ",+SPV_INTEL_arbitrary_precision_integers"
-                            ",+SPV_INTEL_variable_length_array";
-  ExtArg = ExtArg + DefaultExtArg + INTELExtArg;
-
-  // Other args
-  ExtArg += ",+SPV_INTEL_bfloat16_conversion"
-            ",+SPV_KHR_uniform_group_instructions"
-            ",+SPV_INTEL_optnone"
-            ",+SPV_KHR_subgroup_rotate"
-            ",+SPV_INTEL_usm_storage_classes"
-            ",+SPV_EXT_shader_atomic_float16_add"
-            ",+SPV_KHR_bit_instructions";
-
-  BackendArgs.push_back(TCArgs.MakeArgString(ExtArg));
+  // TODO: A list of SPIR-V extensions that are supported by the SPIR-V backend
+  // is growing. Let's postpone the decision on which extensions to enable until
+  // - the list is stable, and
+  // - we decide on a mapping of user requested extensions into backend's ones.
+  // Meanwhile we enable all the SPIR-V backend extensions.
+  BackendArgs.push_back(TCArgs.MakeArgString("--spirv-ext=all"));
+  // TODO:
+  // - handle -Xspirv-translator option to avoid "argument unused during
+  // compilation" error
+  // - handle --spirv-ext=+<extension> and --spirv-ext=-<extension> options
 }
 
 // Utility function to gather all llvm-spirv options.

clang/test/Driver/sycl-spirv-backend.cpp

@@ -3,4 +3,4 @@
 ///
 // RUN: %clangxx -fsycl -fsycl-use-spirv-backend-for-spirv-gen -### %s 2>&1 | FileCheck %s
 
-// CHECK: llc{{.*}} "-filetype=obj" "-mtriple=spirv64-unknown-unknown" "-O0" "--avoid-spirv-capabilities=Shader" "--translator-compatibility-mode" "--spirv-ext=
+// CHECK: llc{{.*}} "-filetype=obj" "-mtriple=spirv64{{[^-]*}}-unknown-unknown" "--avoid-spirv-capabilities=Shader" "--translator-compatibility-mode" "--spirv-ext=