[SYCL][SPIRV] Enable only required extensions for SPIRV Backend. (#20584)

SPIR-V backend recently started to support extensions not supported by
drivers (e.g. SPV_KHR_float_controls2). At the same time, SPIR-V backend
doesn't support the syntax for disabling specific extensions (i.e.
--spirv-ext=-<extension>). We need to come up with a list of SPIR-V
extensions that are supported by the backend, but also by the driver.
This patch introduces the first approach for such a list.

Author: maarquitos14

clang/lib/Driver/ToolChains/Clang.cpp

@@ -10446,12 +10446,48 @@ static void getSPIRVBackendOpts(const llvm::opt::ArgList &TCArgs,
       TCArgs.MakeArgString("--avoid-spirv-capabilities=Shader"));
   BackendArgs.push_back(
       TCArgs.MakeArgString("--translator-compatibility-mode"));
-  // 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"));
+
+  // SPIR-V backend recently started to support extensions not supported by
+  // drivers (e.g. SPV_KHR_float_controls2). At the same time, SPIR-V backend
+  // doesn't support the syntax for disabling specific extensions (i.e.
+  // --spirv-ext=-<extension>). We need to come up with a list of SPIR-V
+  // extensions that are supported by the backend, but also by the driver. Below
+  // is the first approach for such a list.
+  // FIXME: A priori, we wouldn't expect
+  // SPV_EXT_relaxed_printf_string_address_space to be required, but without
+  // it, some SYCL E2E tests fail. Let's keep it until we figure out what's
+  // the problem.
+  std::string ExtArg("-spirv-ext=");
+  std::string DefaultExtArg = "+SPV_EXT_relaxed_printf_string_address_space"
+                              ",+SPV_EXT_shader_atomic_float16_add"
+                              ",+SPV_EXT_shader_atomic_float_add"
+                              ",+SPV_EXT_shader_atomic_float_min_max";
+  std::string IntelExtArg = ",+SPV_INTEL_2d_block_io"
+                            ",+SPV_INTEL_arbitrary_precision_integers"
+                            ",+SPV_INTEL_bfloat16_conversion"
+                            ",+SPV_INTEL_bindless_images"
+                            ",+SPV_INTEL_cache_controls"
+                            ",+SPV_INTEL_float_controls2"
+                            ",+SPV_INTEL_fp_max_error"
+                            ",+SPV_INTEL_function_pointers"
+                            ",+SPV_INTEL_inline_assembly"
+                            ",+SPV_INTEL_joint_matrix"
+                            ",+SPV_INTEL_long_composites"
+                            ",+SPV_INTEL_subgroups"
+                            ",+SPV_INTEL_tensor_float32_conversion"
+                            ",+SPV_INTEL_variable_length_array";
+  std::string KHRExtArg = ",+SPV_KHR_16bit_storage"
+                          ",+SPV_KHR_cooperative_matrix"
+                          ",+SPV_KHR_expect_assume"
+                          ",+SPV_KHR_float_controls"
+                          ",+SPV_KHR_linkonce_odr"
+                          ",+SPV_KHR_no_integer_wrap_decoration"
+                          ",+SPV_KHR_non_semantic_info"
+                          ",+SPV_KHR_shader_clock"
+                          ",+SPV_KHR_uniform_group_instructions";
+  ExtArg = ExtArg + DefaultExtArg + IntelExtArg + KHRExtArg;
+  BackendArgs.push_back(TCArgs.MakeArgString(ExtArg));
+
   // TODO:
   // - handle -Xspirv-translator option to avoid "argument unused during
   // compilation" error

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

@@ -3,4 +3,31 @@
 ///
 // RUN: %clangxx -fsycl -fsycl-use-spirv-backend-for-spirv-gen -### %s 2>&1 | FileCheck %s
 
-// CHECK: llc{{.*}} "-filetype=obj" "-mtriple=spirv64{{[^-]*}}-unknown-unknown" "--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=
+// CHECK-SAME: +SPV_EXT_relaxed_printf_string_address_space
+// CHECK-SAME:,+SPV_EXT_shader_atomic_float16_add
+// CHECK-SAME:,+SPV_EXT_shader_atomic_float_add
+// CHECK-SAME:,+SPV_EXT_shader_atomic_float_min_max
+// CHECK-SAME:,+SPV_INTEL_2d_block_io
+// CHECK-SAME:,+SPV_INTEL_arbitrary_precision_integers
+// CHECK-SAME:,+SPV_INTEL_bfloat16_conversion
+// CHECK-SAME:,+SPV_INTEL_bindless_images
+// CHECK-SAME:,+SPV_INTEL_cache_controls
+// CHECK-SAME:,+SPV_INTEL_float_controls2
+// CHECK-SAME:,+SPV_INTEL_fp_max_error
+// CHECK-SAME:,+SPV_INTEL_function_pointers
+// CHECK-SAME:,+SPV_INTEL_inline_assembly
+// CHECK-SAME:,+SPV_INTEL_joint_matrix
+// CHECK-SAME:,+SPV_INTEL_long_composites
+// CHECK-SAME:,+SPV_INTEL_subgroups
+// CHECK-SAME:,+SPV_INTEL_tensor_float32_conversion
+// CHECK-SAME:,+SPV_INTEL_variable_length_array
+// CHECK-SAME:,+SPV_KHR_16bit_storage
+// CHECK-SAME:,+SPV_KHR_cooperative_matrix
+// CHECK-SAME:,+SPV_KHR_expect_assume
+// CHECK-SAME:,+SPV_KHR_float_controls
+// CHECK-SAME:,+SPV_KHR_linkonce_odr
+// CHECK-SAME:,+SPV_KHR_no_integer_wrap_decoration
+// CHECK-SAME:,+SPV_KHR_non_semantic_info
+// CHECK-SAME:,+SPV_KHR_shader_clock
+// CHECK-SAME:,+SPV_KHR_uniform_group_instructions"