[Driver][SYCL] Enable generation of spv based fat objects (#4608)

When generating fat objects with -fsycl, our default behavior is to
generate and store the LLVM-IR for the device side compilation.  Update
the behavior, introducing -fsycl-device-obj=arg (where arg is spirv or
llvmir) to create the desired 'object' contents.

This is a precursor to the enabling the ability to consume these spv
based objects (or llvm-ir) seamlessly.

Author: mdtoguchi

clang/include/clang/Driver/Options.td

@@ -2687,10 +2687,16 @@ defm sycl_id_queries_fit_in_int: BoolFOption<"sycl-id-queries-fit-in-int",
   LangOpts<"SYCLValueFitInMaxInt">, DefaultTrue,
   PosFlag<SetTrue, [], "Assume">, NegFlag<SetFalse, [], "Do not assume">,
   BothFlags<[CC1Option, CoreOption], " that SYCL ID queries fit within MAX_INT.">>;
+def fsycl_device_obj_EQ : Joined<["-"], "fsycl-device-obj=">,
+  Flags<[CoreOption]>, Values<"spirv,llvmir">, HelpText<"Specify format of "
+  "device code stored in the resulting object. Valid values are: spirv, llvmir "
+  "(default)">;
 def fsycl_use_bitcode : Flag<["-"], "fsycl-use-bitcode">,
-  Flags<[CC1Option, CoreOption]>, HelpText<"Use LLVM bitcode instead of SPIR-V in fat objects">;
+  Alias<fsycl_device_obj_EQ>, AliasArgs<["llvmir"]>, Flags<[CoreOption]>,
+  HelpText<"Use LLVM bitcode instead of SPIR-V in fat objects">;
 def fno_sycl_use_bitcode : Flag<["-"], "fno-sycl-use-bitcode">,
-  Flags<[CC1Option, CoreOption]>, HelpText<"Use SPIR-V instead of LLVM bitcode in fat objects">;
+  Alias<fsycl_device_obj_EQ>, AliasArgs<["spirv"]>, Flags<[CoreOption]>,
+  HelpText<"Use SPIR-V instead of LLVM bitcode in fat objects">;
 def fsycl_link_EQ : Joined<["-"], "fsycl-link=">,
   Flags<[CC1Option, CoreOption]>, HelpText<"Generate partially linked device and host object to be used at various stages of compilation">, Values<"image,early">;
 def fsycl_link : Flag<["-"], "fsycl-link">, Alias<fsycl_link_EQ>,

clang/lib/Driver/Driver.cpp

@@ -4202,19 +4202,22 @@ class OffloadingActionBuilder final {
           if ((SYCLDeviceOnly || Args.hasArg(options::OPT_emit_llvm)) &&
               Args.hasArg(options::OPT_S))
             OutputType = types::TY_LLVM_IR;
-          if (SYCLDeviceOnly) {
-            if (Args.hasFlag(options::OPT_fno_sycl_use_bitcode,
-                             options::OPT_fsycl_use_bitcode, false)) {
-              auto *CompileAction =
-                  C.MakeAction<CompileJobAction>(A, types::TY_LLVM_BC);
-              A = C.MakeAction<SPIRVTranslatorJobAction>(CompileAction,
-                                                         types::TY_SPIRV);
+          // Use of -fsycl-device-obj=spirv converts the original LLVM-IR
+          // file to SPIR-V for later consumption.
+          if ((SYCLDeviceOnly || FinalPhase != phases::Link) &&
+              Args.getLastArgValue(options::OPT_fsycl_device_obj_EQ)
+                  .equals_insensitive("spirv")) {
+            auto *CompileAction =
+                C.MakeAction<CompileJobAction>(A, types::TY_LLVM_BC);
+            A = C.MakeAction<SPIRVTranslatorJobAction>(CompileAction,
+                                                       types::TY_SPIRV);
+            if (SYCLDeviceOnly)
               continue;
-            }
+          } else {
+            if (Args.hasArg(options::OPT_fsyntax_only))
+              OutputType = types::TY_Nothing;
+            A = C.MakeAction<CompileJobAction>(A, OutputType);
           }
-          if (Args.hasArg(options::OPT_fsyntax_only))
-            OutputType = types::TY_Nothing;
-          A = C.MakeAction<CompileJobAction>(A, OutputType);
           DeviceCompilerInput = A;
         }
         const DeviceTargetInfo &DevTarget = SYCLTargetInfoList.back();

clang/lib/Driver/ToolChains/SYCL.cpp

@@ -350,9 +350,8 @@ void SYCL::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   for (const auto &II : Inputs) {
     if (!II.isFilename())
       continue;
-    if (Args.hasFlag(options::OPT_fsycl_use_bitcode,
-                     options::OPT_fno_sycl_use_bitcode, true) ||
-        Args.hasArg(options::OPT_foffload_static_lib_EQ))
+    if (!Args.getLastArgValue(options::OPT_fsycl_device_obj_EQ)
+             .equals_insensitive("spirv"))
       SpirvInputs.push_back(II);
     else {
       const char *LLVMSpirvOutputFile = constructLLVMSpirvCommand(

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

@@ -0,0 +1,36 @@
+///
+/// Tests for SPIR-V related objects
+///
+
+// REQUIRES: clang-driver
+
+/// -fsycl-device-obj=spirv
+// RUN: %clangxx -target x86_64-unknown-linux-gnu -c -fsycl -fsycl-device-obj=spirv -### %s 2>&1 | \
+// RUN:  FileCheck %s -check-prefix SPIRV_DEVICE_OBJ
+// SPIRV_DEVICE_OBJ: clang{{.*}} "-cc1" "-triple" "spir64-unknown-unknown"
+// SPIRV_DEVICE_OBJ-SAME: "-aux-triple" "x86_64-unknown-linux-gnu"
+// SPIRV_DEVICE_OBJ-SAME: "-fsycl-is-device"
+// SPIRV_DEVICE_OBJ-SAME: "-o" "[[DEVICE_BC:.+\.bc]]"
+// SPIRV_DEVICE_OBJ: llvm-spirv{{.*}} "-o" "[[DEVICE_SPV:.+\.spv]]"
+// SPIRV_DEVICE_OBJ-SAME: "[[DEVICE_BC]]"
+// SPIRV_DEVICE_OBJ: clang{{.*}} "-cc1" "-triple" "x86_64-unknown-linux-gnu"
+// SPIRV_DEVICE_OBJ-SAME: "-fsycl-is-host"
+// SPIRV_DEVICE_OBJ-SAME: "-o" "[[HOST_OBJ:.+\.o]]"
+// SPIRV_DEVICE_OBJ: clang-offload-bundler{{.*}} "-type=o"
+// SPIRV_DEVICE_OBJ-SAME: "-inputs=[[DEVICE_SPV]],[[HOST_OBJ]]"
+
+// RUN: %clangxx -target x86_64-unknown-linux-gnu -c -fsycl -fsycl-device-obj=spirv -ccc-print-phases %s 2>&1 | \
+// RUN:  FileCheck %s -check-prefix SPIRV_DEVICE_OBJ_PHASES
+// SPIRV_DEVICE_OBJ_PHASES: 0: input, "[[INPUTSRC:.+\.cpp]]", c++, (device-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 1: preprocessor, {0}, c++-cpp-output, (device-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 2: compiler, {1}, ir, (device-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 3: llvm-spirv, {2}, spirv, (device-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 4: offload, "device-sycl (spir64-unknown-unknown)" {3}, spirv
+// SPIRV_DEVICE_OBJ_PHASES: 5: input, "[[INPUTSRC]]", c++, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 6: append-footer, {5}, c++, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 7: preprocessor, {6}, c++-cpp-output, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 8: offload, "host-sycl (x86_64-unknown-linux-gnu)" {7}, "device-sycl (spir64-unknown-unknown)" {3}, c++-cpp-output
+// SPIRV_DEVICE_OBJ_PHASES: 9: compiler, {8}, ir, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 10: backend, {9}, assembler, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 11: assembler, {10}, object, (host-sycl)
+// SPIRV_DEVICE_OBJ_PHASES: 12: clang-offload-bundler, {4, 11}, object, (host-sycl)