[Driver] Add an option to do ESIMD lowering in sycl-post-link (#3197)

This is one of the patches for moving ESIMD passes from clang FE (BackendUtils.cpp) to sycl-post-link.

Author: DenisBakhvalov

clang/include/clang/Driver/Options.td

@@ -2398,6 +2398,10 @@ def fsycl_device_code_split_esimd : Flag<["-"], "fsycl-device-code-split-esimd">
   Flags<[CC1Option, CoreOption]>, HelpText<"Split SYCL and ESIMD kernels into separate modules">;
 def fno_sycl_device_code_split_esimd : Flag<["-"], "fno-sycl-device-code-split-esimd">,
   Flags<[CC1Option, CoreOption]>, HelpText<"Don't split SYCL and ESIMD kernels into separate modules">;
+def fsycl_device_code_lower_esimd : Flag<["-"], "fsycl-device-code-lower-esimd">,
+  Flags<[CC1Option, CoreOption]>, HelpText<"Lower ESIMD-specific constructs">;
+def fno_sycl_device_code_lower_esimd : Flag<["-"], "fno-sycl-device-code-lower-esimd">,
+  Flags<[CC1Option, CoreOption]>, HelpText<"Do not lower ESIMD-specific constructs">;
 defm sycl_id_queries_fit_in_int: OptInFFlag<"sycl-id-queries-fit-in-int", "Assume", "Do not assume", " that SYCL ID queries fit within MAX_INT.", [CC1Option,CoreOption], LangOpts<"SYCLValueFitInMaxInt">>;
 def fsycl_use_bitcode : Flag<["-"], "fsycl-use-bitcode">,
   Flags<[CC1Option, CoreOption]>, HelpText<"Use LLVM bitcode instead of SPIR-V in fat objects">;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -8321,6 +8321,9 @@ void SYCLPostLink::ConstructJob(Compilation &C, const JobAction &JA,
     if (TCArgs.hasFlag(options::OPT_fsycl_device_code_split_esimd,
                        options::OPT_fno_sycl_device_code_split_esimd, true))
       addArgs(CmdArgs, TCArgs, {"-split-esimd"});
+    if (TCArgs.hasFlag(options::OPT_fsycl_device_code_lower_esimd,
+                       options::OPT_fno_sycl_device_code_lower_esimd, false))
+      addArgs(CmdArgs, TCArgs, {"-lower-esimd"});
   }
   // specialization constants processing is mandatory
   auto *SYCLPostLink = llvm::dyn_cast<SYCLPostLinkJobAction>(&JA);

clang/test/Driver/sycl-offload-with-split.c

@@ -316,3 +316,15 @@
 // RUN:   %clang_cl -### -fsycl -fintelfpga %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-SPLIT
 // CHK-ESIMD-SPLIT: sycl-post-link{{.*}} "-split-esimd"
 // CHK-NO-ESIMD-SPLIT-NOT: sycl-post-link{{.*}} "-split-esimd"
+
+// Check lowering of ESIMD device code.
+// RUN:   %clang    -### -fsycl %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// RUN:   %clang_cl -### -fsycl %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// RUN:   %clang    -### -fsycl -fsycl-device-code-lower-esimd %s 2>&1 | FileCheck %s -check-prefixes=CHK-ESIMD-LOWER
+// RUN:   %clang_cl -### -fsycl -fsycl-device-code-lower-esimd %s 2>&1 | FileCheck %s -check-prefixes=CHK-ESIMD-LOWER
+// RUN:   %clang    -### -fsycl -fno-sycl-device-code-lower-esimd %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// RUN:   %clang_cl -### -fsycl -fno-sycl-device-code-lower-esimd %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// RUN:   %clang    -### -fsycl -fintelfpga %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// RUN:   %clang_cl -### -fsycl -fintelfpga %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-ESIMD-LOWER
+// CHK-ESIMD-LOWER: sycl-post-link{{.*}} "-lower-esimd"
+// CHK-NO-ESIMD-LOWER-NOT: sycl-post-link{{.*}} "-lower-esimd"