Partially revert "[Driver][SYCL] Use existing option for device-only … (#15328)

…and some cleanup (#15274)"

This partially reverts commit fd4b409,
undoing the change to alias -fsycl-device-only and --offload-device-only
but keeping the other cleanups, and adds a test showing why the alias
does not work.

Fixes #15319

Author: hvdijk

clang/include/clang/Driver/Options.td

@@ -6813,7 +6813,7 @@ def fintelfpga : Flag<["-"], "fintelfpga">,
   MarshallingInfoFlag<LangOpts<"IntelFPGA">>,
   HelpText<"Perform ahead-of-time compilation for FPGA">;
 def fsycl_device_only : Flag<["-"], "fsycl-device-only">,
-  Alias<offload_device_only>, HelpText<"Compile SYCL kernels for device">;
+  HelpText<"Compile SYCL kernels for device">;
 def fsycl_embed_ir : Flag<["-"], "fsycl-embed-ir">,
   HelpText<"Embed LLVM IR for runtime kernel fusion">;
 defm sycl_esimd_force_stateless_mem : BoolFOption<"sycl-esimd-force-stateless-mem",

clang/lib/Driver/Driver.cpp

@@ -854,19 +854,6 @@ static bool addSYCLDefaultTriple(Compilation &C,
   return true;
 }
 
-// Special function that checks if -fsycl-device-only was passed on the
-// command line.  -fsycl-device-only is an alias of --offload-device-only.
-static bool hasSYCLDeviceOnly(const ArgList &Args) {
-  if (const Arg *SYCLDeviceOnlyArg =
-          Args.getLastArg(options::OPT_offload_device_only)) {
-    while (SYCLDeviceOnlyArg->getAlias())
-      SYCLDeviceOnlyArg = SYCLDeviceOnlyArg->getAlias();
-    if (SYCLDeviceOnlyArg->getSpelling().contains("sycl-device-only"))
-      return true;
-  }
-  return false;
-}
-
 void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
                                               InputList &Inputs) {
 
@@ -1089,7 +1076,7 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
   bool HasValidSYCLRuntime =
       C.getInputArgs().hasFlag(options::OPT_fsycl, options::OPT_fno_sycl,
                                false) ||
-      hasSYCLDeviceOnly(C.getInputArgs());
+      C.getInputArgs().hasArg(options::OPT_fsycl_device_only);
 
   Arg *SYCLfpga = C.getInputArgs().getLastArg(options::OPT_fintelfpga);
 
@@ -1758,12 +1745,13 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   if (Args.getLastArg(options::OPT_fsycl_dump_device_code_EQ))
     DumpDeviceCode = true;
 
-  if (const Arg *A = Args.getLastArg(options::OPT_offload_host_only,
-                                     options::OPT_offload_device_only,
-                                     options::OPT_offload_host_device)) {
+  if (const Arg *A = Args.getLastArg(
+          options::OPT_offload_host_only, options::OPT_offload_device_only,
+          options::OPT_fsycl_device_only, options::OPT_offload_host_device)) {
     if (A->getOption().matches(options::OPT_offload_host_only))
       Offload = OffloadHost;
-    else if (A->getOption().matches(options::OPT_offload_device_only))
+    else if (A->getOption().matches(options::OPT_offload_device_only) ||
+             A->getOption().matches(options::OPT_fsycl_device_only))
       Offload = OffloadDevice;
     else
       Offload = OffloadHostDevice;
@@ -3138,7 +3126,7 @@ void Driver::BuildInputs(const ToolChain &TC, DerivedArgList &Args,
   Arg *InputTypeArg = nullptr;
   bool IsSYCL =
       Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false) ||
-      hasSYCLDeviceOnly(Args);
+      Args.hasArg(options::OPT_fsycl_device_only);
 
   // The last /TC or /TP option sets the input type to C or C++ globally.
   if (Arg *TCTP = Args.getLastArgNoClaim(options::OPT__SLASH_TC,

clang/test/Driver/sycl-device.cpp

@@ -3,9 +3,11 @@
 // RUN:   | FileCheck -check-prefix=CHECK-DEFAULT %s
 // CHECK-DEFAULT-NOT: "-fsycl-is-device"
 
-/// Check "-fsycl-is-device" is passed when compiling for device:
+/// Check "-fsycl-is-device" is passed when compiling for device, including when --config is used:
 // RUN:   %clang -### -fsycl-device-only %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-SYCL-DEV %s
+// RUN:   %clang -### --config=%S/Inputs/empty.cfg -fsycl-device-only %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-SYCL-DEV %s
 // CHECK-SYCL-DEV: "-fsycl-is-device"{{.*}} "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include{{[/\\]+}}sycl" "-internal-isystem" "{{.*}}bin{{[/\\]+}}..{{[/\\]+}}include"
 
 /// Check that "-Wno-sycl-strict" is set on compiler invocation with "-fsycl"