[SYCL][Driver] Fix autodetection of the -Xsycl-target-backend triple (intel#4463)

intel#4175 introduced automatic addition
of the generic spir64 device target when any section of the input
objects had this triple assigned to it. As a result, the actual list
of toolchains started exceeding the user-provided one by 1 item.

After intel#4239, the above became a
problem. The dispatch of -Xsycl-target-* arguments started happening
earlier in theflow, which broke the following use-case:
```
clang++ -fsycl -fsycl-targets=spir64_gen gen-obj.o
gen-and-spir64-obj.o -Xsycl-target-backend "-device *"
```
A fix for now is to ignore the autodetected spir64 target when
propagating the -Xsycl-target-backend arguments. A permanent solution
would involve a re-design of -Xsycl-target-backend handling so that it
took place only once in the flow, or belating the addition of the
autodetected generic triple into the list of device targets.

Signed-off-by: Artem Gindinson <[email protected]>

Author: Artem Gindinson

clang/lib/Driver/Driver.cpp

@@ -4779,6 +4779,7 @@ class OffloadingActionBuilder final {
       bool HasValidSYCLRuntime = C.getInputArgs().hasFlag(
           options::OPT_fsycl, options::OPT_fno_sycl, false);
       bool SYCLfpgaTriple = false;
+      bool ShouldAddDefaultTriple = true;
       if (SYCLTargets || SYCLAddTargets) {
         if (SYCLTargets) {
           llvm::StringMap<StringRef> FoundNormalizedTriples;
@@ -4799,7 +4800,6 @@ class OffloadingActionBuilder final {
             if (TT.getSubArch() == llvm::Triple::SPIRSubArch_fpga)
               SYCLfpgaTriple = true;
           }
-          addSYCLDefaultTriple(C, SYCLTripleList);
         }
         if (SYCLAddTargets) {
           for (StringRef Val : SYCLAddTargets->getValues()) {
@@ -4813,6 +4813,7 @@ class OffloadingActionBuilder final {
 
             // populate the AOT binary inputs vector.
             SYCLAOTInputs.push_back(std::make_pair(TT, TF));
+            ShouldAddDefaultTriple = false;
           }
         }
       } else if (HasValidSYCLRuntime) {
@@ -4822,7 +4823,6 @@ class OffloadingActionBuilder final {
         const char *SYCLTargetArch = SYCLfpga ? "spir64_fpga" : "spir64";
         SYCLTripleList.push_back(
             C.getDriver().MakeSYCLDeviceTriple(SYCLTargetArch));
-        addSYCLDefaultTriple(C, SYCLTripleList);
         if (SYCLfpga)
           SYCLfpgaTriple = true;
       }
@@ -4859,7 +4859,10 @@ class OffloadingActionBuilder final {
       }
 
       DeviceLinkerInputs.resize(ToolChains.size());
-      return initializeGpuArchMap();
+      bool GpuInitHasErrors = initializeGpuArchMap();
+      if (ShouldAddDefaultTriple)
+        addSYCLDefaultTriple(C, SYCLTripleList);
+      return GpuInitHasErrors;
     }
 
     bool canUseBundlerUnbundler() const override {

clang/test/Driver/sycl-offload.cpp

@@ -97,9 +97,18 @@
 // NO_IMPLIED_DEVICE: clang-offload-bundler{{.*}} "-type=o" "-targets=sycl-spir64-unknown-unknown"{{.*}} "-check-section"
 // NO_IMPLIED_DEVICE-NOT: clang-offload-bundler{{.*}} "-targets={{.*}}spir64-unknown-unknown{{.*}}" "-unbundle"
 
-/// Passing in the default triple should allow for -Xsycl-target options
+/// Passing in the default triple should allow for -Xsycl-target options, both the
+/// "=<triple>" and the default spelling
 // RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fsycl-targets=spir64 -Xsycl-target-backend=spir64 -DFOO -Xsycl-target-linker=spir64 -DFOO2 %S/Inputs/SYCL/objlin64.o 2>&1 \
 // RUN:    | FileCheck -check-prefixes=SYCL_TARGET_OPT %s
 // RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -Xsycl-target-backend=spir64 -DFOO -Xsycl-target-linker=spir64 -DFOO2 %S/Inputs/SYCL/objlin64.o 2>&1 \
 // RUN:    | FileCheck -check-prefixes=SYCL_TARGET_OPT %s
 // SYCL_TARGET_OPT: clang-offload-wrapper{{.*}} "-compile-opts=-DFOO" "-link-opts=-DFOO2"
+// RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fsycl-targets=spir64_x86_64 -Xsycl-target-backend -DFOO %S/Inputs/SYCL/objlin64.o 2>&1 \
+// RUN:    | FileCheck -check-prefixes=SYCL_TARGET_OPT_AOT %s
+// RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fsycl-targets=spir64_gen -Xsycl-target-backend -DFOO %S/Inputs/SYCL/objlin64.o 2>&1 \
+// RUN:    | FileCheck -check-prefixes=SYCL_TARGET_OPT_AOT %s
+// RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fsycl-targets=spir64_fpga -Xsycl-target-backend -DFOO %S/Inputs/SYCL/objlin64.o 2>&1 \
+// RUN:    | FileCheck -check-prefixes=SYCL_TARGET_OPT_AOT %s
+// SYCL_TARGET_OPT_AOT-NOT: error: cannot deduce implicit triple value for '-Xsycl-target-backend'
+// SYCL_TARGET_OPT_AOT: {{opencl-aot|ocloc|aoc}}{{.*}} "-DFOO"