[SYCL][Driver] Device link job should not be added for non-existent inputs (#836)

When compiling with only libraries (no source) there should be no device
linking step added.  We were already preventing the library from being added
to the link list, but we were still adding the device link.

Signed-off-by: Michael D Toguchi <[email protected]>

Author: mdtoguchi

clang/lib/Driver/Driver.cpp

@@ -3414,6 +3414,9 @@ class OffloadingActionBuilder final {
           ++TC;
           continue;
         }
+        if (LI.empty())
+          // Current list is empty, nothing to process.
+          continue;
 
         // Perform a check for device kernels.  This is done for FPGA when an
         // aocx or aocr based file is found.

clang/test/Driver/sycl-offload-intelfpga.cpp

@@ -88,23 +88,22 @@
 // RUN:  llc -filetype=obj -o %t-aocx.o %t-aocx.bc
 // RUN:  llvm-ar crv %t_aocx.a %t.o %t-aocx.o
 // RUN:  %clangxx -target x86_64-unknown-linux-gnu -fsycl -fintelfpga %t_aocx.a -ccc-print-phases 2>&1 \
-// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX-PHASES,CHK-FPGA-AOCX-PHASES-DEFAULT %s
+// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX-PHASES %s
 // RUN:  %clang_cl -fsycl -fintelfpga %t_aocx.a -ccc-print-phases 2>&1 \
-// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX-PHASES,CHK-FPGA-AOCX-PHASES-CL %s
+// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX-PHASES %s
 // CHK-FPGA-AOCX-PHASES: 0: input, "{{.*}}", object, (host-sycl)
 // CHK-FPGA-AOCX-PHASES: 1: linker, {0}, image, (host-sycl)
-// CHK-FPGA-AOCX-PHASES: 2: linker, {}, spirv, (device-sycl)
-// CHK-FPGA-AOCX-PHASES: 3: backend-compiler, {2}, fpga-aocx, (device-sycl)
-// CHK-FPGA-AOCX-PHASES: 4: clang-offload-wrapper, {3}, object, (device-sycl)
-// CHK-FPGA-AOCX-PHASES-DEFAULT: 5: offload, "host-sycl (x86_64-unknown-linux-gnu)" {1}, "device-sycl (spir64_fpga-unknown-unknown-sycldevice)" {4}, image
-// CHK-FPGA-AOCX-PHASES-CL: 5: offload, "host-sycl (x86_64-pc-windows-msvc)" {1}, "device-sycl (spir64_fpga-unknown-unknown-sycldevice-coff)" {4}, image
 
 // RUN:  %clangxx -target x86_64-unknown-linux-gnu -fsycl -fintelfpga %t_aocx.a -### 2>&1 \
-// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX %s
+// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX,CHK-FPGA-AOCX-LIN %s
+// RUN:  %clang_cl -fsycl -fintelfpga %t_aocx.a -### 2>&1 \
+// RUN:  | FileCheck -check-prefixes=CHK-FPGA-AOCX,CHK-FPGA-AOCX-WIN %s
 // CHK-FPGA-AOCX: clang-offload-bundler{{.*}} "-type=ao" "-targets=sycl-fpga_aocx-intel-unknown-sycldevice" "-inputs=[[LIBINPUT:.+\.a]]" "-outputs=[[BUNDLEOUT:.+\.aocx]]" "-unbundle"
-// CHK-FPGA-AOCX: clang-offload-wrapper{{.*}} "-o=[[WRAPOUT:.+\.bc]]" "-host=x86_64-unknown-linux-gnu" "-target=spir64_fpga" "-kind=sycl" "[[BUNDLEOUT]]"
-// CHK-FPGA-AOCX: llc{{.*}} "-filetype=obj" "-o" "[[LLCOUT:.+\.o]]" "[[WRAPOUT]]"
-// CHK-FPGA-AOCX: ld{{.*}} "[[LIBINPUT]]" "[[LLCOUT]]"
+// CHK-FPGA-AOCX: clang-offload-wrapper{{.*}} "-o=[[WRAPOUT:.+\.bc]]" {{.*}} "-target=spir64_fpga" "-kind=sycl" "[[BUNDLEOUT]]"
+// CHK-FPGA-AOCX-LIN: llc{{.*}} "-filetype=obj" "-o" "[[LLCOUT:.+\.o]]" "[[WRAPOUT]]"
+// CHK-FPGA-AOCX-WIN: llc{{.*}} "-filetype=obj" "-o" "[[LLCOUT2:.+\.obj]]" "[[WRAPOUT]]"
+// CHK-FPGA-AOCX-LIN: ld{{.*}} "[[LIBINPUT]]" "[[LLCOUT]]"
+// CHK-FPGA-AOCX-WIN: link{{.*}} "[[LIBINPUT]]" "[[LLCOUT2]]"
 
 /// -fintelfpga -fsycl-link from source
 // RUN: touch %t.cpp

clang/test/Driver/sycl-offload.c

@@ -793,5 +793,12 @@
 // RUN:  | FileCheck -check-prefix=DUP-OPT %s
 // DUP-OPT-NOT: aoc{{.*}} "-DBLAH" {{.*}} "-DBLAH"
 
+/// passing of only a library should not create a device link
+// RUN: %clang -ccc-print-phases -fsycl -lsomelib 2>&1 \
+// RUN:  | FileCheck -check-prefix=LIB-NODEVICE %s
+// LIB-NODEVICE: 0: input, "somelib", object, (host-sycl)
+// LIB-NODEVICE: 1: linker, {0}, image, (host-sycl)
+// LIB-NODEVICE-NOT: linker, {{.*}}, spirv, (device-sycl)
+
 // TODO: SYCL specific fail - analyze and enable
 // XFAIL: windows-msvc