[Build] Reduces build time for SYCL target (#10996)

* [Build] Removes tensorboard from skip list since it has been removed

* Improve SYCL config for Tensorflow (#98)

Only libtensorflow attempts to link against libComputeCpp.so now,
other targets should only utilise the headers. Added more if_sycl
statements to BUILD files.

* [Build] Fixes typos & linkstatic=1 -> linkstatic=0

* [Build] Cleans SYCL dependency, linkstatic = 0

* [Build] No need to link syclrt tensorflow/BUILD

* sycl_runtime is needed in kernels/BUILD due to inclusion

3 files changed, 7 insertions, 8 deletions

diff --git a/tensorflow/core/BUILD b/tensorflow/core/BUILD
index 27544c9961..a23c801bd7 100644
--- a/tensorflow/core/BUILD
+++ b/tensorflow/core/BUILD
@@ -121,7 +121,6 @@ load(
     "//third_party/mkl:build_defs.bzl",
     "if_mkl",
 )
-load("@local_config_sycl//sycl:build_defs.bzl", "if_sycl")
 
 # -----------------------------------------------------------------------------
 # Public targets
@@ -820,7 +819,7 @@ cc_library(
         ":test",
         "//tensorflow/core/kernels:constant_op",
         "//tensorflow/core/kernels:ops_util",
-        "//tensorflow/core/platform/default/build_config:gtest",  # + if_sycl([":sycl_runtime"])
+        "//tensorflow/core/platform/default/build_config:gtest",
     ],
 )
 
@@ -1850,7 +1849,7 @@ cc_library(
         "common_runtime/sycl/sycl_device_context.h",
     ]),
     copts = tf_copts(),
-    linkstatic = 1,
+    linkstatic = 0,
     deps = [
         ":core_cpu",
         ":core_cpu_internal",
@@ -1862,7 +1861,7 @@ cc_library(
         "//third_party/eigen3",
         "@local_config_sycl//sycl:sycl",
     ],
-    alwayslink = 1,
+    alwayslink = 0,
 )
 
 # -----------------------------------------------------------------------------
diff --git a/third_party/sycl/crosstool/computecpp.tpl b/third_party/sycl/crosstool/computecpp.tpl
index 94c5e6aaad..8b0a7a7d4a 100755
--- a/third_party/sycl/crosstool/computecpp.tpl
+++ b/third_party/sycl/crosstool/computecpp.tpl
@@ -15,7 +15,7 @@ COMPUTECPP_INCLUDE = COMPUTECPP_ROOT + 'include'
 
 def main():
   remove_flags = ('-Wl,--no-undefined', '-Wno-unused-but-set-variable', '-Wignored-attributes')
-    # remove -fsamotoze-coverage from string with g++
+  # remove -fsanitize-coverage from string with g++
   if 'g++' in CPU_CXX_COMPILER:
     remove_flags += ('-fsanitize-coverage',)
   compiler_flags = [flag for flag in sys.argv[1:] if not flag.startswith(remove_flags)]
@@ -43,7 +43,7 @@ def main():
 
   # create a blacklist of folders that will be skipped when compiling with ComputeCpp
   skip_extensions = [".cu.cc"]
-  skip_folders = ["tensorflow/compiler", "tensorflow/docs_src", "tensorflow/tensorboard", "third_party", "external", "hexagon"]
+  skip_folders = ["tensorflow/compiler", "tensorflow/docs_src", "third_party", "external", "hexagon"]
   skip_folders = [(folder + '/') for folder in skip_folders]
   # if compiling external project skip computecpp
   if any(compiled_file_name.endswith(_ext) for _ext in skip_extensions) or any(_folder in output_file_name for _folder in skip_folders):
@@ -79,7 +79,7 @@ def main():
                                       '-Xclang', '-cl-denorms-are-zero', '-Xclang', '-cl-fp32-correctly-rounded-divide-sqrt']
   # disable flags enabling SIMD instructions
   computecpp_device_compiler_flags += [flag for flag in compiler_flags if \
-    not any(x in flag.lower() for x in ('-fsanitize', '=native', '=core2', 'msse', 'vectorize', 'mavx', 'mmmx', 'm3dnow', 'fma'))]
+    not any(x in flag.lower() for x in ('-fsanitize', '-fno-canonical-system-headers', '=native', '=core2', 'msse', 'vectorize', 'mavx', 'mmmx', 'm3dnow', 'fma'))]
 
   x = call([COMPUTECPP_DRIVER] + computecpp_device_compiler_flags)
   if x == 0:
diff --git a/third_party/sycl/sycl/BUILD.tpl b/third_party/sycl/sycl/BUILD.tpl
index c66a9f007d..6cad190630 100755
--- a/third_party/sycl/sycl/BUILD.tpl
+++ b/third_party/sycl/sycl/BUILD.tpl
@@ -33,7 +33,7 @@ cc_library(
         sycl_library_path("ComputeCpp")
     ],
     includes = ["include/"],
-    linkstatic = 1,
+    linkstatic = 0,
 )
 
 cc_library(