sw:vec_iree: Fix model_input CMake rule

Split the gen_mlmodel_input script into two parts: Download URL and
generate the c-embedded library. In this way, we can add the proper
output file dependency of the CMake rule, so --target clean can clean
the generated files, and any update of the source path can trigger the
rebuild.

Change-Id: I96b89e99f7b722a56be4dea7151c4b8fd495bd7a

build_tools/download_url.py

diff --git a/build_tools/download_url.py b/build_tools/download_url.py
new file mode 100755
index 0000000..e8aa650
--- /dev/null
+++ b/build_tools/download_url.py
@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+"""Download file from URL."""
+import argparse
+import urllib.request
+
+args = parser = argparse.ArgumentParser(
+    description='Download files from URL.')
+parser.add_argument('--u', dest='img_url', required=True,
+                    help='Input image URL')
+parser.add_argument('--o', dest='output_file',
+                    help='Output binary name', required=True)
+args = parser.parse_args()
+
+if __name__ == '__main__':
+    urllib.request.urlretrieve(args.img_url, args.output_file)

build_tools/gen_mlmodel_input.py

diff --git a/build_tools/gen_mlmodel_input.py b/build_tools/gen_mlmodel_input.py
index 5bd8918..5a910a1 100755
--- a/build_tools/gen_mlmodel_input.py
+++ b/build_tools/gen_mlmodel_input.py
@@ -1,8 +1,7 @@
 #!/usr/bin/env python3
-"""Generate ML model inputs from external images."""
+"""Generate ML model inputs from images."""
 import argparse
 import os
-import sys
 import struct
 import urllib.request
 
@@ -20,7 +19,6 @@
                     help='Model input shape (example: "1, 224, 224, 3")', required=True)
 parser.add_argument('--q', dest='is_quant', action='store_true',
                     help='Indicate it is quant model (default: False)')
-parser.add_argument('--u', dest='img_url', help='Input image URL')
 args = parser.parse_args()
 
 
@@ -33,9 +31,9 @@
                 file.write(struct.pack("<f", d))
 
 
-def gen_mlmodel_input(input_name, output_file, input_shape, is_quant, img_url):
+def gen_mlmodel_input(input_name, output_file, input_shape, is_quant):
     if not os.path.exists(input_name):
-        urllib.request.urlretrieve(img_url, input_name)
+        raise RuntimeError("Input file %s doesn't exist" % {input_name})
     if len(input_shape) < 3:
         raise ValueError("Input shape < 3 dimensions")
     resized_img = Image.open(input_name).resize(
@@ -49,7 +47,5 @@
 if __name__ == '__main__':
     # convert input shape to a list
     input_shape = [int(x) for x in args.input_shape.split(',')]
-    # remove whitespace in image URL if any
-    img_url = args.img_url.replace(' ', '')
     gen_mlmodel_input(args.input_name, args.output_file,
-                      input_shape, args.is_quant, img_url)
+                      input_shape, args.is_quant)

cmake/iree_model_input.cmake

diff --git a/cmake/iree_model_input.cmake b/cmake/iree_model_input.cmake
index 9d66348..bb28d37 100644
--- a/cmake/iree_model_input.cmake
+++ b/cmake/iree_model_input.cmake
@@ -32,14 +32,32 @@
     ${ARGN}
   )
 
-  get_filename_component(EXT_STR "${_RULE_SRC}" LAST_EXT)
+  string(REGEX REPLACE "[ \t\r\n]" "" _RULE_SRC_TRIM ${_RULE_SRC})
+  string(REGEX MATCH "^https:" _RULE_SRC_URL ${_RULE_SRC_TRIM})
+  if (_RULE_SRC_URL)
+    get_filename_component(_INPUT_FILENAME "${_RULE_SRC}" NAME)
+    set(_ARGS)
+    set(_DOWNLOAD_SCRIPT "${CMAKE_SOURCE_DIR}/build_tools/download_url.py")
+    list(APPEND _ARGS "--u=${_RULE_SRC_TRIM}")
+    list(APPEND _ARGS "--o=${_INPUT_FILENAME}")
+    add_custom_command(
+      OUTPUT
+        ${_INPUT_FILENAME}
+      COMMAND
+        ${_DOWNLOAD_SCRIPT} ${_ARGS}
+      DEPENDS
+        ${_DOWNLOAD_SCRIPT}
+    )
+  else()
+    set(_INPUT_FILENAME ${_RULE_SRC_TRIM})
+  endif()
+
   set(_GEN_INPUT_SCRIPT "${CMAKE_SOURCE_DIR}/build_tools/gen_mlmodel_input.py")
   set(_OUTPUT_BINARY ${_RULE_NAME}.bin)
   set(_ARGS)
-  list(APPEND _ARGS "--i=${_RULE_NAME}${EXT_STR}")
+  list(APPEND _ARGS "--i=${_INPUT_FILENAME}")
   list(APPEND _ARGS "--o=${_OUTPUT_BINARY}")
   list(APPEND _ARGS "--s=${_RULE_SHAPE}")
-  list(APPEND _ARGS "--u=${_RULE_SRC}")
   if(_RULE_QUANT)
     list(APPEND _ARGS "--q")
   endif()
@@ -49,6 +67,9 @@
       ${_OUTPUT_BINARY}
     COMMAND
       ${_GEN_INPUT_SCRIPT} ${_ARGS}
+    DEPENDS
+      ${_GEN_INPUT_SCRIPT}
+      ${_INPUT_FILENAME}
   )
 
   iree_c_embed_data(