Add --dump-spirv option to tint_unittests

The --dump-spirv option tells tint_unittests to output the
SPIR-V assembly text for a module which did not make the SPIR-V reader
fail.  This lets us get extract a corpus of SPIR-V modules, and
lets us more easily verify that the test shaders are valid in the first
place.

Also:
- Add test/extract-spvasm.py to split that output to separate SPIR-V
  assembly files
- Add optional second argument test/test-all.sh to specify a directory
  look for input files.
- BUILD.gn:  Add dependency from //test:tint_unittests_main to
  //test:tint_unittests_config to pick up source dependency on
  the internal header of the SPIRV-Tools optimizer, needed by
  the indirection through src/reader/spirv/parser_impl_test_helper.h

This is useful for bulk testing

Fixed: tint:756
Change-Id: I4fe232ac736003f7d9be35544328302d652381ea
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/49605
Auto-Submit: David Neto <dneto@google.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>

test/extract-spvasm.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+
+# Copyright 2021 The Tint Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Extract SPIR-V assembly dumps from the output of
+#    tint_unittests --dump-spirv
+# Writes each module to a distinct filename, which is a sanitized
+# form of the test name, and with a ".spvasm" suffix.
+#
+# Usage:
+#    tint_unittests --dump-spirv | python3 extract-spvasm.py
+
+
+import sys
+import re
+
+def extract():
+    test_name = ''
+    in_spirv = False
+    parts = []
+    for line in sys.stdin:
+        run_match = re.match('\[ RUN\s+\]\s+(\S+)', line)
+        if run_match:
+            test_name = run_match.group(1)
+            test_name = re.sub('[^0-9a-zA-Z]', '_', test_name) + '.spvasm'
+        elif re.match('BEGIN ConvertedOk', line):
+            parts = []
+            in_spirv = True
+        elif re.match('END ConvertedOk', line):
+            with open(test_name, 'w') as f:
+                f.write('; Test: ' + test_name + '\n')
+                for l in parts:
+                    f.write(l)
+                f.close()
+        elif in_spirv:
+            parts.append(line)
+
+def main(argv):
+    if '--help' in argv or '-h' in argv:
+        print('Extract SPIR-V from the output of tint_unittests --dump-spirv\n')
+        print('Usage:\n    tint_unittests --dump-spirv | python3 extract-spvasm.py\n')
+        print('Writes each module to a distinct filename, which is a sanitized')
+        print('form of the test name, and with a ".spvasm" suffix.')
+        return 1
+    else:
+        extract()
+        return 0
+
+if __name__ == '__main__':
+    exit(main(sys.argv[1:]))