py: Divide "split" and "cat" phases of qstr extraction for better efficiency.

E.g. for stmhal, accumulated preprocessed output may grow large due to
bloated vendor headers, and then reprocessing tens of megabytes on each
build make take couple of seconds on fast hardware (=> potentially dozens
of seconds on slow hardware). So instead, split once after each change,
and only cat repetitively (guaranteed to be fast, as there're thousands
of lines involved at most).

py/makeqstrdefs.py

@@ -87,6 +87,8 @@ def cat_together():
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(description='Generates qstr definitions from a specified source')
 
+    parser.add_argument('command',
+        help='Command (split/cat)')
     parser.add_argument('input_filename',
         help='Name of the input file (when not specified, the script reads standard input)')
     parser.add_argument('output_dir',
@@ -100,11 +102,9 @@ if __name__ == "__main__":
     except OSError:
         pass
 
-    if args.input_filename:
-        infile = open(args.input_filename, 'r')
-    else:
-        infile = sys.stdin
+    if args.command == "split":
+        with open(args.input_filename) as infile:
+            process_file(infile)
 
-    file_data = process_file(infile)
-    infile.close()
-    cat_together()
+    if args.command == "cat":
+        cat_together()

py/mkrules.mk

@@ -90,9 +90,14 @@ $(HEADER_BUILD)/qstr.i.last: $(SRC_QSTR) | $(HEADER_BUILD)/mpversion.h
 	    $(CPP) $(QSTR_GEN_EXTRA_CFLAGS) $(CFLAGS) $? >$(HEADER_BUILD)/qstr.i.last; \
 	fi
 
-$(QSTR_DEFS_COLLECTED): $(HEADER_BUILD)/qstr.i.last
+$(HEADER_BUILD)/qstr.split: $(HEADER_BUILD)/qstr.i.last
 	$(ECHO) "GEN $@"
-	$(Q)$(PYTHON) $(PY_SRC)/makeqstrdefs.py $(HEADER_BUILD)/qstr.i.last $(HEADER_BUILD)/qstr $(QSTR_DEFS_COLLECTED)
+	$(Q)$(PYTHON) $(PY_SRC)/makeqstrdefs.py split $(HEADER_BUILD)/qstr.i.last $(HEADER_BUILD)/qstr $(QSTR_DEFS_COLLECTED)
+	$(Q)touch $@
+
+$(QSTR_DEFS_COLLECTED): $(HEADER_BUILD)/qstr.split
+	$(ECHO) "GEN $@"
+	$(Q)$(PYTHON) $(PY_SRC)/makeqstrdefs.py cat $(HEADER_BUILD)/qstr.i.last $(HEADER_BUILD)/qstr $(QSTR_DEFS_COLLECTED)
 
 # $(sort $(var)) removes duplicates
 #