sqlite/ext/wasm/fiddle.make

#!/do/not/make
#^^^ help emacs select edit mode
#
# Intended to include'd by ./GNUmakefile.
#######################################################################
MAKEFILE.fiddle := $(lastword $(MAKEFILE_LIST))

########################################################################
# shell.c and its build flags...
make-np-0 := make -C  $(dir.top) -n -p
make-np-1 := sed -e 's/(TOP)/(dir.top)/g'
$(eval $(shell $(make-np-0) | grep -e '^SHELL_OPT ' | $(make-np-1)))
$(eval $(shell $(make-np-0) | grep -e '^SHELL_SRC ' | $(make-np-1)))
# ^^^ can't do that in 1 invocation b/c newlines get stripped
ifeq (,$(SHELL_OPT))
$(error Could not parse SHELL_OPT from $(dir.top)/Makefile.)
endif
ifeq (,$(SHELL_SRC))
$(error Could not parse SHELL_SRC from $(dir.top)/Makefile.)
endif
$(dir.top)/shell.c: $(SHELL_SRC) $(dir.top)/tool/mkshellc.tcl
	$(MAKE) -C $(dir.top) shell.c
# /shell.c
########################################################################

fiddle.emcc-flags = \
  $(emcc.cflags) $(emcc_opt_full) \
  --minify 0 \
  -sALLOW_TABLE_GROWTH \
  -sABORTING_MALLOC \
  -sSTRICT_JS \
  -sENVIRONMENT=web,worker \
  -sMODULARIZE \
  -sDYNAMIC_EXECUTION=0 \
  -sWASM_BIGINT=$(emcc_enable_bigint) \
  -sEXPORT_NAME=$(sqlite3.js.init-func) \
  $(sqlite3.js.flags.--post-js) \
  -sEXPORTED_RUNTIME_METHODS=@$(dir.wasm)/EXPORTED_RUNTIME_METHODS.fiddle \
  -sEXPORTED_FUNCTIONS=@$(dir.wasm)/EXPORTED_FUNCTIONS.fiddle \
  $(SQLITE_OPT) $(SHELL_OPT) \
  -DSQLITE_SHELL_FIDDLE
# -D_POSIX_C_SOURCE is needed for strdup() with emcc

fiddle.EXPORTED_FUNCTIONS.in := \
    EXPORTED_FUNCTIONS.fiddle.in \
    EXPORTED_FUNCTIONS.api

EXPORTED_FUNCTIONS.fiddle: $(fiddle.EXPORTED_FUNCTIONS.in) $(MAKEFILE.fiddle)
	sort -u $(fiddle.EXPORTED_FUNCTIONS.in) > $@

fiddle-module.js := $(dir.fiddle)/fiddle-module.js
fiddle-module.wasm := $(subst .js,.wasm,$(fiddle-module.js))
fiddle.cses := $(dir.top)/shell.c $(sqlite3-wasm.c)

SOAP.js := sqlite3-opfs-async-proxy.js
$(dir.fiddle)/$(SOAP.js): $(SOAP.js)
	cp $< $@

$(eval $(call call-make-pre-js,fiddle-module))
$(fiddle-module.js): $(MAKEFILE) $(MAKEFILE.fiddle) \
    EXPORTED_FUNCTIONS.fiddle EXPORTED_RUNTIME_METHODS.fiddle \
    $(fiddle.cses) $(pre-post-fiddle-module.deps) $(dir.fiddle)/$(SOAP.js)
	$(emcc.bin) -o $@ $(fiddle.emcc-flags) \
    $(pre-post-common.flags) $(pre-post-fiddle-module.flags) \
    $(fiddle.cses)
	$(maybe-wasm-strip) $(fiddle-module.wasm)
	gzip < $@ > $@.gz
	gzip < $(fiddle-module.wasm) > $(fiddle-module.wasm).gz

$(dir.fiddle)/fiddle.js.gz: $(dir.fiddle)/fiddle.js
	gzip < $< > $@

clean: clean-fiddle
clean-fiddle:
	rm -f $(fiddle-module.js) $(fiddle-module.js).gz \
        $(fiddle-module.wasm) $(fiddle-module.wasm).gz \
        $(dir.fiddle)/$(SOAP.js) \
        $(dir.fiddle)/fiddle-module.worker.js \
        EXPORTED_FUNCTIONS.fiddle
.PHONY: fiddle
fiddle: $(fiddle-module.js) $(dir.fiddle)/fiddle.js.gz
all: fiddle

########################################################################
# Explanation of the emcc build flags follows. Full docs for these can
# be found at:
#
#  https://github.com/emscripten-core/emscripten/blob/main/src/settings.js
#
# -sENVIRONMENT=web: elides bootstrap code related to non-web JS
#  environments like node.js. Removing this makes the output a tiny
#  tick larger but hypothetically makes it more portable to
#  non-browser JS environments.
#
# -sMODULARIZE: changes how the generated code is structured to avoid
#  declaring a global Module object and instead installing a function
#  which loads and initializes the module. The function is named...
#
# -sEXPORT_NAME=jsFunctionName (see -sMODULARIZE)
#
# -sEXPORTED_RUNTIME_METHODS=@/absolute/path/to/file: a file
#  containing a list of emscripten-supplied APIs, one per line, which
#  must be exported into the generated JS. Must be an absolute path!
#
# -sEXPORTED_FUNCTIONS=@/absolute/path/to/file: a file containing a
#  list of C functions, one per line, which must be exported via wasm
#  so they're visible to JS. C symbols names in that file must all
#  start with an underscore for reasons known only to the emcc
#  developers. e.g., _sqlite3_open_v2 and _sqlite3_finalize. Must be
#  an absolute path!
#
# -sSTRICT_JS ensures that the emitted JS code includes the 'use
#  strict' option. Note that -sSTRICT is more broadly-scoped and
#  results in build errors.
#
# -sALLOW_TABLE_GROWTH is required for (at a minimum) the UDF-binding
#  feature. Without it, JS functions cannot be made to proxy C-side
#  callbacks.
#
# -sABORTING_MALLOC causes the JS-bound _malloc() to abort rather than
#  return 0 on OOM. If set to 0 then all code which uses _malloc()
#  must, just like in C, check the result before using it, else
#  they're likely to corrupt the JS/WASM heap by writing to its
#  address of 0. It is, as of this writing, enabled in Emscripten by
#  default but we enable it explicitly in case that default changes.
#
# -sDYNAMIC_EXECUTION=0 disables eval() and the Function constructor.
#  If the build runs without these, it's preferable to use this flag
#  because certain execution environments disallow those constructs.
#  This flag is not strictly necessary, however.
#
# -sWASM_BIGINT is UNTESTED but "should" allow the int64-using C APIs
#  to work with JS/wasm, insofar as the JS environment supports the
#  BigInt type. That support requires an extremely recent browser:
#  Safari didn't get that support until late 2020.
#
# --no-entry: for compiling library code with no main(). If this is
#  not supplied and the code has a main(), it is called as part of the
#  module init process. Note that main() is #if'd out of shell.c
#  (renamed) when building in wasm mode.
#
# --pre-js/--post-js=FILE relative or absolute paths to JS files to
#  prepend/append to the emcc-generated bootstrapping JS. It's
#  easier/faster to develop with separate JS files (reduces rebuilding
#  requirements) but certain configurations, namely -sMODULARIZE, may
#  require using at least a --pre-js file. They can be used
#  individually and need not be paired.
#
# -O0..-O3 and -Oz: optimization levels affect not only C-style
#  optimization but whether or not the resulting generated JS code
#  gets minified. -O0 compiles _much_ more quickly than -O3 or -Oz,
#  and doesn't minimize any JS code, so is recommended for
#  development. -O3 or -Oz are recommended for deployment, but
#  primarily because -Oz will shrink the wasm file notably. JS-side
#  minification makes little difference in terms of overall
#  distributable size.
#
# --minify 0: disables minification of the generated JS code,
#  regardless of optimization level. Minification of the JS has
#  minimal overall effect in the larger scheme of things and results
#  in JS files which can neither be edited nor viewed as text files in
#  Fossil (which flags them as binary because of their extreme line
#  lengths). Interestingly, whether or not the comments in the
#  generated JS file get stripped is unaffected by this setting and
#  depends entirely on the optimization level. Higher optimization
#  levels reduce the size of the JS considerably even without
#  minification.
#
########################################################################