scripts/emcc.sh: cache lto .a files in build/emsdk-cache

Author: justjake

Makefile

@@ -2,9 +2,10 @@
 CC=clang
 EMSDK_VERSION=3.1.7
 EMSDK_DOCKER_IMAGE=emscripten/emsdk:$(EMSDK_VERSION)
-EMCC=EMSDK_VERSION=$(EMSDK_VERSION) EMSDK_DOCKER_IMAGE=$(EMSDK_DOCKER_IMAGE) scripts/emcc.sh
+EMCC=EMSDK_VERSION=$(EMSDK_VERSION) EMSDK_DOCKER_IMAGE=$(EMSDK_DOCKER_IMAGE) EMSDK_DOCKER_CACHE=$(THIS_DIR)/$(BUILD_EMSDK_CACHE)/$(EMSDK_VERSION) scripts/emcc.sh
 GENERATE_TS=$(VARIANT_GENERATE_TS_ENV) npx ts-node generate.ts
 PRETTIER=npx prettier
+THIS_DIR := $(dir $(abspath $(firstword $(MAKEFILE_LIST))))
 
 DEBUG_MAKE=1
 
@@ -40,6 +41,7 @@ WRAPPER_ROOT=c
 BUILD_ROOT=build
 BUILD_WRAPPER=$(BUILD_ROOT)/wrapper
 BUILD_QUICKJS=$(BUILD_ROOT)/quickjs
+BUILD_EMSDK_CACHE=$(BUILD_ROOT)/emsdk-cache
 BUILD_TS=ts/generated
 
 # QuickJS
@@ -174,15 +176,15 @@ NATIVE: $(BUILD_WRAPPER)/test.$(VARIANT).exe
 
 $(BUILD_WRAPPER)/test.$(VARIANT).exe: $(BUILD_WRAPPER)/test.$(VARIANT).o $(BUILD_WRAPPER)/interface.$(VARIANT).o $(VARIANT_QUICKJS_OBJS)
 	$(MKDIRP)
-	$(CC) $(VARIANT_CFLAGS) -o $@ $< 
+	$(CC) $(VARIANT_CFLAGS) -o $@ $<
 
 $(BUILD_WRAPPER)/test.$(VARIANT).o: $(WRAPPER_ROOT)/test.c $(WRAPPER_ROOT)/interface.h
 	$(MKDIRP)
-	$(CC) $(VARIANT_CFLAGS) -o $@ $< 
+	$(CC) $(VARIANT_CFLAGS) -o $@ $<
 
 $(BUILD_WRAPPER)/%.NATIVE_$(RELEASE)_$(SYNC).o: $(WRAPPER_ROOT)/%.c
 	$(MKDIRP)
-	$(CC) $(VARIANT_CFLAGS) -o $@ $< 
+	$(CC) $(VARIANT_CFLAGS) -o $@ $<
 
 $(BUILD_QUICKJS)/%.NATIVE_$(RELEASE)_$(SYNC).o: $(QUICKJS_ROOT)/%.c
 	$(MKDIRP)
@@ -195,7 +197,7 @@ $(WRAPPER_ROOT)/interface.h: $(WRAPPER_ROOT)/interface.c generate.ts
 ###############################################################################
 # WASM variants
 WASM: $(BUILD_TS)/emscripten-module.$(VARIANT).js $(BUILD_TS)/emscripten-module.$(VARIANT).d.ts GENERATE
-GENERATE: $(BUILD_TS)/ffi.$(VARIANT).ts 
+GENERATE: $(BUILD_TS)/ffi.$(VARIANT).ts
 WASM_SYMBOLS=$(BUILD_WRAPPER)/symbols.json $(BUILD_WRAPPER)/asyncify-remove.json $(BUILD_WRAPPER)/asyncify-imports.json
 
 $(BUILD_TS)/emscripten-module.$(VARIANT).js: $(BUILD_WRAPPER)/interface.$(VARIANT).o $(VARIANT_QUICKJS_OBJS) $(WASM_SYMBOLS) | scripts/emcc.sh
@@ -228,4 +230,4 @@ $(BUILD_WRAPPER)/asyncify-remove.json:
 
 $(BUILD_WRAPPER)/asyncify-imports.json:
 	$(MKDIRP)
-	$(GENERATE_TS) async-callback-symbols $@
+	$(GENERATE_TS) async-callback-symbols $@

scripts/emcc.sh

@@ -2,14 +2,46 @@
 # Use system emcc if installed, otherwise use Docker.
 set -eo pipefail
 
-if [[ -z "$EMSDK_USE_DOCKER" ]] && command -v emcc > /dev/null ; then
-  if emcc --version | grep "$EMSDK_VERSION" > /dev/null ; then
+if [[ -z "$EMSDK_USE_DOCKER" ]] && command -v emcc >/dev/null; then
+  if emcc --version | grep "$EMSDK_VERSION" >/dev/null; then
     exec emcc "$@"
   fi
 fi
 
+if [[ -z "$EMSDK_CACHE" ]]; then
+  echo "EMSDK_CACHE must be set to a path"
+fi
+
 DOCKER_ARGV=(
-  run --rm -v "$(pwd):$(pwd)" -u "$(id -u):$(id -g)" -w "$(pwd)" "${EMSDK_DOCKER_IMAGE}" emcc "$@"
+  run --rm
+  -v "$(pwd):$(pwd)"
+  -u "$(id -u):$(id -g)"
+  -w "$(pwd)"
+)
+
+if [[ -n "$EMSDK_DOCKER_CACHE" ]]; then
+  # There are some files that are not pre-build in the Docker image,
+  # and take a while to be automatically generated by emsdk.
+  # We cache these on the host inside EMSDK_DOCKER_CACHE.
+  EMSDK_DOCKER_CACHE_PATHS=(
+    sysroot/lib/wasm32-emscripten/lto
+    sysroot/lib/wasm32-emscripten/thinlto
+    sysroot/lib/wasm32-emscripten/pic
+  )
+  for dir in "${EMSDK_DOCKER_CACHE_PATHS[@]}"; do
+    host="$EMSDK_DOCKER_CACHE/$dir"
+    guest="/emsdk/upstream/emscripten/cache/$dir"
+
+    mkdir -p "$host"
+    DOCKER_ARGV+=(
+      -v "$host:$guest"
+    )
+  done
+fi
+
+DOCKER_ARGV+=(
+  "${EMSDK_DOCKER_IMAGE}" emcc "$@"
 )
+
 set -x
-exec docker "${DOCKER_ARGV[@]}"
+exec docker "${DOCKER_ARGV[@]}"