avs_pc: add wasm source map so avs debugging in chrome is possible (#72)

docs/debug_wasm.md

@@ -0,0 +1,46 @@
+# AVS WASM Debugging
+
+## Develop
+
+When working with the web app it is sometimes helpful to debug the AVS. 
+To do this you need to create the WASM file with debug information.
+
+### Build WASM with source map
+
+This creates wasm file with debug information
+
+```bash
+$ make dist_wasm WASM_DEBUG=1
+```
+
+### Link avs project ro wire_webapp
+
+After you have built the wasm, link your local build of `@wireapp/avs` to your local `wire-webapp` like: 
+
+```bash
+$ cd cd build/dist/wasm/
+$ yarn link
+```
+Use `yarn link @wireapp/avs` in the root directory of your local `wire-webapp`.
+
+If that doesn't work, there is still the hard way ;)
+
+Add `@wireapp/avs` directly in the `package.json` of `wire-webapp` like
+
+```json
+{
+  "dependencies": {
+    "@wireapp/avs": "file:../wire-avs/build/dist/wasm/"
+  }
+}
+```
+
+### Debugging WebAssembly in Chrome
+
+To get the debug information you need a Chrome extension:
+Install the [C/C++ DevTools Support (DWARF) Chrome extension](https://chromewebstore.google.com/detail/cc++-devtools-support-dwa/pdcpmagijalfljmkmjngeonclgbbannb)
+
+![DevTools](./assets/chrome_develop_tool.png "DevTools")
+
+Have fun!
+

mk/dist.mk

@@ -431,11 +431,16 @@ else
 EMCC 	:= $(WASM_PATH)/emcc
 endif
 
+ifeq ($(WASM_DEBUG),1)
+DIST_WASM_WITH_SOURCE_MAP := -gsource-map -g
+else
+DIST_WASM_WITH_SOURCE_MAP :=
+endif
 
 $(DIST_WASM_JS_TARGET):
 	$(MAKE) AVS_OS=wasm AVS_ARCH=generic avs
 	@mkdir -p $(BUILD_DIST_WASM)/src
-	$(EMCC) -o $(DIST_WASM_JS_TARGET) \
+	$(EMCC) $(DIST_WASM_WITH_SOURCE_MAP) -o $(DIST_WASM_JS_TARGET) \
 		$(BUILD_BASE)/wasm-generic/lib/libavscore.a \
 		$(BUILD_BASE)/wasm-generic/lib/libre.a \
 		$(BUILD_BASE)/wasm-generic/lib/libsodium.a \