Merge pull request #15447 from eska014/html5-optmode

Build WebAssembly release module with -Os to decrease file size

platform/javascript/detect.py

@@ -49,8 +49,14 @@ def configure(env):
     ## Build type
 
     if (env["target"] == "release"):
-        env.Append(CCFLAGS=['-O3'])
-        env.Append(LINKFLAGS=['-O3'])
+        # Use -Os to prioritize optimizing for reduced file size. This is
+        # particularly valuable for the web platform because it directly
+        # decreases download time.
+        # -Os reduces file size by around 5 MiB over -O3. -Oz only saves about
+        # 100 KiB over -Os, which does not justify the negative impact on
+        # run-time performance.
+        env.Append(CCFLAGS=['-Os'])
+        env.Append(LINKFLAGS=['-Os'])
 
     elif (env["target"] == "release_debug"):
         env.Append(CCFLAGS=['-O2', '-DDEBUG_ENABLED'])