run closure in -O3, it makes sense there with the other unsafe optimizations

3 files changed, 18 insertions, 8 deletions

diff --git a/emcc b/emcc
index 1a4dc470..ad729ac5 100755
--- a/emcc
+++ b/emcc
@@ -159,10 +159,17 @@ Options that are modified or new in %s include:
   -O2                      As -O1, plus the relooper (loop recreation),
                            plus LLVM -O2 optimizations
   -O3                      As -O2, plus dangerous optimizations that may
-                           break the generated code! This is not
-                           recommended at all, see the wiki for more
-                           details (you can try -O2 and then add
-                           dangerous optimizations one by one).
+                           break the generated code! This turns on
+
+                              INLINING_LIMIT = 0
+                              DOUBLE_MODE = 0
+                              PRECISE_I64_MATH = 0
+                              and the closure compiler
+
+                           This is not recommended at all. A better idea
+                           is to try each of these separately on top of
+                           -O2 to see what works. See the wiki for more
+                           information.
 
   -s OPTION=VALUE          JavaScript code generation option passed
                            into the emscripten compiler. For the
@@ -206,12 +213,13 @@ Options that are modified or new in %s include:
                            (see --llvm-opts), setting this to 1 has no
                            effect.
 
-  --closure <on>           0: No closure compiler (default)
+  --closure <on>           0: No closure compiler (default in -O2 and below)
                            1: Run closure compiler. This greatly reduces
                            code size and may in some cases increase
                            runtime speed (although the opposite can also
                            occur). Note that it takes time to run, and
-                           may require some changes to the code.
+                           may require some changes to the code. This
+                           is run by default in -O3.
 
   --js-transform <cmd>     <cmd> will be called on the generated code
                            before it is optimized. This lets you modify
@@ -756,6 +764,7 @@ try:
   if llvm_opts is None: llvm_opts = LLVM_OPT_LEVEL[opt_level]
   if llvm_lto is None: llvm_lto = llvm_opts > 0
   if opt_level <= 0: keep_debug = True # always keep debug in -O0
+  if closure is None and opt_level == 3: closure = True
 
   if DEBUG: start_time = time.time() # done after parsing arguments, which might affect debug state
 
diff --git a/tests/runner.py b/tests/runner.py
index 259d8188..abd925bf 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -8292,14 +8292,14 @@ Options that are modified or new in %s include:
           (['-o', 'something.js', '-O2'],                   2, None, 0, 1),
           (['-o', 'something.js', '-O2', '--closure', '0'], 2, None, 0, 0),
           (['-o', 'something.js', '-O2', '-g'],             2, None, 0, 0),
-          (['-o', 'something.js', '-O3'],                   3, None, 0, 1),
+          (['-o', 'something.js', '-O3'],                   3, None, 1, 1),
           (['-o', 'something.js', '-O3', '--closure', '0'], 3, None, 0, 0),
           # and, test compiling to bitcode first
           (['-o', 'something.bc'], 0, [],      0, 0),
           (['-o', 'something.bc'], 0, ['-O0'], 0, 0),
           (['-o', 'something.bc'], 1, ['-O1'], 0, 0),
           (['-o', 'something.bc'], 2, ['-O2'], 0, 0),
-          (['-o', 'something.bc'], 3, ['-O3'], 0, 0),
+          (['-o', 'something.bc'], 3, ['-O3'], 1, 0),
           (['-O1', '-o', 'something.bc'], 0, [], 0, 0), # -Ox is ignored and warned about
         ]:
           print params, opt_level, bc_params, closure, has_malloc
diff --git a/tools/shared.py b/tools/shared.py
index 401a580b..0282fbb1 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -566,6 +566,7 @@ class Settings:
         if opt_level >= 2:
           Settings.RELOOP = 1
         if opt_level >= 3:
+          # Aside from these, -O3 also runs closure compiler
           Settings.INLINING_LIMIT = 0
           Settings.DOUBLE_MODE = 0
           Settings.PRECISE_I64_MATH = 0