4 files changed, 42 insertions, 21 deletions

diff --git a/src/ir/effects.h b/src/ir/effects.h
index e33a33818..f24f0ac3f 100644
--- a/src/ir/effects.h
+++ b/src/ir/effects.h
@@ -71,7 +71,8 @@ public:
   bool calls = false;
   std::set<Index> localsRead;
   std::set<Index> localsWritten;
-  std::set<Name> globalsRead;
+  std::set<Name> mutableGlobalsRead;
+  std::set<Name> immutableGlobalsRead;
   std::set<Name> globalsWritten;
   bool readsMemory = false;
   bool writesMemory = false;
@@ -128,8 +129,11 @@ public:
   bool accessesLocal() const {
     return localsRead.size() + localsWritten.size() > 0;
   }
+  bool accessesMutableGlobal() const {
+    return globalsWritten.size() + mutableGlobalsRead.size() > 0;
+  }
   bool accessesGlobal() const {
-    return globalsRead.size() + globalsWritten.size() > 0;
+    return accessesMutableGlobal() + immutableGlobalsRead.size() > 0;
   }
   bool accessesMemory() const { return calls || readsMemory || writesMemory; }
   bool accessesTable() const { return calls || readsTable || writesTable; }
@@ -156,10 +160,9 @@ public:
     return globalsWritten.size() || writesMemory || writesTable ||
            writesStruct || writesArray || isAtomic || calls;
   }
-  bool readsGlobalState() const {
-    return globalsRead.size() || readsMemory || readsTable ||
-           readsMutableStruct || readsImmutableStruct || readsArray ||
-           isAtomic || calls;
+  bool readsMutableGlobalState() const {
+    return mutableGlobalsRead.size() || readsMemory || readsTable ||
+           readsMutableStruct || readsArray || isAtomic || calls;
   }
 
   bool hasNonTrapSideEffects() const {
@@ -233,17 +236,17 @@ public:
         return true;
       }
     }
-    if ((other.calls && accessesGlobal()) ||
-        (calls && other.accessesGlobal())) {
+    if ((other.calls && accessesMutableGlobal()) ||
+        (calls && other.accessesMutableGlobal())) {
       return true;
     }
     for (auto global : globalsWritten) {
-      if (other.globalsRead.count(global) ||
+      if (other.mutableGlobalsRead.count(global) ||
           other.globalsWritten.count(global)) {
         return true;
       }
     }
-    for (auto global : globalsRead) {
+    for (auto global : mutableGlobalsRead) {
       if (other.globalsWritten.count(global)) {
         return true;
       }
@@ -292,8 +295,11 @@ public:
     for (auto i : other.localsWritten) {
       localsWritten.insert(i);
     }
-    for (auto i : other.globalsRead) {
-      globalsRead.insert(i);
+    for (auto i : other.mutableGlobalsRead) {
+      mutableGlobalsRead.insert(i);
+    }
+    for (auto i : other.immutableGlobalsRead) {
+      immutableGlobalsRead.insert(i);
     }
     for (auto i : other.globalsWritten) {
       globalsWritten.insert(i);
@@ -445,7 +451,11 @@ private:
       parent.localsWritten.insert(curr->index);
     }
     void visitGlobalGet(GlobalGet* curr) {
-      parent.globalsRead.insert(curr->name);
+      if (parent.module.getGlobal(curr->name)->mutable_ == Mutable) {
+        parent.mutableGlobalsRead.insert(curr->name);
+      } else {
+        parent.immutableGlobalsRead.insert(curr->name);
+      }
     }
     void visitGlobalSet(GlobalSet* curr) {
       parent.globalsWritten.insert(curr->name);
@@ -768,7 +778,7 @@ public:
     if (localsWritten.size() > 0) {
       effects |= SideEffects::WritesLocal;
     }
-    if (globalsRead.size() > 0) {
+    if (mutableGlobalsRead.size() + immutableGlobalsRead.size() > 0) {
       effects |= SideEffects::ReadsGlobal;
     }
     if (globalsWritten.size() > 0) {
diff --git a/src/js/binaryen.js-post.js b/src/js/binaryen.js-post.js
index 3f8b6545b..ee90aa1fc 100644
--- a/src/js/binaryen.js-post.js
+++ b/src/js/binaryen.js-post.js
@@ -3181,7 +3181,9 @@ Module['getExpressionInfo'] = function(expr) {
 
 // Gets the side effects of the specified expression
 Module['getSideEffects'] = function(expr, module) {
-  return Module['_BinaryenExpressionGetSideEffects'](expr, module);
+  assert(module); // guard against incorrect old API usage: a module must be
+                  // provided here.
+  return Module['_BinaryenExpressionGetSideEffects'](expr, module['ptr']);
 };
 
 Module['createType'] = function(types) {
diff --git a/src/passes/LoopInvariantCodeMotion.cpp b/src/passes/LoopInvariantCodeMotion.cpp
index 1007e57b3..f339f8126 100644
--- a/src/passes/LoopInvariantCodeMotion.cpp
+++ b/src/passes/LoopInvariantCodeMotion.cpp
@@ -120,9 +120,10 @@ struct LoopInvariantCodeMotion
         // The rest of the loop's effects matter too, we must also
         // take into account global state like interacting loads and
         // stores.
-        bool unsafeToMove =
-          effects.writesGlobalState() || effectsSoFar.invalidates(effects) ||
-          (effects.readsGlobalState() && loopEffects.writesGlobalState());
+        bool unsafeToMove = effects.writesGlobalState() ||
+                            effectsSoFar.invalidates(effects) ||
+                            (effects.readsMutableGlobalState() &&
+                             loopEffects.writesGlobalState());
         // TODO: look into optimizing this with exceptions. for now, disallow
         if (effects.throws || loopEffects.throws) {
           unsafeToMove = true;
diff --git a/src/passes/SimplifyGlobals.cpp b/src/passes/SimplifyGlobals.cpp
index 0943c04fe..be7cc6ca1 100644
--- a/src/passes/SimplifyGlobals.cpp
+++ b/src/passes/SimplifyGlobals.cpp
@@ -123,11 +123,19 @@ struct GlobalUseScanner : public WalkerPass<PostWalker<GlobalUseScanner>> {
     // See if reading a specific global is the only effect the first has.
     EffectAnalyzer firstEffects(getPassOptions(), *getModule(), first);
 
-    if (firstEffects.globalsRead.size() != 1) {
+    if (firstEffects.immutableGlobalsRead.size() +
+          firstEffects.mutableGlobalsRead.size() !=
+        1) {
       return Name();
     }
-    auto global = *firstEffects.globalsRead.begin();
-    firstEffects.globalsRead.clear();
+    Name global;
+    if (firstEffects.immutableGlobalsRead.size() == 1) {
+      global = *firstEffects.immutableGlobalsRead.begin();
+      firstEffects.immutableGlobalsRead.clear();
+    } else {
+      global = *firstEffects.mutableGlobalsRead.begin();
+      firstEffects.mutableGlobalsRead.clear();
+    }
     if (firstEffects.hasAnything()) {
       return Name();
     }