Add EH support for OptimizeInstructions (#2608)

- Adds support for `Try` in `optimizeBoolean` function
- Adds support for `Try` in `getFallThrough` function
- Adds approximate cost values for instructions in EH and reference
  types proposals.

5 files changed, 69 insertions, 25 deletions

diff --git a/src/ir/cost.h b/src/ir/cost.h
index 37f2611dd..e89fb9d17 100644
--- a/src/ir/cost.h
+++ b/src/ir/cost.h
@@ -726,6 +726,18 @@ struct CostAnalyzer : public Visitor<CostAnalyzer, Index> {
   Index visitDrop(Drop* curr) { return visit(curr->value); }
   Index visitReturn(Return* curr) { return maybeVisit(curr->value); }
   Index visitHost(Host* curr) { return 100; }
+  Index visitRefNull(RefNull* curr) { return 1; }
+  Index visitRefIsNull(RefIsNull* curr) { return 1; }
+  Index visitRefFunc(RefFunc* curr) { return 1; }
+  Index visitTry(Try* curr) {
+    // We assume no exception will be thrown in most cases
+    return visit(curr->body);
+  }
+  Index visitThrow(Throw* curr) { return 100; }
+  Index visitRethrow(Rethrow* curr) { return 100; }
+  Index visitBrOnExn(BrOnExn* curr) {
+    return 1 + visit(curr->exnref) + curr->sent.size();
+  }
   Index visitNop(Nop* curr) { return 0; }
   Index visitUnreachable(Unreachable* curr) { return 0; }
 };
diff --git a/src/ir/properties.h b/src/ir/properties.h
index 01e78563d..1dbb0e096 100644
--- a/src/ir/properties.h
+++ b/src/ir/properties.h
@@ -18,6 +18,8 @@
 #define wasm_ir_properties_h
 
 #include "ir/bits.h"
+#include "ir/effects.h"
+#include "ir/iteration.h"
 #include "wasm.h"
 
 namespace wasm {
@@ -68,6 +70,10 @@ inline bool isNamedControlFlow(Expression* curr) {
   return false;
 }
 
+inline bool isConstantExpression(const Expression* curr) {
+  return curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>();
+}
+
 // Check if an expression is a sign-extend, and if so, returns the value
 // that is extended, otherwise nullptr
 inline Expression* getSignExtValue(Expression* curr) {
@@ -153,7 +159,9 @@ inline Index getZeroExtBits(Expression* curr) {
 
 // Returns a falling-through value, that is, it looks through a local.tee
 // and other operations that receive a value and let it flow through them.
-inline Expression* getFallthrough(Expression* curr) {
+inline Expression* getFallthrough(Expression* curr,
+                                  const PassOptions& passOptions,
+                                  FeatureSet features) {
   // If the current node is unreachable, there is no value
   // falling through.
   if (curr->type == Type::unreachable) {
@@ -161,36 +169,36 @@ inline Expression* getFallthrough(Expression* curr) {
   }
   if (auto* set = curr->dynCast<LocalSet>()) {
     if (set->isTee()) {
-      return getFallthrough(set->value);
+      return getFallthrough(set->value, passOptions, features);
     }
   } else if (auto* block = curr->dynCast<Block>()) {
     // if no name, we can't be broken to, and then can look at the fallthrough
     if (!block->name.is() && block->list.size() > 0) {
-      return getFallthrough(block->list.back());
+      return getFallthrough(block->list.back(), passOptions, features);
     }
   } else if (auto* loop = curr->dynCast<Loop>()) {
-    return getFallthrough(loop->body);
+    return getFallthrough(loop->body, passOptions, features);
   } else if (auto* iff = curr->dynCast<If>()) {
     if (iff->ifFalse) {
       // Perhaps just one of the two actually returns.
       if (iff->ifTrue->type == Type::unreachable) {
-        return getFallthrough(iff->ifFalse);
+        return getFallthrough(iff->ifFalse, passOptions, features);
       } else if (iff->ifFalse->type == Type::unreachable) {
-        return getFallthrough(iff->ifTrue);
+        return getFallthrough(iff->ifTrue, passOptions, features);
       }
     }
   } else if (auto* br = curr->dynCast<Break>()) {
     if (br->condition && br->value) {
-      return getFallthrough(br->value);
+      return getFallthrough(br->value, passOptions, features);
+    }
+  } else if (auto* tryy = curr->dynCast<Try>()) {
+    if (!EffectAnalyzer(passOptions, features, tryy->body).throws) {
+      return getFallthrough(tryy->body, passOptions, features);
     }
   }
   return curr;
 }
 
-inline bool isConstantExpression(const Expression* curr) {
-  return curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>();
-}
-
 } // namespace Properties
 
 } // namespace wasm
diff --git a/src/passes/AvoidReinterprets.cpp b/src/passes/AvoidReinterprets.cpp
index 4df75dd15..91a20912d 100644
--- a/src/passes/AvoidReinterprets.cpp
+++ b/src/passes/AvoidReinterprets.cpp
@@ -36,7 +36,10 @@ static bool canReplaceWithReinterpret(Load* load) {
          load->bytes == load->type.getByteSize();
 }
 
-static Load* getSingleLoad(LocalGraph* localGraph, LocalGet* get) {
+static Load* getSingleLoad(LocalGraph* localGraph,
+                           LocalGet* get,
+                           const PassOptions& passOptions,
+                           FeatureSet features) {
   std::set<LocalGet*> seen;
   seen.insert(get);
   while (1) {
@@ -48,7 +51,7 @@ static Load* getSingleLoad(LocalGraph* localGraph, LocalGet* get) {
     if (!set) {
       return nullptr;
     }
-    auto* value = Properties::getFallthrough(set->value);
+    auto* value = Properties::getFallthrough(set->value, passOptions, features);
     if (auto* parentGet = value->dynCast<LocalGet>()) {
       if (seen.count(parentGet)) {
         // We are in a cycle of gets, in unreachable code.
@@ -98,9 +101,12 @@ struct AvoidReinterprets : public WalkerPass<PostWalker<AvoidReinterprets>> {
 
   void visitUnary(Unary* curr) {
     if (isReinterpret(curr)) {
+      FeatureSet features = getModule()->features;
       if (auto* get =
-            Properties::getFallthrough(curr->value)->dynCast<LocalGet>()) {
-        if (auto* load = getSingleLoad(localGraph, get)) {
+            Properties::getFallthrough(curr->value, getPassOptions(), features)
+              ->dynCast<LocalGet>()) {
+        if (auto* load =
+              getSingleLoad(localGraph, get, getPassOptions(), features)) {
           auto& info = infos[load];
           info.reinterpreted = true;
         }
@@ -130,22 +136,27 @@ struct AvoidReinterprets : public WalkerPass<PostWalker<AvoidReinterprets>> {
       std::map<Load*, Info>& infos;
       LocalGraph* localGraph;
       Module* module;
+      const PassOptions& passOptions;
 
       FinalOptimizer(std::map<Load*, Info>& infos,
                      LocalGraph* localGraph,
-                     Module* module)
-        : infos(infos), localGraph(localGraph), module(module) {}
+                     Module* module,
+                     const PassOptions& passOptions)
+        : infos(infos), localGraph(localGraph), module(module),
+          passOptions(passOptions) {}
 
       void visitUnary(Unary* curr) {
         if (isReinterpret(curr)) {
-          auto* value = Properties::getFallthrough(curr->value);
+          auto* value = Properties::getFallthrough(
+            curr->value, passOptions, module->features);
           if (auto* load = value->dynCast<Load>()) {
             // A reinterpret of a load - flip it right here if we can.
             if (canReplaceWithReinterpret(load)) {
               replaceCurrent(makeReinterpretedLoad(load, load->ptr));
             }
           } else if (auto* get = value->dynCast<LocalGet>()) {
-            if (auto* load = getSingleLoad(localGraph, get)) {
+            if (auto* load = getSingleLoad(
+                  localGraph, get, passOptions, module->features)) {
               auto iter = infos.find(load);
               if (iter != infos.end()) {
                 auto& info = iter->second;
@@ -188,7 +199,7 @@ struct AvoidReinterprets : public WalkerPass<PostWalker<AvoidReinterprets>> {
                                 ptr,
                                 load->type.reinterpret());
       }
-    } finalOptimizer(infos, localGraph, getModule());
+    } finalOptimizer(infos, localGraph, getModule(), getPassOptions());
 
     finalOptimizer.walk(func->body);
   }
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 90abed825..3e3863e95 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -200,8 +200,11 @@ struct LocalInfo {
 
 struct LocalScanner : PostWalker<LocalScanner> {
   std::vector<LocalInfo>& localInfo;
+  const PassOptions& passOptions;
 
-  LocalScanner(std::vector<LocalInfo>& localInfo) : localInfo(localInfo) {}
+  LocalScanner(std::vector<LocalInfo>& localInfo,
+               const PassOptions& passOptions)
+    : localInfo(localInfo), passOptions(passOptions) {}
 
   void doWalkFunction(Function* func) {
     // prepare
@@ -236,7 +239,8 @@ struct LocalScanner : PostWalker<LocalScanner> {
       return;
     }
     // an integer var, worth processing
-    auto* value = Properties::getFallthrough(curr->value);
+    auto* value = Properties::getFallthrough(
+      curr->value, passOptions, getModule()->features);
     auto& info = localInfo[curr->index];
     info.maxBits = std::max(info.maxBits, getMaxBits(value, this));
     auto signExtBits = LocalInfo::kUnknown;
@@ -289,7 +293,8 @@ struct OptimizeInstructions
   void doWalkFunction(Function* func) {
     // first, scan locals
     {
-      LocalScanner scanner(localInfo);
+      LocalScanner scanner(localInfo, getPassOptions());
+      scanner.setModule(getModule());
       scanner.walkFunction(func);
     }
     // main walk
@@ -347,7 +352,9 @@ struct OptimizeInstructions
         Index extraShifts;
         auto bits = Properties::getAlmostSignExtBits(binary, extraShifts);
         if (extraShifts == 0) {
-          if (auto* load = Properties::getFallthrough(ext)->dynCast<Load>()) {
+          if (auto* load =
+                Properties::getFallthrough(ext, getPassOptions(), features)
+                  ->dynCast<Load>()) {
             // pattern match a load of 8 bits and a sign extend using a shl of
             // 24 then shr_s of 24 as well, etc.
             if (LoadUtils::canBeSigned(load) &&
@@ -984,6 +991,11 @@ private:
     } else if (auto* select = boolean->dynCast<Select>()) {
       select->ifTrue = optimizeBoolean(select->ifTrue);
       select->ifFalse = optimizeBoolean(select->ifFalse);
+    } else if (auto* tryy = boolean->dynCast<Try>()) {
+      if (tryy->type == Type::i32) {
+        tryy->body = optimizeBoolean(tryy->body);
+        tryy->catchBody = optimizeBoolean(tryy->catchBody);
+      }
     }
     // TODO: recurse into br values?
     return boolean;
diff --git a/src/passes/Precompute.cpp b/src/passes/Precompute.cpp
index 21393c1cf..3a886166c 100644
--- a/src/passes/Precompute.cpp
+++ b/src/passes/Precompute.cpp
@@ -327,7 +327,8 @@ private:
           continue; // already known constant
         }
         auto value = setValues[set] =
-          precomputeValue(Properties::getFallthrough(set->value));
+          precomputeValue(Properties::getFallthrough(
+            set->value, getPassOptions(), getModule()->features));
         if (value.isConcrete()) {
           for (auto* get : localGraph.setInfluences[set]) {
             work.insert(get);