refactor an optimizeBoolean method

kripken · kripken · commit 3d6b218cc288 · 2016-09-10T16:05:16.000-07:00
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
@@ -214,37 +214,41 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions,
       if (get && get->name == set->name) {
         ExpressionManipulator::nop(curr);
       }
+    } else if (auto* iff = curr->dynCast<If>()) {
+      iff->condition = optimizeBoolean(iff->condition);
     } else if (auto* select = curr->dynCast<Select>()) {
+      select->condition = optimizeBoolean(select->condition);
       auto* condition = select->condition->dynCast<Unary>();
       if (condition && condition->op == EqZInt32) {
-        auto* condition2 = condition->value->dynCast<Unary>();
-        if (condition2 && condition2->op == EqZInt32) {
-          // double eqz
-          select->condition = condition2->value;
-        } else {
-          // flip select, eqz input and flippable
-          EffectAnalyzer ifTrue(select->ifTrue);
-          EffectAnalyzer ifFalse(select->ifFalse);
-          if (!ifTrue.invalidates(ifFalse)) {
-            select->condition = condition->value;
-            std::swap(select->ifTrue, select->ifFalse);
-          }
+        // flip select to remove eqz, if we can reorder
+        EffectAnalyzer ifTrue(select->ifTrue);
+        EffectAnalyzer ifFalse(select->ifFalse);
+        if (!ifTrue.invalidates(ifFalse)) {
+          select->condition = condition->value;
+          std::swap(select->ifTrue, select->ifFalse);
         }
       }
     } else if (auto* br = curr->dynCast<Break>()) {
       if (br->condition) {
-        auto* condition = br->condition->dynCast<Unary>();
-        if (condition && condition->op == EqZInt32) {
-          auto* condition2 = condition->value->dynCast<Unary>();
-          if (condition2 && condition2->op == EqZInt32) {
-            // double eqz
-            br->condition = condition2->value;
-          }
-        }
+        br->condition = optimizeBoolean(br->condition);
       }
     }
     return nullptr;
   }
+
+private:
+
+  Expression* optimizeBoolean(Expression* boolean) {
+    auto* condition = boolean->dynCast<Unary>();
+    if (condition && condition->op == EqZInt32) {
+      auto* condition2 = condition->value->dynCast<Unary>();
+      if (condition2 && condition2->op == EqZInt32) {
+        // double eqz
+        return condition2->value;
+      }
+    }
+    return boolean;
+  }
 };
 
 Pass *createOptimizeInstructionsPass() {
diff --git a/src/passes/OptimizeInstructions.wast b/src/passes/OptimizeInstructions.wast
@@ -34,21 +34,6 @@
         (call_import $any.expr (i32.const 1))
       )
     )
-    ;; eqz^2 is eliminatable if the output is boolean (note that for if-else, the above rule handles it in two operations)
-    (block
-      (if
-        (i32.eqz
-          (i32.eqz
-            (call_import $i32.expr (i32.const 0))
-          )
-        )
-        (call_import $any.expr (i32.const 1))
-      )
-      (if
-        (call_import $i32.expr (i32.const 0))
-        (call_import $any.expr (i32.const 1))
-      )
-    )
     ;; equal 0 => eqz
     (block
       (i32.eq
diff --git a/src/passes/OptimizeInstructions.wast.processed b/src/passes/OptimizeInstructions.wast.processed
@@ -34,21 +34,6 @@
 "(call_import $any.expr (i32.const 1))\n"
 ")\n"
 ")\n"
-";; eqz^2 is eliminatable if the output is boolean (note that for if-else, the above rule handles it in two operations)\n"
-"(block\n"
-"(if\n"
-"(i32.eqz\n"
-"(i32.eqz\n"
-"(call_import $i32.expr (i32.const 0))\n"
-")\n"
-")\n"
-"(call_import $any.expr (i32.const 1))\n"
-")\n"
-"(if\n"
-"(call_import $i32.expr (i32.const 0))\n"
-"(call_import $any.expr (i32.const 1))\n"
-")\n"
-")\n"
 ";; equal 0 => eqz\n"
 "(block\n"
 "(i32.eq\n"
