handle negative zero properly in asm2wasm

3 files changed, 13 insertions, 9 deletions

diff --git a/src/asm2wasm.h b/src/asm2wasm.h
index 07e771108..5d88b8f38 100644
--- a/src/asm2wasm.h
+++ b/src/asm2wasm.h
@@ -346,6 +346,9 @@ private:
         assert(isInteger32(num));
         return Literal((int32_t)num);
       }
+      if (ast[1] == PLUS && ast[2][0] == UNARY_PREFIX && ast[2][1] == MINUS && ast[2][2][0] == NUM) {
+        return Literal((double)-ast[2][2][1]->getNumber());
+      }
       if (ast[1] == MINUS && ast[2][0] == UNARY_PREFIX && ast[2][1] == PLUS && ast[2][2][0] == NUM) {
         return Literal((double)-ast[2][2][1]->getNumber());
       }
@@ -785,12 +788,9 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
       return ret;
     } else if (what == UNARY_PREFIX) {
       if (ast[1] == PLUS) {
-        if (ast[2][0] == NUM) {
-          auto ret = allocator.alloc<Const>();
-          ret->value.type = WasmType::f64;
-          ret->value.f64 = ast[2][1]->getNumber();
-          ret->type = ret->value.type;
-          return ret;
+        Literal literal = checkLiteral(ast);
+        if (literal.type != none) {
+          return allocator.alloc<Const>()->set(literal);
         }
         auto ret = process(ast[2]); // we are a +() coercion
         if (ret->type == i32) {
diff --git a/test/unit.asm.js b/test/unit.asm.js
index 5695c3059..7575dfead 100644
--- a/test/unit.asm.js
+++ b/test/unit.asm.js
@@ -75,6 +75,9 @@ function () {
     Math_fround(5.0);
     Math_fround(0.0);
   }
+  function negZero() {
+    return +-0;
+  }
 
   function z() {
   }
diff --git a/test/unit.wast b/test/unit.wast
index 24692ba1c..1f1027556 100644
--- a/test/unit.wast
+++ b/test/unit.wast
@@ -8,9 +8,7 @@
     (local $temp f64)
     (block
       (set_local $temp
-        (f64.convert_s/i32
-          (i32.const -2147483648)
-        )
+        (f64.const -2147483648)
       )
       (set_local $temp
         (f64.const -2147483648)
@@ -247,6 +245,9 @@
       (f32.const 0)
     )
   )
+  (func $negZero (result f64)
+    (f64.const -0)
+  )
   (func $z
     (nop)
   )