wasm2js: more js optimization (#2050)

* Emit ints as signed, so -1 isn't a big unsigned number.
* x - -c (where c is a constant) is larger than x + c in js (but not wasm)
* +(+x) => +x
* Avoid unnecessary coercions on calls, return, load, etc. - we just need coercions when entering or exiting "wasm" (not internally), and on actual operations that need them.

1 files changed, 4 insertions, 6 deletions

diff --git a/test/wasm2js/switch.2asm.js b/test/wasm2js/switch.2asm.js
index f60adde0f..fd7245dc2 100644
--- a/test/wasm2js/switch.2asm.js
+++ b/test/wasm2js/switch.2asm.js
@@ -139,8 +139,8 @@ function asmFunc(global, env, buffer) {
     $7$hi = i64toi32_i32$5;
     break switch_;
    }
-   i64toi32_i32$5 = 4294967295;
-   $7_1 = 4294967291;
+   i64toi32_i32$5 = -1;
+   $7_1 = -5;
    $7$hi = i64toi32_i32$5;
   }
   i64toi32_i32$5 = $7$hi;
@@ -186,8 +186,6 @@ function asmFunc(global, env, buffer) {
  }
  
  function legalstub$1($0_2, $1_2) {
-  $0_2 = $0_2 | 0;
-  $1_2 = $1_2 | 0;
   var i64toi32_i32$2 = 0, i64toi32_i32$4 = 0, i64toi32_i32$0 = 0, i64toi32_i32$1 = 0, i64toi32_i32$3 = 0, $12 = 0, $13 = 0, $4_1 = 0, $4$hi = 0, $7$hi = 0, $2_2 = 0, $2$hi = 0;
   i64toi32_i32$0 = 0;
   $4_1 = $0_2;
@@ -214,7 +212,7 @@ function asmFunc(global, env, buffer) {
   i64toi32_i32$2 = $7$hi;
   i64toi32_i32$3 = $12;
   i64toi32_i32$2 = i64toi32_i32$1 | i64toi32_i32$2;
-  i64toi32_i32$2 = $1(i64toi32_i32$0 | i64toi32_i32$3, i64toi32_i32$2 | 0) | 0;
+  i64toi32_i32$2 = $1(i64toi32_i32$0 | i64toi32_i32$3, i64toi32_i32$2);
   i64toi32_i32$0 = i64toi32_i32$HIGH_BITS;
   $2_2 = i64toi32_i32$2;
   $2$hi = i64toi32_i32$0;
@@ -235,7 +233,7 @@ function asmFunc(global, env, buffer) {
   }
   setTempRet0($13 | 0);
   i64toi32_i32$2 = $2$hi;
-  return $2_2 | 0;
+  return $2_2;
  }
  
  var FUNCTION_TABLE = [];