wasm2js: Don't remove an | 0 or >>> 0 in a boolean context (#2993)

It is usually fine to do if (x | 0) => if (x) since it just cares if the
value is 0 or not. However, if the cast turns it into 0, then that is
incorrect, which the fuzzer found as

-2147483648 + -2147483648 | 0
(the sum is 2^32, which | 0 is 0).

We can maybe look into doing this in a safe way, but for now
just remove it. It doesn't have a big impact on code size as this
is pretty rare (e.g. the minimal runtime code size test is not
broken by this).

2 files changed, 8 insertions, 8 deletions

diff --git a/test/wasm2js/br_table_temp.2asm.js.opt b/test/wasm2js/br_table_temp.2asm.js.opt
index eba815912..f588a3430 100644
--- a/test/wasm2js/br_table_temp.2asm.js.opt
+++ b/test/wasm2js/br_table_temp.2asm.js.opt
@@ -12619,7 +12619,7 @@ function asmFunc(global, env, buffer) {
  
  function $63($0) {
   $0 = $0 | 0;
-  if ($0 - 1) {
+  if ($0 - 1 | 0) {
    $0 = 9
   } else {
    $0 = 8
diff --git a/test/wasm2js/emscripten.2asm.js.opt b/test/wasm2js/emscripten.2asm.js.opt
index d697fa7c7..35f2958e0 100644
--- a/test/wasm2js/emscripten.2asm.js.opt
+++ b/test/wasm2js/emscripten.2asm.js.opt
@@ -83,34 +83,34 @@ function asmFunc(global, env, buffer) {
   if (HEAPU8[144] < 3) {
    bar()
   }
-  if (bools(314159) >>> 7) {
+  if (bools(314159) >>> 7 | 0) {
    bar()
   }
   if (bools(314159) >> 8) {
    bar()
   }
-  if (~~getf32()) {
+  if (~~getf32() >>> 0) {
    bar()
   }
   if (~~getf32()) {
    bar()
   }
-  if (~~getf64()) {
+  if (~~getf64() >>> 0) {
    bar()
   }
   if (~~getf64()) {
    bar()
   }
-  if ((geti32() + geti32() | 0) + geti32()) {
+  if ((geti32() + geti32() | 0) + geti32() | 0) {
    bar()
   }
-  if (geti32() + (geti32() + geti32() | 0)) {
+  if (geti32() + (geti32() + geti32() | 0) | 0) {
    bar()
   }
-  if (geti32() + geti32() + (geti32() + geti32())) {
+  if (geti32() + geti32() + (geti32() + geti32()) | 0) {
    bar()
   }
-  if (geti32() + geti32() + (geti32() + geti32()) + (geti32() + geti32() + (geti32() + geti32()))) {
+  if (geti32() + geti32() + (geti32() + geti32()) + (geti32() + geti32() + (geti32() + geti32())) | 0) {
    bar()
   }
  }