wasm2js: Stop emitting nan and infinity (#5391)

As noted in #4739, legacy language emitting nan and infinity
exists, with the observation that it can be removed once asm.js
is no longer used and global NaN is available.

This commit removes that asm.js-specific code accordingly.

1 files changed, 6 insertions, 14 deletions

diff --git a/src/emscripten-optimizer/simple_ast.h b/src/emscripten-optimizer/simple_ast.h
index eb43209cc..e4c886dd8 100644
--- a/src/emscripten-optimizer/simple_ast.h
+++ b/src/emscripten-optimizer/simple_ast.h
@@ -919,25 +919,17 @@ struct JSPrinter {
   void printName(Ref node) { emit(node->getCString()); }
 
   static char* numToString(double d, bool finalize = true) {
-    // If this number is NaN or infinite then things are a bit tricky. In JS we
-    // want to eventually use `NaN` and/or `Infinity`, but neither of those
-    // identifiers are valid in asm.js. Instead we have to explicitly import
-    // `NaN` and `Infinity` from the global environment, and those names are
-    // bound locally in an asm function as `nan` and `infinity`.
-    //
-    // TODO: the JS names of `NaN` and `Infinity` should be used once literal
-    // asm.js code isn't generated any more
     if (std::isnan(d)) {
       if (std::signbit(d)) {
-        return (char*)"-nan";
+        return (char*)"-NaN";
       } else {
-        return (char*)"nan";
+        return (char*)"NaN";
       }
     } else if (!std::isfinite(d)) {
       if (std::signbit(d)) {
-        return (char*)"-infinity";
+        return (char*)"-Infinity";
       } else {
-        return (char*)"infinity";
+        return (char*)"Infinity";
       }
     }
     bool neg = d < 0;
@@ -1193,10 +1185,10 @@ struct JSPrinter {
       ensure(1);                  // we temporarily append a 0
       char* curr = buffer + last; // ensure might invalidate
       buffer[used] = 0;
-      if (strstr(curr, "infinity")) {
+      if (strstr(curr, "Infinity")) {
         return;
       }
-      if (strstr(curr, "nan")) {
+      if (strstr(curr, "NaN")) {
         return;
       }
       if (strchr(curr, '.')) {