this.a = 0;

function f(y) {
  // Direct eval to make an extensible environment. Variables lookups within
  // nested environments are now dynamic.
  eval("");

  {
    // Block lexical environment whose shape guard we want to omit.
    let w = y;

    function g() {
      // BindName "a"                # ENV
      // Dup                         # ENV ENV
      // GetBoundName "a"            # ENV ENV.a
      // GetAliasedVar "w" (hops = 0, slot = 2) # ENV ENV.a w
      // CheckAliasedLexical "w" (hops = 0, slot = 2) # ENV ENV.a w
      // Add                         # ENV (ENV.a += w)
      // NopIsAssignOp               # ENV (ENV.a += w)
      // SetName "a"                 # (ENV.a += w)
      // Pop                         #
      a += w;
    }

    for (var i = 0; i < 150; ++i) {
      // Introduce a new binding in the global lexical environment which
      // shadows the global property "a".
      if (i === 100) {
        evaluate("let a = 1000");
      }
      g();
    }

    assertEq(a, 1050);
    assertEq(globalThis.a, 100);
  }
}
f(1);