[wasm2js] Support nonzero offsets in memory.atomic.wait32 (#5489)

The assertion that the offset is zero does not necessarily hold for code that
uses this instruction via the clang builtin. Add support so that Emscripten
wasm2js tests pass in the presence of such code.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/wasm2js.h b/src/wasm2js.h
index eddb26866..08969b8ba 100644
--- a/src/wasm2js.h
+++ b/src/wasm2js.h
@@ -2989,7 +2989,8 @@ void Wasm2JSGlue::emitSpecialSupport() {
       )";
     } else if (import->base == ABI::wasm2js::ATOMIC_WAIT_I32) {
       out << R"(
-  function wasm2js_atomic_wait_i32(ptr, expected, timeoutLow, timeoutHigh) {
+  function wasm2js_atomic_wait_i32(offset, ptr, expected, timeoutLow, timeoutHigh) {
+    ptr = (ptr + offset) >> 2;
     var timeout = Infinity;
     if (timeoutHigh >= 0) {
       // Convert from nanoseconds to milliseconds
@@ -2997,7 +2998,7 @@ void Wasm2JSGlue::emitSpecialSupport() {
       timeout = ((timeoutLow >>> 0) / 1e6) + timeoutHigh * (4294967296 / 1e6);
     }
     var view = new Int32Array(bufferView.buffer); // TODO cache
-    var result = Atomics.wait(view, ptr >> 2, expected, timeout);
+    var result = Atomics.wait(view, ptr, expected, timeout);
     if (result == 'ok') return 0;
     if (result == 'not-equal') return 1;
     if (result == 'timed-out') return 2;