[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.

Author: tlively

src/abi/js.h

@@ -82,8 +82,9 @@ inline void ensureHelpers(Module* wasm, IString specific = IString()) {
   ensureImport(MEMORY_FILL, {Type::i32, Type::i32, Type::i32}, Type::none);
   ensureImport(MEMORY_COPY, {Type::i32, Type::i32, Type::i32}, Type::none);
   ensureImport(DATA_DROP, {Type::i32}, Type::none);
-  ensureImport(
-    ATOMIC_WAIT_I32, {Type::i32, Type::i32, Type::i32, Type::i32}, Type::i32);
+  ensureImport(ATOMIC_WAIT_I32,
+               {Type::i32, Type::i32, Type::i32, Type::i32, Type::i32},
+               Type::i32);
   ensureImport(
     ATOMIC_RMW_I64,
     {Type::i32, Type::i32, Type::i32, Type::i32, Type::i32, Type::i32},

src/passes/I64ToI32Lowering.cpp

@@ -478,10 +478,10 @@ struct I64ToI32Lowering : public WalkerPass<PostWalker<I64ToI32Lowering>> {
 
   void visitAtomicWait(AtomicWait* curr) {
     // The last parameter is an i64, so we cannot leave it as it is
-    assert(curr->offset == 0);
     replaceCurrent(builder->makeCall(
       ABI::wasm2js::ATOMIC_WAIT_I32,
-      {curr->ptr,
+      {builder->makeConst(int32_t(curr->offset)),
+       curr->ptr,
        curr->expected,
        curr->timeout,
        builder->makeLocalGet(fetchOutParam(curr->timeout), Type::i32)},

src/wasm2js.h

@@ -2989,15 +2989,16 @@ 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
       // Taken from convertI32PairToI53 in emscripten's library_int53.js
       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;

test/passes/remove-non-js-ops.txt

@@ -14,7 +14,7 @@
  (type $f64_=>_none (func (param f64)))
  (type $i32_i32_i32_i32_=>_none (func (param i32 i32 i32 i32)))
  (type $i32_=>_none (func (param i32)))
- (type $i32_i32_i32_i32_=>_i32 (func (param i32 i32 i32 i32) (result i32)))
+ (type $i32_i32_i32_i32_i32_=>_i32 (func (param i32 i32 i32 i32 i32) (result i32)))
  (type $i32_i32_i32_i32_i32_i32_=>_i32 (func (param i32 i32 i32 i32 i32 i32) (result i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $none_=>_none (func))
@@ -28,7 +28,7 @@
  (import "env" "wasm2js_memory_fill" (func $wasm2js_memory_fill (param i32 i32 i32)))
  (import "env" "wasm2js_memory_copy" (func $wasm2js_memory_copy (param i32 i32 i32)))
  (import "env" "wasm2js_data_drop" (func $wasm2js_data_drop (param i32)))
- (import "env" "wasm2js_atomic_wait_i32" (func $wasm2js_atomic_wait_i32 (param i32 i32 i32 i32) (result i32)))
+ (import "env" "wasm2js_atomic_wait_i32" (func $wasm2js_atomic_wait_i32 (param i32 i32 i32 i32 i32) (result i32)))
  (import "env" "wasm2js_atomic_rmw_i64" (func $wasm2js_atomic_rmw_i64 (param i32 i32 i32 i32 i32 i32) (result i32)))
  (import "env" "wasm2js_get_stashed_bits" (func $wasm2js_get_stashed_bits (result i32)))
  (import "env" "wasm2js_trap" (func $wasm2js_trap))

test/wasm2js/atomics_32.2asm.js

@@ -24,15 +24,16 @@
 memorySegments[0] = base64DecodeToExistingUint8Array(new Uint8Array(6), 0, "aGVsbG8s");
 memorySegments[1] = base64DecodeToExistingUint8Array(new Uint8Array(6), 0, "d29ybGQh");
 
-  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
       // Taken from convertI32PairToI53 in emscripten's library_int53.js
       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;
@@ -119,7 +120,7 @@ function asmFunc(imports) {
   Atomics.load(HEAP32, 1028 >> 2) | 0;
   Atomics.store(HEAP32, 100 >> 2, 200);
   i64toi32_i32$0 = -1;
-  wasm2js_atomic_wait_i32(4 | 0, 8 | 0, -1 | 0, i64toi32_i32$0 | 0) | 0;
+  wasm2js_atomic_wait_i32(4 | 0, 8 | 0, 16 | 0, -1 | 0, i64toi32_i32$0 | 0) | 0;
   wasm2js_memory_init(0, 512, 0, 4);
   wasm2js_memory_init(1, 1024, 4, 2);
   Atomics.notify(HEAP32, 4 >> 2, 2);

test/wasm2js/atomics_32.2asm.js.opt

@@ -24,15 +24,16 @@
 memorySegments[0] = base64DecodeToExistingUint8Array(new Uint8Array(6), 0, "aGVsbG8s");
 memorySegments[1] = base64DecodeToExistingUint8Array(new Uint8Array(6), 0, "d29ybGQh");
 
-  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
       // Taken from convertI32PairToI53 in emscripten's library_int53.js
       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;
@@ -117,7 +118,7 @@ function asmFunc(imports) {
   Atomics.load(HEAPU16, 514);
   Atomics.load(HEAP32, 257);
   Atomics.store(HEAP32, 25, 200);
-  wasm2js_atomic_wait_i32(4, 8, -1, -1) | 0;
+  wasm2js_atomic_wait_i32(4, 8, 16, -1, -1) | 0;
   wasm2js_memory_init(0, 512, 0, 4);
   wasm2js_memory_init(1, 1024, 4, 2);
   Atomics.notify(HEAP32, 1, 2);

test/wasm2js/atomics_32.wast

@@ -12,7 +12,7 @@
     (local.set $x (i32.atomic.load16_u (i32.const 1028)))
     (local.set $x (i32.atomic.load (i32.const 1028)))
     (i32.atomic.store (i32.const 100) (i32.const 200))
-    (local.set $x (memory.atomic.wait32 (i32.const 4) (i32.const 8) (i64.const -1)))
+    (local.set $x (memory.atomic.wait32 offset=4 (i32.const 8) (i32.const 16) (i64.const -1)))
     (memory.init 0 (i32.const 512) (i32.const 0) (i32.const 4))
     (memory.init 1 (i32.const 1024) (i32.const 4) (i32.const 2))
     (local.set $x (memory.atomic.notify (i32.const 4) (i32.const 2)))