[wasm][test] Initializer exprs. for element segments

Element segments and tables in tests used an ad-hoc mechanism to
describe the different types of initializer expressions, e.g. an number
which could denote either the value of a constant or the index of a
global. This CL tidies up and generalizes the test infrastructure by
directly using WasmInitExpr in those cases.

Additional changes:
- Introduce WasmElemSegment class.
- Remove obsolete --experimental-wasm-bulk-memory flag from tests.
- Rename WasmInitExpr.type -> kind.
- Remove dependency of wasm-module-builder from mjsunit.js (except in
  assertTraps).

Change-Id: I716254a04ceea9ceb8ac6b848e12e1637f618f0d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2857638
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74368}

test/mjsunit/regress/wasm/regress-1187831.js

@@ -11,7 +11,7 @@ builder.addMemory(16, 32, false, true);
 builder.addType(makeSig([kWasmI32, kWasmI32, kWasmI32], [kWasmI32]));
 builder.addType(makeSig([], []));
 builder.setTableBounds(1, 1);
-builder.addElementSegment(0, 0, false, [0]);
+builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0]);
 // Generate function 1 (out of 1).
 builder.addFunction(undefined, 0 /* sig */)
   .addBodyWithEnd([

test/mjsunit/regress/wasm/regress-739768.js

@@ -24,7 +24,7 @@ let builder1 = new WasmModuleBuilder();
 builder1.setName('module_1');
 builder1.addFunction('main', kSig_i_v).addBody([kExprUnreachable]);
 builder1.addImportedTable('z', 'table');
-builder1.addElementSegment(0, 0, false, [0], true);
+builder1.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0]);
 let module1 = new WebAssembly.Module(builder1.toBuffer());
 let instance1 =
     new WebAssembly.Instance(module1, {z: {table: instance0.exports.table}});

test/mjsunit/regress/wasm/regress-803788.js

@@ -11,7 +11,7 @@ let q_table = builder.addImportedTable("q", "table")
 let q_base = builder.addImportedGlobal("q", "base", kWasmI32);
 let q_fun = builder.addImport("q", "fun", kSig_v_v);
 builder.addType(kSig_i_ii);
-builder.addElementSegment(0, q_base, true, [ q_fun ])
+builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(q_base), [q_fun]);
 let module = new WebAssembly.Module(builder.toBuffer());
 let table = new WebAssembly.Table({
   element: "anyfunc",

test/mjsunit/regress/wasm/regress-817380.js

@@ -19,6 +19,7 @@ const builder2 = new WasmModuleBuilder();
 const mul_import = builder2.addImport('q', 'wasm_mul', kSig_i_ii);
 builder2.addImportedTable('q', 'table');
 const glob_import = builder2.addImportedGlobal('q', 'glob', kWasmI32);
-builder2.addElementSegment(0, glob_import, true, [mul_import]);
+builder2.addActiveElementSegment(0, WasmInitExpr.GlobalGet(glob_import),
+                                 [mul_import]);
 builder2.instantiate(
     {q: {glob: 0, js_div: i => i, wasm_mul: mul, table: table}});

test/mjsunit/regress/wasm/regress-834619.js

@@ -33,7 +33,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
         kExprCallIndirect, 0, kTableZero
       ])
       .exportFunc();
-    builder.addElementSegment(0, 0, false, [0, 1, 1, 0]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0, 1, 1, 0]);
 
     return builder.instantiate({q: {f2: i1.exports.f2, f1: i1.exports.f1}});
   })();

test/mjsunit/regress/wasm/regress-v8-9106.js

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-bulk-memory
-
 // Make sure DCHECK doesn't fire when passive data segment is at the end of the
 // module.
 let bytes = new Uint8Array([

test/mjsunit/wasm/bulk-memory.js

@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-bulk-memory
-
-load("test/mjsunit/wasm/wasm-module-builder.js");
+load('test/mjsunit/wasm/wasm-module-builder.js');
 
 (function TestPassiveDataSegment() {
   const builder = new WasmModuleBuilder();
@@ -29,7 +27,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
 
 function getMemoryInit(mem, segment_data) {
   const builder = new WasmModuleBuilder();
-  builder.addImportedMemory("", "mem", 0);
+  builder.addImportedMemory('', 'mem', 0);
   builder.addPassiveDataSegment(segment_data);
   builder.addFunction('init', kSig_v_iii)
       .addBody([
@@ -160,7 +158,7 @@ function getMemoryFill(mem) {
 (function TestElemDropActive() {
   const builder = new WasmModuleBuilder();
   builder.setTableBounds(5, 5);
-  builder.addElementSegment(0, 0, false, [0, 0, 0]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0, 0, 0]);
   builder.addFunction('drop', kSig_v_v)
       .addBody([
         kNumericPrefix, kExprElemDrop,
@@ -185,7 +183,8 @@ function getMemoryFill(mem) {
   assertEquals(0, view[kPageSize - 1]);
 
   // Instantiation fails, memory remains unmodified.
-  assertThrows(() => builder.instantiate({m: {memory}}), WebAssembly.RuntimeError);
+  assertThrows(
+      () => builder.instantiate({m: {memory}}), WebAssembly.RuntimeError);
 
   assertEquals(0, view[kPageSize - 1]);
   // The second segment is not initialized.
@@ -203,14 +202,17 @@ function getMemoryFill(mem) {
   const f = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 42]);
 
   const tableIndex = 0;
-  const isGlobal = false;
-  builder.addElementSegment(tableIndex, 0, isGlobal, [f.index, f.index]);
+  builder.addActiveElementSegment(
+      tableIndex,
+      WasmInitExpr.I32Const(0),
+      [f.index, f.index]);
   builder.addDataSegment(0, [42]);
 
   // Instantiation fails, but still modifies the table. The memory is not
   // modified, since data segments are initialized after element segments.
   assertThrows(
-      () => builder.instantiate({m: {memory, table}}), WebAssembly.RuntimeError);
+      () => builder.instantiate({m: {memory, table}}),
+      WebAssembly.RuntimeError);
 
   assertEquals(0, view[0]);
 })();

test/mjsunit/wasm/compiled-module-serialization.js

@@ -220,7 +220,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
       .exportAs("main");
 
     builder.setTableBounds(kTableSize, kTableSize);
-    builder.addElementSegment(0, 0, false, [f1.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [f1.index]);
     builder.addExportOfKind("table", kExternalTable, 0);
 
     return new WebAssembly.Module(builder.toBuffer());
@@ -241,7 +241,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
     .exportAs("main");
 
   builder.addImportedTable("z", "table", kTableSize, kTableSize);
-  builder.addElementSegment(0, 1, false, [f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(1), [f2.index]);
   var m2_bytes = builder.toBuffer();
   var m2 = new WebAssembly.Module(m2_bytes);
 

test/mjsunit/wasm/externref-table.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-reftypes --experimental-wasm-bulk-memory
+// Flags: --experimental-wasm-reftypes
 
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
@@ -50,7 +50,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   print(arguments.callee.name);
 
   const builder = new WasmModuleBuilder();
-  builder.addDeclarativeElementSegment([null]);
+  builder.addDeclarativeElementSegment([WasmInitExpr.RefNull(kWasmFuncRef)],
+                                        kWasmFuncRef);
   builder.addFunction('drop', kSig_v_v)
       .addBody([kNumericPrefix, kExprElemDrop, 0])
       .exportFunc();
@@ -66,7 +67,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
 
   const builder = new WasmModuleBuilder();
   const table = builder.addTable(kWasmAnyFunc, 10);
-  builder.addDeclarativeElementSegment([null]);
+  builder.addDeclarativeElementSegment([WasmInitExpr.RefNull(kWasmFuncRef)],
+                                       kWasmFuncRef);
   builder.addFunction('init', kSig_v_v)
       .addBody([
         kExprI32Const, 0, kExprI32Const, 0, kExprI32Const, 1, kNumericPrefix,

test/mjsunit/wasm/import-table.js

@@ -41,8 +41,8 @@ let kTableSize = 50;
     let f17 = addConstFunc(builder, 17);
     builder.addExport("f15", f15);
     builder.addExport("f17", f17);
-    builder.addElementSegment(0, 15, false, [f15]);
-    builder.addElementSegment(0, 1, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(15), [f15]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(1), [call.index]);
 
     var mod1 = builder.toModule();
   }
@@ -62,10 +62,10 @@ let kTableSize = 50;
         ])
         .exportAs("call");
     let f26 = addConstFunc(builder, 26);
-    builder.addElementSegment(0, 17, false, [f17]);
-    builder.addElementSegment(0, 21, false, [f21]);
-    builder.addElementSegment(0, 26, false, [f26]);
-    builder.addElementSegment(0, 5, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(17), [f17]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(21), [f21]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(26), [f26]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(5), [call.index]);
 
     var mod2 = builder.toModule();
   }
@@ -112,8 +112,8 @@ function addConstFuncUsingGlobal(builder, val) {
     let f18 = addConstFuncUsingGlobal(builder, 18);
     builder.addExport("f14", f14);
     builder.addExport("f18", f18);
-    builder.addElementSegment(0, 14, false, [f14]);
-    builder.addElementSegment(0, 1, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(14), [f14]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(1), [call.index]);
 
     var mod1 = builder.toModule();
   }
@@ -133,10 +133,10 @@ function addConstFuncUsingGlobal(builder, val) {
         ])
         .exportAs("call");
     let f28 = addConstFuncUsingGlobal(builder, 28);
-    builder.addElementSegment(0, 18, false, [f18]);
-    builder.addElementSegment(0, 22, false, [f22]);
-    builder.addElementSegment(0, 28, false, [f28]);
-    builder.addElementSegment(0, 5, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(18), [f18]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(22), [f22]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(28), [f28]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(5), [call.index]);
 
     var mod2 = builder.toModule();
   }
@@ -192,8 +192,8 @@ function addConstFuncUsingMemory(builder, val) {
     let f19 = addConstFuncUsingMemory(builder, 19);
     builder.addExport("f13", f13);
     builder.addExport("f19", f19);
-    builder.addElementSegment(0, 13, false, [f13]);
-    builder.addElementSegment(0, 1, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(13), [f13]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(1), [call.index]);
 
     var mod1 = builder.toModule();
   }
@@ -215,10 +215,10 @@ function addConstFuncUsingMemory(builder, val) {
         ])
         .exportAs("call");
     let f29 = addConstFuncUsingMemory(builder, 29);
-    builder.addElementSegment(0, 19, false, [f19]);
-    builder.addElementSegment(0, 23, false, [f23]);
-    builder.addElementSegment(0, 29, false, [f29]);
-    builder.addElementSegment(0, 5, false, [call.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(19), [f19]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(23), [f23]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(29), [f29]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(5), [call.index]);
 
     var mod2 = builder.toModule();
   }

test/mjsunit/wasm/indirect-call-non-zero-table.js

@@ -67,11 +67,12 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
     .exportAs('return_call_invalid_sig');
 
   // We want to crash if we call through the table with index 0.
-  builder.addElementSegment(placeholder, 0, false,
+  builder.addActiveElementSegment(placeholder, WasmInitExpr.I32Const(0),
     [f_unreachable, f_unreachable, f_unreachable]);
-  builder.addElementSegment(table1, 0, false, [f1, f2, f3]);
+  builder.addActiveElementSegment(table1, WasmInitExpr.I32Const(0),
+                                  [f1, f2, f3]);
   // Keep one slot in table2 uninitialized. We should trap if we call it.
-  builder.addElementSegment(table2, 1, false,
+  builder.addActiveElementSegment(table2, WasmInitExpr.I32Const(1),
     [f_unreachable, f_unreachable, f4, f5]);
 
   const instance = builder.instantiate();
@@ -126,7 +127,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
       kExprCallIndirect, sig_index, t1])
     .exportAs('call');
 
-  builder.addElementSegment(t1, g, true, [f1.index]);
+  builder.addActiveElementSegment(t1, WasmInitExpr.GlobalGet(g), [f1.index]);
   const base1 = 3;
   const base2 = 5;
 
@@ -162,14 +163,16 @@ function js_div(a, b) { return (a / b) | 0; }
 
   let div = builder.addImport("q", "js_div", kSig_i_ii);
   builder.addImportedTable("q", "placeholder", kTableSize, kTableSize);
-  let table_index = builder.addImportedTable("q", "table", kTableSize, kTableSize);
+  let table_index = builder.addImportedTable("q", "table", kTableSize,
+                                             kTableSize);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
 
   let sig_index = builder.addType(kSig_i_ii);
   builder.addFunction("placeholder", sig_index)
     .addBody([kExprLocalGet, 0]);
 
-  builder.addElementSegment(table_index, g, true, [div]);
+  builder.addActiveElementSegment(table_index, WasmInitExpr.GlobalGet(g),
+                                  [div]);
   builder.addFunction("main", kSig_i_ii)
     .addBody([
       kExprI32Const, 55,  // --

test/mjsunit/wasm/indirect-calls.js

@@ -169,7 +169,8 @@ function AddFunctions(builder) {
       .exportAs("main");
 
     builder.setTableBounds(length, length);
-    builder.addElementSegment(0, base, false, [f.add.index, f.sub.index, f.mul.index]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(base),
+                                    [f.add.index, f.sub.index, f.mul.index]);
 
     return builder.instantiate();
   }
@@ -207,7 +208,8 @@ function AddFunctions(builder) {
 
   builder.setTableBounds(10, 10);
   var g = builder.addImportedGlobal("fff", "base", kWasmI32);
-  builder.addElementSegment(0, g, true, [f.mul.index, f.add.index, f.sub.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g),
+                                  [f.mul.index, f.add.index, f.sub.index]);
 
   var module = new WebAssembly.Module(builder.toBuffer());
 

test/mjsunit/wasm/indirect-tables.js

@@ -50,8 +50,8 @@ function js_div(a, b) { return (a / b) | 0; }
 
   builder.setTableBounds(10, 10);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
-  builder.addElementSegment(
-      0, g, true, [f.mul.index, f.add.index, f.sub.index, d]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g),
+                                  [f.mul.index, f.add.index, f.sub.index, d]);
   builder.addExportOfKind("table", kExternalTable, 0);
 
   let module = new WebAssembly.Module(builder.toBuffer());
@@ -109,8 +109,8 @@ function js_div(a, b) { return (a / b) | 0; }
   let f = AddFunctions(builder);
   builder.setTableBounds(kTableSize, kTableSize);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
-  builder.addElementSegment(
-      0, g, true, [f.mul.index, f.add.index, f.sub.index, d]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g),
+                                  [f.mul.index, f.add.index, f.sub.index, d]);
   builder.addExportOfKind("table", kExternalTable, 0);
 
   let m1 = new WebAssembly.Module(builder.toBuffer());
@@ -179,8 +179,8 @@ function js_div(a, b) { return (a / b) | 0; }
   builder.addImportedTable("q", "table", kTableSize, kTableSize);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
   let f = AddFunctions(builder);
-  builder.addElementSegment(
-      0, g, true, [f.mul.index, f.add.index, f.sub.index, d]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g),
+                                  [f.mul.index, f.add.index, f.sub.index, d]);
   builder.addFunction("main", kSig_i_ii)
     .addBody([
       kExprI32Const, 55,  // --
@@ -256,7 +256,7 @@ function js_div(a, b) { return (a / b) | 0; }
       kExprLocalGet, 0,
       kExprCallIndirect, sig_index, kTableZero])  // --
     .exportAs("main");
-  builder.addElementSegment(0, g, true, [f.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g), [f.index]);
 
   let module = new WebAssembly.Module(builder.toBuffer());
 
@@ -297,7 +297,7 @@ function js_div(a, b) { return (a / b) | 0; }
     .exportAs("main");
 
   builder.setTableBounds(kTableSize, kTableSize);
-  builder.addElementSegment(0, 0, false, [f1.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [f1.index]);
   builder.addExportOfKind("table", kExternalTable, 0);
 
   var m1 = new WebAssembly.Module(builder.toBuffer());
@@ -316,7 +316,7 @@ function js_div(a, b) { return (a / b) | 0; }
     .exportAs("main");
 
   builder.addImportedTable("z", "table", kTableSize, kTableSize);
-  builder.addElementSegment(0, 1, false, [f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(1), [f2.index]);
 
   var m2 = new WebAssembly.Module(builder.toBuffer());
 
@@ -411,7 +411,7 @@ function js_div(a, b) { return (a / b) | 0; }
       kExprLocalGet, 0,
       kExprCallIndirect, sig_index, kTableZero])  // --
     .exportAs("main");
-  builder.addElementSegment(0, g, true, [g]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g), [g]);
   let module = new WebAssembly.Module(builder.toBuffer());
 
   var instances = [];
@@ -542,7 +542,8 @@ function js_div(a, b) { return (a / b) | 0; }
       let offset = i + 1;
       let len = i + 2;
       let index = indexes[i];
-      builder.addElementSegment(0, offset, false, new Array(len).fill(index));
+      builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                      new Array(len).fill(index));
     }
 
     let instance = builder.instantiate();
@@ -586,7 +587,7 @@ function js_div(a, b) { return (a / b) | 0; }
   builder1.setName('module_1');
   builder1.addFunction('f', kSig_i_i).addBody([kExprLocalGet, 0]);
   builder1.addImportedTable('z', 'table');
-  builder1.addElementSegment(0, 0, false, [0]);
+  builder1.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0]);
   let module1 = new WebAssembly.Module(builder1.toBuffer());
   let instance1 =
       new WebAssembly.Instance(module1, {z: {table: instance0.exports.table}});
@@ -622,9 +623,10 @@ function js_div(a, b) { return (a / b) | 0; }
   let instance1 = new WebAssembly.Instance(module1, {'':{memory:mem_1}});
 
   builder = new WasmModuleBuilder();
-  builder.addFunction('main', kSig_i_v).addBody([kExprI32Const, 0, kExprI32LoadMem, 0, 0]);
+  builder.addFunction('main', kSig_i_v)
+         .addBody([kExprI32Const, 0, kExprI32LoadMem, 0, 0]);
   builder.addImportedTable('', 'table');
-  builder.addElementSegment(0, 0, false, [0]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0]);
   builder.addImportedMemory('', 'memory', 1);
 
 
@@ -732,7 +734,7 @@ function js_div(a, b) { return (a / b) | 0; }
 
   builder.setTableBounds(10, 10);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
-  builder.addElementSegment(0, g, true, [j, w]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g), [j, w]);
 
   let module = new WebAssembly.Module(builder.toBuffer());
   for (var i = 0; i < 5; i++) {
@@ -781,11 +783,12 @@ function js_div(a, b) { return (a / b) | 0; }
     .exportAs("main");
 
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
-  builder.addElementSegment(0, g, true, [j, w]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g), [j, w]);
 
   let module = new WebAssembly.Module(builder.toBuffer());
   for (var i = 0; i < 5; i++) {
-    let instance = new WebAssembly.Instance(module, {q: {base: i, js_div: js_div, wasm_mul: wasm_mul, table: table}});
+    let instance = new WebAssembly.Instance(
+      module, {q: {base: i, js_div: js_div, wasm_mul: wasm_mul, table: table}});
     let j = i + 1;
 
     assertEquals((44/j)|0, instance.exports.main(j, i+0));
@@ -821,7 +824,7 @@ function js_div(a, b) { return (a / b) | 0; }
         kExprCallIndirect, 0, kTableZero
       ])
       .exportFunc();
-    builder.addElementSegment(0, 0, false, [0, 1, 1, 0]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0, 1, 1, 0]);
 
     return builder.instantiate({q: {f2: i1.exports.f2, f1: i1.exports.f1}});
   })();
@@ -884,7 +887,7 @@ function js_div(a, b) { return (a / b) | 0; }
       ])
       .exportFunc();
     builder.exportMemoryAs("memory");
-    builder.addElementSegment(0, 0, false, [0, 1, 2, 3]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0, 1, 2, 3]);
     var instance = builder.instantiate({q: {f1: f100, f2: f200, f3: f300}});
     setMemI32(instance, 0, 5000000);
     setMemI32(instance, 4, 6000000);

test/mjsunit/wasm/multi-table-element-section.js

@@ -32,7 +32,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
     const f2 = builder_for_import.addFunction('f2', kSig_i_v)
       .addBody([kExprI32Const, value2]).index;
 
-    builder_for_import.addElementSegment(t1, offset1, false, [f1, f2]);
+    builder_for_import.addActiveElementSegment(t1, WasmInitExpr.I32Const(offset1),
+                                         [f1, f2]);
     const instance_for_import = builder_for_import.instantiate();
     const table1 = instance_for_import.exports.table;
     assertEquals(value1, table1.get(offset1)());
@@ -55,11 +56,12 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
     .addBody([kExprI32Const, value5]).index;
 
 
-  builder.addElementSegment(t2, offset2, false, [f3, f4]);
-  builder.addElementSegment(t3, offset3, false, [f5, f4]);
-  builder.addElementSegment(t4, offset4, false, [f3, f5]);
+  builder.addActiveElementSegment(t2, WasmInitExpr.I32Const(offset2), [f3, f4]);
+  builder.addActiveElementSegment(t3, WasmInitExpr.I32Const(offset3), [f5, f4]);
+  builder.addActiveElementSegment(t4, WasmInitExpr.I32Const(offset4), [f3, f5]);
   // Add one more overlapping offset
-  builder.addElementSegment(t4, offset4 + 1, false, [f4, f3]);
+  builder.addActiveElementSegment(t4, WasmInitExpr.I32Const(offset4 + 1),
+                                  [f4, f3]);
 
   const instance = builder.instantiate(instance_for_import);
   // table2 == table1

test/mjsunit/wasm/reference-tables.js

@@ -115,7 +115,8 @@ load('test/mjsunit/wasm/wasm-module-builder.js');
           .addBody([kExprLocalGet, 0, kExprLocalGet, 1, kExprI32Sub])
           .exportFunc();
 
-  var table = builder.addTable(wasmRefType(binary_type), 3, 3, addition.index);
+  var table = builder.addTable(wasmRefType(binary_type), 3, 3,
+                               WasmInitExpr.RefFunc(addition.index));
 
   builder.addFunction('init', kSig_v_v)
       .addBody([

test/mjsunit/wasm/return-calls.js

@@ -140,7 +140,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   // Arbitrary location in the table.
   const tableIndex = 3;
 
-  builder.addElementSegment(0, tableIndex,false,[pick]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(tableIndex),[pick]);
 
   let main = builder.addFunction("main", kSig_i_iii)
         .addBody([

test/mjsunit/wasm/table-access.js

@@ -117,8 +117,10 @@ const dummy_func = exports.set_table_func1;
 
   const offset1 = 3;
   const offset2 = 9;
-  builder.addElementSegment(t1, offset1, false, [f1.index, f2.index]);
-  builder.addElementSegment(t2, offset2, false, [f3.index, f1.index]);
+  builder.addActiveElementSegment(t1, WasmInitExpr.I32Const(offset1),
+                                  [f1.index, f2.index]);
+  builder.addActiveElementSegment(t2, WasmInitExpr.I32Const(offset2),
+                                  [f3.index, f1.index]);
 
   const instance = builder.instantiate();
 

test/mjsunit/wasm/table-copy-externref.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-bulk-memory --experimental-wasm-reftypes
+// Flags: --experimental-wasm-reftypes
 
 load('test/mjsunit/wasm/wasm-module-builder.js');
 

test/mjsunit/wasm/table-copy.js

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --experimental-wasm-bulk-memory
-
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 function addFunction(builder, k) {

test/mjsunit/wasm/table-get.js

@@ -11,7 +11,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f2.index]);
 
   const instance = builder.instantiate();
 
@@ -27,7 +28,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22])
                     .exportAs("f2");
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f2.index]);
 
   const instance = builder.instantiate();
 
@@ -42,8 +44,10 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f2.index]);
-  builder.addElementSegment(0, offset + 1, false, [f1.index, f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f2.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset + 1),
+                                  [f1.index, f2.index]);
 
   const instance = builder.instantiate();
 
@@ -55,10 +59,12 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   print(arguments.callee.name);
   const builder = new WasmModuleBuilder();
   const table = builder.addTable(kWasmAnyFunc, 20).exportAs("table");
-  const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]).exportAs("f1");
+  const f1 = builder.addFunction('f', kSig_i_v)
+                    .addBody([kExprI32Const, 11]).exportAs("f1");
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f1.index, f1.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f1.index, f1.index]);
 
   const instance = builder.instantiate();
 
@@ -78,7 +84,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f1.index, f1.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f1.index, f1.index]);
 
   const instance = builder.instantiate();
 
@@ -97,7 +104,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f1.index, f1.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f1.index, f1.index]);
 
   const instance = builder.instantiate();
   assertEquals(null, instance.exports.table.get(offset - 1));
@@ -111,7 +119,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const f2 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 22]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, f1.index, f1.index]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, f1.index, f1.index]);
 
   const instance = builder.instantiate();
   assertThrows(() => instance.exports.table.get(size + 3), RangeError);
@@ -125,7 +134,8 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const import1 = builder.addImport("q", "fun", kSig_i_ii);
   const f1 = builder.addFunction('f', kSig_i_v).addBody([kExprI32Const, 11]);
   const offset = 3;
-  builder.addElementSegment(0, offset, false, [f1.index, import1]);
+  builder.addActiveElementSegment(0, WasmInitExpr.I32Const(offset),
+                                  [f1.index, import1]);
 
   const instance = builder.instantiate({q: {fun: () => 33}});
   assertEquals(33, instance.exports.table.get(offset + 1)());

test/mjsunit/wasm/table-grow.js

@@ -132,7 +132,7 @@ let id = (() => {  // identity exported function
 
   builder.addImportedTable("q", "table", 5, 32);
   let g = builder.addImportedGlobal("q", "base", kWasmI32);
-  builder.addElementSegment(0, g, true,
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g),
       [funcs.mul.index, funcs.add.index, funcs.sub.index]);
   builder.addExportOfKind("table", kExternalTable, 0);
   let module = new WebAssembly.Module(builder.toBuffer());
@@ -179,7 +179,7 @@ let id = (() => {  // identity exported function
   let t = builder.addImport("q", "exp_ten", sig_i_v);
 
   builder.setTableBounds(7, 35);
-  builder.addElementSegment(0, g1, true, [a, i, t]);
+  builder.addActiveElementSegment(0, WasmInitExpr.GlobalGet(g1), [a, i, t]);
 
   builder.addExportOfKind("table", kExternalTable, 0);
   let module = new WebAssembly.Module(builder.toBuffer());
@@ -212,7 +212,8 @@ let id = (() => {  // identity exported function
   let funcs = addFunctions(builder1);
 
   builder1.addImportedTable("q", "table", 6, 36);
-  builder1.addElementSegment(0, g, true,
+  builder1.addActiveElementSegment(
+      0, WasmInitExpr.GlobalGet(g),
       [funcs.mul.index, funcs.add.index, funcs.sub.index]);
   let module1 = new WebAssembly.Module(builder1.toBuffer());
 
@@ -228,7 +229,7 @@ let id = (() => {  // identity exported function
   }
 
   for (let i = 3; i < 10; i++) {
-    let instance1 = new WebAssembly.Instance(module1, {q: {base: i, table: table}});
+    new WebAssembly.Instance(module1, {q: {base: i, table: table}});
     verifyTableFuncs(i);
     var prev = table.length;
     assertEquals(prev,     table.grow(3));
@@ -264,7 +265,7 @@ let id = (() => {  // identity exported function
         kExprLocalGet, 0,
         kExprCallIndirect, index_i_ii, kTableZero])
       .exportAs("main");
-    builder.addElementSegment(0, 0, false, [0]);
+    builder.addActiveElementSegment(0, WasmInitExpr.I32Const(0), [0]);
     return new WebAssembly.Module(builder.toBuffer());
   }
 

test/mjsunit/wasm/wasm-module-builder.js

@@ -24,7 +24,9 @@ function bytes(...input) {
   for (let i = 0; i < input.length; i++) {
     let val = input[i];
     if (typeof val == 'string') {
-      assertEquals(1, val.length, 'string inputs must have length 1');
+      if (val.length != 1) {
+        throw new Error('string inputs must have length 1');
+      }
       val = val.charCodeAt(0);
     }
     view[i] = val | 0;
@@ -122,11 +124,11 @@ function wasmRefType(index) {
 let kWasmI31Ref = 0x6a;
 let kWasmRttWithDepth = 0x69;
 function wasmRtt(index, depth) {
-  return { opcode: kWasmRttWithDepth, index: index, depth: depth };
+  return {opcode: kWasmRttWithDepth, index: index, depth: depth};
 }
 let kWasmRtt = 0x68;
 function wasmRttNoDepth(index) {
-  return { opcode: kWasmRtt, index: index };
+  return {opcode: kWasmRtt, index: index};
 }
 let kWasmDataRef = 0x67;
 
@@ -824,20 +826,21 @@ let kTrapElemSegmentDropped = 10;
 let kTrapRethrowNull = 11;
 
 let kTrapMsgs = [
-  'unreachable',
-  'memory access out of bounds',
-  'divide by zero',
-  'divide result unrepresentable',
-  'remainder by zero',
-  'float unrepresentable in integer range',
-  'table index is out of bounds',
-  'null function or function signature mismatch',
-  'operation does not support unaligned accesses',
-  'data segment has been dropped',
-  'element segment has been dropped',
-  'rethrowing null value'
+  'unreachable',                                    // --
+  'memory access out of bounds',                    // --
+  'divide by zero',                                 // --
+  'divide result unrepresentable',                  // --
+  'remainder by zero',                              // --
+  'float unrepresentable in integer range',         // --
+  'table index is out of bounds',                   // --
+  'null function or function signature mismatch',   // --
+  'operation does not support unaligned accesses',  // --
+  'data segment has been dropped',                  // --
+  'element segment has been dropped',               // --
+  'rethrowing null value'                           // --
 ];
 
+// This requires test/mjsunit/mjsunit.js.
 function assertTraps(trap, code) {
   assertThrows(code, WebAssembly.RuntimeError, kTrapMsgs[trap]);
 }
@@ -940,7 +943,7 @@ class Binary {
   }
 
   emit_init_expr(expr) {
-    switch (expr.type) {
+    switch (expr.kind) {
       case kExprGlobalGet:
         this.emit_u8(kExprGlobalGet);
         this.emit_u32v(expr.value);
@@ -1070,28 +1073,28 @@ class WasmFunctionBuilder {
 
 class WasmInitExpr {
   static I32Const(value) {
-    return {type: kExprI32Const, value: value};
+    return {kind: kExprI32Const, value: value};
   }
   static I64Const(value) {
-    return {type: kExprI64Const, value: value};
+    return {kind: kExprI64Const, value: value};
   }
   static F32Const(value) {
-    return {type: kExprF32Const, value: value};
+    return {kind: kExprF32Const, value: value};
   }
   static F64Const(value) {
-    return {type: kExprF64Const, value: value};
+    return {kind: kExprF64Const, value: value};
   }
   static S128Const(value) {
-    return {type: kSimdPrefix, value: value};
+    return {kind: kSimdPrefix, value: value};
   }
   static GlobalGet(index) {
-    return {type: kExprGlobalGet, value: index};
+    return {kind: kExprGlobalGet, value: index};
   }
   static RefFunc(index) {
-    return {type: kExprRefFunc, value: index};
+    return {kind: kExprRefFunc, value: index};
   }
   static RefNull(type) {
-    return {type: kExprRefNull, value: type};
+    return {kind: kExprRefNull, value: type};
   }
 
   static defaultFor(type) {
@@ -1130,14 +1133,14 @@ class WasmGlobalBuilder {
 }
 
 class WasmTableBuilder {
-  constructor(module, type, initial_size, max_size, init_func_index) {
+  constructor(module, type, initial_size, max_size, init_expr) {
     this.module = module;
     this.type = type;
     this.initial_size = initial_size;
-    this.has_max = max_size != undefined;
+    this.has_max = max_size !== undefined;
     this.max_size = max_size;
-    this.init_func_index = init_func_index;
-    this.has_init = init_func_index != undefined;
+    this.init_expr = init_expr;
+    this.has_init = init_expr !== undefined;
   }
 
   exportAs(name) {
@@ -1148,14 +1151,17 @@ class WasmTableBuilder {
 }
 
 function makeField(type, mutability) {
-  assertEquals(
-      'boolean', typeof mutability, 'field mutability must be boolean');
+  if ((typeof mutability) != 'boolean') {
+    throw new Error('field mutability must be boolean');
+  }
   return {type: type, mutability: mutability};
 }
 
 class WasmStruct {
   constructor(fields) {
-    assertTrue(Array.isArray(fields), 'struct fields must be an array');
+    if (!Array.isArray(fields)) {
+      throw new Error('struct fields must be an array');
+    }
     this.fields = fields;
   }
 }
@@ -1166,6 +1172,41 @@ class WasmArray {
   }
 }
 
+class WasmElemSegment {
+  constructor(table, offset, type, elements, is_decl) {
+    this.table = table;
+    this.offset = offset;
+    this.type = type;
+    this.elements = elements;
+    this.is_decl = is_decl;
+    // Invariant checks.
+    if ((table === undefined) != (offset === undefined)) {
+      throw new Error("invalid element segment");
+    }
+    for (let elem of elements) {
+      if (((typeof elem) == 'number') != (type === undefined)) {
+        throw new Error("invalid element");
+      }
+    }
+  }
+
+  is_active() {
+    return this.table !== undefined;
+  }
+
+  is_passive() {
+    return this.table === undefined && !this.is_decl;
+  }
+
+  is_declarative() {
+    return this.table === undefined && this.is_decl;
+  }
+
+  expressions_as_elements() {
+    return this.type !== undefined;
+  }
+}
+
 class WasmModuleBuilder {
   constructor() {
     this.types = [];
@@ -1259,7 +1300,7 @@ class WasmModuleBuilder {
   }
 
   addGlobal(type, mutable, init) {
-    if (init == undefined) init = WasmInitExpr.defaultFor(type);
+    if (init === undefined) init = WasmInitExpr.defaultFor(type);
     let glob = new WasmGlobalBuilder(this, type, mutable, init);
     glob.index = this.globals.length + this.num_imported_globals;
     this.globals.push(glob);
@@ -1267,13 +1308,13 @@ class WasmModuleBuilder {
   }
 
   addTable(
-      type, initial_size, max_size = undefined, init_func_index = undefined) {
+      type, initial_size, max_size = undefined, init_expr = undefined) {
     if (type == kWasmI32 || type == kWasmI64 || type == kWasmF32 ||
         type == kWasmF64 || type == kWasmS128 || type == kWasmVoid) {
       throw new Error('Tables must be of a reference type');
     }
     let table = new WasmTableBuilder(
-        this, type, initial_size, max_size, init_func_index);
+        this, type, initial_size, max_size, init_expr);
     table.index = this.tables.length + this.num_imported_tables;
     this.tables.push(table);
     return table;
@@ -1379,7 +1420,7 @@ class WasmModuleBuilder {
   }
 
   addExportOfKind(name, kind, index) {
-    if (index == undefined && kind != kExternalTable &&
+    if (index === undefined && kind != kExternalTable &&
         kind != kExternalMemory) {
       throw new Error(
           'Index for exports other than tables/memories must be provided');
@@ -1415,28 +1456,29 @@ class WasmModuleBuilder {
     this.exports.push({name: name, kind: kExternalMemory, index: 0});
   }
 
-  addElementSegment(table, base, is_global, array) {
-    this.element_segments.push({
-      table: table,
-      base: base,
-      is_global: is_global,
-      array: array,
-      is_active: true,
-      is_declarative: false
-    });
-    return this;
+  // {offset} is an initializer expression.
+  // If {type} is undefined, then {elements} are function indices. Otherwise,
+  // they are initializer expressions.
+  addActiveElementSegment(table, offset, elements, type) {
+    this.element_segments.push(
+        new WasmElemSegment(table, offset, type, elements, false));
+    return this.element_segments.length - 1;
   }
 
-  addPassiveElementSegment(array) {
+  // If {type} is undefined, then {elements} are function indices. Otherwise,
+  // they are initializer expressions.
+  addPassiveElementSegment(elements, type) {
     this.element_segments.push(
-        {array: array, is_active: false, is_declarative: false});
-    return this;
+      new WasmElemSegment(undefined, undefined, type, elements, false));
+    return this.element_segments.length - 1;
   }
 
-  addDeclarativeElementSegment(array) {
+  // If {type} is undefined, then {elements} are function indices. Otherwise,
+  // they are initializer expressions.
+  addDeclarativeElementSegment(elements, type) {
     this.element_segments.push(
-        {array: array, is_active: false, is_declarative: true});
-    return this;
+      new WasmElemSegment(undefined, undefined, type, elements, true));
+    return this.element_segments.length - 1;
   }
 
   appendToTable(array) {
@@ -1455,7 +1497,7 @@ class WasmModuleBuilder {
     if (table.has_max && table_size > table.max_size) {
       table.max_size = table_size;
     }
-    return this.addElementSegment(0, base, false, array);
+    return this.addActiveElementSegment(0, WasmInitExpr.I32Const(base), array);
   }
 
   setTableBounds(min, max = undefined) {
@@ -1572,9 +1614,7 @@ class WasmModuleBuilder {
           section.emit_u32v(table.initial_size);
           if (table.has_max) section.emit_u32v(table.max_size);
           if (table.has_init) {
-            section.emit_u8(kExprRefFunc);
-            section.emit_u32v(table.init_func_index);
-            section.emit_u8(kExprEnd);
+            section.emit_init_expr(table.init_expr);
           }
         }
       });
@@ -1587,8 +1627,9 @@ class WasmModuleBuilder {
         section.emit_u8(1);  // one memory entry
         const has_max = wasm.memory.max !== undefined;
         if (wasm.memory.is_memory64) {
-          assertFalse(
-              wasm.memory.shared, 'sharing memory64 is not supported (yet)');
+          if (wasm.memory.shared) {
+            throw new Error('sharing memory64 is not supported (yet)');
+          }
           section.emit_u8(
               has_max ? kLimitsMemory64WithMaximum : kLimitsMemory64NoMaximum);
           section.emit_u64v(wasm.memory.min);
@@ -1662,62 +1703,65 @@ class WasmModuleBuilder {
     if (wasm.element_segments.length > 0) {
       if (debug) print('emitting element segments @ ' + binary.length);
       binary.emit_section(kElementSectionCode, section => {
-        var inits = wasm.element_segments;
-        section.emit_u32v(inits.length);
-
-        for (let init of inits) {
-          if (init.is_active) {
-            // Active segment.
-            if (init.table == 0) {
-              section.emit_u32v(kActiveNoIndex);
-            } else {
-              section.emit_u32v(kActiveWithIndex);
-              section.emit_u32v(init.table);
-            }
-            if (init.is_global) {
-              section.emit_u8(kExprGlobalGet);
+        var segments = wasm.element_segments;
+        section.emit_u32v(segments.length);
+
+        for (let segment of segments) {
+          // Emit flag and header.
+          // Each case below corresponds to a flag from
+          // https://webassembly.github.io/spec/core/binary/modules.html#element-section
+          // (not in increasing order).
+          if (segment.is_active()) {
+            if (segment.table == 0 && segment.type === undefined) {
+              if (segment.expressions_as_elements()) {
+                section.emit_u8(0x04);
+                section.emit_init_expr(segment.offset);
+              } else {
+                section.emit_u8(0x00)
+                section.emit_init_expr(segment.offset);
+              }
             } else {
-              section.emit_u8(kExprI32Const);
-            }
-            section.emit_u32v(init.base);
-            section.emit_u8(kExprEnd);
-            if (init.table != 0) {
-              section.emit_u8(kExternalFunction);
-            }
-            section.emit_u32v(init.array.length);
-            for (let index of init.array) {
-              section.emit_u32v(index);
-            }
-          } else if (
-              init.is_declarative &&
-              init.array.every(index => index !== null)) {
-            section.emit_u8(kDeclarative);
-            section.emit_u8(kExternalFunction);
-            section.emit_u32v(init.array.length);
-            for (let index of init.array) {
-              section.emit_u32v(index);
+              if (segment.expressions_as_elements()) {
+                section.emit_u8(0x06);
+                section.emit_u32v(segment.table);
+                section.emit_init_expr(segment.offset);
+                section.emit_type(segment.type);
+              } else {
+                section.emit_u8(0x02);
+                section.emit_u32v(segment.table);
+                section.emit_init_expr(segment.offset);
+                section.emit_u8(kExternalFunction);
+              }
             }
           } else {
-            // Passive or declarative segment with elements.
-            section.emit_u8(
-                init.is_declarative ? kDeclarativeWithElements :
-                                      kPassiveWithElements);  // flags
-            section.emit_u8(kWasmAnyFunc);
-            section.emit_u32v(init.array.length);
-            for (let index of init.array) {
-              if (index === null) {
-                section.emit_u8(kExprRefNull);
-                section.emit_u8(kWasmAnyFunc);
-                section.emit_u8(kExprEnd);
+            if (segment.expressions_as_elements()) {
+              if (segment.is_passive()) {
+                section.emit_u8(0x05);
+              } else {
+                section.emit_u8(0x07);
+              }
+              section.emit_type(segment.type);
+            } else {
+              if (segment.is_passive()) {
+                section.emit_u8(0x01);
               } else {
-                section.emit_u8(kExprRefFunc);
-                section.emit_u32v(index);
-                section.emit_u8(kExprEnd);
+                section.emit_u8(0x03);
               }
+              section.emit_u8(kExternalFunction);
+            }
+          }
+
+          // Emit elements.
+          section.emit_u32v(segment.elements.length);
+          for (let element of segment.elements) {
+            if (segment.expressions_as_elements()) {
+              section.emit_init_expr(element);
+            } else {
+              section.emit_u32v(element);
             }
           }
         }
-      });
+      })
     }
 
     // If there are any passive data segments, add the DataCount section.