v8/test/mjsunit/wasm/multiple-code-spaces.js

// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --allow-natives-syntax --randomize-all-allocations
// Flags: --wasm-far-jump-table --wasm-max-initial-code-space-reservation=1

load('test/mjsunit/wasm/wasm-module-builder.js');

// Instantiate bigger modules, until at least four separate code spaces have
// been allocated.
// Each function calls through many of the previous functions to execute the
// jump table(s) sufficiently.

let num_functions = 50;
while (true) {
  print(`Trying ${num_functions} functions...`);
  if (num_functions > 1e6) {
    throw new Error('We should have hit four code spaces by now');
  }
  const builder = new WasmModuleBuilder();
  builder.addMemory(1, 1, false);
  builder.addFunction('f0', kSig_i_i).addBody([kExprGetLocal, 0]);
  // Generate some code per function to fill the code space.
  // Each function contains a number of loads that will not be executed
  // (inside an "if (i == 0)" block). They increase the code size a bit so we
  // do not need too many functions.
  // Each function f<n> with argument {i} then calls f<n/10> with argument
  // {i + 1} and returns whatever that function returns.
  const body_template = [
    kExprGetLocal, 0, kExprI32Eqz, kExprIf, kWasmStmt,  // if (i == 0)
    kExprGetLocal, 0                                    // get i
  ];
  for (let i = 0; i < 1000; ++i) body_template.push(kExprI32LoadMem, 0, 0);
  body_template.push(
      kExprDrop, kExprEnd,                              // end if
      kExprGetLocal, 0, kExprI32Const, 1, kExprI32Add,  // i + 1
      kExprCallFunction                                 // call f<?>
  );
  for (let i = 1; i < num_functions; ++i) {
    const body = body_template.slice();
    body.push(...wasmSignedLeb(Math.floor(i / 10)));
    builder.addFunction('f' + i, kSig_i_i).addBody(body);
  }
  builder.addExport('f', num_functions - 1);
  const instance = builder.instantiate();
  let expected = 17;
  for (let i = num_functions - 1; i > 0; i = Math.floor(i / 10)) ++expected;
  assertEquals(expected, instance.exports.f(17));
  const num_code_spaces = %WasmNumCodeSpaces(instance);
  print(`--> ${num_code_spaces} code spaces.`);
  if (num_code_spaces >= 4) break;
  num_functions *= 2;
}