v8/test/mjsunit/wasm/load-elimination.js

// Copyright 2021 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: --experimental-wasm-gc

// This tests are meant to examine if Turbofan CsaLoadElimination works
// correctly for wasm. The TurboFan graphs can be examined with --trace-turbo.
d8.file.execute("test/mjsunit/wasm/wasm-module-builder.js");

// Fresh objects, known offsets
(function LoadEliminationtFreshKnownTest() {
  print(arguments.callee.name);

  let builder = new WasmModuleBuilder();
  let struct = builder.addStruct([makeField(kWasmI32, true),
                                  makeField(kWasmI32, true)]);

  builder.addFunction("main", makeSig([kWasmI32], [kWasmI32]))
    .addLocals(wasmOptRefType(struct), 1)
    .addBody([
      kExprI32Const, 10,  // local1 = struct(10, 100);
      kExprI32Const, 100,
      kGCPrefix, kExprRttCanon, struct,
      kGCPrefix, kExprStructNewWithRtt, struct,
      kExprLocalSet, 1,
      kExprLocalGet, 0,  // Split control based on an unknown value
      kExprIf, kWasmI32,
        kExprLocalGet, 1,  // local1.field1 = 42
        kExprI32Const, 42,
        kGCPrefix, kExprStructSet, struct, 1,
        kExprLocalGet, 1,  // local1.field1
        kGCPrefix, kExprStructGet, struct, 1,
      kExprElse,
        kExprLocalGet, 1,  // local1.field1 = 11
        kExprI32Const, 11,
        kGCPrefix, kExprStructSet, struct, 1,
        kExprLocalGet, 1,  // local1.field1 = 22
        kExprI32Const, 22,
        kGCPrefix, kExprStructSet, struct, 1,
        kExprLocalGet, 1,    // local1.field1 + local1.field1
        kGCPrefix, kExprStructGet, struct, 1,
        kExprLocalGet, 1,
        kGCPrefix, kExprStructGet, struct, 1,
        kExprI32Add,
      kExprEnd,
      kExprLocalGet, 1,  // return if-result * (local1.field1 + local1.field0)
      kGCPrefix, kExprStructGet, struct, 0,
      kExprLocalGet, 1,
      kGCPrefix, kExprStructGet, struct, 1,
      kExprI32Add,
      kExprI32Mul
    ])
    .exportFunc();

  let instance = builder.instantiate({});
  assertEquals(instance.exports.main(1), 42 * (42 + 10));
  assertEquals(instance.exports.main(0), (22 + 22) * (22 + 10));
})();

(function LoadEliminationtConstantKnownTest() {
  print(arguments.callee.name);

  let builder = new WasmModuleBuilder();
  let struct = builder.addStruct([makeField(kWasmI32, true)]);

  let replaced_value = 55
  let param_1_value = 42
  let init_value_1 = 5
  let init_value_2 = 17

  let tester = builder.addFunction("tester", makeSig(
      [wasmRefType(struct), wasmRefType(struct)], [kWasmI32]))
    .addBody([
      kExprLocalGet, 0,
      kGCPrefix, kExprStructGet, struct, 0,

      kExprLocalGet, 0,
      kExprI32Const, replaced_value,
      kGCPrefix, kExprStructSet, struct, 0,

      // We should eliminate this load and replace it with replaced_value
      kExprLocalGet, 0,
      kGCPrefix, kExprStructGet, struct, 0,

      kExprLocalGet, 1,
      kExprI32Const, param_1_value,
      kGCPrefix, kExprStructSet, struct, 0,

      // Although we could eliminate this load before, we cannot anymore,
      // because the parameters may alias.
      kExprLocalGet, 0,
      kGCPrefix, kExprStructGet, struct, 0,

      kExprI32Add, kExprI32Add
    ]);

  function buildStruct(value) {
    return [kExprI32Const, value, kGCPrefix, kExprRttCanon, struct,
            kGCPrefix, kExprStructNewWithRtt, struct];
  }

  builder.addFunction("main_non_aliasing", kSig_i_v)
    .addBody([
      ...buildStruct(init_value_1), ...buildStruct(init_value_2),
      kExprCallFunction, tester.index])
    .exportFunc();

  builder.addFunction("main_aliasing", kSig_i_v)
    .addLocals(wasmOptRefType(struct), 1)
    .addBody([
      ...buildStruct(init_value_1), kExprLocalSet, 0,
      kExprLocalGet, 0, kExprRefAsNonNull,
      kExprLocalGet, 0, kExprRefAsNonNull,
      kExprCallFunction, tester.index])
    .exportFunc();

  let instance = builder.instantiate({});
  assertEquals(init_value_1 + replaced_value + replaced_value,
               instance.exports.main_non_aliasing());
  assertEquals(init_value_1 + replaced_value + param_1_value,
               instance.exports.main_aliasing());
})();

(function LoadEliminationtArbitraryKnownTest() {
  print(arguments.callee.name);

  let builder = new WasmModuleBuilder();
  let struct = builder.addStruct([makeField(kWasmI32, true)]);

  let initial_value = 19;
  let replacing_value_1 = 55;
  let replacing_value_2 = 37;

  let id = builder.addFunction("id", makeSig([wasmOptRefType(struct)],
                                             [wasmOptRefType(struct)]))
      .addBody([kExprLocalGet, 0])

  builder.addFunction("main", kSig_i_v)
    .addLocals(wasmOptRefType(struct), 2)
    .addBody([
      // We store a fresh struct in local0
      kExprI32Const, initial_value,
      kGCPrefix, kExprRttCanon, struct,
      kGCPrefix, kExprStructNewWithRtt, struct,
      kExprLocalSet, 0,

      // We pass it through a function and store it to local1. local1 may now
      // alias with anything.
      kExprLocalGet, 0, kExprCallFunction, id.index, kExprLocalSet, 1,

      kExprLocalGet, 0,
      kExprI32Const, replacing_value_1,
      kGCPrefix, kExprStructSet, struct, 0,

      // We should eliminate this load.
      kExprLocalGet, 0, kGCPrefix, kExprStructGet, struct, 0,

      kExprLocalGet, 1,
      kExprI32Const, replacing_value_2,
      kGCPrefix, kExprStructSet, struct, 0,

      // We should not eliminate this load.
      kExprLocalGet, 0, kGCPrefix, kExprStructGet, struct, 0,

      kExprI32Add])
    .exportFunc();

  let instance = builder.instantiate({});
  assertEquals(replacing_value_1 + replacing_value_2, instance.exports.main());
})();

(function LoadEliminationtFreshUnknownTest() {
  print(arguments.callee.name);

  let builder = new WasmModuleBuilder();
  let array = builder.addArray(kWasmI64, true);

  // parameter: unknown array index
  builder.addFunction("main", makeSig([kWasmI32], [kWasmI32]))
    .addLocals(wasmOptRefType(array), 1)
    .addBody([
      kExprI32Const, 5,
      kGCPrefix, kExprRttCanon, array,
      kGCPrefix, kExprArrayNewDefaultWithRtt, array,
      kExprLocalSet, 1,

      kExprLocalGet, 1,  // a[i] = i for i = {0..4}
      kExprI32Const, 0,
      kExprI64Const, 0,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 1,
      kExprI32Const, 1,
      kExprI64Const, 1,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 1,
      kExprI32Const, 2,
      kExprI64Const, 2,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 1,
      kExprI32Const, 3,
      kExprI64Const, 3,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 1,
      kExprI32Const, 4,
      kExprI64Const, 4,
      kGCPrefix, kExprArraySet, array,

      // Get a constant index a[4] before setting unknown indices
      kExprLocalGet, 1,
      kExprI32Const, 4,
      kGCPrefix, kExprArrayGet, array,

      kExprLocalGet, 1,  // Set a[local0] = 33
      kExprLocalGet, 0,
      kExprI64Const, 33,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 1,  // Get a[local0]
      kExprLocalGet, 0,
      kGCPrefix, kExprArrayGet, array,

      kExprLocalGet, 1,  // Known index load cannot be eliminated anymore
      kExprI32Const, 3,
      kGCPrefix, kExprArrayGet, array,

      // A load from different unknown index a[local0 + 1] cannot be eliminated
      kExprLocalGet, 1,
      kExprLocalGet, 0,
      kExprI32Const, 1,
      kExprI32Add,
      kGCPrefix, kExprArrayGet, array,

      kExprI64Add, // return a[4] * (a[local0] - (a[3] + a[local0 + 1]))
      kExprI64Sub,
      kExprI64Mul,
      kExprI32ConvertI64  // To not have to worry about BigInts in JS world
    ])
    .exportFunc();

  let instance = builder.instantiate({});
  assertEquals(4 * (33 - (3 + 1)), instance.exports.main(0));
  assertEquals(4 * (33 - (3 + 2)), instance.exports.main(1));
  assertEquals(4 * (33 - (3 + 3)), instance.exports.main(2));
  assertEquals(4 * (33 - (33 + 4)), instance.exports.main(3));
})();

(function LoadEliminationtAllBetsAreOffTest() {
  print(arguments.callee.name);

  let builder = new WasmModuleBuilder();
  let struct = builder.addStruct([makeField(kWasmI32, true)]);
  let array = builder.addArray(kWasmI32, true);

  let value_0 = 19;
  let value_1 = 55;
  let value_2 = 2;

  let id = builder.addFunction("id", makeSig([wasmOptRefType(array)],
                                             [wasmOptRefType(array)]))
      .addBody([kExprLocalGet, 0])

  // parameters: array, index
  let tester = builder.addFunction("tester",
      makeSig([wasmRefType(array), kWasmI32], [kWasmI32]))
    .addLocals(wasmOptRefType(struct), 1)
    .addLocals(wasmOptRefType(array), 1)
    .addBody([
      // We store a fresh struct in local1
      kExprI32Const, 0,
      kGCPrefix, kExprRttCanon, struct,
      kGCPrefix, kExprStructNewWithRtt, struct,
      kExprLocalSet, 2,

      // We pass the array parameter through a function and store it to local2.
      kExprLocalGet, 0, kExprCallFunction, id.index, kExprLocalSet, 3,

      // Set the parameter array, the fresh struct, then the arbitrary array to
      // an unknown offset.
      kExprLocalGet, 0,
      kExprI32Const, 5,
      kExprI32Const, value_0,
      kGCPrefix, kExprArraySet, array,

      kExprLocalGet, 2,
      kExprI32Const, value_1,
      kGCPrefix, kExprStructSet, struct, 0,

      kExprLocalGet, 3,
      kExprLocalGet, 1,
      kExprI32Const, value_2,
      kGCPrefix, kExprArraySet, array,

      // Neither load can be eliminated.
      kExprLocalGet, 0,
      kExprI32Const, 5,
      kGCPrefix, kExprArrayGet, array,

      kExprLocalGet, 2,
      kGCPrefix, kExprStructGet, struct, 0,

      kExprI32Add]);

  builder.addFunction("main", kSig_i_i)
    .addBody([
      kExprI32Const, 10, kGCPrefix, kExprRttCanon, array,
      kGCPrefix, kExprArrayNewDefaultWithRtt, array,
      kExprI32Const, 7,
      kExprCallFunction, tester.index,
    ])
    .exportFunc();

  let instance = builder.instantiate({});
  assertEquals(value_0 + value_1, instance.exports.main());
})();