[turbofan] Optimize truncated safe integer multiplications.

test/cctest/compiler/test-simplified-lowering.cc

 // Copyright 2014 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.
 
 // TODO(jochen): Remove this after the setting is turned on globally.
 #define V8_IMMINENT_DEPRECATION_WARNINGS
 
 #include <limits>
 
 #include "src/compiler/access-builder.h"
@@ skipping 1587 matching lines @@
   t.LowerAllNodesAndLowerChanges();
   t.GenerateCode();
 
   FOR_INT32_INPUTS(i) {
     int32_t x = 0 - *i;
     t.CheckNumberCall(static_cast<double>(x), static_cast<double>(*i));
   }
 }
 
 
-TEST(NumberMultiply_TruncatingToInt32) {
-  int32_t constants[] = {-100, -10, -1, 0, 1, 100, 1000};
-
-  for (size_t i = 0; i < arraysize(constants); i++) {
-    TestingGraph t(Type::Signed32());
-    Node* k = t.jsgraph.Constant(constants[i]);
-    Node* mul = t.graph()->NewNode(t.simplified()->NumberMultiply(), t.p0, k);
-    Node* trunc = t.graph()->NewNode(t.simplified()->NumberToInt32(), mul);
-    t.Return(trunc);
-    t.Lower();
-
-    CHECK_EQ(IrOpcode::kInt32Mul, mul->opcode());
-  }
-}
-
-
 TEST(RunNumberMultiply_TruncatingToInt32) {
   int32_t constants[] = {-100, -10, -1, 0, 1, 100, 1000, 3000999};
 
   for (size_t i = 0; i < arraysize(constants); i++) {
     double k = static_cast<double>(constants[i]);
     SimplifiedLoweringTester<Object*> t(kMachAnyTagged);
     Node* num = t.NumberToInt32(t.Parameter(0));
     Node* mul = t.NumberMultiply(num, t.jsgraph.Constant(k));
     Node* trunc = t.NumberToInt32(mul);
     t.Return(trunc);
@@ skipping 336 matching lines @@
     t.Return(use);
     t.Lower();
 
     CHECK_EQ(d.expected, OpParameter<MachineType>(phi));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8