[turbofan] fold constants in compares

test/unittests/compiler/machine-operator-reducer-unittest.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.
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/typer.h"
 #include "test/unittests/compiler/graph-unittest.h"
@@ skipping 214 matching lines @@
 const uint32_t kUint32Values[] = {
     0x00000000, 0x00000001, 0xffffffff, 0x1b09788b, 0x04c5fce8, 0xcc0de5bf,
     0x273a798e, 0x187937a3, 0xece3af83, 0x5495a16b, 0x0b668ecc, 0x11223344,
     0x0000009e, 0x00000043, 0x0000af73, 0x0000116b, 0x00658ecc, 0x002b3b4c,
     0x88776655, 0x70000000, 0x07200000, 0x7fffffff, 0x56123761, 0x7fffff00,
     0x761c4761, 0x80000000, 0x88888888, 0xa0000000, 0xdddddddd, 0xe0000000,
     0xeeeeeeee, 0xfffffffd, 0xf0000000, 0x007fffff, 0x003fffff, 0x001fffff,
     0x000fffff, 0x0007ffff, 0x0003ffff, 0x0001ffff, 0x0000ffff, 0x00007fff,
     0x00003fff, 0x00001fff, 0x00000fff, 0x000007ff, 0x000003ff, 0x000001ff};
 
+
+int32_t RandomInt32(base::RandomNumberGenerator* rng) {
+  int index = rng->NextInt(static_cast<int>(arraysize(kInt32Values)));
+  return kInt32Values[index];
+}
+
 }  // namespace
 
 
 // -----------------------------------------------------------------------------
 // Unary operators
 
 
 namespace {
 
 struct UnaryOperator {
@@ skipping 892 matching lines @@
                                           Uint32Constant(x | 0xffffu)),
                          effect, control);
 
     Reduction r = Reduce(node);
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(),
                 IsStore(rep, base, index, value, effect, control));
   }
 }
 
+
+TEST_F(MachineOperatorReducerTest, ConstantFoldCompare32) {
+  base::RandomNumberGenerator rng;
+  TRACED_FOREACH(int32_t, c_0, kInt32Values) {
+    const int32_t c_1 = RandomInt32(&rng);
+    const int32_t c_2 = RandomInt32(&rng);
+    {
+      Node* const k_0 = Int32Constant(c_0);
+      Node* const k_1 = Int32Constant(c_1);
+      Node* const k_2 = Int32Constant(c_2);
+      Node* const p0 = Parameter(0);
+      Node* const add_0 = graph()->NewNode(machine()->Int32Add(), p0, k_0);
+      Node* const add_1 = graph()->NewNode(machine()->Int32Add(), add_0, k_1);
+      Node* const node =
+          graph()->NewNode(machine()->Int32LessThan(), add_1, k_2);
+      Reduction r = Reduce(node);
+      ASSERT_TRUE(r.Changed());
+      EXPECT_THAT(r.replacement(),
+                  IsInt32LessThan(p0, IsInt32Constant(c_2 - c_1 - c_0)));
+    }
+    {
+      Node* const k_0 = Int32Constant(c_0);
+      Node* const k_1 = Int32Constant(c_1);
+      Node* const k_2 = Int32Constant(c_2);
+      Node* const p0 = Parameter(0);
+      Node* const add_0 = graph()->NewNode(machine()->Int32Add(), p0, k_0);
+      Node* const add_1 = graph()->NewNode(machine()->Int32Add(), add_0, k_1);
+      Node* const node =
+          graph()->NewNode(machine()->Int32LessThan(), k_2, add_1);
+      Reduction r = Reduce(node);
+      ASSERT_TRUE(r.Changed());
+      EXPECT_THAT(r.replacement(),
+                  IsInt32LessThan(IsInt32Constant(c_2 - c_1 - c_0), p0));
+    }
+  }
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8