[turbofan]: More optimizations to add and subtract operations on x64

test/unittests/compiler/x64/instruction-selector-x64-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 "test/unittests/compiler/instruction-selector-unittest.h"
 
 #include "src/compiler/node-matchers.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 226 matching lines @@
   ASSERT_EQ(1U, s[0]->OutputCount());
   EXPECT_TRUE(s.IsSameAsFirst(s[0]->OutputAt(0)));
   EXPECT_EQ(s.ToVreg(t), s.ToVreg(s[0]->OutputAt(0)));
 }
 
 
 // -----------------------------------------------------------------------------
 // Addition.
 
 
-TEST_F(InstructionSelectorTest, Int32AddWithInt32AddWithParameters) {
+TEST_F(InstructionSelectorTest, Int32AddWithInt32ParametersLea) {
   StreamBuilder m(this, kMachInt32, kMachInt32, kMachInt32);
   Node* const p0 = m.Parameter(0);
   Node* const p1 = m.Parameter(1);
   Node* const a0 = m.Int32Add(p0, p1);
-  m.Return(m.Int32Add(a0, p0));
+  USE(a0);
+  // Additional uses of input to add chooses lea
+  Node* const a1 = m.Int32Add(p0, p1);
+  m.Return(m.Int32Add(a0, a1));
   Stream s = m.Build();
-  ASSERT_EQ(2U, s.size());
+  ASSERT_EQ(3U, s.size());
   EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
   ASSERT_EQ(2U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p1), s.ToVreg(s[0]->InputAt(1)));
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
 }
 
 
-TEST_F(InstructionSelectorTest, Int32AddConstantAsLea) {
+TEST_F(InstructionSelectorTest, Int32AddConstantAsLeaSingle) {
   StreamBuilder m(this, kMachInt32, kMachInt32);
   Node* const p0 = m.Parameter(0);
   Node* const c0 = m.Int32Constant(15);
+  // If there is only a single use of an add's input, still use lea and not add,
+  // it is faster.
   m.Return(m.Int32Add(p0, c0));
   Stream s = m.Build();
   ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
   EXPECT_EQ(kMode_MRI, s[0]->addressing_mode());
   ASSERT_EQ(2U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
   EXPECT_TRUE(s[0]->InputAt(1)->IsImmediate());
 }
 
 
-TEST_F(InstructionSelectorTest, Int32AddCommutedConstantAsLea) {
+TEST_F(InstructionSelectorTest, Int32AddConstantAsInc) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(1);
+  // If there is only a single use of an add's input and the immediate constant
+  // for the add is 1, use inc.
+  m.Return(m.Int32Add(p0, c0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Inc32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_None, s[0]->addressing_mode());
+  ASSERT_EQ(1U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+}
+
+
+TEST_F(InstructionSelectorTest, Int32AddConstantAsDec) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(-1);
+  // If there is only a single use of an add's input and the immediate constant
+  // for the add is -11, use dec.
+  m.Return(m.Int32Add(p0, c0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Dec32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_None, s[0]->addressing_mode());
+  ASSERT_EQ(1U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+}
+
+
+TEST_F(InstructionSelectorTest, Int32AddConstantAsLeaDouble) {
   StreamBuilder m(this, kMachInt32, kMachInt32);
   Node* const p0 = m.Parameter(0);
   Node* const c0 = m.Int32Constant(15);
+  // A second use of an add's input uses lea
+  Node* const a0 = m.Int32Add(p0, c0);
+  USE(a0);
+  m.Return(m.Int32Add(p0, c0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_MRI, s[0]->addressing_mode());
+  ASSERT_EQ(2U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+  EXPECT_TRUE(s[0]->InputAt(1)->IsImmediate());
+}
+
+
+TEST_F(InstructionSelectorTest, Int32AddCommutedConstantAsLeaSingle) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(15);
+  // If there is only a single use of an add's input, still use lea... it's
+  // generally faster than the add to reduce register pressure.
   m.Return(m.Int32Add(c0, p0));
   Stream s = m.Build();
   ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_MRI, s[0]->addressing_mode());
+  ASSERT_EQ(2U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+  EXPECT_TRUE(s[0]->InputAt(1)->IsImmediate());
+}
+
+
+TEST_F(InstructionSelectorTest, Int32AddCommutedConstantAsLeaDouble) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(15);
+  // A second use of an add's input uses lea
+  Node* const a0 = m.Int32Add(c0, p0);
+  USE(a0);
+  m.Return(m.Int32Add(c0, p0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
   EXPECT_EQ(kMode_MRI, s[0]->addressing_mode());
   ASSERT_EQ(2U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
   EXPECT_TRUE(s[0]->InputAt(1)->IsImmediate());
 }
 
 
 TEST_F(InstructionSelectorTest, Int32AddScaled2Mul) {
   StreamBuilder m(this, kMachInt32, kMachInt32, kMachInt32);
@@ skipping 314 matching lines @@
   ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kX64Lea32, s[0]->arch_opcode());
   EXPECT_EQ(kMode_MR8I, s[0]->addressing_mode());
   ASSERT_EQ(3U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
   EXPECT_EQ(s.ToVreg(p1), s.ToVreg(s[0]->InputAt(1)));
   EXPECT_TRUE(s[0]->InputAt(2)->IsImmediate());
 }
 
 
+TEST_F(InstructionSelectorTest, Int32SubConstantAsInc) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(-1);
+  // If there is only a single use of an add's input and the immediate constant
+  // for the add is 1, use inc.
+  m.Return(m.Int32Sub(p0, c0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Inc32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_None, s[0]->addressing_mode());
+  ASSERT_EQ(1U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+}
+
+
+TEST_F(InstructionSelectorTest, Int32SubConstantAsDec) {
+  StreamBuilder m(this, kMachInt32, kMachInt32);
+  Node* const p0 = m.Parameter(0);
+  Node* const c0 = m.Int32Constant(1);
+  // If there is only a single use of an sub's input and the immediate constant
+  // for the add is 1, use dec.
+  m.Return(m.Int32Sub(p0, c0));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Dec32, s[0]->arch_opcode());
+  EXPECT_EQ(kMode_None, s[0]->addressing_mode());
+  ASSERT_EQ(1U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+}
+
+
 // -----------------------------------------------------------------------------
 // Multiplication.
 
 
 TEST_F(InstructionSelectorTest, Int32MulWithInt32MulWithParameters) {
   StreamBuilder m(this, kMachInt32, kMachInt32, kMachInt32);
   Node* const p0 = m.Parameter(0);
   Node* const p1 = m.Parameter(1);
   Node* const m0 = m.Int32Mul(p0, p1);
   m.Return(m.Int32Mul(m0, p0));
@@ skipping 89 matching lines @@
     EXPECT_EQ(x, s.ToInt32(s[0]->InputAt(1)));
     ASSERT_EQ(1U, s[0]->OutputCount());
     EXPECT_TRUE(s.IsSameAsFirst(s[0]->Output()));
     EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8