[Turbofan] Add the concept of aliasing to RegisterConfiguration.

test/unittests/register-configuration-unittest.cc

+// Copyright 2016 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/register-configuration.h"
+#include "testing/gtest-support.h"
+
+namespace v8 {
+namespace internal {
+
+const MachineRepresentation kFloat32 = MachineRepresentation::kFloat32;
+const MachineRepresentation kFloat64 = MachineRepresentation::kFloat64;
+
+class RegisterConfigurationUnitTest : public ::testing::Test {
+ public:
+  RegisterConfigurationUnitTest() {}
+  virtual ~RegisterConfigurationUnitTest() {}
+
+ private:
+};
+
+TEST_F(RegisterConfigurationUnitTest, BasicProperties) {
+  const int kNumGeneralRegs = 3;
+  const int kNumDoubleRegs = 4;
+  const int kNumAllocatableGeneralRegs = 2;
+  const int kNumAllocatableDoubleRegs = 2;
+  int general_codes[kNumAllocatableGeneralRegs] = {1, 2};
+  int double_codes[kNumAllocatableDoubleRegs] = {2, 3};
+
+  RegisterConfiguration test(
+      kNumGeneralRegs, kNumDoubleRegs, kNumAllocatableGeneralRegs,
+      kNumAllocatableDoubleRegs, RegisterConfiguration::OVERLAP, general_codes,
+      double_codes, nullptr, nullptr, nullptr);
+
+  EXPECT_EQ(test.num_general_registers(), kNumGeneralRegs);
+  EXPECT_EQ(test.num_double_registers(), kNumDoubleRegs);
+  EXPECT_EQ(test.num_allocatable_general_registers(),
+            kNumAllocatableGeneralRegs);
+  EXPECT_EQ(test.num_allocatable_double_registers(), kNumAllocatableDoubleRegs);
+  EXPECT_EQ(test.num_allocatable_float_registers(), kNumAllocatableDoubleRegs);
+
+  EXPECT_EQ(test.allocatable_general_codes_mask(),
+            (1 << general_codes[0]) | (1 << general_codes[1]));
+  EXPECT_EQ(test.GetAllocatableGeneralCode(0), general_codes[0]);
+  EXPECT_EQ(test.GetAllocatableGeneralCode(1), general_codes[1]);
+  EXPECT_EQ(test.allocatable_double_codes_mask(),
+            (1 << double_codes[0]) | (1 << double_codes[1]));
+  EXPECT_EQ(test.GetAllocatableDoubleCode(0), double_codes[0]);
+  EXPECT_EQ(test.GetAllocatableDoubleCode(1), double_codes[1]);
+}
+
+TEST_F(RegisterConfigurationUnitTest, Aliasing) {
+  const int kNumGeneralRegs = 3;
+  const int kNumDoubleRegs = 4;
+  const int kNumAllocatableGeneralRegs = 2;
+  const int kNumAllocatableDoubleRegs = 3;
+  int general_codes[] = {1, 2};
+  int double_codes[] = {2, 3, 16};  // reg 16 should not alias registers 32, 33.
+
+  RegisterConfiguration test(
+      kNumGeneralRegs, kNumDoubleRegs, kNumAllocatableGeneralRegs,
+      kNumAllocatableDoubleRegs, RegisterConfiguration::COMBINE, general_codes,
+      double_codes, nullptr, nullptr, nullptr);
+
+  // There are 3 allocatable double regs, but only 2 can alias float regs.
+  EXPECT_EQ(test.num_allocatable_float_registers(), 4);
+
+  // Test that float registers combine in pairs to form double registers.
+  EXPECT_EQ(test.GetAllocatableFloatCode(0), double_codes[0] * 2);
+  EXPECT_EQ(test.GetAllocatableFloatCode(1), double_codes[0] * 2 + 1);
+  EXPECT_EQ(test.GetAllocatableFloatCode(2), double_codes[1] * 2);
+  EXPECT_EQ(test.GetAllocatableFloatCode(3), double_codes[1] * 2 + 1);
+
+  // Registers alias themselves.
+  EXPECT_TRUE(test.AreAliases(kFloat32, 0, kFloat32, 0));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 0, kFloat64, 0));
+  // Registers don't alias other registers of the same size.
+  EXPECT_FALSE(test.AreAliases(kFloat32, 1, kFloat32, 0));
+  EXPECT_FALSE(test.AreAliases(kFloat64, 1, kFloat64, 0));
+  // Float registers combine in pairs and alias double registers.
+  EXPECT_TRUE(test.AreAliases(kFloat32, 0, kFloat64, 0));
+  EXPECT_TRUE(test.AreAliases(kFloat32, 1, kFloat64, 0));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 0, kFloat32, 0));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 0, kFloat32, 1));
+
+  EXPECT_FALSE(test.AreAliases(kFloat32, 0, kFloat64, 1));
+  EXPECT_FALSE(test.AreAliases(kFloat32, 1, kFloat64, 1));
+
+  EXPECT_TRUE(test.AreAliases(kFloat64, 0, kFloat32, 1));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 1, kFloat32, 2));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 1, kFloat32, 3));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 2, kFloat32, 4));
+  EXPECT_TRUE(test.AreAliases(kFloat64, 2, kFloat32, 5));
+
+  int alias_base_index = -1;
+  EXPECT_EQ(test.GetAliases(kFloat32, 0, kFloat32, &alias_base_index), 1);
+  EXPECT_EQ(alias_base_index, 0);
+  EXPECT_EQ(test.GetAliases(kFloat64, 1, kFloat64, &alias_base_index), 1);
+  EXPECT_EQ(alias_base_index, 1);
+  EXPECT_EQ(test.GetAliases(kFloat32, 0, kFloat64, &alias_base_index), 1);
+  EXPECT_EQ(alias_base_index, 0);
+  EXPECT_EQ(test.GetAliases(kFloat32, 1, kFloat64, &alias_base_index), 1);
+  EXPECT_EQ(test.GetAliases(kFloat32, 2, kFloat64, &alias_base_index), 1);
+  EXPECT_EQ(alias_base_index, 1);
+  EXPECT_EQ(test.GetAliases(kFloat32, 3, kFloat64, &alias_base_index), 1);
+  EXPECT_EQ(alias_base_index, 1);
+  EXPECT_EQ(test.GetAliases(kFloat64, 0, kFloat32, &alias_base_index), 2);
+  EXPECT_EQ(alias_base_index, 0);
+  EXPECT_EQ(test.GetAliases(kFloat64, 1, kFloat32, &alias_base_index), 2);
+  EXPECT_EQ(alias_base_index, 2);
+
+  // Non-allocatable codes still alias.
+  EXPECT_EQ(test.GetAliases(kFloat64, 2, kFloat32, &alias_base_index), 2);
+  EXPECT_EQ(alias_base_index, 4);
+  // High numbered double registers don't alias nonexistent single registers.
+  EXPECT_EQ(
+      test.GetAliases(kFloat64, RegisterConfiguration::kMaxFPRegisters / 2,
+                      kFloat32, &alias_base_index),
+      0);
+  EXPECT_EQ(
+      test.GetAliases(kFloat64, RegisterConfiguration::kMaxFPRegisters / 2 + 1,
+                      kFloat32, &alias_base_index),
+      0);
+  EXPECT_EQ(test.GetAliases(kFloat64, RegisterConfiguration::kMaxFPRegisters,
+                            kFloat32, &alias_base_index),
+            0);
+}
+
+}  // namespace internal
+}  // namespace v8