[Turbofan] Allow compiler to elide complex aliasing code.

src/register-configuration.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/register-configuration.h"
 #include "src/globals.h"
 #include "src/macro-assembler.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 39 matching lines @@
 STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
               DoubleRegister::kMaxNumRegisters);
 
 class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
  public:
   explicit ArchDefaultRegisterConfiguration(CompilerSelector compiler)
       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kMaxNumRegisters,
 #if V8_TARGET_ARCH_IA32
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_X87
             kMaxAllocatableGeneralRegisterCount,
             compiler == TURBOFAN ? 1 : kMaxAllocatableDoubleRegisterCount,
-            AliasingKind::OVERLAP,
 #elif V8_TARGET_ARCH_X64
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_ARM
             FLAG_enable_embedded_constant_pool
                 ? (kMaxAllocatableGeneralRegisterCount - 1)
                 : kMaxAllocatableGeneralRegisterCount,
             CpuFeatures::IsSupported(VFP32DREGS)
                 ? kMaxAllocatableDoubleRegisterCount
                 : (ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_COUNT) 0),
-            AliasingKind::COMBINE,
 #elif V8_TARGET_ARCH_ARM64
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_MIPS
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_MIPS64
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_PPC
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_S390
             kMaxAllocatableGeneralRegisterCount,
-            kMaxAllocatableDoubleRegisterCount, AliasingKind::OVERLAP,
+            kMaxAllocatableDoubleRegisterCount,
 #else
 #error Unsupported target architecture.
 #endif
             kAllocatableGeneralCodes, kAllocatableDoubleCodes,
+            kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE,
             kGeneralRegisterNames, kFloatRegisterNames, kDoubleRegisterNames) {
   }
 };
 
 
 template <RegisterConfiguration::CompilerSelector compiler>
 struct RegisterConfigurationInitializer {
   static void Construct(ArchDefaultRegisterConfiguration* config) {
     new (config) ArchDefaultRegisterConfiguration(compiler);
   }
@@ skipping 16 matching lines @@
 const RegisterConfiguration* RegisterConfiguration::ArchDefault(
     CompilerSelector compiler) {
   return compiler == TURBOFAN
              ? &kDefaultRegisterConfigurationForTurboFan.Get()
              : &kDefaultRegisterConfigurationForCrankshaft.Get();
 }
 
 RegisterConfiguration::RegisterConfiguration(
     int num_general_registers, int num_double_registers,
     int num_allocatable_general_registers, int num_allocatable_double_registers,
-    AliasingKind fp_aliasing_kind, const int* allocatable_general_codes,
-    const int* allocatable_double_codes,
-    const char* const* general_register_names,
+    const int* allocatable_general_codes, const int* allocatable_double_codes,
+    AliasingKind fp_aliasing_kind, const char* const* general_register_names,
     const char* const* float_register_names,
     const char* const* double_register_names)
     : num_general_registers_(num_general_registers),
       num_float_registers_(0),
       num_double_registers_(num_double_registers),
       num_allocatable_general_registers_(num_allocatable_general_registers),
       num_allocatable_double_registers_(num_allocatable_double_registers),
       num_allocatable_float_registers_(0),
-      fp_aliasing_kind_(fp_aliasing_kind),
       allocatable_general_codes_mask_(0),
       allocatable_double_codes_mask_(0),
       allocatable_general_codes_(allocatable_general_codes),
       allocatable_double_codes_(allocatable_double_codes),
+      fp_aliasing_kind_(fp_aliasing_kind),
       general_register_names_(general_register_names),
       float_register_names_(float_register_names),
       double_register_names_(double_register_names) {
   DCHECK(num_general_registers_ <= RegisterConfiguration::kMaxGeneralRegisters);
   DCHECK(num_double_registers_ <= RegisterConfiguration::kMaxFPRegisters);
   for (int i = 0; i < num_allocatable_general_registers_; ++i) {
     allocatable_general_codes_mask_ |= (1 << allocatable_general_codes_[i]);
   }
   for (int i = 0; i < num_allocatable_double_registers_; ++i) {
     allocatable_double_codes_mask_ |= (1 << allocatable_double_codes_[i]);
@@ skipping 70 matching lines @@
     // Alias indices are out of float register range.
     return false;
   }
   return index == other_index / 2;
 }
 
 #undef REGISTER_COUNT
 
 }  // namespace internal
 }  // namespace v8