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      1 // Copyright 2009 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #include "v8.h"
     29 
     30 #include "codegen-inl.h"
     31 #include "register-allocator-inl.h"
     32 
     33 namespace v8 {
     34 namespace internal {
     35 
     36 // -------------------------------------------------------------------------
     37 // Result implementation.
     38 
     39 
     40 Result::Result(Register reg, NumberInfo::Type info) {
     41   ASSERT(reg.is_valid() && !RegisterAllocator::IsReserved(reg));
     42   CodeGeneratorScope::Current()->allocator()->Use(reg);
     43   value_ = TypeField::encode(REGISTER)
     44       | NumberInfoField::encode(info)
     45       | DataField::encode(reg.code_);
     46 }
     47 
     48 
     49 Result::ZoneObjectList* Result::ConstantList() {
     50   static ZoneObjectList list(10);
     51   return &list;
     52 }
     53 
     54 
     55 NumberInfo::Type Result::number_info() {
     56   ASSERT(is_valid());
     57   if (!is_constant()) return NumberInfoField::decode(value_);
     58   Handle<Object> value = handle();
     59   if (value->IsSmi()) return NumberInfo::kSmi;
     60   if (value->IsHeapNumber()) return NumberInfo::kHeapNumber;
     61   return NumberInfo::kUnknown;
     62 }
     63 
     64 
     65 void Result::set_number_info(NumberInfo::Type info) {
     66   ASSERT(is_valid());
     67   value_ = value_ & ~NumberInfoField::mask();
     68   value_ = value_ | NumberInfoField::encode(info);
     69 }
     70 
     71 
     72 // -------------------------------------------------------------------------
     73 // RegisterAllocator implementation.
     74 
     75 
     76 Result RegisterAllocator::AllocateWithoutSpilling() {
     77   // Return the first free register, if any.
     78   int num = registers_.ScanForFreeRegister();
     79   if (num == RegisterAllocator::kInvalidRegister) {
     80     return Result();
     81   }
     82   return Result(RegisterAllocator::ToRegister(num));
     83 }
     84 
     85 
     86 Result RegisterAllocator::Allocate() {
     87   Result result = AllocateWithoutSpilling();
     88   if (!result.is_valid()) {
     89     // Ask the current frame to spill a register.
     90     ASSERT(cgen_->has_valid_frame());
     91     Register free_reg = cgen_->frame()->SpillAnyRegister();
     92     if (free_reg.is_valid()) {
     93       ASSERT(!is_used(free_reg));
     94       return Result(free_reg);
     95     }
     96   }
     97   return result;
     98 }
     99 
    100 
    101 Result RegisterAllocator::Allocate(Register target) {
    102   // If the target is not referenced, it can simply be allocated.
    103   if (!is_used(target)) {
    104     return Result(target);
    105   }
    106   // If the target is only referenced in the frame, it can be spilled and
    107   // then allocated.
    108   ASSERT(cgen_->has_valid_frame());
    109   if (cgen_->frame()->is_used(target) && count(target) == 1)  {
    110     cgen_->frame()->Spill(target);
    111     ASSERT(!is_used(target));
    112     return Result(target);
    113   }
    114   // Otherwise (if it's referenced outside the frame) we cannot allocate it.
    115   return Result();
    116 }
    117 
    118 
    119 } }  // namespace v8::internal
    120