v8/test/unittests/interpreter/bytecode-register-allocator-unittest.cc
rmcilroy 27fe988b85 [Interpreter] Replace BytecodeRegisterAllocator with a simple bump pointer.
There are only a few occasions where we allocate a register in an outer
expression allocation scope, which makes the costly free-list approach
of the BytecodeRegisterAllocator unecessary. This CL replaces all
occurrences with moves to the accumulator and stores to a register
allocated in the correct scope. By doing this, we can simplify the
BytecodeRegisterAllocator to be a simple bump-pointer allocator
with registers released in the same order as allocated.

The following changes are also made:
 - Make BytecodeRegisterOptimizer able to use registers which have been
   unallocated, but not yet reused
 - Remove RegisterExpressionResultScope and rename
   AccumulatorExpressionResultScope to ValueExpressionResultScope
 - Introduce RegisterList to represent consecutive register
   allocations, and use this for operands to call bytecodes.

By avoiding the free-list handling, this gives another couple of
percent on CodeLoad.

BUG=v8:4280

Review-Url: https://codereview.chromium.org/2369873002
Cr-Commit-Position: refs/heads/master@{#39905}
2016-09-30 09:03:25 +00:00

97 lines
3.5 KiB
C++

// 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/v8.h"
#include "src/interpreter/bytecode-array-builder.h"
#include "src/interpreter/bytecode-register-allocator.h"
#include "test/unittests/test-utils.h"
namespace v8 {
namespace internal {
namespace interpreter {
class BytecodeRegisterAllocatorTest : public TestWithIsolateAndZone {
public:
BytecodeRegisterAllocatorTest() : allocator_(0) {}
~BytecodeRegisterAllocatorTest() override {}
BytecodeRegisterAllocator* allocator() { return &allocator_; }
private:
BytecodeRegisterAllocator allocator_;
};
TEST_F(BytecodeRegisterAllocatorTest, SimpleAllocations) {
CHECK_EQ(allocator()->maximum_register_count(), 0);
Register reg0 = allocator()->NewRegister();
CHECK_EQ(reg0.index(), 0);
CHECK_EQ(allocator()->maximum_register_count(), 1);
CHECK_EQ(allocator()->next_register_index(), 1);
CHECK(allocator()->RegisterIsLive(reg0));
allocator()->ReleaseRegisters(0);
CHECK(!allocator()->RegisterIsLive(reg0));
CHECK_EQ(allocator()->maximum_register_count(), 1);
CHECK_EQ(allocator()->next_register_index(), 0);
reg0 = allocator()->NewRegister();
Register reg1 = allocator()->NewRegister();
CHECK_EQ(reg0.index(), 0);
CHECK_EQ(reg1.index(), 1);
CHECK(allocator()->RegisterIsLive(reg0));
CHECK(allocator()->RegisterIsLive(reg1));
CHECK_EQ(allocator()->maximum_register_count(), 2);
CHECK_EQ(allocator()->next_register_index(), 2);
allocator()->ReleaseRegisters(1);
CHECK(allocator()->RegisterIsLive(reg0));
CHECK(!allocator()->RegisterIsLive(reg1));
CHECK_EQ(allocator()->maximum_register_count(), 2);
CHECK_EQ(allocator()->next_register_index(), 1);
}
TEST_F(BytecodeRegisterAllocatorTest, RegisterListAllocations) {
CHECK_EQ(allocator()->maximum_register_count(), 0);
RegisterList reg_list = allocator()->NewRegisterList(3);
CHECK_EQ(reg_list.first_register().index(), 0);
CHECK_EQ(reg_list.register_count(), 3);
CHECK_EQ(reg_list[0].index(), 0);
CHECK_EQ(reg_list[1].index(), 1);
CHECK_EQ(reg_list[2].index(), 2);
CHECK_EQ(allocator()->maximum_register_count(), 3);
CHECK_EQ(allocator()->next_register_index(), 3);
CHECK(allocator()->RegisterIsLive(reg_list[2]));
Register reg = allocator()->NewRegister();
RegisterList reg_list_2 = allocator()->NewRegisterList(2);
CHECK_EQ(reg.index(), 3);
CHECK_EQ(reg_list_2.first_register().index(), 4);
CHECK_EQ(reg_list_2.register_count(), 2);
CHECK_EQ(reg_list_2[0].index(), 4);
CHECK_EQ(reg_list_2[1].index(), 5);
CHECK_EQ(allocator()->maximum_register_count(), 6);
CHECK_EQ(allocator()->next_register_index(), 6);
CHECK(allocator()->RegisterIsLive(reg));
CHECK(allocator()->RegisterIsLive(reg_list_2[1]));
allocator()->ReleaseRegisters(reg.index());
CHECK(!allocator()->RegisterIsLive(reg));
CHECK(!allocator()->RegisterIsLive(reg_list_2[0]));
CHECK(!allocator()->RegisterIsLive(reg_list_2[1]));
CHECK(allocator()->RegisterIsLive(reg_list[2]));
CHECK_EQ(allocator()->maximum_register_count(), 6);
CHECK_EQ(allocator()->next_register_index(), 3);
RegisterList empty_reg_list = allocator()->NewRegisterList(0);
CHECK_EQ(empty_reg_list.first_register().index(), 0);
CHECK_EQ(empty_reg_list.register_count(), 0);
CHECK_EQ(allocator()->maximum_register_count(), 6);
CHECK_EQ(allocator()->next_register_index(), 3);
}
} // namespace interpreter
} // namespace internal
} // namespace v8