commit 27fe988b85e9b0b77eb5c376d4bdd1350dfc3e17
author rmcilroy <rmcilroy@chromium.org> Fri Sep 30 09:02:59 2016
committer Commit bot <commit-bot@chromium.org> Fri Sep 30 09:03:25 2016
tree be97ce9f1737b272a3a08653a3b9b0c54fd13b1d
parent ee605756b3b92f4b3b23874eef8eed276271a8eb

[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}