tree eecf36e8e9d8112e765ad8840eb2d27f8d0415ab
parent f8bdd9f3a002970e4b8fdcf6fe6730116f1626c3
author Zheng Xu <zheng.xu@arm.com> 1429267736 +0800
committer Zheng Xu <zheng.xu@arm.com> 1429268048 +0800

Opt compiler: Implement parallel move resolver without using swap.

The algorithm of ParallelMoveResolverNoSwap() is almost the same with
ParallelMoveResolverWithSwap(), except the way we resolve the circular
dependency. NoSwap() uses additional scratch register to resolve the
circular dependency. For example, (0->1) (1->2) (2->0) will be performed
as (2->scratch) (1->2) (0->1) (scratch->0).

On architectures without swap register support, NoSwap() can reduce the
number of moves from 3x(N-1) to (N+1) when there is circular dependency
with N moves.

And also, NoSwap() algorithm does not depend on architecture register
layout information, which means it can support register pairs on arm32
and X/W, D/S registers on arm64 without additional modification.

Change-Id: Idf56bd5469bb78c0e339e43ab16387428a082318