Android 3.0和4.0中的JIT编译器改进

Question

当Just in Time编译器在2.2版中添加到Android时,还发布了许多关于它如何工作的详细信息.在Android 3.0的官方说明中还提到"各种改进的JIT基础设施",但我一直没能找到有关这些改进的任何信息,也没有我发现有关JIT的任何细节的Android 4.0.JIT在最新版本中是否保持相对不变,或者是否有关于这些改进的信息？

编辑:如下面的答案中所述,我找到了一些描述改进的更改日志条目.任何其他信息仍然会受到赞赏.

Answer 1

在检查了其公共GIT存储库中的Dalvik VM源代码并按照此处所述搜索其更改日志之后,我看到除了错误修正之外,唯一最近的主要JIT相关更改似乎是:

Date: Tue Jul 3 13:13:07 2012 -0700
[X86] X86 trace JIT compiler support

This patch provides a fully functional x86 trace JIT compiler for Dalvik
VM. It is built on top of the existing x86 fast interpreter
with bug fixes and needed extension to support trace JIT interface. The
x86 trace JIT code generator was developed independent of the existing
template-based code generator and thus does not share exactly the same
infrastructure. Included in this patch are:

* Deprecated and removed the x86-atom fast interpreter that is no
  longer functional since ICS.
* Augmented x86 fast interpreter to provide interfaces for x86 trace JIT
  compiler.
* Added x86 trace JIT code generator with full JDWP debugging support.
* Method JIT and self-verification mode are not supported.

The x86 code generator uses the x86 instruction encoder/decoder library
from the Apache Harmony project. Additional wrapper extension and bug
fixes were added to support the x86 trace JIT code generator. The x86
instruction encoder/decoder is embedded inside the x86 code generator
under the libenc subdirectory.

和

Date: Wed May 2 14:27:16 2012 -0700
[MIPS] Dalvik fast interpreter support and JIT implementation