[Orc] New JIT APIs.


[Orc] New JIT APIs.

This patch adds a new set of JIT APIs to LLVM. The aim of these new APIs is to
cleanly support a wider range of JIT use cases in LLVM, and encourage the
development and contribution of re-usable infrastructure for LLVM JIT use-cases.

These APIs are intended to live alongside the MCJIT APIs, and should not affect
existing clients.

Included in this patch:

  1. New headers in include/llvm/ExecutionEngine/Orc that provide a set of components for building JIT infrastructure. Implementation code for these headers lives in lib/ExecutionEngine/Orc.
  1. A prototype re-implementation of MCJIT (OrcMCJITReplacement) built out of the new components.
  1. Minor changes to RTDyldMemoryManager needed to support the new components. These changes should not impact existing clients.
  1. A new flag for lli, -use-orcmcjit, which will cause lli to use the OrcMCJITReplacement class as its underlying execution engine, rather than MCJIT itself.

Tests to follow shortly.

Special thanks to Michael Ilseman, Pete Cooper, David Blaikie, Eric Christopher,
Justin Bogner, and Jim Grosbach for extensive feedback and discussion.


lhamesJan 23 2015, 1:25 PM
rL226939: Move the accessor functions from DIExpression::iterator into a wrapper