[LLVMdev] Removal of GVStub methods from MachineCodeEmitter, ELFWriter, and MachOWriter

[Aaron Gray]

 I have done a possible cleanup patch for the MachineCodeEmitter, ELFWriter,
and MachOWriter classes. It removes the two startGVStub(), and
finishGVStub() JIT specific methods.

You may remember the following comments :-

    /// JIT SPECIFIC FUNCTIONS - DO NOT IMPLEMENT THESE HERE!

To get rid of these easily turned out to be a semicomplex modification
because of the JITInfo classes dependance on MachineCodeEmitter and the
GVStub methods. Also the fact that JITEmitter is hidden and quite a large
class in a .cpp file.

At first I did this by introducing a JITCodeEmitter class between
MachineCodeEmitter and the (un)hidden JITEmitter. But this lead to more
dependancies and they lead on to more.

I have now made class header for JITEmitter putting it in the llvm
namespace. There were several other header dependancies as a result and
lib/ExecutionEngine/JIT/JIT.h and lib/ExecutionEngine/JIT/JITDwarfEmitter.h
required moving to the include/llvm/ExecutionEngine/JIT directory as a
result to make them visible to JIT.h and dependants.

    * create JITEmitter.h and made class JITEmitter visible in llvm
namespace
    * moved lib/ExecutionEngine/JIT/JIT.h to
include/llvm/ExecutionEngine/JIT
    * moved lib/ExecutionEngine/JIT/JITDwarfEmitter.h to
include/llvm/ExecutionEngine/JIT
    * removed JIT specific startGVStub()'s functions and finishGVStub() from
MachineCodeEmitter, ELFWriter, and  MachOWriter classes.
     * modified include/llvm/Target/TargetJITInfo.h to use JITEmitter rather
than MachineCodeEmitter.
    * modified :-
        - lib/Target/PowerPC/PPCJITInfo.h
        - lib/Target/PowerPC/PPCJITInfo.cpp
        - lib/Target/ARM/ARMJITInfo.cpp
        - lib/Target/ARM/ARMJITInfo.h
        - lib/Target/Alpha/AlphaJITInfo.cpp
        - lib/Target/Alpha/AlphaJITInfo.h
        - lib/Target/X86/X86JITInfo.h
        - lib/Target/X86/X86JITInfo.cpp
        to use JITEmitter rather than MachineCodeEmitter.
    * renamed multiple MCE's to JE's
    * removed unneed getCodeEmitter()'s in JITEmitter.cpp class JIT.
    * modified lib/ExecutionEngine/JIT/TargetSelect.cpp to use
include/llvm/ExecutionEngine/JIT/JIT.h include file
     * modified lib/ExecutionEngine/JIT/Intercept.cpp to use
include/llvm/ExecutionEngine/JIT/JIT.h include file

I was wondering whether it would be better to call the JITEmitter
class JITCodeEmitter and have JCE's instead of JE's.

I dont think there are any other issues I missed or need tidying up either.
I removed some getCodeEmitter and accompanying redundant assertions from
JITEmitter.cpp JIT class methods, AFAICT this is only cruft.

Anyway here's the patch :-

    http://www.aarongray.org/LLVM/patches/llvm-JITEmitter.patch

There was another way I considered that was having a second MCE for writting
global data and stubs to. I believe this would not require making JITEmitter
and friend visible, but may introduce more runtime overhead.

If you could have a look at this patch and see what you think.

If things go well I will be working on patches for the ELFWriter and an
accompanying COFFWriter. I know I promised this before but unfortunate
circumstances stopped me working on it back then.

Hopefully I can do some ground work and incremental patches to get some code
generated then look at the ABI issues on Windows.

Cheers,

Aaron
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