[LLVMdev] Convert a function to "main"

[Pablo González de Aledo]

Hi, I'm somehow a newby with llvm, I've been working with it for 4 months.

I'm trying to convert a function to 'main' in order to execute this
concrete function only when the program is run. To do so, I've been able to
remove all other functions from the module, and change the function name to
"main".

I've then allocated new registers for all the formal parameters in the
function definition, and update all the subsequent references to the
parameters to the allocated values. (I don't care if the correct value is
not passed to the function).

To continue, I need to remove the arguments of the function. Here is where
I start having problems. I've tried to do so in three different ways:

* Create a new function "main" without arguments and copy all basic-block's
from the original function to the new one. I've had problems with this
approach because of cloning not updating operators of the basic-block
instructions. Thanks to
http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-June/051063.html I've
solved this partially, but I'm still facing problems when updating branch
instructions.
* Since all parameters are now useless, I've tried to pass the -deadargelim
optimization pass with opt -deadargelim < file-1.bc > file-2.bc. However,
the optimization pass does not realize by itself that the function
parameters are not being used, and does not eliminate them.
* I've tried delete( function->arg_begin() ); with a (somehow predicted)
segmentation fault.
* I've read
http://llvm.org/docs/doxygen/html/DeadArgumentElimination_8cpp_source.html to
try to understand how deadargelim eliminates the unused arguments of a
function, but I'm not able to fully understand the code.

Which one is the best approach to remove the unused arguments of the
function?. I'm stuck here.

Thanks a lot !!
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