llvm dev - Dec 2012 - [LLVMdev] how to get and modify a global variable inside a module

recently, i use LLVM API to write a program to read *.ll and excute it
automatically. 
Further more, i want to change some global variables inside a module. 
i tried some functions provided by Module.h and ExecutionEngine.h but none
were seemed to match my need. 
did someone have the experience or some advices? 
thank you ;) 



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Hi Dong Chen,

You can write a ModulePass class and implement a runOnModule method.
Inside this method you can access Module::global_iterator and get a
reference to all global variables of a module. With this reference,
you can change this variable. But be careful, you may need to change
also the references to those variables. Have a look to the method
GlobalVariable::use_begin and use_end. They give you references to the
users of the global variable.

I hope this helps,
Regards,
Eduardo

On Wed, Dec 5, 2012 at 9:07 AM, Dong Chen <jameschennerd at gmail.com>
wrote:
> recently, i use LLVM API to write a program to read *.ll and excute it
> automatically.
> Further more, i want to change some global variables inside a module.
> i tried some functions provided by Module.h and ExecutionEngine.h but none
> were seemed to match my need.
> did someone have the experience or some advices?
> thank you ;)
>
>
>
> --
> View this message in context:
http://llvm.1065342.n5.nabble.com/how-to-get-and-modify-a-global-variable-inside-a-module-tp52289.html
> Sent from the LLVM - Dev mailing list archive at Nabble.com.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On 05/12/12 12:07, Dong Chen wrote:
> recently, i use LLVM API to write a program to read *.ll and excute it
> automatically.
> Further more, i want to change some global variables inside a module.
> i tried some functions provided by Module.h and ExecutionEngine.h but none
> were seemed to match my need.
> did someone have the experience or some advices?
> thank you ;)
You can get hold of the global variable by passing it's name to
Module::getNamedValue.  For modification it depends on what kind of modification
you have in mind, so please clarify.

Ciao, Duncan.

hi Eduardo,
thanks for your attention, i checked the iterator, but i didn't see any
fucntion can return or modify the main memory address of a global variable
inside the module. 
can you provide some reference code or program can achieve this?
thank you very much



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hi Duncan Sands,
i have tried the functions:
GlobalValue *  getNamedValue (StringRef Name) const  
GlobalVariable *  getGlobalVariable (StringRef Name, bool
AllowInternal=false) const  
GlobalVariable *  getNamedGlobal (StringRef Name) const  
but i think these functions just return the ID or something else (not the
Global Variable's main memory address, i am not sure)
here is the thing. i want to know the exact main memory address of the
Global Varibale's address when ExecutionEngine execut the *.ll code. further
more, i want to change the address, is it possible?
do you have some good idea?
thank you very much



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