llvm dev - May 2010 - [LLVMdev] How to create Global Variables using LLVM API?

I am new to LLVM API. and I am experimenting with it. 
I want to create Global Variables in a module.
I am able to create local variables using IRBuilder class. I tried using
GlobalVariable class to create global variables.
but it doesn't work. my code looks like this:

Module* mod = new Module("test", getGlobalContext());
Constant* c = mod->getOrInsertFunction("main",
IntegerType::get(getGlobalContext(), 32), NULL);
Function* main = cast<Function> (c);
main->setCallingConv(CallingConv::C);
Twine s("foo");
StringRef s1("foo");
Constant *cons = ConstantArray::get(getGlobalContext(),s1, true);
GlobalVariable val(*mod, (Type*)
ArrayType::get(Type::getInt8Ty(getGlobalContext()), 4),
true,GlobalValue::ExternalLinkage, cons, s);


Application stops running after reaching the last line. can somebody help me
out here?


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subramanyam wrote:
>
> I am new to LLVM API. and I am experimenting with it.
> I want to create Global Variables in a module.
> I am able to create local variables using IRBuilder class. I tried using
> GlobalVariable class to create global variables.
> but it doesn't work. my code looks like this:
>
> Module* mod = new Module("test", getGlobalContext());
> Constant* c = mod->getOrInsertFunction("main",
> IntegerType::get(getGlobalContext(), 32), NULL);
> Function* main = cast<Function>  (c);
> main->setCallingConv(CallingConv::C);
> Twine s("foo");
> StringRef s1("foo");
> Constant *cons = ConstantArray::get(getGlobalContext(),s1, true);
> GlobalVariable val(*mod, (Type*)
> ArrayType::get(Type::getInt8Ty(getGlobalContext()), 4),
> true,GlobalValue::ExternalLinkage, cons, s);
Firstly, don't cast to Type*. You need to #include
"llvm/DerivedTypes.h"
instead. But that's not your bug.

Don't allocate GlobalVariable val on the stack. You need to 'new'
it,
ala. 'GlobalVariable *val = new GlobalVariable(...);'

I haven't tried running your code, but give that a shot!

Nick


>
>
> Application stops running after reaching the last line. can somebody help
me
> out here?
>
>

Thanks. It works. 
Actually, the signature of the constructor given in the online documentation
is different from the actual source code.

Nick Lewycky wrote:
> 
> subramanyam wrote:
>>
>> I am new to LLVM API. and I am experimenting with it.
>> I want to create Global Variables in a module.
>> I am able to create local variables using IRBuilder class. I tried
using
>> GlobalVariable class to create global variables.
>> but it doesn't work. my code looks like this:
>>
>> Module* mod = new Module("test", getGlobalContext());
>> Constant* c = mod->getOrInsertFunction("main",
>> IntegerType::get(getGlobalContext(), 32), NULL);
>> Function* main = cast<Function>  (c);
>> main->setCallingConv(CallingConv::C);
>> Twine s("foo");
>> StringRef s1("foo");
>> Constant *cons = ConstantArray::get(getGlobalContext(),s1, true);
>> GlobalVariable val(*mod, (Type*)
>> ArrayType::get(Type::getInt8Ty(getGlobalContext()), 4),
>> true,GlobalValue::ExternalLinkage, cons, s);
> 
> Firstly, don't cast to Type*. You need to #include
"llvm/DerivedTypes.h"
> instead. But that's not your bug.
> 
> Don't allocate GlobalVariable val on the stack. You need to
'new' it,
> ala. 'GlobalVariable *val = new GlobalVariable(...);'
> 
> I haven't tried running your code, but give that a shot!
> 
> Nick
> 
> 
> 
>>
>>
>> Application stops running after reaching the last line. can somebody
help
>> me
>> out here?
>>
>>
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> 
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