[LLVMdev] LLVM AllocaInst and StoreInst

[David Jones]

As you may have noticed, although the assertions from the debug+assert LLVM
build are factually correct, for the purposes of debugging code linked
against it, it's not all that useful.

I have found it useful to build a wrapper layer around LLVM in my project.
The primary purpose of the wrapper was to isolate my application from
changes in the LLVM API, as it seems to be a moving target. However, for
places where I trigger LLVM's assertions frequently, I have "copied" those
assertions into my wrapper to do the same checks prior to calling into
LLVM, and to produce useful diagnostics in the case of failure.

For example, I often get argument mismatches between a function call and
its definition. So, in my callFunction wrapper, I do the type checks, and
in the event of failure, I print out:
- the name of the function being called
- the position of the argument whose type mismatches
- the formal and actual types in question.

You can consider doing the same - create a wrapper around your calls into
LLVM, and add better diagnostics where required.

If there is sufficient interest, I might document better what I did.



On Mon, Aug 4, 2014 at 8:18 AM, Prakash Premkumar <prakash.prax at gmail.com>
wrote:

> Hi,
>
> I am trying to write a simple interpreter.
>
> I am trying to generate LLVM IR for assignment operation. The code for the
> generation part looks like this
>
> llvm::Value* codeGenSymTab(llvm::LLVMContext& context) {
>>     printf("\n CodeGen SymTab \n");
>>     Value *num = ConstantInt::get(Type::getInt64Ty(context),
>> aTable.value, true);
>>     Value *alloc = new AllocaInst(IntegerType::get(context, 32),
>> aTable.variableName,entry);
>>     StoreInst *ptr = new StoreInst(num,alloc,false,entry);
>> }
>
>
> Here goes the SymTab definition:
>
> struct SymTab {
>      char* variableName;
>      int value;
>      llvm::Value* (*codeGen)(llvm::LLVMContext& context);
> };
>
>
> When I try to execute the output file,I get the following error:
>
> Assertion failed: (getOperand(0)->getType() ==
>> cast<PointerType>(getOperand(1)->getType())->getElementType() && "Ptr must
>> be a pointer to Val type!"), function AssertOK, file Instructions.cpp, line
>> 1084.
>> Abort trap: 6
>
>
> Can you help me resolve it ?
>
> Thanks
> Prakash
>
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