[LLVMdev] malloc vs malloc

[Chris Lattner]

On Jan 12, 2009, at 8:24 AM, Dan Gohman wrote:

>
> On Jan 11, 2009, at 11:22 AM, Chris Lattner wrote:
>
>>>> There is no good reason for malloc to be an instruction anymore.
>>>> I'd
>>>> be very happy if it got removed.  Even if we keep it, malloc/alloca
>>>> should be extended to optionally take 64-bit sizes.
>>>
>>> I'm curious. Do we want to keep the free instruction?
>>
>> No, there's no reason to.
>
>
> There still are reasons to have it; just grep around for FreeInst.
> Function
> attributes are not yet sufficient to replace all of those yet.
>
> And if the ailgnment attribute on MallocInst were implemented, perhaps
> via posix_memalign or other target-specific mechanisms, then  
> MallocInst
> would also have a reason to be kept.

isa<FreeInst>(X) can be replaced with:

bool isFree(Instruction *X) {
   if (CallInst *CI = dyn_cast<CallInst>(X))
     if (Function *F = CI->getCalledFunction())
       if (F->isName("free") && F->hasExternalLinkage())
         return true;
   return false;
}

There is no need to have an actual IR object for it.  posix_memalign,  
calloc, valloc and others are all great reasons why we shouldn't have  
a MallocInst either.

-Chris