[llvm-commits] [llvm] r89523 - /llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp

[Eric Christopher]

On Dec 4, 2009, at 10:24 PM, Chris Lattner wrote:

> 
> On Dec 4, 2009, at 10:06 PM, Eric Christopher wrote:
> 
>>>> 
>>>> The lower to "unknown" is merely a placeholder that keeps current behavior.
>>> 
>>> What do you mean?
>>> 
>> 
>> We're lowering to unknown in simplifylibcall because I haven't had time to write the rest of the pass yet :)
>> 
>>>> We do lower to unknown at codegen time already if we didn't before.  It should be all lowered before we get to codegen in one way or another.
>>> 
>>> Is there code that lowers memcpy_chk(.. unknown)  -> memcpy that happens at codegen time?  If not, lowering the object size intrinsic only will pessimize real cases, no?
>> 
>> It would, but we should only get there unoptimized. I see what you mean though and I can get something to do the conversion in the unoptimized case if you'd like, but I probably wouldn't worry about it otherwise.
> 
> Many memfoo calls will have an unknown length.  We want to make sure to get a call to memfoo (instead of memfoo_chk) for both performance and code size reasons.

After IRC discussion, I understand :) I'll move some things around and make sure that things happen in good time.

-eric