[llvm-commits] [llvm] r85346 - in /llvm/trunk: include/llvm/CodeGen/Passes.h lib/CodeGen/BranchFolding.cpp lib/CodeGen/BranchFolding.h lib/CodeGen/IfConversion.cpp lib/CodeGen/LLVMTargetMachine.cpp lib/Target/ARM/ARMTargetMachine.cpp

[Dale Johannesen]

On Oct 28, 2009, at 10:38 AMPDT, Chris Lattner wrote:

>
> On Oct 28, 2009, at 10:21 AM, Dale Johannesen wrote:
>
>>> If so, yes, I think that would work.  In fact, I think it would be a
>>> good idea.  At -O2, that would mean that we would be optimizing for
>>> performance at a small cost in code size.  That's a more aggressive
>>> change than mine, but I think it would be a good idea.
>>>
>>> Shall I go ahead with that?
>>
>> Branch folding is a size optimization.  It would not surprise me if
>> turning it off completely at
>> -O3 was the right thing for performance.  My only strong belief is
>> that any change should be based on measurements, not arguments.
>
> Doesn't it also do some code layout to encourage better fall- 
> throughs etc?

Yes; I meant tail merging, not all of branch folding, sorry.