[llvm-commits] [llvm] r125357 - in /llvm/trunk: lib/Target/ARM/ARMISelLowering.cpp test/CodeGen/ARM/fcopysign.ll

[Evan Cheng]

On Feb 11, 2011, at 2:19 PM, Chris Lattner wrote:

> 
> On Feb 11, 2011, at 1:13 PM, Evan Cheng wrote:
> 
>>> Is there something wrong with the generic lowering code for copysign?  Why does arm have its own implementation?
>>> 
>>> -Chris
>> 
>> The generic implementation isn't going to be performant. The custom lowering make use of ARM specific nodes to split / combine D registers to / from GPRs when it's profitable.
> 
> Doesn't bitcast(i64->f64) do the right thing (getting legalized into split/combine d regs) on ARM?

Right. But the generic lowering doesn't do that and it's not always the right thing to do.

Evan

> 
> -Chris