[llvm-commits] [llvm] r125357 - in /llvm/trunk: lib/Target/ARM/ARMISelLowering.cpp test/CodeGen/ARM/fcopysign.ll
Evan Cheng
evan.cheng at apple.com
Fri Feb 11 14:53:49 PST 2011
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
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