[llvm-commits] [llvm] r82778 - /llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp

[Sandeep Patel]

Why aren't the front-ends responsible for selecting the intrinsics again?

deep

On Fri, Sep 25, 2009 at 5:31 PM, Chris Lattner <clattner at apple.com> wrote:
>
> On Sep 25, 2009, at 10:23 AM, Dale Johannesen wrote:
>
>> Author: johannes
>> Date: Fri Sep 25 12:23:22 2009
>> New Revision: 82778
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=82778&view=rev
>> Log:
>> Generate FSQRT from calls to the sqrt function, which
>> allows appropriate backends to generate a sqrt instruction.
>>
>> On x86, this isn't done at -O0 because we go through
>> FastISel instead.  This is a behavior change from before
>> this series of sqrt patches started.  I think this is OK
>> considering that compile speed is most important at -O0, but
>> could be convinced otherwise.
>
> I'm fine with fastisel not doing this, but it should only happen if
> the sqrt function is readonly, otherwise the errno update is lost.
>
> -Chris
>
>>
>>
>> Modified:
>>    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
>>
>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp?rev=82778&r1=82777&r2=82778&view=diff
>>
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> ======================================================================
>> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
>> (original)
>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp Fri
>> Sep 25 12:23:22 2009
>> @@ -4576,6 +4576,15 @@
>>                                    Tmp.getValueType(), Tmp));
>>           return;
>>         }
>> +      } else if (Name == "sqrt" || Name == "sqrtf" || Name ==
>> "sqrtl") {
>> +        if (I.getNumOperands() == 2 &&   // Basic sanity checks.
>> +            I.getOperand(1)->getType()->isFloatingPoint() &&
>> +            I.getType() == I.getOperand(1)->getType()) {
>> +          SDValue Tmp = getValue(I.getOperand(1));
>> +          setValue(&I, DAG.getNode(ISD::FSQRT, getCurDebugLoc(),
>> +                                   Tmp.getValueType(), Tmp));
>> +          return;
>> +        }
>>       }
>>     }
>>   } else if (isa<InlineAsm>(I.getOperand(0))) {
>>
>>
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