[llvm-commits] [llvm] r93448 - /llvm/trunk/lib/Analysis/InlineCost.cpp

[Duncan Sands]

Hi Eric, if you check the code in SelectionDAGBuilder.cpp, you will see that
it checks more than just the name before deciding whether to change into a
SDag node.  For example, here is the code for sqrt:

       } 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() &&
             I.onlyReadsMemory()) {
           SDValue Tmp = getValue(I.getOperand(1));
           setValue(&I, DAG.getNode(ISD::FSQRT, getCurDebugLoc(),
                                    Tmp.getValueType(), Tmp));
           return;
         }

Notice how it checks I.onlyReadsMemory to see if sqrt writes errno or not?
Also, your code (and that in SDag) suffers from not being turn-offable.
How about factoring the checks out of SelectionDAGBuilder.cpp and reusing
them here?

Ciao,

Duncan.