+Value *LibCallSimplifier::optimizeLog(CallInst *CI, IRBuilder<> &B) {
+ Function *Callee = CI->getCalledFunction();
+ Value *Ret = nullptr;
+ StringRef Name = Callee->getName();
+ if (UnsafeFPShrink && hasFloatVersion(Name))
+ Ret = optimizeUnaryDoubleFP(CI, B, true);
+ FunctionType *FT = Callee->getFunctionType();
+
+ // Just make sure this has 1 argument of FP type, which matches the
+ // result type.
+ if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
+ !FT->getParamType(0)->isFloatingPointTy())
+ return Ret;
+
+ if (!canUseUnsafeFPMath(CI->getParent()->getParent()))
+ return Ret;
+ Value *Op1 = CI->getArgOperand(0);
+ auto *OpC = dyn_cast<CallInst>(Op1);
+ if (!OpC)
+ return Ret;
+
+ // log(pow(x,y)) -> y*log(x)
+ // This is only applicable to log, log2, log10.
+ if (Name != "log" && Name != "log2" && Name != "log10")
+ return Ret;
+
+ IRBuilder<>::FastMathFlagGuard Guard(B);
+ FastMathFlags FMF;
+ FMF.setUnsafeAlgebra();
+ B.SetFastMathFlags(FMF);
+
+ LibFunc::Func Func;
+ Function *F = OpC->getCalledFunction();
+ StringRef FuncName = F->getName();
+ if ((TLI->getLibFunc(FuncName, Func) && TLI->has(Func) &&
+ Func == LibFunc::pow) || F->getIntrinsicID() == Intrinsic::pow)
+ return B.CreateFMul(OpC->getArgOperand(1),
+ EmitUnaryFloatFnCall(OpC->getOperand(0), Callee->getName(), B,
+ Callee->getAttributes()), "mul");
+ return Ret;
+}
+