[LLVMdev] llvm.powi intrinsic

Jon Sargeant delta17 at cox.net
Mon Nov 26 17:55:38 PST 2007


The purpose of the llvm.powi intrinsic isn't clear to me.  Why is 
llvm.powi preferable to multiplication and division for small constant 
powers (e.g., 1/x, x*x, etc.)?  Why is it preferable to llvm.pow for 
large variable powers?  I'm also curious about the time bound.  I'm 
assuming that powi(x,1000000) doesn't do a million multiplications... 
Do any architectures have an integer power instruction of some sort?


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