[LLVMdev] [RFC][Float2Int] Converting (fcmp Pred, x * F, y) to (ICmp ...)

[Stephen Canon]

> On Apr 29, 2015, at 2:33 PM, Matt Arsenault <arsenm2 at gmail.com> wrote:
> 
>> On Apr 29, 2015, at 10:06 AM, Silviu Baranga <Silviu.Baranga at arm.com <mailto:Silviu.Baranga at arm.com>> wrote:
>> 
>> Note that dividing by an integer constant should be a cheap operation
>> compared to FP multiplication and comparison as this would get lowered to a
>> multiply+subtract+shift sequence (and should certainly be true on cores with no
>> FP unit)
>>  
> 
> This is not true on the targets I care about. The integer division (which, even with the division by constant expansion to multiplies with magic constants) would be significantly more expensive.

What targets *does* this benefit?  Soft-float targets and Cortex-A8?

Anyway, both integer and floating-point multiplication and division are monotonic, so it suffices to check the two values of x that bracket y/f.

– Steve
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