Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!uwm.edu!rpi!bu.edu!snorkelwacker!husc6!encore!pinocchio.encore.com From: jkenton@pinocchio.encore.com (Jeff Kenton) Newsgroups: comp.arch Subject: Re: speculative execution Message-ID: <12976@encore.Encore.COM> Date: 17 Oct 90 11:38:15 GMT References: Sender: news@Encore.COM Lines: 20 From article , by rbw00@ccc.amdahl.com ( 213 Richard Wilmot): > > Please NO. Save me from deferred traps. The CDC 6600 and some others > could produce several FP results that were illegal values FOR ANY OTHER > OPERATIONS. So exception traps took place not when/where you produced the > result but later when you tried to use it. Then the game was to guess where > you produced this value. > What you are describing is fairly close to the idea of NaN (Not a Number) required by the IEEE spec for floating point calculations. The operation which produces a NaN ( 0/0, infinity - infinity, inf / inf ) *will* trap when it occurs, but the NaNs will trap when they are used (if the trap is enabled). ----- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ----- ----- jeff kenton: consulting at jkenton@pinocchio.encore.com ----- ----- always at (617) 894-4508 ----- ----- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -----