[llvm] r178925 - Correct the PPC A2 misprediction penalty

[Hal Finkel]

----- Original Message -----
> From: "David Blaikie" <dblaikie at gmail.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: llvm-commits at cs.uiuc.edu
> Sent: Sunday, April 28, 2013 9:56:44 AM
> Subject: Re: [llvm] r178925 - Correct the PPC A2 misprediction penalty
> 
> 
> 
> Testable?

Yes, and I think that it was later covered by the early if-conversion tests. If not, I'll add something.

Thanks again,
Hal

> On Apr 6, 2013 10:31 AM, "Hal Finkel" < hfinkel at anl.gov > wrote:
> 
> 
> Author: hfinkel
> Date: Fri Apr 5 18:28:58 2013
> New Revision: 178925
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=178925&view=rev
> Log:
> Correct the PPC A2 misprediction penalty
> 
> The manual states that there is a minimum of 13 cycles from when the
> mispredicted branch is issued to when the correct branch target is
> issued.
> 
> Modified:
> llvm/trunk/lib/Target/PowerPC/PPCScheduleA2.td
> 
> Modified: llvm/trunk/lib/Target/PowerPC/PPCScheduleA2.td
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCScheduleA2.td?rev=178925&r1=178924&r2=178925&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/PowerPC/PPCScheduleA2.td (original)
> +++ llvm/trunk/lib/Target/PowerPC/PPCScheduleA2.td Fri Apr 5 18:28:58
> 2013
> @@ -759,7 +759,7 @@ def PPCA2Model : SchedMachineModel {
> let LoadLatency = 6; // Optimistic load latency assuming bypass.
> // This is overriden by OperandCycles if the
> // Itineraries are queried instead.
> - let MispredictPenalty = 6;
> + let MispredictPenalty = 13;
> 
> let Itineraries = PPCA2Itineraries;
> }
> 
> 
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