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[AArch64] Conditional selects are expensive on out-of-order cores.

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Specifically Cortex-A57. This probably applies to Cyclone too but I haven't enabled it for that as I can't test it.

This gives ~4% improvement on SPEC 174.vpr, and ~1% in 471.omnetpp.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214957 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
James Molloy 2014-08-06 10:42:18 +00:00
parent a341a8070a
commit c2482dfc39
1 changed files with 4 additions and 0 deletions
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4
lib/Target/AArch64/AArch64ISelLowering.cpp
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@ -477,6 +477,10 @@ AArch64TargetLowering::AArch64TargetLowering(TargetMachine &TM)
setOperationAction(ISD::FROUND, Ty, Legal);
}
}
// Prefer likely predicted branches to selects on out-of-order cores.
if (Subtarget->isCortexA57())
PredictableSelectIsExpensive = true;
}
void AArch64TargetLowering::addTypeForNEON(EVT VT, EVT PromotedBitwiseVT) {