[PATCH] D56907: [TTI] Add generic USUBSAT costs

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: include/llvm/CodeGen/BasicTTIImpl.h:1278
+      Cost += ConcreteTTI->getCmpSelInstrCost(BinaryOperator::ICmp, RetTy,
+                                              CondTy, nullptr);
+      Cost += ConcreteTTI->getCmpSelInstrCost(BinaryOperator::Select, RetTy,
----------------
nikic wrote:
> RKSimon wrote:
> > nikic wrote:
> > > Should we omit the icmp cost for the scalar case, on the assumption that it will be handled as an overflow flag instead?
> > Maybe just add those as x86 entries for now unless you want to add cost support for add/sub overflow/carry intrinsics as well?
> Having X86 entries would be fine as well, though I think that the availability of overflow flags for scalar add/sub is a reasonable enough assumption to make even for the generic cost model.
I've raised D57090 which will allow us to use overflow costs.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56907/new/

https://reviews.llvm.org/D56907