[llvm] 48c74bb - [SampleProfileInference] Work around odr-use of const non-inline static data member to fix -O0 builds after D120508

[David Blaikie via llvm-commits]

Sorry, didn't see this earlier, but came across it looking at a
similar change recently - could you add a definition of this instead
of a cast, so it's not a trip-hazard for future development?


On Tue, Mar 8, 2022 at 2:35 PM Fangrui Song via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
>
> Author: Fangrui Song
> Date: 2022-03-08T14:34:53-08:00
> New Revision: 48c74bb2e2a72830f1068823bfc2f6fd4b53d427
>
> URL: https://github.com/llvm/llvm-project/commit/48c74bb2e2a72830f1068823bfc2f6fd4b53d427
> DIFF: https://github.com/llvm/llvm-project/commit/48c74bb2e2a72830f1068823bfc2f6fd4b53d427.diff
>
> LOG: [SampleProfileInference] Work around odr-use of const non-inline static data member to fix -O0 builds after D120508
>
> MinBaseDistance may be odr-used by std::max, leading to an undefined symbol linker error:
>
> ```
> ld.lld: error: undefined symbol: (anonymous namespace)::MinCostMaxFlow::MinBaseDistance
> >>> referenced by SampleProfileInference.cpp:744 (/home/ray/llvm-project/llvm/lib/Transforms/Utils/SampleProfileInference.cpp:744)
> >>>               lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SampleProfileInference.cpp.o:((anonymous namespace)::FlowAdjuster::jumpDistance(llvm::FlowJump*) const)
> ```
>
> Since llvm-project is still using C++ 14, workaround it with a cast.
>
> Added:
>
>
> Modified:
>     llvm/lib/Transforms/Utils/SampleProfileInference.cpp
>
> Removed:
>
>
>
> ################################################################################
> diff  --git a/llvm/lib/Transforms/Utils/SampleProfileInference.cpp b/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
> index 298c36b7ecd3d..6f56f1c432c2e 100644
> --- a/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
> +++ b/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
> @@ -741,7 +741,7 @@ class FlowAdjuster {
>    /// parts to a multiple of 1 / BaseDistance.
>    int64_t jumpDistance(FlowJump *Jump) const {
>      uint64_t BaseDistance =
> -        std::max(MinCostMaxFlow::MinBaseDistance,
> +        std::max(static_cast<uint64_t>(MinCostMaxFlow::MinBaseDistance),
>                   std::min(Func.Blocks[Func.Entry].Flow,
>                            MinCostMaxFlow::AuxCostUnlikely / NumBlocks()));
>      if (Jump->IsUnlikely)
>
>
>
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