[llvm] r259208 - [RS4GC] Minor local cleanup to StabilizeOrder; NFC

[David Blaikie via llvm-commits]

On Fri, Jan 29, 2016 at 8:50 AM, Sanjoy Das via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: sanjoy
> Date: Fri Jan 29 10:50:34 2016
> New Revision: 259208
>
> URL: http://llvm.org/viewvc/llvm-project?rev=259208&view=rev
> Log:
> [RS4GC] Minor local cleanup to StabilizeOrder; NFC
>
>  - Locally declare struct, and call it BaseDerivedPair
>  - Use a lambda to compare, instead of a singleton with uninitialized
>    fields
>  - Add a constructor to BaseDerivedPair and use SmallVector::emplace_back
>
> Modified:
>     llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp?rev=259208&r1=259207&r2=259208&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp Fri Jan
> 29 10:50:34 2016
> @@ -1516,33 +1516,32 @@ makeStatepointExplicitImpl(const CallSit
>    CreateGCRelocates(LiveVariables, LiveStartIdx, BasePtrs, Token,
> Builder);
>  }
>
> -namespace {
> -struct NameOrdering {
> -  Value *Base;
> -  Value *Derived;
> -
> -  bool operator()(NameOrdering const &a, NameOrdering const &b) {
> -    return -1 == a.Derived->getName().compare(b.Derived->getName());
> -  }
> -};
> -}
> -
>  static void StabilizeOrder(SmallVectorImpl<Value *> &BaseVec,
>                             SmallVectorImpl<Value *> &LiveVec) {
>    assert(BaseVec.size() == LiveVec.size());
>
> -  SmallVector<NameOrdering, 64> Temp;
> -  for (size_t i = 0; i < BaseVec.size(); i++) {
> -    NameOrdering v;
> -    v.Base = BaseVec[i];
> -    v.Derived = LiveVec[i];
> -    Temp.push_back(v);
> -  }
> +  struct BaseDerivedPair {
> +    Value *Base;
> +    Value *Derived;
> +
> +    BaseDerivedPair(Value *B, Value *D) : Base(B), Derived(D) {}
>

You could drop this ctor


> +  };
> +
> +  SmallVector<BaseDerivedPair, 64> NameOrdering;
> +  NameOrdering.reserve(BaseVec.size());
> +
> +  for (size_t i = 0, e = BaseVec.size(); i < e; i++)
> +    NameOrdering.emplace_back(BaseVec[i], LiveVec[i]);
>

And just use braced init here:
push_back({BaseVec[i], LiveVec[i]});


> +
> +  auto Compare = [](BaseDerivedPair &L, BaseDerivedPair &R) {
> +    return L.Derived->getName() < R.Derived->getName();
> +  };
> +
> +  std::sort(NameOrdering.begin(), NameOrdering.end(), Compare);
>

I'd probably just inline the lambda into the sort call.


>
> -  std::sort(Temp.begin(), Temp.end(), NameOrdering());
>    for (size_t i = 0; i < BaseVec.size(); i++) {
>

But, honestly - it'd be really nice if we could just sort these in place.
But that'd probably require a few abstractions we don't have just yet (a
range merge/zip tool mostly).


> -    BaseVec[i] = Temp[i].Base;
> -    LiveVec[i] = Temp[i].Derived;
> +    BaseVec[i] = NameOrdering[i].Base;
> +    LiveVec[i] = NameOrdering[i].Derived;
>    }
>  }
>
>
>
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