[llvm] [RISCV][TTI] Add shuffle costing for masked slide lowering (PR #128537)

[Philip Reames via llvm-commits]

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@@ -413,6 +413,36 @@ bool llvm::getShuffleDemandedElts(int SrcWidth, ArrayRef<int> Mask,
   return true;
 }
 
+bool llvm::isMaskedSlidePair(ArrayRef<int> Mask, int NumElts,
+                             std::pair<int, int> SrcInfo[2]) {
+  int SignalValue = NumElts * 2;
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preames wrote:

../llvm-project/llvm/lib/Analysis/VectorUtils.cpp: In function ‘bool llvm::isMaskedSlidePair(llvm::ArrayRef<int>, int, std::array<std::pair<int, int>, 2>&)’:
../llvm-project/llvm/lib/Analysis/VectorUtils.cpp:419:41: error: ‘NumElts’ is not a constant expression
  419 |   constexpr int SignalValue = NumElts * 2;

I will make it const instead.

https://github.com/llvm/llvm-project/pull/128537