[llvm] [AMDGPU] Add flag to enable expensive trip counts for runtime unroll. (PR #171735)

[Matt Arsenault via llvm-commits]

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@@ -124,6 +130,8 @@ void AMDGPUTTIImpl::getUnrollingPreferences(
   // We want to run unroll even for the loops which have been vectorized.
   UP.UnrollVectorizedLoop = true;
 
+  UP.AllowExpensiveTripCount = UnrollRuntimeExpensiveTripCount;
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arsenm wrote:

Right, you can move the flag you are adding here to there instead 

https://github.com/llvm/llvm-project/pull/171735