[llvm] [LoopVectorizer] Add a -force-vscale-for-tuning override option. (PR #156916)

[Florian Hahn via llvm-commits]

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@@ -1473,6 +1477,11 @@ class LoopVectorizationCostModel {
   /// vscale_range.min == vscale_range.max then return vscale_range.max, else
   /// return the value returned by the corresponding TTI method.
   void initializeVScaleForTuning() {
+    if (VScaleForTuningOpt.getNumOccurrences()) {
+      VScaleForTuning = VScaleForTuningOpt;
+      return;
+    }
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fhahn wrote:

Is the purpose of the option to deliberately override the function attribute?


Does this have to be LV specific? Could this be handled in `getVScaleForTuning`?

https://github.com/llvm/llvm-project/pull/156916