[PATCH] D96019: [LoopVectorize] NFC: Change selectVectorizationFactor to work on ElementCount.

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen created this revision.
sdesmalen added reviewers: dmgreen, fhahn, gilr, david-arm.
Herald added a subscriber: hiraditya.
sdesmalen requested review of this revision.
Herald added a project: LLVM.

This patch is NFC and changes occurrences of `unsigned Width`
and `unsigned i` to work on type ElementCount instead.

This patch is a preparatory patch with the ultimate goal of making
`computeMaxVF()` return both a max fixed VF and a max scalable VF,
so that `selectVectorizationFactor()` can pick the most cost-effective
vectorization factor.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D96019

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp


Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5792,7 +5792,7 @@
   LLVM_DEBUG(dbgs() << "LV: Scalar loop costs: " << ExpectedCost << ".\n");
   assert(ExpectedCost.isValid() && "Unexpected invalid cost for scalar loop");
 
-  unsigned Width = 1;
+  auto Width = ElementCount::getFixed(1);
   const float ScalarCost = *ExpectedCost.getValue();
   float Cost = ScalarCost;
 
@@ -5804,13 +5804,14 @@
     Cost = std::numeric_limits<float>::max();
   }
 
-  for (unsigned i = 2; i <= MaxVF.getFixedValue(); i *= 2) {
+  for (auto i = ElementCount::getFixed(2); ElementCount::isKnownLE(i, MaxVF);
+       i *= 2) {
     // Notice that the vector loop needs to be executed less times, so
     // we need to divide the cost of the vector loops by the width of
     // the vector elements.
-    VectorizationCostTy C = expectedCost(ElementCount::getFixed(i));
+    VectorizationCostTy C = expectedCost(i);
     assert(C.first.isValid() && "Unexpected invalid cost for vector loop");
-    float VectorCost = *C.first.getValue() / (float)i;
+    float VectorCost = *C.first.getValue() / (float)i.getKnownMinValue();
     LLVM_DEBUG(dbgs() << "LV: Vector loop of width " << i
                       << " costs: " << (int)VectorCost << ".\n");
     if (!C.second && !ForceVectorization) {
@@ -5823,7 +5824,7 @@
     // If profitable add it to ProfitableVF list.
     if (VectorCost < ScalarCost) {
       ProfitableVFs.push_back(VectorizationFactor(
-          {ElementCount::getFixed(i), (unsigned)VectorCost}));
+          {i, (unsigned)VectorCost}));
     }
 
     if (VectorCost < Cost) {
@@ -5836,16 +5837,16 @@
     reportVectorizationFailure("There are conditional stores.",
         "store that is conditionally executed prevents vectorization",
         "ConditionalStore", ORE, TheLoop);
-    Width = 1;
+    Width = ElementCount::getFixed(1);
     Cost = ScalarCost;
   }
 
-  LLVM_DEBUG(if (ForceVectorization && Width > 1 && Cost >= ScalarCost) dbgs()
+  LLVM_DEBUG(if (ForceVectorization && !Width.isScalar() && Cost >= ScalarCost) dbgs()
              << "LV: Vectorization seems to be not beneficial, "
              << "but was forced by a user.\n");
   LLVM_DEBUG(dbgs() << "LV: Selecting VF: " << Width << ".\n");
-  VectorizationFactor Factor = {ElementCount::getFixed(Width),
-                                (unsigned)(Width * Cost)};
+  VectorizationFactor Factor = {Width,
+                                (unsigned)(Width.getKnownMinValue() * Cost)};
   return Factor;
 }
 


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