[llvm] b4efc0f - [LV] Break up condition in selectEpilogueVectorizationFactor loop (NFCI)

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2023-07-03T22:39:40+01:00
New Revision: b4efc0f070baefa6a308f0cf4d23cd71ad608deb

URL: https://github.com/llvm/llvm-project/commit/b4efc0f070baefa6a308f0cf4d23cd71ad608deb
DIFF: https://github.com/llvm/llvm-project/commit/b4efc0f070baefa6a308f0cf4d23cd71ad608deb.diff

LOG: [LV] Break up condition in selectEpilogueVectorizationFactor loop (NFCI)

Restructure the loop as suggested in D154264 to increase readability and
make it easier to extend.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index bf0ce24c318ea0..b60c538c535327 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5699,13 +5699,21 @@ VectorizationFactor LoopVectorizationPlanner::selectEpilogueVectorizationFactor(
       EstimatedRuntimeVF *= *VScale;
   }
 
-  for (auto &NextVF : ProfitableVFs)
-    if (((!NextVF.Width.isScalable() && MainLoopVF.isScalable() &&
-          ElementCount::isKnownLT(NextVF.Width, EstimatedRuntimeVF)) ||
-         ElementCount::isKnownLT(NextVF.Width, MainLoopVF)) &&
-        (Result.Width.isScalar() || isMoreProfitable(NextVF, Result)) &&
-        hasPlanWithVF(NextVF.Width))
+  for (auto &NextVF : ProfitableVFs) {
+    // Skip candidate VFs without a corresponding VPlan.
+    if (!hasPlanWithVF(NextVF.Width))
+      continue;
+
+    // Skip candidate VFs with widths >= the estimate runtime VF (scalable
+    // vectors) or the VF of the main loop (fixed vectors).
+    if ((!NextVF.Width.isScalable() && MainLoopVF.isScalable() &&
+         ElementCount::isKnownGE(NextVF.Width, EstimatedRuntimeVF)) ||
+        ElementCount::isKnownGE(NextVF.Width, MainLoopVF))
+      continue;
+
+    if (Result.Width.isScalar() || isMoreProfitable(NextVF, Result))
       Result = NextVF;
+  }
 
   if (Result != VectorizationFactor::Disabled())
     LLVM_DEBUG(dbgs() << "LEV: Vectorizing epilogue loop with VF = "