[PATCH] D64972: [Loop Peeling] Do not close further unroll/peel if profile based peeling was not used

[Serguei Katkov via Phabricator via llvm-commits]

skatkov updated this revision to Diff 211029.
skatkov retitled this revision from "[Loop Peeling] Do not close further unroll/peel if not full peeling happens" to "[Loop Peeling] Do not close further unroll/peel if profile based peeling was not used".
skatkov added a comment.

Test is updated to show what this patch changes.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64972/new/

https://reviews.llvm.org/D64972

Files:
  llvm/include/llvm/Analysis/TargetTransformInfo.h
  llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
  llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
  llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll


Index: llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
===================================================================
--- llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
+++ llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
@@ -643,3 +643,4 @@
 for.end:
   ret void
 }
+; CHECK-NOT: llvm.loop.unroll.disable
\ No newline at end of file
Index: llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -275,6 +275,7 @@
     LLVM_DEBUG(dbgs() << "Force-peeling first " << UnrollForcePeelCount
                       << " iterations.\n");
     UP.PeelCount = UnrollForcePeelCount;
+    UP.PeelProfiledIterations = true;
     return;
   }
 
@@ -321,6 +322,7 @@
                         << " iteration(s) to turn"
                         << " some Phis into invariants.\n");
       UP.PeelCount = DesiredPeelCount;
+      UP.PeelProfiledIterations = false;
       return;
     }
   }
@@ -330,6 +332,9 @@
   if (TripCount)
     return;
 
+  // Do not apply profile base peeling if it is disabled.
+  if (!UP.PeelProfiledIterations)
+    return;
   // If we don't know the trip count, but have reason to believe the average
   // trip count is low, peeling should be beneficial, since we will usually
   // hit the peeled section.
Index: llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -202,6 +202,7 @@
   UP.UpperBound = false;
   UP.AllowPeeling = true;
   UP.UnrollAndJam = false;
+  UP.PeelProfiledIterations = true;
   UP.UnrollAndJamInnerLoopThreshold = 60;
 
   // Override with any target specific settings
@@ -1139,7 +1140,7 @@
   // If the loop was peeled, we already "used up" the profile information
   // we had, so we don't want to unroll or peel again.
   if (UnrollResult != LoopUnrollResult::FullyUnrolled &&
-      (IsCountSetExplicitly || UP.PeelCount))
+      (IsCountSetExplicitly || (UP.PeelProfiledIterations && UP.PeelCount)))
     L->setLoopAlreadyUnrolled();
 
   return UnrollResult;
Index: llvm/include/llvm/Analysis/TargetTransformInfo.h
===================================================================
--- llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -475,6 +475,11 @@
     bool UnrollRemainder;
     /// Allow unroll and jam. Used to enable unroll and jam for the target.
     bool UnrollAndJam;
+    /// Allow peeling basing on profile. Uses to enable peeling off all
+    /// iterations basing on provided profile.
+    /// If the value is true the peeling cost model can decide to peel only
+    /// some iteration and in this case it will set this to false.
+    bool PeelProfiledIterations;
     /// Threshold for unroll and jam, for inner loop size. The 'Threshold'
     /// value above is used during unroll and jam for the outer loop size.
     /// This value is used in the same manner to limit the size of the inner


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