[llvm] 398b497 - [NFC] LoopRotate: do issue debug message when not rotating due to instr count

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2020-03-17T09:26:09+03:00
New Revision: 398b497cd0e20ca7245bf30c12c761b444581da5

URL: https://github.com/llvm/llvm-project/commit/398b497cd0e20ca7245bf30c12c761b444581da5
DIFF: https://github.com/llvm/llvm-project/commit/398b497cd0e20ca7245bf30c12c761b444581da5.diff

LOG: [NFC] LoopRotate: do issue debug message when not rotating due to instr count

It is somewhat problematic to notice this issue otherwise.

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/LoopRotationUtils.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp b/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
index 39be3d3831f0..8804bba975b6 100644
--- a/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
@@ -314,8 +314,14 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
                    L->dump());
         return Rotated;
       }
-      if (Metrics.NumInsts > MaxHeaderSize)
+      if (Metrics.NumInsts > MaxHeaderSize) {
+        LLVM_DEBUG(dbgs() << "LoopRotation: NOT rotating - contains "
+                          << Metrics.NumInsts
+                          << " instructions, which is more than the threshold ("
+                          << MaxHeaderSize << " instructions): ";
+                   L->dump());
         return Rotated;
+      }
     }
 
     // Now, this loop is suitable for rotation.