[PATCH] D28179: Make sure total loop body weight is preserved in loop peeling

[David Li via Phabricator via llvm-commits]

davidxl added inline comments.


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Comment at: lib/Transforms/Utils/LoopUnrollPeel.cpp:338
   uint64_t TrueWeight, FalseWeight;
-  uint64_t ExitWeight = 0, BackEdgeWeight = 0;
+  uint64_t ExitWeight = 0, LoopBodyWeight = 0;
   if (LatchBR->extractProfMetadata(TrueWeight, FalseWeight)) {
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Might be better to name it 

CurHeaderWeight or just HeaderWeight


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Comment at: lib/Transforms/Utils/LoopUnrollPeel.cpp:351
 
     // The exit weight of the previous iteration is the header entry weight
     // of the current iteration. So this is exactly how many dynamic iterations
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This comment is not accurate. Better 

"Subtract the exit weight from the current header weight -- the exit weight is exactly ..."


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Comment at: lib/Transforms/Utils/LoopUnrollPeel.cpp:393
   if (ExitWeight) {
+    // The backedge count is the difference of remaining loop body weight and
+    // loop body entry count. If the remaining loop body weight is smaller than
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remaining loop body weight --> current header weight

loop body entry count --> current loop exit weight


https://reviews.llvm.org/D28179