[PATCH] D83187: [LoopUnroll] Update branch weight for remainder loop

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea accepted this revision.
asbirlea added a comment.
This revision is now accepted and ready to land.

lgtm with 2 nits to clarify/fix.



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Comment at: llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp:521
+                              : TrueWeight;
+    uint64_t BackEdgeWeight = (UnrollFactor - 1) * ExitWeight;
+    BasicBlock *Header = RemainderLoop->getHeader();
----------------
Nit: not sure if possible: is it correct if `UnrollFactor = 1` to set `BackEdgeWeight = 0`?


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Comment at: llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp:808
+  if (remainderLoop && !UnrollRemainder) {
+    uint64_t TrueWeight, FalseWeight;
+    if (LatchBR->extractProfMetadata(TrueWeight, FalseWeight)) {
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hoyFB wrote:
> davidxl wrote:
> > It is better to fold this part into the update method too with one additional parameter for unroll factor.
> I ended up passing the original loop into the helper as well.
Nit: remove if braces.


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https://reviews.llvm.org/D83187