From: Philip Reames <listmail@philipreames.com>
Date: Thu, 3 Jun 2021 21:14:59 +0000 (-0700)
Subject: A couple style tweaks on top of 5c0d1b2f9 [nfc]
X-Git-Tag: llvmorg-14-init~4920
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cddcc4cff5052bc8a2311fea83f54b0caa1cbb4c;p=platform%2Fupstream%2Fllvm.git

A couple style tweaks on top of 5c0d1b2f9 [nfc]
---

diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index fa0a514..76036dc 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -411,6 +411,10 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
       dbgs() << "  No single exiting block\n";
   });
 
+  // Warning: ExactTripCount is the exact trip count for the block ending in
+  // ExitingBI, not neccessarily an exact exit count *for the loop*.  The
+  // distinction comes when we have an exiting latch, but the loop exits
+  // through another exit first.
   const unsigned ExactTripCount = ExitingBI ?
     SE->getSmallConstantTripCount(L,ExitingBI->getParent()) : 0;
   const bool ExactUnroll = (ExactTripCount && ExactTripCount == ULO.Count);
@@ -762,13 +766,13 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
             return None;
           return j == 0;
         }
-        if (ExactUnroll)
-          return j == 0;
-        // Full, but non-exact unrolling
+        // Complete (but possibly inexact) unrolling
         if (j == 0)
           return true;
         if (MaxTripCount && j >= MaxTripCount)
           return false;
+        // Warning: ExactTripCount is the trip count of the exiting
+        // block which ends in ExitingBI, not neccessarily the loop.
         if (ExactTripCount && j != ExactTripCount)
           return false;
         return None;