From 38a02f09f5f7487d4df19aa35fdc07b083b361b5 Mon Sep 17 00:00:00 2001 From: Anna Thomas Date: Fri, 27 Jan 2017 17:57:05 +0000 Subject: [PATCH] NFC: Add debug tracing for more cases where loop unrolling fails. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293313 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/LoopUnroll.cpp | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp index 5c3c94008d3..4fc7f410412 100644 --- a/lib/Transforms/Utils/LoopUnroll.cpp +++ b/lib/Transforms/Utils/LoopUnroll.cpp @@ -306,8 +306,10 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, Count = TripCount; // Don't enter the unroll code if there is nothing to do. - if (TripCount == 0 && Count < 2 && PeelCount == 0) + if (TripCount == 0 && Count < 2 && PeelCount == 0) { + DEBUG(dbgs() << "Won't unroll; almost nothing to do\n"); return false; + } assert(Count > 0); assert(TripMultiple > 0); @@ -362,8 +364,12 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, PreserveLCSSA)) { if (Force) RuntimeTripCount = false; - else + else { + DEBUG( + dbgs() << "Wont unroll; prolog and epilog code could not be inserted " + "when assuming runtime trip count\n"); return false; + } } // Notify ScalarEvolution that the loop will be substantially changed, -- 2.50.1