Tighten the invariants around LoopBase::invalidate

Summary:
With this change:
 - Methods in LoopBase trip an assert if the receiver has been invalidated
 - LoopBase::clear frees up the memory held the LoopBase instance

This change also shuffles things around as necessary to work with this stricter invariant.

Reviewers: chandlerc

Subscribers: mehdi_amini, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D38055

llvm-svn: 313708

1 files changed, 7 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 1008f2c606b..40fcf97d657 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -1045,18 +1045,19 @@ static bool tryToUnrollLoop(
     UP.Count = TripCount;
 
   // Unroll the loop.
-  if (!UnrollLoop(L, UP.Count, TripCount, UP.Force, UP.Runtime,
-                  UP.AllowExpensiveTripCount, UseUpperBound, MaxOrZero,
-                  TripMultiple, UP.PeelCount, UP.UnrollRemainder,
-                  LI, &SE, &DT, &AC, &ORE,
-                  PreserveLCSSA))
+  LoopUnrollStatus UnrollStatus = UnrollLoop(
+      L, UP.Count, TripCount, UP.Force, UP.Runtime, UP.AllowExpensiveTripCount,
+      UseUpperBound, MaxOrZero, TripMultiple, UP.PeelCount, UP.UnrollRemainder,
+      LI, &SE, &DT, &AC, &ORE, PreserveLCSSA);
+  if (UnrollStatus == LoopUnrollStatus::Unmodified)
     return false;
 
   // If loop has an unroll count pragma or unrolled by explicitly set count
   // mark loop as unrolled to prevent unrolling beyond that requested.
   // If the loop was peeled, we already "used up" the profile information
   // we had, so we don't want to unroll or peel again.
-  if (IsCountSetExplicitly || UP.PeelCount)
+  if (UnrollStatus != LoopUnrollStatus::FullyUnrolled &&
+      (IsCountSetExplicitly || UP.PeelCount))
     SetLoopAlreadyUnrolled(L);
 
   return true;