diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/Utils/LoopUnroll.cpp | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp index ecd3854c210..ce4ce934283 100644 --- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp @@ -377,6 +377,15 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, LoopBlocksDFS::RPOIterator BlockEnd = DFS.endRPO(); std::vector<BasicBlock*> UnrolledLoopBlocks = L->getBlocks(); + + // Loop Unrolling might create new loops. While we do preserve LoopInfo, we + // might break loop-simplified form for these loops (as they, e.g., would + // share the same exit blocks). We'll keep track of loops for which we can + // break this so that later we can re-simplify them. + SmallSetVector<Loop *, 4> LoopsToSimplify; + for (Loop *SubLoop : *L) + LoopsToSimplify.insert(SubLoop); + for (unsigned It = 1; It != Count; ++It) { std::vector<BasicBlock*> NewBlocks; SmallDenseMap<const Loop *, Loop *, 4> NewLoops; @@ -407,6 +416,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, "Expected parent loop before sub-loop in RPO"); NewLoop = new Loop; NewLoopParent->addChildLoop(NewLoop); + LoopsToSimplify.insert(NewLoop); // Forget the old loop, since its inputs may have changed. if (SE) @@ -658,6 +668,11 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, if (!OuterL && !CompletelyUnroll) OuterL = L; if (OuterL) { + // OuterL includes all loops for which we can break loop-simplify, so + // it's sufficient to simplify only it (it'll recursively simplify inner + // loops too). + // TODO: That potentially might be compile-time expensive. We should try + // to fix the loop-simplified form incrementally. simplifyLoop(OuterL, DT, LI, SE, AC, PreserveLCSSA); // LCSSA must be performed on the outermost affected loop. The unrolled @@ -673,6 +688,10 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force, else assert(OuterL->isLCSSAForm(*DT) && "Loops should be in LCSSA form after loop-unroll."); + } else { + // Simplify loops for which we might've broken loop-simplify form. + for (Loop *SubLoop : LoopsToSimplify) + simplifyLoop(SubLoop, DT, LI, SE, AC, PreserveLCSSA); } } |
