From 4c0fb60923bd45a297757929800a8ba97b531cbb Mon Sep 17 00:00:00 2001 From: Michael Zolotukhin Date: Wed, 9 Dec 2015 18:20:28 +0000 Subject: [PATCH] Revert "Revert r253253 and r253126: "Don't recompute LCSSA after loop-unrolling when possible."" The bug in IndVarSimplify was fixed in r254976, r254977, so I'm reapplying the original patch for avoiding redundant LCSSA recomputation. This reverts commit ffe3b434e505e403146aff00be0c177bb6d13466. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255133 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/LoopUnroll.cpp | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp index ad4c388e406..44dde1b51cf 100644 --- a/lib/Transforms/Utils/LoopUnroll.cpp +++ b/lib/Transforms/Utils/LoopUnroll.cpp @@ -221,6 +221,12 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, // Are we eliminating the loop control altogether? bool CompletelyUnroll = Count == TripCount; + SmallVector ExitBlocks; + L->getExitBlocks(ExitBlocks); + Loop *ParentL = L->getParentLoop(); + bool AllExitsAreInsideParentLoop = !ParentL || + std::all_of(ExitBlocks.begin(), ExitBlocks.end(), + [&](BasicBlock *BB) { return ParentL->contains(BB); }); // We assume a run-time trip count if the compiler cannot // figure out the loop trip count and the unroll-runtime @@ -544,7 +550,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, if (!OuterL && !CompletelyUnroll) OuterL = L; if (OuterL) { - simplifyLoop(OuterL, DT, LI, PP, SE, AC); + bool Simplified = simplifyLoop(OuterL, DT, LI, PP, SE, AC); // LCSSA must be performed on the outermost affected loop. The unrolled // loop's last loop latch is guaranteed to be in the outermost loop after @@ -554,7 +560,11 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, while (OuterL->getParentLoop() != LatchLoop) OuterL = OuterL->getParentLoop(); - formLCSSARecursively(*OuterL, *DT, LI, SE); + if (CompletelyUnroll && (!AllExitsAreInsideParentLoop || Simplified)) + formLCSSARecursively(*OuterL, *DT, LI, SE); + else + assert(OuterL->isLCSSAForm(*DT) && + "Loops should be in LCSSA form after loop-unroll."); } } -- 2.34.1