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.
llvm-svn: 255133
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index ad4c388..44dde1b 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -221,6 +221,12 @@
// Are we eliminating the loop control altogether?
bool CompletelyUnroll = Count == TripCount;
+ SmallVector<BasicBlock *, 4> 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 @@
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 @@
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.");
}
}