Invoke SimplifyIndVar when we partially unroll a loop. Fixes PR10534.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137203 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index 6b2f9ef..ad39853 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -29,6 +29,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/SimplifyIndVar.h"
using namespace llvm;
// TODO: Should these be here or in LoopUnroll?
@@ -130,6 +131,9 @@
///
/// If a LoopPassManager is passed in, and the loop is fully removed, it will be
/// removed from the LoopPassManager as well. LPM can also be NULL.
+///
+/// This utility preserves LoopInfo. If DominatorTree or ScalarEvolution are
+/// available it must also preseve those analyses.
bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
unsigned TripMultiple, LoopInfo *LI, LPPassManager *LPM) {
BasicBlock *Preheader = L->getLoopPreheader();
@@ -163,7 +167,8 @@
// Notify ScalarEvolution that the loop will be substantially changed,
// if not outright eliminated.
- if (ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>())
+ ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>();
+ if (SE)
SE->forgetLoop(L);
if (TripCount != 0)
@@ -374,6 +379,24 @@
}
}
+ // FIXME: Reconstruct dom info, because it is not preserved properly.
+ // Incrementally updating domtree after loop unrolling woud be easy.
+ if (DominatorTree *DT = LPM->getAnalysisIfAvailable<DominatorTree>())
+ DT->runOnFunction(*L->getHeader()->getParent());
+
+ // Simplify any new induction variables in the partially unrolled loop.
+ if (SE && !CompletelyUnroll) {
+ SmallVector<WeakVH, 16> DeadInsts;
+ simplifyLoopIVs(L, SE, LPM, DeadInsts);
+
+ // Aggressively clean up dead instructions that simplifyLoopIVs already
+ // identified. Any remaining should be cleaned up below.
+ while (!DeadInsts.empty())
+ if (Instruction *Inst =
+ dyn_cast_or_null<Instruction>(&*DeadInsts.pop_back_val()))
+ RecursivelyDeleteTriviallyDeadInstructions(Inst);
+ }
+
// At this point, the code is well formed. We now do a quick sweep over the
// inserted code, doing constant propagation and dead code elimination as we
// go.