[UnrollRuntime] Invalidate SCEVs for modified phis in ConnectEpilog.

ConnectEpilog adds new incoming values to exit phi nodes which can
change the SCEV for the phi after 20d798bd47ec51.

Fix is analog to cfc741bc0e029.

Fixes #56282.

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 1a94532..79f4357 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -191,7 +191,8 @@ static void ConnectEpilog(Loop *L, Value *ModVal, BasicBlock *NewExit,
                           BasicBlock *Exit, BasicBlock *PreHeader,
                           BasicBlock *EpilogPreHeader, BasicBlock *NewPreHeader,
                           ValueToValueMapTy &VMap, DominatorTree *DT,
-                          LoopInfo *LI, bool PreserveLCSSA)  {
+                          LoopInfo *LI, bool PreserveLCSSA,
+                          ScalarEvolution &SE) {
   BasicBlock *Latch = L->getLoopLatch();
   assert(Latch && "Loop must have a latch");
   BasicBlock *EpilogLatch = cast<BasicBlock>(VMap[Latch]);
@@ -232,6 +233,7 @@ static void ConnectEpilog(Loop *L, Value *ModVal, BasicBlock *NewExit,
 
     // Add incoming PreHeader from branch around the Loop
     PN.addIncoming(UndefValue::get(PN.getType()), PreHeader);
+    SE.forgetValue(&PN);
 
     Value *V = PN.getIncomingValueForBlock(Latch);
     Instruction *I = dyn_cast<Instruction>(V);
@@ -900,9 +902,8 @@ bool llvm::UnrollRuntimeLoopRemainder(
   if (UseEpilogRemainder) {
     // Connect the epilog code to the original loop and update the
     // PHI functions.
-    ConnectEpilog(L, ModVal, NewExit, LatchExit, PreHeader,
-                  EpilogPreHeader, NewPreHeader, VMap, DT, LI,
-                  PreserveLCSSA);
+    ConnectEpilog(L, ModVal, NewExit, LatchExit, PreHeader, EpilogPreHeader,
+                  NewPreHeader, VMap, DT, LI, PreserveLCSSA, *SE);
 
     // Update counter in loop for unrolling.
     // Use an incrementing IV.  Pre-incr/post-incr is backedge/trip count.