[LoopUnrollRuntime] Invalidate SCEV for exit phi in ConnectProlog.

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

Fix is analog to cfc741bc0e029.

Fixes #56286.

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 79f4357..cd3b6c1 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -73,7 +73,8 @@ static void ConnectProlog(Loop *L, Value *BECount, unsigned Count,
                           BasicBlock *OriginalLoopLatchExit,
                           BasicBlock *PreHeader, BasicBlock *NewPreHeader,
                           ValueToValueMapTy &VMap, DominatorTree *DT,
-                          LoopInfo *LI, bool PreserveLCSSA) {
+                          LoopInfo *LI, bool PreserveLCSSA,
+                          ScalarEvolution &SE) {
   // Loop structure should be the following:
   // Preheader
   //  PrologHeader
@@ -133,6 +134,7 @@ static void ConnectProlog(Loop *L, Value *BECount, unsigned Count,
         PN.setIncomingValueForBlock(NewPreHeader, NewPN);
       else
         PN.addIncoming(NewPN, PrologExit);
+      SE.forgetValue(&PN);
     }
   }
 
@@ -927,7 +929,7 @@ bool llvm::UnrollRuntimeLoopRemainder(
     // Connect the prolog code to the original loop and update the
     // PHI functions.
     ConnectProlog(L, BECount, Count, PrologExit, LatchExit, PreHeader,
-                  NewPreHeader, VMap, DT, LI, PreserveLCSSA);
+                  NewPreHeader, VMap, DT, LI, PreserveLCSSA, *SE);
   }
 
   // If this loop is nested, then the loop unroller changes the code in the any