[LoopRotate] Unconditionally get ScalarEvolution.

[fhahn]

Summary

LoopRotate is a loop pass and SE should always be available.

[asbirlea]

lgtm.

llvm/lib/Transforms/Scalar/LoopRotation.cpp

97

AFAICT this also holds true for the DominatorTreeWrapperPass.

[fhahn]

llvm/lib/Transforms/Scalar/LoopRotation.cpp

97

Yep. I'll commit this with both fixed.

llvm/lib/Transforms/Scalar/LoopRotation.cpp

public:
   bool runOnLoop(Loop *L, LPPassManager &LPM) override {
     if (skipLoop(L))
       return false;
     Function &F = *L->getHeader()->getParent();
 
     auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
     const auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
     auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
     auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
     auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
-    auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
-    auto *SE = SEWP ? &SEWP->getSE() : nullptr;
+    auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
     const SimplifyQuery SQ = getBestSimplifyQuery(*this, F);
     Optional<MemorySSAUpdater> MSSAU;
     if (EnableMSSALoopDependency) {
       MemorySSA *MSSA = &getAnalysis<MemorySSAWrapperPass>().getMSSA();
       MSSAU = MemorySSAUpdater(MSSA);
     }
-    return LoopRotation(L, LI, TTI, AC, DT, SE,
+    return LoopRotation(L, LI, TTI, AC, DT, &SE,
                         MSSAU.hasValue() ? MSSAU.getPointer() : nullptr, SQ,
                         false, MaxHeaderSize, false);
   }
 };
 }
 
 char LoopRotateLegacyPass::ID = 0;
 INITIALIZE_PASS_BEGIN(LoopRotateLegacyPass, "loop-rotate", "Rotate Loops",