[NFC][LoopSimplify] modernize for loops over LoopInfo

This patch modifies two for loops to use the range based syntax.
Since they are equivalent, this patch is tagged NFC.

Differential Revision: https://reviews.llvm.org/D90069

Author: tammela

llvm/lib/Transforms/Utils/LoopSimplify.cpp

@@ -834,8 +834,8 @@ bool LoopSimplify::runOnFunction(Function &F) {
   bool PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
 
   // Simplify each loop nest in the function.
-  for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
-    Changed |= simplifyLoop(*I, DT, LI, SE, AC, MSSAU.get(), PreserveLCSSA);
+  for (auto *L : *LI)
+    Changed |= simplifyLoop(L, DT, LI, SE, AC, MSSAU.get(), PreserveLCSSA);
 
 #ifndef NDEBUG
   if (PreserveLCSSA) {
@@ -864,9 +864,9 @@ PreservedAnalyses LoopSimplifyPass::run(Function &F,
 
   // Note that we don't preserve LCSSA in the new PM, if you need it run LCSSA
   // after simplifying the loops. MemorySSA is preserved if it exists.
-  for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
+  for (auto *L : *LI)
     Changed |=
-        simplifyLoop(*I, DT, LI, SE, AC, MSSAU.get(), /*PreserveLCSSA*/ false);
+        simplifyLoop(L, DT, LI, SE, AC, MSSAU.get(), /*PreserveLCSSA*/ false);
 
   if (!Changed)
     return PreservedAnalyses::all();