[llvm] [SCEV] Make PHI handling fully iterative. (PR #226624)

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git-clang-format --diff origin/main HEAD --extensions h,cpp -- llvm/include/llvm/Analysis/ScalarEvolution.h llvm/lib/Analysis/ScalarEvolution.cpp --diff_from_common_commit
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``````````diff
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 24002beb0..38eafb084 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -5399,9 +5399,10 @@ static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
 //    will return the pair {NewAddRec, SmallPredsVec} where:
 //         NewAddRec = {%Start,+,%Step}
 //         SmallPredsVec = {P1, P2, P3} as follows:
-//           P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
-//           P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
-//           P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
+//           P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags:
+//           <nssw> P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32)
+//           to i64) P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32)
+//           to i64)
 //    The returned pair means that SymbolicPHI can be rewritten into NewAddRec
 //    under the predicates {P1,P2,P3}.
 //    This predicated rewrite will be cached in PredicatedSCEVRewrites:

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https://github.com/llvm/llvm-project/pull/226624