Merge commit 37b7207651b4 from llvm-project (by zhongyunde@huawei.com):

  [SimplifyCFG] Fix crash when there is unreachable large index (#88616)

  The large case index out of scope is dead code, but it is still be
  created for TableContents in SwitchLookupTable::SwitchLookupTable,
  so make sure the table size after growing should not get smaller.

  Fix llvm/llvm-project#88607

This should fix "Assertion failed: (idx < size()), function operator[]"
when building the science/dynare port.

PR:		276104, 278320
Reported by:	yuri
MFC after:	1 month

contrib/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -6710,9 +6710,11 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
           return SwitchLookupTable::WouldFitInRegister(
               DL, UpperBound, KV.second /* ResultType */);
         })) {
+      // There may be some case index larger than the UpperBound (unreachable
+      // case), so make sure the table size does not get smaller.
+      TableSize = std::max(UpperBound, TableSize);
       // The default branch is unreachable after we enlarge the lookup table.
       // Adjust DefaultIsReachable to reuse code path.
-      TableSize = UpperBound;
       DefaultIsReachable = false;
     }
   }