[llvm] [SimplifyCFG] Find the smallest table considering overflow in `switchToLookupTable` (PR #67885)

[Nikita Popov via llvm-commits]

================
@@ -6519,17 +6518,60 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
   SmallDenseMap<PHINode *, Type *> ResultTypes;
   SmallVector<PHINode *, 4> PHIs;
 
-  for (SwitchInst::CaseIt E = SI->case_end(); CI != E; ++CI) {
-    ConstantInt *CaseVal = CI->getCaseValue();
-    if (CaseVal->getValue().slt(MinCaseVal->getValue()))
-      MinCaseVal = CaseVal;
-    if (CaseVal->getValue().sgt(MaxCaseVal->getValue()))
-      MaxCaseVal = CaseVal;
+  SmallVector<ConstantInt *, 8> CaseVals;
+  for (auto CI : SI->cases()) {
+    ConstantInt *CaseVal = CI.getCaseValue();
+    CaseVals.push_back(CaseVal);
+  }
----------------
nikic wrote:

```suggestion
  for (auto CI : SI->cases())
    CaseVals.push_back(CI.getCaseValue());
```

https://github.com/llvm/llvm-project/pull/67885