[llvm] [SimplifyCFG][NFC] Renumber blocks when changing func (PR #186666)

[Fangrui Song via llvm-commits]

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@@ -380,9 +380,13 @@ PreservedAnalyses SimplifyCFGPass::run(Function &F,
     DT = &AM.getResult<DominatorTreeAnalysis>(F);
   if (!simplifyFunctionCFG(F, TTI, DT, Options))
     return PreservedAnalyses::all();
+  // If we removed some blocks, update block numbers to keep dense numbering.
+  F.renumberBlocks();
   PreservedAnalyses PA;
-  if (RequireAndPreserveDomTree)
+  if (RequireAndPreserveDomTree) {
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MaskRay wrote:

Aside: This `RequireAndPreserveDomTree` cl::opt (default  false), was added in 
e1133179587dd895962a2fe4d6eb0cb1e63b5ee2 (2020)

https://github.com/llvm/llvm-project/pull/186666