[llvm] [StructurizeCFG] Hoist and simplify zero-cost incoming else phi values (PR #139605)

[via llvm-commits]

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@@ -413,6 +455,41 @@ INITIALIZE_PASS_DEPENDENCY(RegionInfoPass)
 INITIALIZE_PASS_END(StructurizeCFGLegacyPass, "structurizecfg",
                     "Structurize the CFG", false, false)
 
+/// Because the SCC order of Then and Else blocks is arbitrary, structurization
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ruiling wrote:

Talking about the arbitrary order of then/else block is a little bit confusing here. Because we treated the first visited successor as `Then` block, and the other one as `Else` block throughout the code implementation. Maybe just remove it to avoid such confusion.

https://github.com/llvm/llvm-project/pull/139605