[PATCH] D82005: [InstCombine] Replace selects with Phis

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

Some more test cases I would suggest:

- An incoming multi-edge (same predecessor occurring multiple times) from a switch.
- A select operand coming from the terminator of a predecessor block, e.g. an invoke result.
- A select with a very obviously non-dominating input. All the existing examples look "salvageable" in some way (via phi translation or hoisting).



================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:2466
+                   m_Br(m_Not(m_Specific(Cond)), m_BasicBlock(TrueSucc),
+                        m_BasicBlock(FalseSucc)))) {
+    IfTrue = Sel.getFalseValue();
----------------
This looks like dead code, as we canonicalize branch of not by swapping successors. Might change with D81089, but for now it should be fine to just drop it.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:2494
+    PN->addIncoming(Inputs[Pred], Pred);
+  }
+  PN->takeName(&Sel);
----------------
Nit: Unnecessary braces.


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