[llvm] [DAGCombiner] Ensure poison-generating flags are stripped in `freeze` op (PR #114582)

[Antonio Frighetto via llvm-commits]

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@@ -16151,6 +16151,7 @@ SDValue DAGCombiner::visitFREEZE(SDNode *N) {
                              SVN->getMask());
   } else {
     // NOTE: this strips poison generating flags.
+    N0->dropFlags(SDNodeFlags::PoisonGeneratingFlags);
----------------
antoniofrighetto wrote:

Quite strange. I just tried again and confirm the node returned here:

https://github.com/llvm/llvm-project/blob/89a8c71db61282c4e7522ffda5dbee890900dca5/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp#L10321-L10322

is `i32 = select_cc t12, t28, t16, t2, setult:ch`, immediately after visiting freeze in DAGCombiner. I'm happy with your patch too.

https://github.com/llvm/llvm-project/pull/114582