DCE eliminating valid statement for ACATS c34007p

[Richard Kenner]

     > I'm wondering why verify_ssa doesn't detect this.

     It does.  See for instance pr 15740, which had generated an ICE.

But what I don't understand is why it didn't ICE in my case.

     That we don't constantly see problems is indicitive that the
     front-ends are good about using mark_addressable when needed, and so
     the TREE_ADDRESSABLE bit is reliable incoming to the gimplifier.

Right, but there are a few cases where the gimplifier calls it itself
and I suspect you're right that each are suspect.