[llvm-dev] funnel shift, select, and poison
Krzysztof Parzyszek via llvm-dev
llvm-dev at lists.llvm.org
Mon Feb 25 11:44:25 PST 2019
On 2/25/2019 1:35 PM, John Regehr via llvm-dev wrote:
> It is definitely unsound to assume call(poison) == poison, because not
> every function returns a value that is poison-dependent on the
> function's arguments.
That's exactly the same as for a "select".
I'm in favor of a set of simple rules regarding the propagation of
poison, so I lean towards the "one answer" you proposed in the first
> One answer might be "only select and phi stop poison"
except augmented to include calls and invokes.
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