[llvm-dev] funnel shift, select, and poison (original) (raw)
Krzysztof Parzyszek via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 25 11:30:32 PST 2019
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On 2/25/2019 1:24 PM, John Regehr via llvm-dev wrote:
This is a sound transformation only if foo() returns poison when it is called with poison as an argument.
Then how do you interpret "poison has to propagate through calls"?
A typical analysis of a function will either see a call or the inlined body. If "call(poison)" cannot be assumed to be a poison, then a call effectively stops the propagation of a poison.
-Krzysztof
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