[PATCH] D90361: Prevent LICM and machineLICM from hoisting convergent operations

[Xiaoqing Wu via Phabricator via llvm-commits]

xiaoqing_wu added a comment.

In D90361#2361510 <https://reviews.llvm.org/D90361#2361510>, @foad wrote:

>> Results of convergent operations are implicitly affected by the enclosing control flows and should not be hoisted out of arbitrary loops.
>
> I thought it was OK to hoist them out of loops, but not to sink them into loops? The langref says they "should not be made control-dependent on additional values".

In practice, convergent attribute has been used on operations that involve inter-thread communication which results are implicitly affected by the enclosing control flows. This was pointed out in the proposal in https://reviews.llvm.org/D85603. The definition in the current langref doesn't reflect how the attribute is used.


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https://reviews.llvm.org/D90361