llvm

34a1b8ce - [acc] acc.loop verifier now requires parallelism determination flag (#143720)

[acc] acc.loop verifier now requires parallelism determination flag (#143720) The OpenACC specification for `acc loop` describe that a loop's parallelism determination mode is either auto, independent, or seq. The rules are as follows. - As per OpenACC 3.3 standard section 2.9.6 independent clause: A loop construct with no auto or seq clause is treated as if it has the independent clause when it is an orphaned loop construct or its parent compute construct is a parallel construct. - As per OpenACC 3.3 standard section 2.9.7 auto clause: When the parent compute construct is a kernels construct, a loop construct with no independent or seq clause is treated as if it has the auto clause. - Additionally, loops marked with gang, worker, or vector are not guaranteed to be parallel. Specifically noted in 2.9.7 auto clause: If not, or if it is unable to make a determination, it must treat the auto clause as if it is a seq clause, and it must ignore any gang, worker, or vector clauses on the loop construct. The verifier for `acc.loop` was updated to enforce this marking because the context in which a loop appears is not trivially determined once IR transformations begin. For example, orphaned loops are implicitly `independent`, but after inlining into an `acc.kernels` region they would be implicitly considered `auto`. Thus now the verifier requires that a frontend specifically generates acc dialect with this marking since it knows the context.