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DominatorTree, LoopInfo, and ScalarEvolution are function-level analyses that expect to be called only on instructions and basic blocks of the function they were original created for. When Polly outlined a parallel loop body into a separate function, it reused the same analyses seemed to work until new checks to be added in #101198. This patch creates new analyses for the subfunctions. GenDT, GenLI, and GenSE now refer to the analyses of the current region of code. Outside of an outlined function, they refer to the same analysis as used for the SCoP, but are substituted within an outlined function. Additionally to the cross-function queries of DT/LI/SE, we must not create SCEVs that refer to a mix of expressions for old and generated values. Currently, SCEVs themselves do not "remember" which ScalarEvolution analysis they were created for, but mixing them is just as unexpected as using DT/LI across function boundaries. Hence `SCEVLoopAddRecRewriter` was combined into `ScopExpander`. `SCEVLoopAddRecRewriter` only replaced induction variables but left SCEVUnknowns to reference the old function. `SCEVParameterRewriter` would have done so but its job was effectively superseded by `ScopExpander`, and now also `SCEVLoopAddRecRewriter`. Some issues persist put marked with a FIXME in the code. Changing them would possibly cause this patch to be not NFC anymore.
Polly - Polyhedral optimizations for LLVM ----------------------------------------- http://polly.llvm.org/ Polly uses a mathematical representation, the polyhedral model, to represent and transform loops and other control flow structures. Using an abstract representation it is possible to reason about transformations in a more general way and to use highly optimized linear programming libraries to figure out the optimal loop structure. These transformations can be used to do constant propagation through arrays, remove dead loop iterations, optimize loops for cache locality, optimize arrays, apply advanced automatic parallelization, drive vectorization, or they can be used to do software pipelining.