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ScalarEvolution::getSCEV cannot be used during codegen. ScalarEvolution assumes a stable IR and control flow which is under construction during Polly's CodeGen. In particular, it uses DominatorTree for compute the backedge taken count. However the DominatorTree is not updated during codegen. In this case, SCEV was used to determine the base pointer of an array access. Replace it by our own function. Polly generates only GEP and BitCasts for array acceses, i.e. it is sufficient to handle these to to find the base pointer. Fixes llvm.org/PR48422
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.