forked from OSchip/llvm-project
7b6f760fcd
MVE does not have a single sext/zext or trunc instruction that takes the bottom half of a vector and extends to a full width, like NEON has with MOVL. Instead it is expected that this happens through top/bottom instructions. So the MVE equivalent VMOVLT/B instructions take either the even or odd elements of the input and extend them to the larger type, producing a vector with half the number of elements each of double the bitwidth. As there is no simple instruction for a normal extend, we often have to expand sext/zext/trunc into a series of lane moves (or stack loads/stores, which we do not do yet). This pass takes vector code that starts at truncs, looks for interconnected blobs of operations that end with sext/zext and transforms them by adding shuffles so that the lanes are interleaved and the MVE VMOVL/VMOVN instructions can be used. This is done pre-ISel so that it can work across basic blocks. This initial version of the pass just handles a limited set of instructions, not handling constants or splats or FP, which can all come as extensions to this base. Differential Revision: https://reviews.llvm.org/D95804 |
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| Hexagon | ||
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