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LIMITATIONS.md

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Limitations

  • Unsupported Instruction Types
    • Memory
    • Branch
    • CSR instructions
  • Unsupported DataTypes
    • Float (f32,...)
    • Vectors except (v2i16, v4i8)
    • Scalars except (i8, i16, i32, i64)
  • Codegen Limitations (Patterns)
    • GlobalISel only, ISelDAG backwards-compatibility is planned, see Issue #11
    • Single output-only
    • Single basic block (?)
    • No memory access
    • No branches/jumps
  • SIMD Support
    • Work in Progress (GlobalISel limitations need to be fixed first)

Known Bugs

Clang -march parser does not pick up new extensions

Due to issues with the ordering of extensions in RISCVISAInfo.cpp the search algorithm will not find entries which not inserted in the correct order. To deal with this issue the following workaround is recommended:

  • Only generate patches for a single model (CoreDSL file)
  • Make sure that the arch string always starts with an x, or better prefix every arch string with xseal5.