| //===---------------------------------------------------------------------===// |
| // MSP430 backend. |
| //===---------------------------------------------------------------------===// |
| |
| DISCLAIMER: This backend should be considered as highly experimental. I never |
| seen nor worked with this MCU, all information was gathered from datasheet |
| only. The original intention of making this backend was to write documentation |
| of form "How to write backend for dummies" :) Thes notes hopefully will be |
| available pretty soon. |
| |
| Some things are incomplete / not implemented yet (this list surely is not |
| complete as well): |
| |
| 1. Verify, how stuff is handling implicit zext with 8 bit operands (this might |
| be modelled currently in improper way - should we need to mark the superreg as |
| def for every 8 bit instruction?). |
| |
| 2. Libcalls: multiplication, division, remainder. Note, that calling convention |
| for libcalls is incomptible with calling convention of libcalls of msp430-gcc |
| (these cannot be used though due to license restriction). |
| |
| 3. Implement multiplication / division by constant (dag combiner hook?). |
| |
| 4. Implement non-constant shifts. |
| |
| 5. Implement varargs stuff. |
| |
| 6. Verify and fix (if needed) how's stuff playing with i32 / i64. |
| |
| 7. Implement floating point stuff (softfp?) |
| |
| 8. Implement instruction encoding for (possible) direct code emission in the |
| future. |
| |
| 9. Since almost all instructions set flags - implement brcond / select in better |
| way (currently they emit explicit comparison). |
| |
| 10. Handle imm in comparisons in better way (see comment in MSP430InstrInfo.td) |
| |
| 11. Implement hooks for better memory op folding, etc. |
| |
