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