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/3rd_party/llvm/lib/Target/MSP430/README.txt

https://code.google.com/p/softart/
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Possible License(s): LGPL-2.1, BSD-3-Clause, JSON, MPL-2.0-no-copyleft-exception, GPL-2.0, GPL-3.0, LGPL-3.0, BSD-2-Clause
 1//===---------------------------------------------------------------------===//
 2// MSP430 backend.
 3//===---------------------------------------------------------------------===//
 4
 5DISCLAIMER: Thid backend should be considered as highly experimental. I never
 6seen nor worked with this MCU, all information was gathered from datasheet
 7only. The original intention of making this backend was to write documentation
 8of form "How to write backend for dummies" :) Thes notes hopefully will be
 9available pretty soon.
10
11Some things are incomplete / not implemented yet (this list surely is not
12complete as well):
13
141. Verify, how stuff is handling implicit zext with 8 bit operands (this might
15be modelled currently in improper way - should we need to mark the superreg as
16def for every 8 bit instruction?).
17
182. Libcalls: multiplication, division, remainder. Note, that calling convention
19for libcalls is incomptible with calling convention of libcalls of msp430-gcc
20(these cannot be used though due to license restriction).
21
223. Implement multiplication / division by constant (dag combiner hook?).
23
244. Implement non-constant shifts.
25
265. Implement varargs stuff.
27
286. Verify and fix (if needed) how's stuff playing with i32 / i64.
29
307. Implement floating point stuff (softfp?)
31
328. Implement instruction encoding for (possible) direct code emission in the
33future.
34
359. Since almost all instructions set flags - implement brcond / select in better
36way (currently they emit explicit comparison).
37
3810. Handle imm in comparisons in better way (see comment in MSP430InstrInfo.td)
39
4011. Implement hooks for better memory op folding, etc.