Add TODO list :)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70768 91177308-0d34-0410-b5e6-96231b3b80d8

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diff --git a/lib/Target/MSP430/README.txt b/lib/Target/MSP430/README.txt
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+//===---------------------------------------------------------------------===//
+// MSP430 backend.
+//===---------------------------------------------------------------------===//
+
+DISCLAIMER: Thid 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):
+
+0. Implement asmprinting for variables :)
+
+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.