llvm-6502/lib/Target/MSP430
Chandler Carruth b35552d440 Clean up a pile of hacks in our CMake build relating to TableGen.
The first problem to fix is to stop creating synthetic *Table_gen
targets next to all of the LLVM libraries. These had no real effect as
CMake specifies that add_custom_command(OUTPUT ...) directives (what the
'tablegen(...)' stuff expands to) are implicitly added as dependencies
to all the rules in that CMakeLists.txt.

These synthetic rules started to cause problems as we started more and
more heavily using tablegen files from *subdirectories* of the one where
they were generated. Within those directories, the set of tablegen
outputs was still available and so these synthetic rules added them as
dependencies of those subdirectories. However, they were no longer
properly associated with the custom command to generate them. Most of
the time this "just worked" because something would get to the parent
directory first, and run tablegen there. Once run, the files existed and
the build proceeded happily. However, as more and more subdirectories
have started using this, the probability of this failing to happen has
increased. Recently with the MC refactorings, it became quite common for
me when touching a large enough number of targets.

To add insult to injury, several of the backends *tried* to fix this by
adding explicit dependencies back to the parent directory's tablegen
rules, but those dependencies didn't work as expected -- they weren't
forming a linear chain, they were adding another thread in the race.

This patch removes these synthetic rules completely, and adds a much
simpler function to declare explicitly that a collection of tablegen'ed
files are referenced by other libraries. From that, we can add explicit
dependencies from the smaller libraries (such as every architectures
Desc library) on this and correctly form a linear sequence. All of the
backends are updated to use it, sometimes replacing the existing attempt
at adding a dependency, sometimes adding a previously missing dependency
edge.

Please let me know if this causes any problems, but it fixes a rather
persistent and problematic source of build flakiness on our end.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136023 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-26 00:09:08 +00:00
..
InstPrinter Clean up a pile of hacks in our CMake build relating to TableGen. 2011-07-26 00:09:08 +00:00
MCTargetDesc Clean up a pile of hacks in our CMake build relating to TableGen. 2011-07-26 00:09:08 +00:00
TargetInfo
CMakeLists.txt Clean up a pile of hacks in our CMake build relating to TableGen. 2011-07-26 00:09:08 +00:00
Makefile Next round of MC refactoring. This patch factor MC table instantiations, MC 2011-07-14 20:59:42 +00:00
MSP430.h Next round of MC refactoring. This patch factor MC table instantiations, MC 2011-07-14 20:59:42 +00:00
MSP430.td
MSP430AsmPrinter.cpp Separate MCInstPrinter registration from AsmPrinter registration. 2011-07-25 21:20:24 +00:00
MSP430BranchSelector.cpp
MSP430CallingConv.td
MSP430FrameLowering.cpp
MSP430FrameLowering.h
MSP430InstrFormats.td
MSP430InstrInfo.cpp Next round of MC refactoring. This patch factor MC table instantiations, MC 2011-07-14 20:59:42 +00:00
MSP430InstrInfo.h
MSP430InstrInfo.td
MSP430ISelDAGToDAG.cpp
MSP430ISelLowering.cpp land David Blaikie's patch to de-constify Type, with a few tweaks. 2011-07-18 04:54:35 +00:00
MSP430ISelLowering.h land David Blaikie's patch to de-constify Type, with a few tweaks. 2011-07-18 04:54:35 +00:00
MSP430MachineFunctionInfo.h
MSP430MCInstLower.cpp
MSP430MCInstLower.h
MSP430RegisterInfo.cpp Sink getDwarfRegNum, getLLVMRegNum, getSEHRegNum from TargetRegisterInfo down 2011-07-18 20:57:22 +00:00
MSP430RegisterInfo.h Sink getDwarfRegNum, getLLVMRegNum, getSEHRegNum from TargetRegisterInfo down 2011-07-18 20:57:22 +00:00
MSP430RegisterInfo.td
MSP430SelectionDAGInfo.cpp
MSP430SelectionDAGInfo.h
MSP430Subtarget.cpp Next round of MC refactoring. This patch factor MC table instantiations, MC 2011-07-14 20:59:42 +00:00
MSP430Subtarget.h
MSP430TargetMachine.cpp - Move CodeModel from a TargetMachine global option to MCCodeGenInfo. 2011-07-20 07:51:56 +00:00
MSP430TargetMachine.h - Move CodeModel from a TargetMachine global option to MCCodeGenInfo. 2011-07-20 07:51:56 +00:00
README.txt

//===---------------------------------------------------------------------===//
// 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):

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.