[PATCH] D32991: [ELF] Initial migration of AVR target

[Leslie Zhai via Phabricator via llvm-commits]

xiangzhai updated this revision to Diff 101987.
xiangzhai added a comment.

Dear Dylan,

Thanks for your hint!

> This is caused because unless you specify a target mcu, it will default to the bare minimum - the avr2 architecture, as with avr-gcc. Devices that fit into this category do not even have call/jmp instructions, and so you likely just need to pass something like atmega328p as the target CPU to llvm-mc.

Worked :)

  $ /home/zhaixiang/project/llvm/build/bin/llvm-mc -filetype=obj -triple=avr-unknown-linux -mcpu=atmega328p basic-avr.s -o /tmp/basic-avr.o
  $ file /tmp/basic-avr.o
  /tmp/basic-avr.o: ELF 32-bit LSB relocatable, Atmel AVR 8-bit, version 1 (SYSV), not stripped
  $ readelf -r /tmp/basic-avr.o
  
  Relocation section '.rela.text' at offset 0x7c contains 2 entries:
   Offset     Info    Type            Sym.Value  Sym. Name + Addend
  00000000  00000312 R_AVR_CALL        00000000   .text + 4
  00000004  00000312 R_AVR_CALL        00000000   .text + 4

Dear Rui,

> but you need to enable AVR backend when building your LLVM, I guess?



  $ /home/zhaixiang/project/llvm/build/bin/llvm-mc --version
  LLVM (http://llvm.org/):
    LLVM version 5.0.0svn
    Optimized build.
    Default target: x86_64-redhat-linux
    Host CPU: broadwell
  
    Registered Targets:
      ...
      avr        - Atmel AVR Microcontroller
      ...

And I run the testcase:

  $ make check-lld
  [100%] Running lld test suite
  Testing Time: 27.90s
    Expected Passes    : 1146
    Unsupported Tests  : 12
  [100%] Built target check-lld

PS: @dylanmckay please update Buildbot's build optioin, I have experienced False Positive build failures <http://lists.llvm.org/pipermail/llvm-dev/2017-April/112406.html>, I directly added **AVR** to LLVM_ALL_TARGETS  instead of `-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="AVR"` https://reviews.llvm.org/D33348 thoughts?

Then run for the AVR simulator:

  $ simavr -m atmega328p ./basic-avr
  Loaded 8 .text at address 0x0
  avr_gdb_init listening on port 1234

Regards,
Leslie Zhai


Repository:
  rL LLVM

https://reviews.llvm.org/D32991

Files:
  ELF/InputFiles.cpp
  ELF/Target.cpp
  test/ELF/basic-avr.s
  test/lit.cfg

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