[JITLink][AArch32] Tests for ELF::R_ARM_ABS32 and ELF::R_ARM_REL32

[Eymay]

Summary

Testing for Static Data relocations for both ARM and Thumb targets.

[sgraenitz]

This is looking very good already! Nice idea to check ARM and Thumb in one test. I am not sure, however, if it's worth the effort. They both produce R_ARM_ABS32 and R_ARM_REL32. The only difference is the alignment and here Thumb alone would be sufficient:

➜ llvm-objdump -r ...
RELOCATION RECORDS FOR [.text]:                   RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE                     VALUE           OFFSET   TYPE                     VALUE
00000004 R_ARM_ABS32              target          00000002 R_ARM_ABS32              target
00000008 R_ARM_REL32              target          00000006 R_ARM_REL32              target
       ^ ARM is on a 4-byte boundary                     ^ Thumb is 2-byte

What we should do at some point (not necessarily in this patch) is to check whether it works on big-endian targets. Add a eb suffix to the arch in order to test it, e.g. thumbebv7-none-linux-gnueabihf

llvm/test/ExecutionEngine/JITLink/AArch32/ELF_static_data_reloc.s

17

Yes, but it's no data-relocation, so it should be out-of-scope for this test.

[sgraenitz]

llvm/test/ExecutionEngine/JITLink/AArch32/ELF_static_data_reloc.s

34

Is your intention to distinguish command-lines from comments by using // and # respectively? Because then it seems you are rotating them here? All test I know use the same comment marker for both.

[Eymay]

In D157519#4574123, @sgraenitz wrote:

This is looking very good already! Nice idea to check ARM and Thumb in one test. I am not sure, however, if it's worth the effort. They both produce R_ARM_ABS32 and R_ARM_REL32. The only difference is the alignment and here Thumb alone would be sufficient:

➜ llvm-objdump -r ...
RELOCATION RECORDS FOR [.text]:                   RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE                     VALUE           OFFSET   TYPE                     VALUE
00000004 R_ARM_ABS32              target          00000002 R_ARM_ABS32              target
00000008 R_ARM_REL32              target          00000006 R_ARM_REL32              target
       ^ ARM is on a 4-byte boundary                     ^ Thumb is 2-byte

What we should do at some point (not necessarily in this patch) is to check whether it works on big-endian targets. Add a eb suffix to the arch in order to test it, e.g. thumbebv7-none-linux-gnueabihf

Agree, I'd say it is more a proof of concept. These provide the scaffolding to add tests for varying targets.

[Eymay]

Removed non-data relocation checks and standardised comment styling

[Eymay]

Thanks for pointing out.

[Eymay]

replace "//" with "#" entirely

[sgraenitz]

Thanks for the updates! Can we align the assembly in the test a little more with the (now) existing ELF_static_thumb_reloc.s? That may avoid future divergence. Otherwise, this looks good to me.

llvm/test/ExecutionEngine/JITLink/AArch32/ELF_static_data_reloc.s

14

Function addresses are not in scope for this test, so we can drop the comment as well

[Eymay]

Update the test to align with ELF_static_thumb_reloc.s test.

[Eymay]

The disassembly of both ARM and Thumb turned out to be matching but CHECK-INSTR-{ARM,THM} can be added in the future for the lines that diverge.