[PATCH] D57332: [RISCV] Allow parsing of bare symbols with offsets

Tue Jun 18 22:13:29 PDT 2019

jrtc27 added a comment.

In D57332#1549661 <https://reviews.llvm.org/D57332#1549661>, @asb wrote:

> Is this being used in the wild and does it work sensibly with binutils? I'm seeing that binutils seems to be associating the addend with both the emitted R_RISCV_PCREL_HI20 relocation and R_RISCV_RELAX relocation. Maybe this is just a binutils bug and the addend is ignored by the linker but this does seem surprising...
>
>   $ cat t.s 
>   lla a5, a_symbol + (0xFF << 3)
>   $ ./riscv32-unknown-elf-as t.s
>   $ ./riscv32-unknown-elf-readelf -r a.out 
>  
>   Relocation section '.rela.text' at offset 0xec contains 4 entries:
>    Offset     Info    Type            Sym.Value  Sym. Name + Addend
>   00000000  00000617 R_RISCV_PCREL_HI2 00000000   a_symbol + 7f8
>   00000000  00000033 R_RISCV_RELAX                7f8
>   00000004  00000418 R_RISCV_PCREL_LO1 00000000   .L0  + 0
>   00000004  00000033 R_RISCV_RELAX                0
>

Yes, FreeRTOS at least uses it, and we've had to manually patch the source to refer to just the bare symbol and follow it with an `addi` in order to support LLVM. The RELAX addend is probably a bug but I don't think it actually ever gets read.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57332/new/

https://reviews.llvm.org/D57332