[PATCH] D63280: [llvm-objdump] Use <first-symbol>-<offset> as the section start symbol

Fri Jun 21 01:59:15 PDT 2019

peter.smith added a comment.

In D63280#1553187 <https://reviews.llvm.org/D63280#1553187>, @jhenderson wrote:

> > May I ask you to start a thread on https://lists.llvm.org/pipermail/llvm-dev/2019-June to discuss this?
>
> I agree that this needs a wider audience. @ychen, could you go ahead and start that email, please. Feel free to run a draft by me first if you want.

I'll make sure I comment on the list when the email thread starts. Some more data points for you from some gcc 8 toolchains. Arm and AArch64 use <.plt> in the same way as RiscV does. I would prefer this change not to be made for Arm and AArch64. There often can be a lot of target specific decisions made in binutils, we may find that there is little consistency in disassembly across targets.

aarch64-linux-gnu-objdump -d libgomp.so

  Disassembly of section .plt:

  0000000000007700 <.plt>:
      7700:       a9bf7bf0        stp     x16, x30, [sp, #-16]!
      7704:       f0000190        adrp    x16, 3a000 <__FRAME_END__+0xf3a4>
      7708:       f947fe11        ldr     x17, [x16, #4088]
      770c:       913fe210        add     x16, x16, #0xff8
      7710:       d61f0220        br      x17
      7714:       d503201f        nop
      7718:       d503201f        nop
      771c:       d503201f        nop

  0000000000007720 <memcpy at plt>:
      7720:       900001b0        adrp    x16, 3b000 <memcpy at GLIBC_2.17>
      7724:       f9400211        ldr     x17, [x16]
      7728:       91000210        add     x16, x16, #0x0
      772c:       d61f0220        br      x17

arm-linux-gnueabihf-objdump -d libgomp.so

  Disassembly of section .plt:

  0000602c <.plt>:
      602c:       e52de004        push    {lr}            ; (str lr, [sp, #-4]!)
      6030:       e59fe004        ldr     lr, [pc, #4]    ; 603c <.plt+0x10>
      6034:       e08fe00e        add     lr, pc, lr
      6038:       e5bef008        ldr     pc, [lr, #8]!
      603c:       00030fc4        .word   0x00030fc4

  00006040 <calloc at plt>:
      6040:       e28fc600        add     ip, pc, #0, 12
      6044:       e28cca30        add     ip, ip, #48, 20 ; 0x30000
      6048:       e5bcffc4        ldr     pc, [ip, #4036]!        ; 0xfc4

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63280/new/

https://reviews.llvm.org/D63280