[Bug 1890435] Re: gcc-10 breaks on armhf (flaky): internal compiler error: Segmentation fault

[Christian Ehrhardt ]

I was unable to trigger the issue on my rpi4 yet, but as you'd imagine it is rather slow.
But (thanks Dannf) I got access to an X-gene - and carrying my known bad setup there (LXD container export FTW) I was able to recreate this on bare-metal as well.


(Host) Kernel: 5.4.0-58-generic
Model: X-Gene - 8 cores
The guest is Hirsute building qemu 5.0 with r11-5879

I got two known bug signatures - once the common one we see most and
once a different one (that we've seen before with 20200507).

This happened on the first two runs, once it has run some hours I'll
post the rate of success-vs-fails as well.

--- ---

during RTL pass: reload
/root/qemu-5.0/fpu/softfloat.c: In function ‘soft_f64_muladd’:
/root/qemu-5.0/fpu/softfloat.c:1535:1: internal compiler error: Segmentation fault
 1535 | }
      | ^
0x56715f crash_signal
        ../../gcc/gcc/toplev.c:327
0x4599ad add_regs_to_insn_regno_info
        ../../gcc/gcc/lra.c:1445
0x459ab9 add_regs_to_insn_regno_info
        ../../gcc/gcc/lra.c:1537
0x459ab9 add_regs_to_insn_regno_info
        ../../gcc/gcc/lra.c:1537
0x45abc7 lra_update_insn_regno_info(rtx_insn*)
        ../../gcc/gcc/lra.c:1630
0x468985 lra_constraints(bool)
        ../../gcc/gcc/lra-constraints.c:5077
0x45bc15 lra(_IO_FILE*)
        ../../gcc/gcc/lra.c:2329
42d463 do_reload
        ../../gcc/gcc/ira.c:5802
0x42d463 execute
        ../../gcc/gcc/ira.c:5988
Please submit a full bug report,


--- ---

during RTL pass: reload
/root/qemu-5.0/linux-user/syscall.c: In function ‘do_syscall1.constprop’:
/root/qemu-5.0/linux-user/syscall.c:12479:1: internal compiler error: Segmentation fault
12479 | }
      | ^
0x56715f crash_signal
        ../../gcc/gcc/toplev.c:327
0x527e35 extract_plus_operands
        ../../gcc/gcc/rtlanal.c:6320
0x52d84b extract_plus_operands
        ../../gcc/gcc/rtlanal.c:6324
0x52d84b decompose_normal_address
        ../../gcc/gcc/rtlanal.c:6373
0x52d84b decompose_address(address_info*, rtx_def**, machine_mode, unsigned char, rtx_code)
        ../../gcc/gcc/rtlanal.c:6474
0x52dbc3 decompose_mem_address(address_info*, rtx_def*)
        ../../gcc/gcc/rtlanal.c:6493
0x463551 process_address_1
        ../../gcc/gcc/lra-constraints.c:3460
0x464c47 process_address
        ../../gcc/gcc/lra-constraints.c:3734
0x464c47 curr_insn_transform
        ../../gcc/gcc/lra-constraints.c:4049
0x468913 lra_constraints(bool)
        ../../gcc/gcc/lra-constraints.c:5138
0x45bc15 lra(_IO_FILE*)
        ../../gcc/gcc/lra.c:2329
0x42d463 do_reload
        ../../gcc/gcc/ira.c:5802
0x42d463 execute
        ../../gcc/gcc/ira.c:5988
Please submit a full bug report,

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https://bugs.launchpad.net/bugs/1890435

Title:
  gcc-10 breaks on armhf (flaky): internal compiler error: Segmentation
  fault

Status in gcc:
  Confirmed
Status in gcc-10 package in Ubuntu:
  Confirmed

Bug description:
  Hi,
  this could be the same as bug 1887557 but as I don't have enough data I'm filing it as individual issue for now.

  I have only seen this happening on armhf so far.
  In 2 of 5 groovy builds of qemu 5.0 this week I have hit the issue, but it is flaky.

  Flakyness:
  1. different file
  first occurrence
  /<<PKGBUILDDIR>>/target/s390x/excp_helper.c:544:1: internal compiler error: Segmentation fault
  second occurrence
  /<<PKGBUILDDIR>>/linux-user/syscall.c:12479:1: internal compiler error: Segmentation fault

  Being so unreliable I can't provide mcuh more yet.
  I filed it mostly for awareness and so that I can be dup'ed onto the right but if there is a better one.

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