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

[Christian Ehrhardt ]

FYI - another 8 runs without a crash on r10-7093.
My current working theory is that the root cause of the crash might have been added as early as r10-4054 but one or many later changes have increased the chance (think increase the race window or such) for the issue to trigger.
If that assumption is true and with the current testcase it is nearly impossible to properly bisect the "original root cause". And at the same time still hard to find the one that increased the race window - since crashing early does not surely imply we are in the high/low chance area.


We've had many runs with the base versions so that one is really good.
But any other good result we've had so far could - in theory - be challenged and needs ~30 good runs to be somewhat sure (puh that will be a lot of time).

I'm marking the old runs that are debatable with good?<count-of-good-
runs>.

Also we might want to look for just the "new" crash signature.

20190425 good
r10-1014
r10-2027 good?4
r10-2533
r10-3040 good?4
r10-3220
r10-3400 good?4
r10-3450
r10-3475
r10-3478
r10-3593
r10-3622
r10-3657 good?5
r10-3727 good?3
r10-4054 other kind of bad - signature different, and rare?
r10-6080 good?10
r10-7093 bad, but slow to trigger
20200507 bad bad bad

Signatures:
r10-4054 arm_legitimate_address_p (nonimmediate)
r10-7093 add_regs_to_insn_regno_info (lra)
r10-7093 add_regs_to_insn_regno_info (lra)
20200507 extract_plus_operands (lra)
20200507 avoid_constant_pool_reference (lra)
20200507 add_regs_to_insn_regno_info (lra)
ubu-10.2 add_regs_to_insn_regno_info (lra)
ubu-10.2 avoid_constant_pool_reference (lra)
ubu-10.2 thumb2_legitimate_address_p (lra)
ubu-10.2 add_regs_to_insn_regno_info (lra)

Of course it could be that the same root cause surfaces as two different
signatures - but to it could as well be a multitude of issues. Therefore
- for now - "add_regs_to_insn_regno_info (lra)" is what I'll continue to
hunt for.

With some luck (do we have any in this?) the 10 runs on 6080 are sufficient.
Let us try r10-6586 next and plan for 15-30 runs to be sure it is good.
If hitting the issue I'll still re-run it so we can compare multiple signatures.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to gcc-10 in Ubuntu.
https://bugs.launchpad.net/bugs/1890435

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

Status in Groovy:
  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.

To manage notifications about this bug go to:
https://bugs.launchpad.net/groovy/+bug/1890435/+subscriptions