Two days old build breakage on i386.

Thu Jun 26 18:39:53 UTC 2014

Here's some more debug output. Can someone interpret it:

genRaInsn
    cmpxchgl %vI_n1nF,8(%vI_n1nD,%vI_n1nE,4)
    r_dying      =  [%vI_n1nD, %vI_n1nE, %vI_n1nF]
    w_dying      =  []
    virt_read    =  [%vI_n1nD, %vI_n1nE, %vI_n1nF]
    virt_written =  []
    freeregs     =  FreeRegs 4282318848
    assig        =  [n1nD :-> InMem 0,
                     n1nE :-> InReg (RealRegSingle 2), n1nF :-> InReg
(RealRegSingle 3)]
ghc-stage1: panic! (the 'impossible' happened)
  (GHC version 7.9.20140626 for i386-unknown-linux):
RegAllocLinear.allocRegsAndSpill: no spill candidates

    allocating vreg:  VirtualRegI n1nD
    assignment:       [(n1nD,InMem 0),(n1nE,InReg (RealRegSingle
2)),(n1nF,InReg (RealRegSingle 3))]
    freeRegs:         FreeRegs 4282318848
    initFreeRegs:     FreeRegs 4282318861

(i.e. it's the cmpxchg instruction which is causing the failure.)

On Thu, Jun 26, 2014 at 8:17 PM, Johan Tibell <johan.tibell at gmail.com>
wrote:

> I'm trying to understand the output from the register allocator:
>
>   (GHC version 7.9.20140626 for i386-unknown-linux):
>  RegAllocLinear.allocRegsAndSpill: no spill candidates
>
>     allocating vreg:  VirtualRegI n1nD
>     assignment:       [(n1nD,InMem 0),(n1nE,InReg (RealRegSingle
> 2)),(n1nF,InReg (RealRegSingle 3))]
>     freeRegs:         FreeRegs 4282318848
>     initFreeRegs:     FreeRegs 4282318861
>
> Without understanding exactly what's wrong, the message above suggests
> that we're trying to allocate a reg for n1nD, but there's already an
> assignment for that virtual reg, is that right?
>
>
>
> On Thu, Jun 26, 2014 at 3:05 PM, Johan Tibell <johan.tibell at gmail.com>
> wrote:
>
>> Herbert pushed my revert for me a minute ago. Everyone should be good
>> once they sync.
>>
>>
>> On Thu, Jun 26, 2014 at 2:51 PM, Johan Tibell <johan.tibell at gmail.com>
>> wrote:
>>
>>> I guess you don't have 04dd7cb3423f1940242fdfe2ea2e3b8abd68a177 (which
>>> I pushed this morning) which is fine. You should be in a good state now
>>> when d8abf85f8ca176854e9d5d0b12371c4bc402aac3 is reverted.
>>>
>>>
>>> On Thu, Jun 26, 2014 at 2:49 PM, Simon Peyton Jones <
>>> simonpj at microsoft.com> wrote:
>>>
>>>>  git revert d8abf85f8ca176854e9d5d0b12371c4bc402aac3
>>>>
>>>> [master f958079] Revert "Add more primops for atomic ops on byte arrays"
>>>>
>>>> 23 files changed, 86 insertions(+), 1016 deletions(-)
>>>>
>>>> rewrite compiler/nativeGen/CPrim.hs (62%)
>>>>
>>>> delete mode 100644 libraries/ghc-prim/cbits/atomic.c
>>>>
>>>> delete mode 100644
>>>> testsuite/tests/concurrent/should_run/AtomicPrimops.hs
>>>>
>>>> delete mode 100644
>>>> testsuite/tests/concurrent/should_run/AtomicPrimops.stdout
>>>>
>>>> HEAD $ git revert 04dd7cb3423f1940242fdfe2ea2e3b8abd68a177
>>>>
>>>> fatal: bad object 04dd7cb3423f1940242fdfe2ea2e3b8abd68a177
>>>>
>>>> HEAD $
>>>>
>>>> What now?
>>>>
>>>> Simon
>>>>
>>>>
>>>>
>>>> *From:* Johan Tibell [mailto:johan.tibell at gmail.com]
>>>> *Sent:* 26 June 2014 13:25
>>>> *To:* Simon Peyton Jones
>>>> *Cc:* Karel Gardas; ghc-devs
>>>> *Subject:* Re: Two days old build breakage on i386.
>>>>
>>>>
>>>>
>>>> Just to make sure this is the same breakage, are you on an i386 Windows
>>>> machine? If so git revert d8abf85f8ca176854e9d5d0b12371c4bc402aac3
>>>> and 04dd7cb3423f1940242fdfe2ea2e3b8abd68a177 to get unstuck.
>>>>
>>>>
>>>>
>>>> On Thu, Jun 26, 2014 at 2:13 PM, Simon Peyton Jones <
>>>> simonpj at microsoft.com> wrote:
>>>>
>>>>  Aaaargh!  Once again the Windows build is broken.  I am utterly
>>>> stalled.
>>>>
>>>> Moreover -fregs-graph and -fregs-iterative now *silently* do nothing.
>>>>  At least they should elicit warnings saying that they are disabled pending
>>>> the fix to X and Y.
>>>>
>>>> Please can someone bisect to find out which patch is the culprit?
>>>>
>>>> I wish we had a more systematic way to find this out. I hate being the
>>>> main person who gets stuck because some unrelated change has broken the
>>>> Windows build.  (Thanks for Karel, who got to it a day before me.)
>>>>
>>>> Thanks
>>>>
>>>> Simon
>>>>
>>>>
>>>> | -----Original Message-----
>>>> | From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of
>>>> Karel
>>>> | Gardas
>>>> | Sent: 26 June 2014 09:56
>>>> | To: ghc-devs; Johan Tibell
>>>> | Subject: Two days old build breakage on i386.
>>>> |
>>>> |
>>>> | Hello,
>>>> |
>>>> | builders running on i386 building for this platform caught issue which
>>>> | shows as a build breakage:
>>>> |
>>>> | ghc-stage1: panic! (the 'impossible' happened)
>>>> | (GHC version 7.9.20140624 for i386-unknown-linux):
>>>> | RegAllocLinear.allocRegsAndSpill: no spill candidates
>>>> | allocating vreg: VirtualRegI n1Q6
>>>> | assignment: [(c1PV,InMem 2),(n1Q5,InBoth (RealRegSingle 3)
>>>> | 0),(n1Q6,InMem 1),(n1Q7,InMem 3),(n1Q9,InReg (RealRegSingle 2))]
>>>> | freeRegs: FreeRegs 4282318848
>>>> | initFreeRegs: FreeRegs 4282318861
>>>> | Please report this as a GHC bug:
>>>> http://www.haskell.org/ghc/reportabug
>>>> | make[1]: ***
>>>> | [libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.o] Error 1
>>>> | libraries/ghc-prim/ghc.mk:4: recipe for target
>>>> | 'libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.o' failed
>>>> |
>>>> | Have a look for example on linux-i386 buildot log here:
>>>> |
>>>> http://haskell.inf.elte.hu/builders/validator1-linux-x86-head/18/7.html
>>>> |
>>>> | Anyway, this happens on Linux, FreeBSD and Solaris buildbots on i386
>>>> so
>>>> | it's OS independent and probably 32bit/i386 platform specific and it's
>>>> | two days old breakage now. The last two night builds fail on all
>>>> | mentioned buildbots. I'm not sure but perhaps:
>>>> |
>>>> | commit d8abf85f8ca176854e9d5d0b12371c4bc402aac3
>>>> | Author: Johan Tibell <johan.tibell at gmail.com>
>>>> | Date:   Mon Jun 9 11:43:21 2014 +0200
>>>> |
>>>> | triggers that issue? I'm not claiming that the commit is actual
>>>> culprit,
>>>> | this may be just recently un-hidden issue in linear regs allocator on
>>>> | i386!
>>>> |
>>>> | Thanks!
>>>> | Karel
>>>>
>>>> | _______________________________________________
>>>> | ghc-devs mailing list
>>>> | ghc-devs at haskell.org
>>>> | http://www.haskell.org/mailman/listinfo/ghc-devs
>>>>
>>>>
>>>>
>>>
>>>
>>
>
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