llvm dev - May 2012 - [LLVMdev] overlaps generation, RA crasch

Hi,

Recently on trunk, the ovlaps list for a register got a dual entry on my target,
which caused the RA to crash.

Reg
  Subreg1
    Subreg b
  Subreg2
    Subreg b

I have a register with two subregs that have subreg b in common. This causes the
SuperReg to appear twice in the ovelaps list for Subreg b.

As this causes a register allocator to crasch (it evicts a register, and then
inremenets the *AliasI, but the data structure is then not ready to be re-used,
so a dual entry is not expected here),
I suggest that TableGen makes the overlaps list a set (each register present
only once), as I find at least my model very reasonable, and it has worked
before. An alternative might be to change the algorithm in TableGen so that this
will not occur...

/Jonas


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On May 11, 2012, at 6:35 AM, Jonas Paulsson <jonas.paulsson at
ericsson.com> wrote:
> Hi,
>  
> Recently on trunk, the ovlaps list for a register got a dual entry on my
target, which caused the RA to crash.
>  
> Reg
>   Subreg1
>     Subreg b
>   Subreg2
>     Subreg b
>  
> I have a register with two subregs that have subreg b in common. This
causes the SuperReg to appear twice in the ovelaps list for Subreg b
This should be fixed in r156629.

/jakob

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Thanks, this fixed our problem!

________________________________
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Jakob Stoklund Olesen
Sent: den 11 maj 2012 21:02
To: Jonas Paulsson
Cc: LLVM Developers Mailing List
Subject: Re: [LLVMdev] overlaps generation, RA crasch


On May 11, 2012, at 6:35 AM, Jonas Paulsson <jonas.paulsson at
ericsson.com<mailto:jonas.paulsson at ericsson.com>> wrote:

Hi,

Recently on trunk, the ovlaps list for a register got a dual entry on my target,
which caused the RA to crash.

Reg
  Subreg1
    Subreg b
  Subreg2
    Subreg b

I have a register with two subregs that have subreg b in common. This causes the
SuperReg to appear twice in the ovelaps list for Subreg b

This should be fixed in r156629.

/jakob

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