* [Bug target/96787] rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure
2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
@ 2020-08-26 0:18 ` acsawdey at gcc dot gnu.org
2020-08-26 0:24 ` acsawdey at gcc dot gnu.org
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From: acsawdey at gcc dot gnu.org @ 2020-08-26 0:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
--- Comment #1 from acsawdey at gcc dot gnu.org ---
Created attachment 49123
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49123&action=edit
hashtab.c with target power9 attribute on htab_delete()
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
2020-08-26 0:18 ` [Bug target/96787] " acsawdey at gcc dot gnu.org
@ 2020-08-26 0:24 ` acsawdey at gcc dot gnu.org
2020-08-26 0:28 ` acsawdey at gcc dot gnu.org
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From: acsawdey at gcc dot gnu.org @ 2020-08-26 0:24 UTC (permalink / raw)
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--- Comment #2 from acsawdey at gcc dot gnu.org ---
I'm seeing some load-past-store code motion that happens when compiling for
power10 vs power9 that makes me suspicious.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
2020-08-26 0:18 ` [Bug target/96787] " acsawdey at gcc dot gnu.org
2020-08-26 0:24 ` acsawdey at gcc dot gnu.org
@ 2020-08-26 0:28 ` acsawdey at gcc dot gnu.org
2020-08-26 1:14 ` dje at gcc dot gnu.org
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From: acsawdey at gcc dot gnu.org @ 2020-08-26 0:28 UTC (permalink / raw)
To: gcc-bugs
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--- Comment #3 from acsawdey at gcc dot gnu.org ---
Never mind that, all I'm seeing is the lack of save/restore of r2 in the
power10 version.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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2020-08-26 0:28 ` acsawdey at gcc dot gnu.org
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From: dje at gcc dot gnu.org @ 2020-08-26 1:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
David Edelsohn <dje at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2020-08-26
Target Milestone|--- |10.2
CC| |bergner at gcc dot gnu.org
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #4 from David Edelsohn <dje at gcc dot gnu.org> ---
Confirmed.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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2020-08-26 1:14 ` dje at gcc dot gnu.org
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From: wschmidt at gcc dot gnu.org @ 2020-08-26 2:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
--- Comment #5 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
The divergence occurs after .L75 in the two versions. In the P10 version, we
see that the second bctrl has been converted into a bctr. It looks like a tail
call optimization happening, but we aren't at the end of the function. This
happens again later for the second bctrl after .L78.
Why would we think a tail call optimization can happen in the middle of a
block...
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: wschmidt at gcc dot gnu.org @ 2020-08-26 2:39 UTC (permalink / raw)
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Bill Schmidt <wschmidt at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |amodra at gcc dot gnu.org
--- Comment #6 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Ah, I can't read. These really are at the end(s) of the function, so it does
appear to be a tail call optimization that we've decided is legitimate.
It looks like the problem is that we don't set up r12 prior to the tail call.
Unlike the usual case, here we have "mtctr 9" to set up the CTR and r12 still
points to the previously called function. That can't be good.
This is exposed by my recent patch to allow more tail calls in
rs6000_decl_ok_for_sibcall, but it's not clear to me where we need to fix
things up so that r12 gets set.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: wschmidt at gcc dot gnu.org @ 2020-08-26 2:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
--- Comment #7 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
I believe the problem may be that rs6000_sibcall_aix doesn't contain any
handling for indirect calls, whereas similar code for other ABIs, like
rs6000_sibcall_sysv, does. Alan, does this make sense?
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: wschmidt at gcc dot gnu.org @ 2020-08-26 21:12 UTC (permalink / raw)
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--- Comment #8 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
I'm working on a patch.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: cvs-commit at gcc dot gnu.org @ 2020-08-27 16:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by William Schmidt <wschmidt@gcc.gnu.org>:
https://gcc.gnu.org/g:abca87c57847cd04f5e05935ff9ae5121c1ecb1d
commit r11-2908-gabca87c57847cd04f5e05935ff9ae5121c1ecb1d
Author: Bill Schmidt <wschmidt@linux.ibm.com>
Date: Thu Aug 27 11:17:06 2020 -0500
rs6000: Support ELFv2 sibcall for indirect calls [PR96787]
Prior to P10, ELFv2 hasn't implemented nonlocal sibcalls. Now that we do,
we need to be sure that r12 is set up prior to such a call.
2020-08-27 Bill Schmidt <wschmidt@linux.ibm.com>
gcc/
PR target/96787
* config/rs6000/rs6000.c (rs6000_sibcall_aix): Support
indirect call for ELFv2.
gcc/testsuite/
PR target/96787
* gcc.target/powerpc/pr96787-1.c: New.
* gcc.target/powerpc/pr96787-2.c: New.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: wschmidt at gcc dot gnu.org @ 2020-08-27 16:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
Bill Schmidt <wschmidt at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #10 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Work is complete.
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2020-08-26 0:17 [Bug target/96787] New: rs6000 mcpu=power10 miscompiles libiberty htab_delete() causing bootstrap failure acsawdey at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2022-03-13 7:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96787
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.2 |11.0
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