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* [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX
@ 2020-03-14 22:59 dje at gcc dot gnu.org
2021-03-09 18:11 ` [Bug target/94177] " dje at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: dje at gcc dot gnu.org @ 2020-03-14 22:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94177
Bug ID: 94177
Summary: TLS global-dynamic model clobbers function parameter
on AIX
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: dje at gcc dot gnu.org
Target Milestone: ---
Target: powerpc-ibm-aix*
In global-dynamic model, if a TLS variable first is referenced in the argument
list to a function call, GCC can load the parameters to the call before
invoking the function to legitimize the TLS variable, and the legitimize
function clobbers some of the same function argument registers.
extern int foo (char *, int *, int);
int main()
{
static __thread int result;
foo ("%p %u\n", &result, 169);
return 0;
}
$ gcc -fPIC -S bug_tls.c
li 5,169
lwz 10,LCM..1(2)
lwz 9,LC..1(2)
mr 3,10
mr 4,9
bla __tls_get_addr <*** clobbers r4, r5 already loaded with arguments
to foo
mr 9,3
mr 4,9
lwz 3,LC..2(2)
bl .foo
The pattern that generates __tls_get_addr shows that it clobbers r4 and r5
(define_insn "tls_get_addr_internal<mode>"
[(set (reg:P 3)
(unspec:P [(reg:P 3) (reg:P 4)] UNSPEC_TLSTLS))
(clobber (reg:P 0))
(clobber (reg:P 4))
(clobber (reg:P 5))
(clobber (reg:P 11))
(clobber (reg:CC CR0_REGNO))
(clobber (reg:P LR_REGNO))]
"TARGET_XCOFF && HAVE_AS_TLS"
"bla __tls_get_addr")
but GCC overwrites the parameters in calls.c during initial RTL generation.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/94177] TLS global-dynamic model clobbers function parameter on AIX
2020-03-14 22:59 [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX dje at gcc dot gnu.org
@ 2021-03-09 18:11 ` dje at gcc dot gnu.org
2021-04-27 16:32 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: dje at gcc dot gnu.org @ 2021-03-09 18:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94177
David Edelsohn <dje at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2021-03-09
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from David Edelsohn <dje at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/94177] TLS global-dynamic model clobbers function parameter on AIX
2020-03-14 22:59 [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX dje at gcc dot gnu.org
2021-03-09 18:11 ` [Bug target/94177] " dje at gcc dot gnu.org
@ 2021-04-27 16:32 ` cvs-commit at gcc dot gnu.org
2021-04-27 19:01 ` dje at gcc dot gnu.org
2021-05-28 20:49 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-04-27 16:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94177
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Edelsohn <dje@gcc.gnu.org>:
https://gcc.gnu.org/g:a21b399708175f6fc0ac723a0cebc127da421c60
commit r12-165-ga21b399708175f6fc0ac723a0cebc127da421c60
Author: David Edelsohn <dje.gcc@gmail.com>
Date: Sun Apr 11 19:41:26 2021 -0400
aix: TLS precompute register parameters (PR 94177)
AIX uses a compiler-managed TOC for global data, including TLS symbols.
The GCC TOC implementation manages the TOC entries through the constant
pool.
TLS symbols sometimes require a function call to obtain the TLS base
pointer. The arguments to the TLS call can conflict with arguments to
a normal function call if the TLS symbol is an argument in the normal call.
GCC specifically checks for this situation and precomputes the TLS
arguments, but the mechanism to check for this requirement utilizes
legitimate_constant_p(). The necessary result of legitimate_constant_p()
for correct TOC behavior and for correct TLS argument behavior is in
conflict.
This patch adds a new target hook precompute_tls_p() to decide if an
argument should be precomputed regardless of the result from
legitmate_constant_p().
gcc/ChangeLog:
PR target/94177
* calls.c (precompute_register_parameters): Additionally test
targetm.precompute_tls_p to pre-compute argument.
* config/rs6000/aix.h (TARGET_PRECOMPUTE_TLS_P): Define.
* config/rs6000/rs6000.c (rs6000_aix_precompute_tls_p): New.
* target.def (precompute_tls_p): New.
* doc/tm.texi.in (TARGET_PRECOMPUTE_TLS_P): Add hook documentation.
* doc/tm.texi: Regenerated.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/94177] TLS global-dynamic model clobbers function parameter on AIX
2020-03-14 22:59 [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX dje at gcc dot gnu.org
2021-03-09 18:11 ` [Bug target/94177] " dje at gcc dot gnu.org
2021-04-27 16:32 ` cvs-commit at gcc dot gnu.org
@ 2021-04-27 19:01 ` dje at gcc dot gnu.org
2021-05-28 20:49 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: dje at gcc dot gnu.org @ 2021-04-27 19:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94177
David Edelsohn <dje at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |12.0
--- Comment #3 from David Edelsohn <dje at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/94177] TLS global-dynamic model clobbers function parameter on AIX
2020-03-14 22:59 [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX dje at gcc dot gnu.org
` (2 preceding siblings ...)
2021-04-27 19:01 ` dje at gcc dot gnu.org
@ 2021-05-28 20:49 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-05-28 20:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94177
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by David Edelsohn
<dje@gcc.gnu.org>:
https://gcc.gnu.org/g:0be51abf080f1d7515e3777dd5e5a983b47573a8
commit r11-8481-g0be51abf080f1d7515e3777dd5e5a983b47573a8
Author: David Edelsohn <dje.gcc@gmail.com>
Date: Fri Apr 30 14:27:46 2021 -0400
aix: TLS precompute register parameters (PR 94177)
AIX uses a compiler-managed TOC for global data, including TLS symbols.
The GCC TOC implementation manages the TOC entries through the constant
pool.
TLS symbols sometimes require a function call to obtain the TLS base
pointer. The arguments to the TLS call can conflict with arguments to
a normal function call if the TLS symbol is an argument in the normal call.
GCC specifically checks for this situation and precomputes the TLS
arguments, but the mechanism to check for this requirement utilizes
legitimate_constant_p(). The necessary result of legitimate_constant_p()
for correct TOC behavior and for correct TLS argument behavior is in
conflict.
This patch adds a new target hook precompute_tls_p() to decide if an
argument should be precomputed regardless of the result from
legitmate_constant_p().
gcc/ChangeLog:
PR target/94177
* calls.c (precompute_register_parameters): Additionally test
targetm.precompute_tls_p to pre-compute argument.
* config/rs6000/aix.h (TARGET_PRECOMPUTE_TLS_P): Define.
* config/rs6000/rs6000.c (rs6000_aix_precompute_tls_p): New.
* target.def (precompute_tls_p): New.
* doc/tm.texi.in (TARGET_PRECOMPUTE_TLS_P): Add hook documentation.
* doc/tm.texi: Regenerated.
(cherry-picked from commit
a21b399708175f6fc0ac723a0cebc127da421c60)
^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-03-14 22:59 [Bug target/94177] New: TLS global-dynamic model clobbers function parameter on AIX dje at gcc dot gnu.org
2021-03-09 18:11 ` [Bug target/94177] " dje at gcc dot gnu.org
2021-04-27 16:32 ` cvs-commit at gcc dot gnu.org
2021-04-27 19:01 ` dje at gcc dot gnu.org
2021-05-28 20:49 ` cvs-commit at gcc dot gnu.org
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