* [Bug target/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
@ 2021-12-20 16:16 ` pinskia at gcc dot gnu.org
2021-12-20 16:24 ` zsojka at seznam dot cz
` (11 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-20 16:16 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.0
Keywords| |assemble-failure
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug target/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
2021-12-20 16:16 ` [Bug target/103775] " pinskia at gcc dot gnu.org
@ 2021-12-20 16:24 ` zsojka at seznam dot cz
2021-12-20 16:26 ` zsojka at seznam dot cz
` (10 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: zsojka at seznam dot cz @ 2021-12-20 16:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Zdenek Sojka <zsojka at seznam dot cz> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |ice-on-valid-code
--- Comment #1 from Zdenek Sojka <zsojka at seznam dot cz> ---
With slightly different flags, this ICEs instead:
$ aarch64-unknown-linux-gnu-gcc -Og -fno-forward-propagate -free -g testcase.c
during RTL pass: vartrack
testcase.c: In function 'foo':
testcase.c:9:1: internal compiler error: in cselib_record_set, at cselib.c:2617
9 | }
| ^
0x6d97bc cselib_record_set
/repo/gcc-trunk/gcc/cselib.c:2617
0xc7c676 cselib_record_set
/repo/gcc-trunk/gcc/cselib.c:2941
0xc7c676 cselib_record_sets
/repo/gcc-trunk/gcc/cselib.c:2946
0xc7d7aa cselib_process_insn(rtx_insn*)
/repo/gcc-trunk/gcc/cselib.c:3069
0x1458719 vt_initialize
/repo/gcc-trunk/gcc/var-tracking.c:10284
0x145edb2 variable_tracking_main_1
/repo/gcc-trunk/gcc/var-tracking.c:10512
0x145ef5b variable_tracking_main()
/repo/gcc-trunk/gcc/var-tracking.c:10565
0x145ef5b execute
/repo/gcc-trunk/gcc/var-tracking.c:10602
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug target/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
2021-12-20 16:16 ` [Bug target/103775] " pinskia at gcc dot gnu.org
2021-12-20 16:24 ` zsojka at seznam dot cz
@ 2021-12-20 16:26 ` zsojka at seznam dot cz
2021-12-20 16:36 ` [Bug rtl-optimization/103775] " pinskia at gcc dot gnu.org
` (9 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: zsojka at seznam dot cz @ 2021-12-20 16:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
--- Comment #2 from Zdenek Sojka <zsojka at seznam dot cz> ---
(In reply to Zdenek Sojka from comment #1)
> With slightly different flags, this ICEs instead:
Actually, just add -g
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (2 preceding siblings ...)
2021-12-20 16:26 ` zsojka at seznam dot cz
@ 2021-12-20 16:36 ` pinskia at gcc dot gnu.org
2022-01-07 11:50 ` acoplan at gcc dot gnu.org
` (8 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-20 16:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |rtl-optimization
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-12-20
Keywords|ice-on-valid-code |
CC| |pinskia at gcc dot gnu.org
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(insn 12 9 13 2 (set (reg:SI 93 [ _2 ])
(zero_extend:SI (mem/c:QI (plus:DI (reg/f:DI 65 ap)
(const_int 16 [0x10])) [1 u128_1+0 S1 A128])))
"/app/example.cpp":5:35 117 {*zero_extendqisi2_aarch64}
(nil))
Auto-increment then turns it into:
(insn 39 9 12 2 (set (reg/f:DI 114)
(reg/f:DI 65 ap)) "/app/example.cpp":5:35 -1
(nil))
(insn 12 39 13 2 (set (reg:SI 93 [ _2 ])
(zero_extend:SI (mem/c:QI (pre_modify:DI (reg/f:DI 114)
(plus:DI (reg/f:DI 114)
(const_int 16 [0x10]))) [1 u128_1+0 S1 A128])))
"/app/example.cpp":5:35 117 {*zero_extendqisi2_aarch64}
(expr_list:REG_INC (reg/f:DI 114)
(nil)))
But this does not make sense as the result of the modify is not used
afterwards.
found pre add(17) r[115]=r[65]+20
16: r114:DI=ap:DI+0x10
REG_UNUSED r114:DI
15: r95:SI=r113:DI#0
REG_DEAD r113:DI
14: r113:DI=clrsb(r112:DI)
REG_DEAD r112:DI
13: r112:DI=zero_extend(r93:SI)
12: r93:SI=zero_extend([ap:DI+0x10])
12: r93:SI=zero_extend([ap:DI+0x10])
found mem(12) *(r[65]+16)
16: r114:DI=ap:DI+0x10
REG_UNUSED r114:DI
found post add(16) r[114]=r[65]+16
hmm before auto-increment:
(insn 16 15 17 2 (set (reg/f:DI 114)
(plus:DI (reg/f:DI 65 ap)
(const_int 16 [0x10]))) "/app/example.cpp":6:3 124
{*adddi3_aarch64}
(nil))
(insn 17 16 18 2 (set (reg/f:DI 115)
(plus:DI (reg/f:DI 65 ap)
(const_int 20 [0x14]))) "/app/example.cpp":6:3 124
{*adddi3_aarch64}
(expr_list:REG_DEAD (reg/f:DI 114)
(nil)))
114 is dead even before this.
Oh this is because at -Og we are not running DCE. I think there is some DF not
being updated before auto-increment too.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (3 preceding siblings ...)
2021-12-20 16:36 ` [Bug rtl-optimization/103775] " pinskia at gcc dot gnu.org
@ 2022-01-07 11:50 ` acoplan at gcc dot gnu.org
2022-01-17 12:34 ` rguenth at gcc dot gnu.org
` (7 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: acoplan at gcc dot gnu.org @ 2022-01-07 11:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Alex Coplan <acoplan at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |acoplan at gcc dot gnu.org
--- Comment #4 from Alex Coplan <acoplan at gcc dot gnu.org> ---
FWIW both the ICE and assembly failure started with
r12-3252-gcad36f38576a6a781e3c62ab061c68f5b8dab13a:
commit cad36f38576a6a781e3c62ab061c68f5b8dab13a
Author: Roger Sayle <roger@nextmovesoftware.com>
Date: Tue Aug 31 11:45:07 2021
Preserve SUBREG_PROMOTED_VAR_P on (extend:HI (subreg/s:QI (reg:SI))).
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (4 preceding siblings ...)
2022-01-07 11:50 ` acoplan at gcc dot gnu.org
@ 2022-01-17 12:34 ` rguenth at gcc dot gnu.org
2022-03-23 12:27 ` rguenth at gcc dot gnu.org
` (6 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-01-17 12:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
That change probably just made the latent issue trigger.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (5 preceding siblings ...)
2022-01-17 12:34 ` rguenth at gcc dot gnu.org
@ 2022-03-23 12:27 ` rguenth at gcc dot gnu.org
2022-03-24 15:46 ` jakub at gcc dot gnu.org
` (5 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-03-23 12:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (6 preceding siblings ...)
2022-03-23 12:27 ` rguenth at gcc dot gnu.org
@ 2022-03-24 15:46 ` jakub at gcc dot gnu.org
2022-03-24 15:59 ` jakub at gcc dot gnu.org
` (4 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-24 15:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think this is a REE bug.
However inefficient (but we get that because of -Og and
-fno-forward-propagate),
(insn 12 39 13 2 (set (reg:SI 1 x1 [orig:93 _2 ] [93])
(zero_extend:SI (mem/c:QI (pre_modify:DI (reg/f:DI 0 x0 [114])
(plus:DI (reg/f:DI 0 x0 [114])
(const_int 16 [0x10]))) [1 u128_1+0 S1 A128])))
"pr103775.c":5:35 117 {*zero_extendqisi2_aarch64}
(expr_list:REG_INC (reg/f:DI 0 x0 [114])
(nil)))
(insn 13 12 14 2 (set (reg:DI 0 x0 [orig:112 _2 ] [112])
(zero_extend:DI (reg:SI 1 x1 [orig:93 _2 ] [93]))) "pr103775.c":5:16
111 {*zero_extendsidi2_aarch64}
(nil))
is valid, but turning that into:
(insn 12 39 44 2 (set (reg:DI 0 x0)
(zero_extend:DI (mem/c:QI (pre_modify:DI (reg/f:DI 0 x0 [114])
(plus:DI (reg/f:DI 0 x0 [114])
(const_int 16 [0x10]))) [1 u128_1+0 S1 A128])))
"pr103775.c":5:35 119 {*zero_extendqidi2_aarch64}
(expr_list:REG_INC (reg/f:DI 0 x0 [114])
(nil)))
(insn 44 12 14 2 (set (reg:DI 1 x1)
(reg:DI 0 x0)) "pr103775.c":5:35 -1
(nil))
is invalid, as one instruction can't set the same register multiple times.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (7 preceding siblings ...)
2022-03-24 15:46 ` jakub at gcc dot gnu.org
@ 2022-03-24 15:59 ` jakub at gcc dot gnu.org
2022-03-24 16:56 ` jakub at gcc dot gnu.org
` (3 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-24 15:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ebotcazou at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Though, maybe it shouldn't be the duty of every pass to check this and instead
something like insn_invalid_p should reject those?
If so, shall we worry about that just when reload_completed?
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (8 preceding siblings ...)
2022-03-24 15:59 ` jakub at gcc dot gnu.org
@ 2022-03-24 16:56 ` jakub at gcc dot gnu.org
2022-03-25 7:35 ` ebotcazou at gcc dot gnu.org
` (2 subsequent siblings)
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-24 16:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 52682
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52682&action=edit
gcc12-pr103775.patch
This untested patch seems to work.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (9 preceding siblings ...)
2022-03-24 16:56 ` jakub at gcc dot gnu.org
@ 2022-03-25 7:35 ` ebotcazou at gcc dot gnu.org
2022-03-26 15:23 ` cvs-commit at gcc dot gnu.org
2022-03-26 17:25 ` jakub at gcc dot gnu.org
12 siblings, 0 replies; 14+ messages in thread
From: ebotcazou at gcc dot gnu.org @ 2022-03-25 7:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
--- Comment #9 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> This untested patch seems to work.
This looks sensible to me, maybe move the new code up to before the constraint
check since it is always run.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (10 preceding siblings ...)
2022-03-25 7:35 ` ebotcazou at gcc dot gnu.org
@ 2022-03-26 15:23 ` cvs-commit at gcc dot gnu.org
2022-03-26 17:25 ` jakub at gcc dot gnu.org
12 siblings, 0 replies; 14+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-26 15:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:6459e6537632bc06e04e6011ca7fb6488f0e8e7d
commit r12-7832-g6459e6537632bc06e04e6011ca7fb6488f0e8e7d
Author: Jakub Jelinek <jakub@redhat.com>
Date: Sat Mar 26 16:21:36 2022 +0100
ecog: Return 1 from insn_invalid_p if REG_INC reg overlaps some stored reg
[PR103775]
The following testcase ICEs on aarch64-linux with -g and
assembles with a warning otherwise, because it emits
ldrb w0,[x0,16]!
instruction which sets the x0 register multiple times.
Due to disabled DCE (from -Og) we end up before REE with:
(insn 12 39 13 2 (set (reg:SI 1 x1 [orig:93 _2 ] [93])
(zero_extend:SI (mem/c:QI (pre_modify:DI (reg/f:DI 0 x0 [114])
(plus:DI (reg/f:DI 0 x0 [114])
(const_int 16 [0x10]))) [1 u128_1+0 S1 A128])))
"pr103775.c":5:35 117 {*zero_extendqisi2_aarch64}
(expr_list:REG_INC (reg/f:DI 0 x0 [114])
(nil)))
(insn 13 12 14 2 (set (reg:DI 0 x0 [orig:112 _2 ] [112])
(zero_extend:DI (reg:SI 1 x1 [orig:93 _2 ] [93])))
"pr103775.c":5:16 111 {*zero_extendsidi2_aarch64}
(nil))
which is valid but not exactly efficient as x0 is dead after the
insn that auto-increments it. REE turns it into:
(insn 12 39 44 2 (set (reg:DI 0 x0)
(zero_extend:DI (mem/c:QI (pre_modify:DI (reg/f:DI 0 x0 [114])
(plus:DI (reg/f:DI 0 x0 [114])
(const_int 16 [0x10]))) [1 u128_1+0 S1 A128])))
"pr103775.c":5:35 119 {*zero_extendqidi2_aarch64}
(expr_list:REG_INC (reg/f:DI 0 x0 [114])
(nil)))
(insn 44 12 14 2 (set (reg:DI 1 x1)
(reg:DI 0 x0)) "pr103775.c":5:35 -1
(nil))
which is invalid because it sets x0 multiple times, one
in SET_DEST of the PATTERN and once in PRE_MODIFY.
As perhaps other passes than REE might suffer from it, IMHO it is better
to reject this during change validation.
2022-03-26 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/103775
* recog.cc (check_invalid_inc_dec): New function.
(insn_invalid_p): Return 1 if REG_INC operand overlaps
any stored REGs.
* gcc.dg/pr103775.c: New test.
^ permalink raw reply [flat|nested] 14+ messages in thread* [Bug rtl-optimization/103775] [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!'
2021-12-20 16:15 [Bug target/103775] New: [12 Regression] Assembler messages: Warning: unpredictable transfer with writeback -- `ldrb w0,[x0,16]!' zsojka at seznam dot cz
` (11 preceding siblings ...)
2022-03-26 15:23 ` cvs-commit at gcc dot gnu.org
@ 2022-03-26 17:25 ` jakub at gcc dot gnu.org
12 siblings, 0 replies; 14+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-03-26 17:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103775
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 14+ messages in thread