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* [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
@ 2023-02-27 11:50 zsojka at seznam dot cz
2023-02-28 10:37 ` [Bug target/108947] " rguenth at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: zsojka at seznam dot cz @ 2023-02-27 11:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Bug ID: 108947
Summary: [13 Regression] wrong code with -O2
-fno-forward-propagate and vector compare on riscv64
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: riscv64-unknown-linux-gnu
Created attachment 54543
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54543&action=edit
reduced testcase
Output:
$ riscv64-unknown-linux-gnu-gcc -O2 -fno-forward-propagate testcase.c -static
$ qemu-riscv64 -- ./a.out
Aborted
w == { 0, 0 } instead of { 0xffff, 0 }
$ riscv64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-riscv64/bin/riscv64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r13-6353-20230227090511-g529e03b9882-checking-yes-rtl-df-extra-riscv64/bin/../libexec/gcc/riscv64-unknown-linux-gnu/13.0.1/lto-wrapper
Target: riscv64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --with-isa-spec=2.2
--with-sysroot=/usr/riscv64-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=riscv64-unknown-linux-gnu
--with-ld=/usr/bin/riscv64-unknown-linux-gnu-ld
--with-as=/usr/bin/riscv64-unknown-linux-gnu-as --disable-multilib
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r13-6353-20230227090511-g529e03b9882-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.0.1 20230227 (experimental) (GCC)
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
@ 2023-02-28 10:37 ` rguenth at gcc dot gnu.org
2023-03-27 11:51 ` marxin at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-02-28 10:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |13.0
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
2023-02-28 10:37 ` [Bug target/108947] " rguenth at gcc dot gnu.org
@ 2023-03-27 11:51 ` marxin at gcc dot gnu.org
2023-04-05 14:17 ` law at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: marxin at gcc dot gnu.org @ 2023-03-27 11:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
CC| |rzinsly at ventanamicro dot com
Last reconfirmed| |2023-03-27
Keywords|needs-bisection |
Status|UNCONFIRMED |NEW
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r13-4907-g2e886eef7f2b5a same as PR109040.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
2023-02-28 10:37 ` [Bug target/108947] " rguenth at gcc dot gnu.org
2023-03-27 11:51 ` marxin at gcc dot gnu.org
@ 2023-04-05 14:17 ` law at gcc dot gnu.org
2023-04-05 18:41 ` sjames at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: law at gcc dot gnu.org @ 2023-04-05 14:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
*** Bug 109040 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
` (2 preceding siblings ...)
2023-04-05 14:17 ` law at gcc dot gnu.org
@ 2023-04-05 18:41 ` sjames at gcc dot gnu.org
2023-04-08 14:36 ` law at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: sjames at gcc dot gnu.org @ 2023-04-05 18:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Sam James <sjames at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |sjames at gcc dot gnu.org
--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
Note that's substantial discussion (including a patch) in dupe PR109040.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
` (3 preceding siblings ...)
2023-04-05 18:41 ` sjames at gcc dot gnu.org
@ 2023-04-08 14:36 ` law at gcc dot gnu.org
2023-04-14 7:32 ` cvs-commit at gcc dot gnu.org
2023-04-14 7:36 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: law at gcc dot gnu.org @ 2023-04-08 14:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
--- Comment #4 from Jeffrey A. Law <law at gcc dot gnu.org> ---
P1 as this look like a latent issue in combine or simplification routines.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
` (4 preceding siblings ...)
2023-04-08 14:36 ` law at gcc dot gnu.org
@ 2023-04-14 7:32 ` cvs-commit at gcc dot gnu.org
2023-04-14 7:36 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-04-14 7:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
--- Comment #5 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:9d1a6119590ef828f9782a7083d03e535bc2f2cf
commit r13-7178-g9d1a6119590ef828f9782a7083d03e535bc2f2cf
Author: Jakub Jelinek <jakub@redhat.com>
Date: Fri Apr 14 09:20:49 2023 +0200
combine: Fix AND handling for WORD_REGISTER_OPERATIONS targets [PR109040]
The following testcase is miscompiled on riscv since the addition
of *mvconst_internal define_insn_and_split.
We have:
(insn 36 35 39 2 (set (mem/c:SI (plus:SI (reg/f:SI 65 frame)
(const_int -64 [0xffffffffffffffc0])) [2 S4 A128])
(reg:SI 166)) "pr109040.c":9:11 178 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 166)
(nil)))
(insn 39 36 40 2 (set (reg:SI 171)
(zero_extend:SI (mem/c:HI (plus:SI (reg/f:SI 65 frame)
(const_int -64 [0xffffffffffffffc0])) [0 S2 A128])))
"pr109040.c":9:11 111 {*zero_extendhisi2}
(nil))
and RTL DSE's replace_read since r0-86337-g18b526e806ab6455 handles
even different modes like in the above case, and so it optimizes it into:
(insn 47 35 39 2 (set (reg:HI 175)
(subreg:HI (reg:SI 166) 0)) "pr109040.c":9:11 179 {*movhi_internal}
(expr_list:REG_DEAD (reg:SI 166)
(nil)))
(insn 39 47 40 2 (set (reg:SI 171)
(zero_extend:SI (reg:HI 175))) "pr109040.c":9:11 111
{*zero_extendhisi2}
(expr_list:REG_DEAD (reg:HI 175)
(nil)))
Pseudo 166 is result of AND with 0x8084c constant (forced into a register).
Combine attempts to combine the AND with the insn 47 above created by DSE,
and turns it because of WORD_REGISTER_OPERATIONS and its assumption that
all
the subword operations are actually done on word mode into:
(set (subreg:SI (reg:HI 175) 0)
(and:SI (reg:SI 167 [ m ])
(reg:SI 168)))
and later on the ZERO_EXTEND is thrown away.
We then see
(and:SI (subreg:SI (reg:HI 175) 0) (const_int 0x84c))
and optimize that into
(subreg:SI (and:HI (reg:HI 175) (const_int 0x84c)) 0)
which is still fine, in WORD_REGISTER_OPERATIONS the AND in HImode
will set all upper bits up to BITS_PER_WORD to zeros.
But later on simplify_binary_operation_1 or simplify_and_const_int_1
sees that because nonzero_bits ((reg:HI 175), HImode) == 0x84c, we can
optimize the AND into (reg:HI 175). That isn't correct, because while
the low 16 bits of that REG are known to have all bits but 0x84c cleared,
we don't know that all the upper 16 bits are all clear as well.
So, for WORD_REGISTER_OPERATIONS for integral modes smaller than word mode,
we need to check all bits from word_mode in nonzero_bits for the
optimizations.
2023-04-14 Jeff Law <jlaw@ventanamicro.com>
Jakub Jelinek <jakub@redhat.com>
PR target/108947
PR target/109040
* combine.cc (simplify_and_const_int_1): Compute nonzero_bits in
word_mode rather than mode if WORD_REGISTER_OPERATIONS and mode is
smaller than word_mode.
* simplify-rtx.cc (simplify_context::simplify_binary_operation_1)
<case AND>: Likewise.
* gcc.dg/pr108947.c: New test.
* gcc.c-torture/execute/pr109040.c: New test.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/108947] [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64
2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
` (5 preceding siblings ...)
2023-04-14 7:32 ` cvs-commit at gcc dot gnu.org
@ 2023-04-14 7:36 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2023-04-14 7:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108947
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
CC| |jakub at gcc dot gnu.org
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 8+ messages in thread
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2023-02-27 11:50 [Bug target/108947] New: [13 Regression] wrong code with -O2 -fno-forward-propagate and vector compare on riscv64 zsojka at seznam dot cz
2023-02-28 10:37 ` [Bug target/108947] " rguenth at gcc dot gnu.org
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