https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108912
Bug ID: 108912
Summary: A -Wstringop-overflow false positive in
aarch64-linux-gnu-gcc 12.2.0
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: wtc at google dot com
CC: msebor at gcc dot gnu.org
Target Milestone: ---
Created attachment 54522
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54522&action=edit
Reduced test case
Steps to reproduce:
1. Save the attachment in a file named av1_fwd_txfm2d.c.
2. On a Debian x86_64 GNU/Linux system, install the gcc-aarch64-linux-gnu
package:
$ sudo apt install gcc-aarch64-linux-gnu
3. Check the compiler version:
$ /usr/bin/aarch64-linux-gnu-gcc --version
aarch64-linux-gnu-gcc (Debian 12.2.0-3) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
4. Compile the av1_fwd_txfm2d.c file with the following command line:
$ /usr/bin/aarch64-linux-gnu-gcc -march=armv8-a -O3 -DNDEBUG -std=c99 -Wall
-Wdisabled-optimization -Wextra -Wfloat-conversion -Wformat=2
-Wimplicit-function-declaration -Wlogical-op -Wpointer-arith -Wsign-compare
-Wtype-limits -Wuninitialized -Wunused -Wvla -Wstack-usage=100000 -Wshadow
-Wundef -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0 -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -fPIC -o av1_fwd_txfm2d.o -c av1_fwd_txfm2d.c
The compiler emits the following warnings:
In function ‘set_fwd_txfm_non_scale_range’,
inlined from ‘av1_get_fwd_txfm_cfg’ at av1_fwd_txfm2d.c:86:3:
av1_fwd_txfm2d.c:64:31: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
64 | cfg->stage_range_col[i] = (range_mult2_col[i] + 1) >> 1;
| ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
av1_fwd_txfm2d.c: In function ‘av1_get_fwd_txfm_cfg’:
av1_fwd_txfm2d.c:23:10: note: at offset 12 into destination object
‘stage_range_col’ of size 12
23 | int8_t stage_range_col[12];
| ^~~~~~~~~~~~~~~
In function ‘set_fwd_txfm_non_scale_range’,
inlined from ‘av1_get_fwd_txfm_cfg’ at av1_fwd_txfm2d.c:86:3:
av1_fwd_txfm2d.c:64:31: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
64 | cfg->stage_range_col[i] = (range_mult2_col[i] + 1) >> 1;
| ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
av1_fwd_txfm2d.c: In function ‘av1_get_fwd_txfm_cfg’:
av1_fwd_txfm2d.c:23:10: note: at offset 13 into destination object
‘stage_range_col’ of size 12
23 | int8_t stage_range_col[12];
| ^~~~~~~~~~~~~~~
In function ‘set_fwd_txfm_non_scale_range’,
inlined from ‘av1_get_fwd_txfm_cfg’ at av1_fwd_txfm2d.c:86:3:
av1_fwd_txfm2d.c:72:31: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
72 | cfg->stage_range_row[i] =
| ~~~~~~~~~~~~~~~~~~~~~~~~^
73 | (range_mult2_col[cfg->stage_num_col - 1] + range_mult2_row[i]
+ 1) >>
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
74 | 1;
| ~
av1_fwd_txfm2d.c: In function ‘av1_get_fwd_txfm_cfg’:
av1_fwd_txfm2d.c:24:10: note: at offset 12 into destination object
‘stage_range_row’ of size 12
24 | int8_t stage_range_row[12];
| ^~~~~~~~~~~~~~~
In function ‘set_fwd_txfm_non_scale_range’,
inlined from ‘av1_get_fwd_txfm_cfg’ at av1_fwd_txfm2d.c:86:3:
av1_fwd_txfm2d.c:72:31: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
72 | cfg->stage_range_row[i] =
| ~~~~~~~~~~~~~~~~~~~~~~~~^
73 | (range_mult2_col[cfg->stage_num_col - 1] + range_mult2_row[i]
+ 1) >>
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
74 | 1;
| ~
av1_fwd_txfm2d.c: In function ‘av1_get_fwd_txfm_cfg’:
av1_fwd_txfm2d.c:24:10: note: at offset 13 into destination object
‘stage_range_row’ of size 12
24 | int8_t stage_range_row[12];
| ^~~~~~~~~~~~~~~
