https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107459
Bug ID: 107459
Summary: microblaze moddi3 implementation is buggy
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgcc
Assignee: unassigned at gcc dot gnu.org
Reporter: alpsayin at alpsayin dot com
Target Milestone: ---
Created attachment 53791
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53791&action=edit
Disassembly of the submitted code sample
The issue has been mentioned and tried to be amended here:
https://lists.yoctoproject.org/g/meta-xilinx/message/3409
gcc version: 12.1.0 (from zephyrproject-rtos/gcc fork)
system: rhel8.5
compile flags:
-isystem
/home/asayin/zephyr_sdks/microblaze_devel/zephyr/lib/libc/minimal/include
-isystem
/home/asayin/zephyr_sdks/microblaze_devel/zephyr-sdk-0.93.0-47-g4470827/microblazeel-zephyr-elf/bin/../lib/gcc/microblazeel-zephyr-elf/12.1.0/include
-isystem
/home/asayin/zephyr_sdks/microblaze_devel/zephyr-sdk-0.93.0-47-g4470827/microblazeel-zephyr-elf/bin/../lib/gcc/microblazeel-zephyr-elf/12.1.0/include-fixed
-fno-strict-aliasing
-Og
-imacros
/home/asayin/workspace/zephyr/build/zephyr/include/generated/autoconf.h
-ffreestanding
-fno-common
-g
-gdwarf-4
-fdiagnostics-color=always
-mcpu=v9.00.a
-mxl-barrel-shift
-mno-xl-soft-mul
-mxl-multiply-high
-mno-xl-soft-div
-msoft-float
-fdollars-in-identifiers
--sysroot=/home/asayin/zephyr_sdks/microblaze_devel/zephyr-sdk-0.93.0-47-g4470827/microblazeel-zephyr-elf/microblazeel-zephyr-elf
-imacros
/home/asayin/zephyr_sdks/microblaze_devel/zephyr/include/zephyr/toolchain/zephyr_stdint.h
-Wall
-Wformat
-Wformat-security
-Wno-format-zero-length
-Wno-main
-Wno-pointer-sign
-Wpointer-arith
-Wexpansion-to-defined
-Wno-unused-but-set-variable
-Werror=implicit-int
-fno-pic
-fno-pie
-fno-asynchronous-unwind-tables
-fno-reorder-functions
--param=min-pagesize=0
-fno-defer-pop
-fmacro-prefix-map=/home/asayin/workspace/zephyr/samples/hello_world=CMAKE_SOURCE_DIR
-fmacro-prefix-map=/home/asayin/zephyr_sdks/microblaze_devel/zephyr=ZEPHYR_BASE
-fmacro-prefix-map=/home/asayin/zephyr_sdks/microblaze_devel=WEST_TOPDIR
-ffunction-sections
-fdata-sections
-std=c99
-nostdinc
-MD
-MT CMakeFiles/app.dir/src/main.c.obj
-MF CMakeFiles/app.dir/src/main.c.obj.d
-o CMakeFiles/app.dir/src/main.c.obj
-c /home/asayin/workspace/zephyr/samples/hello_world/src/main.c
output: none
preprocessed file: deemed unnecessary due to nature of the bug
attachments: relevant sections of the disassembly
Reproduction should be possible via the below code sample:
void main(void)
{
volatile int64_t delta = 1514821494020000000;
printf("delta = %016lld\n", delta);
printf("NSEC_PER_SEC = %08d\n", NSEC_PER_SEC);
uint32_t res1 = delta % NSEC_PER_SEC;
printf("delta %% (moddi3) NSEC_PER_SEC = %"PRId32" (0x%"PRIx32")\n",
res1, res1);
uint64_t new_tv_sec = delta / NSEC_PER_SEC;
uint32_t res2 = delta - (new_tv_sec * NSEC_PER_SEC);
printf("delta - delta*(delta/NSEC_PER_SEC) = %"PRId32"
(0x%"PRIx32")\n", res2, res2);
}
