[Bug libgcc/107459] New: microblaze moddi3 implementation is buggy

[Bug libgcc/107459] New: microblaze moddi3 implementation is buggy

[alpsayin at alpsayin dot com]

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);
}

[Bug target/107459] microblaze moddi3 implementation is buggy

[alpsayin at alpsayin dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107459

--- Comment #1 from Alp Sayin <alpsayin at alpsayin dot com> ---
Created attachment 53792
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53792&action=edit
Proposed patch (is the original patch)

Proposed patch is the removal of buggy moddi3 implementation and falling back
to gcc's own as per the original intention in the yocto project.

[Bug target/107459] microblaze moddi3 implementation is buggy

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107459

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Please post patches to gcc-patches@gcc.gnu.org