[Bug other/109435] New: [MIPS64R6] Typedef struct alignment returns incorrect results

[Bug other/109435] New: [MIPS64R6] Typedef struct alignment returns incorrect results

[jovan.dmitrovic at syrmia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

            Bug ID: 109435
           Summary: [MIPS64R6] Typedef struct alignment returns incorrect
                    results
           Product: gcc
           Version: 10.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jovan.dmitrovic at syrmia dot com
  Target Milestone: ---

Consider the following testcase:


#include<stdio.h>

typedef struct uint8 {
  unsigned v[8];
} uint8 __attribute__ ((aligned(128)));

unsigned callee(int x, uint8 a) {
    return a.v[0];
}

uint8 identity(uint8 in) {
    return in;
}

int main() {
    uint8 vec = {1, 2, 3, 4, 5, 6, 7, 8};
    printf("res1: %d\n", callee(99, identity(vec)));
    uint8 temp = identity(vec);
    printf("res2: %d\n", callee(99, temp));
}


When this code is compiled for MIPS64 R6, output is as follows:

res1: 3
res2: 1

However, when aligned attribute is removed from the testcase, res1 and res2
become 1,
which are values that were expected in the first place. 
Furthermore, this bug is reproducible only if there is a unused argument x in
function callee. Adding more arguments or switching their places also produces
expected values. Type of x doesn't seem to impact the result.

[Bug other/109435] [MIPS64R6] Typedef struct alignment returns incorrect results

[jovan.dmitrovic at syrmia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

--- Comment #1 from Jovan Dmitrović <jovan.dmitrovic at syrmia dot com> ---
This is compile command that I used:

mipsisa64r6-linux-gnuabi64-gcc -march=mips64r6 -mabi=64 -O0 -o foo foo.c
-static

I used the MIPS gcc package from Ubuntu's package repository.
Also, I used qemu-mips64 to run the executable file.

[Bug target/109435] overaligned structs are not passed correctly for mips64

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=88469

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The aarch64 and arm backends had a similar issue which was fixed too.

[Bug target/109435] overaligned structs are not passed correctly for mips64

[jovan.dmitrovic at syrmia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

--- Comment #3 from Jovan Dmitrović <jovan.dmitrovic at syrmia dot com> ---
Tentative patch posted on the mailing list:

https://gcc.gnu.org/pipermail/gcc-patches/2023-May/619949.html

[Bug target/109435] overaligned structs are not passed correctly for mips64

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by YunQiang Su <syq@gcc.gnu.org>:

https://gcc.gnu.org/g:e20abdb749d0c0c8552da998ff8ec139b830f5eb

commit r14-2205-ge20abdb749d0c0c8552da998ff8ec139b830f5eb
Author: Jovan Dmitrovic <Jovan.Dmitrovic@Syrmia.com>
Date:   Mon Jun 26 17:00:20 2023 +0200

    mips: Fix overaligned function arguments [PR109435]

    This patch changes alignment for typedef types when passed as
    arguments, making the alignment equal to the alignment of
    original (aliased) types.

    This change makes it impossible for a typedef type to have
    alignment that is less than its size.

    2023-06-27  Jovan DmitroviÄ  <jovan.dmitrovic@syrmia.com>

    gcc/ChangeLog:

            PR target/109435
            * config/mips/mips.cc (mips_function_arg_alignment): Returns
            the alignment of function argument. In case of typedef type,
            it returns the aligment of the aliased type.
            (mips_function_arg_boundary): Relocated calculation of the
            aligment of function arguments.

    gcc/testsuite/ChangeLog:

            * gcc.target/mips/align-1-n64.c: New test.
            * gcc.target/mips/align-1-o32.c: New test.

[Bug target/109435] overaligned structs are not passed correctly for mips64

[syq at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109435

YunQiang Su <syq at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |syq at gcc dot gnu.org

--- Comment #5 from YunQiang Su <syq at gcc dot gnu.org> ---
Fixed by commit:

https://gcc.gnu.org/g:e20abdb749d0c0c8552da998ff8ec139b830f5eb