[LLVMdev] Mips backend 3.2 va_arg possible bug

[Akira Hatanaka]

Could you file a bug?

On Wed, Feb 27, 2013 at 2:47 AM, Stavropoulos Nikos <
n.stavropoulos at think-silicon.com> wrote:

> i have this code
>
> typedef long long L;
> typedef integer I;
> void test2(auto L p0, auto L p1, auto L p2, auto L p4, ...)
> {
>   va_list select;
>
>   va_start (select, p4);
>
>   report( va_arg(select,L) );
>   report( va_arg(select,I) );
>   report( va_arg(select,L) );
>
>   va_end (select);
> }
>
> int main(void)
> {
>     test2(1, 2, 3, 4, 5LL, 6, 7LL);
>     return 0;
> }
>
> report is  just a function that prints the results.
>
> in main the assemply code seems to be ok but in test2 function does
> something that seems to be wrong
>
>
> i use "llc  -march=mipsel -relocation-model=static -asm-verbose
> -mattr=+condmov,-muldivadd,+single-float,-fp64,+o32,-bitcount " command
>
> in function  we report the values of a long long value then an integer
> value
> and then again a long long
> so the problem is that  in the test2 function there is an         addiu
> $3, $2, 4
> that  causes the third long long value to be read from wrong address.
> mipsel.s <http://llvm.1065342.n5.nabble.com/file/n55498/mipsel.s>
>
>         .set    nomacro
> # BB#0:                                 # %entry
>         addiu   $sp, $sp, -24
>         sw      $ra, 20($sp)            # 4-byte Folded Spill
>         addiu   $2, $sp, 56
>         sw      $2, 16($sp)
>         addiu   $2, $2, 8
>         sw      $2, 16($sp)
>         lw      $5, 60($sp)
>         lw      $4, 56($sp)
>         jal     _Z6reportx
>         nop
>
>         lw      $2, 16($sp)
> #problem starts here
>
>         addiu   $3, $2, 4
>
> #problem stops here
>         sw      $3, 16($sp)
>         lw      $4, 0($2)
>         jal     _Z6reporti
>         nop
>         lw      $2, 16($sp)
>         addiu   $3, $2, 8
>         sw      $3, 16($sp)
>         lw      $5, 4($2)
>         lw      $4, 0($2)
>
>         jal     _Z6reportx
>         nop
>         lw      $ra, 20($sp)            # 4-byte Folded Reload
>         addiu   $sp, $sp, 24
>         jr      $ra
>         nop
>         .set    macro
>         .set    reorder
>         .end    _Z5test2xxxxz
>
>
>
>
> --
> View this message in context:
> http://llvm.1065342.n5.nabble.com/LLVMdev-Mips-backend-3-2-va-arg-possible-bug-tp55498.html
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