[LLVMdev] Mips backend 3.2 va_arg possible bug

[Stavropoulos Nikos]

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




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