[Bug c/49934] New: gcc 4.6.1 messes up code

[Bug c/49934] New: gcc 4.6.1 messes up code

[andy_code at mailup dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49934

           Summary: gcc 4.6.1 messes up code
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: andy_code@mailup.net


here is the original function 

void keypad_isr(void) 
{ 
    /*  read a character from the key buffer */ 
    FPGA_UART_DATA     *ptr;          /* volatile register makes no dif */
    FPGA_UART_DATA     kpd; 
    int g; 
    int n; 
    KEYBUFFER     *kb; 
    char     ch; 

    kb    = &key_buffer; 
    asm(" halt");          /* just for debugging */ 
    ptr = FPGA_UART;   /* make a pointer to the FPGA register */ 
    // read upto 8 keys from the keypad 
    for( n = 0; n < 8 ; n++ ) 
    { 
        kpd    = *ptr;        /* read from register  (only do this ONCE) */ 
        g = kpd.fifo_cnt; 
        if(g == 0) 
            return; 
        ch = (char) kpd.rx_data; 
        kb->status = ch; 
        if( ch != 0 && ch != -1 ) 
        { 
            if ( kb->current_location >= MAX_KEY_BUFFERS_SIZE-1 ) 
            { 
                kb->current_location = MAX_KEY_BUFFERS_SIZE-1; 
            } 
            kb->key_buff[kb->current_location] = ch; 
            kb->current_location++; 
        } 
    } 
} 

ok now here is my problem, gcc does not use an address register for the
pointer, and it insists on reading the FPGA directly twice ???? 
here is generated assembly from gcc. 

dat's not wot I rit...

keypad_isr: 
        lea (-12,%sp),%sp 
     movem.l #1036,(%sp) 
        move.w -1073741664,%d0       
        clr.l %d1 
        move.w %d0,%d1                   
        moveq #13,%d2 
        lsr.l %d2,%d1 
        tst.b %d1 
        jeq .L3 
        moveq #8,%d1 
        lea key_buffer+33,%a1 
        lea key_buffer,%a0 
        lea key_buffer+1,%a2 
        jra .L5 
.L8: 
        move.w -1073741664,%d0       <<< --- look its done it again ????? 
        clr.l %d2 
        move.w %d0,%d2                  <<< --- ARRRGGGgg its knackered my FPGA 
        moveq #13,%d3 
        lsr.l %d3,%d2 
        tst.b %d2 
        jeq .L3 
.L5: 
        move.b %d0,%d2 
        move.b %d0,(%a1) 
        move.l %d2,%d0 
        addq.l #1,%d0 
        and.l #255,%d0 
        moveq #1,%d3 
        cmp.l %d0,%d3 
        jcc .L6 
        clr.l %d0 
        move.b (%a0),%d0 
        move.b #30,%d3 
        cmp.l %d0,%d3 
        jcc .L7 
        move.b #31,(%a0) 
.L7: 
        move.b (%a0),%d0 
        clr.l %d3 
        move.b %d0,%d3 
        move.b %d2,(%a2,%d3.l) 
        addq.l #1,%d0 
        move.b %d0,(%a0) 
.L6: 
        subq.l #1,%d1 
     jne .L8 
.L3: 
        movem.l (%sp),#1036 
        lea (12,%sp),%sp 
        rts

[Bug c/49934] gcc 4.6.1 messes up code

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49934

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2011.08.01 14:49:11
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-01 14:49:11 UTC ---
The testcase does not compile.  You didn't specify what optimization option
you used nor for what target.

Please provide information according to http://gcc.gnu.org/bugs.html

[Bug c/49934] gcc 4.6.1 messes up code

[andy_code at mailup dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49934

--- Comment #2 from andy <andy_code at mailup dot net> 2011-08-02 08:13:11 UTC ---
sorry, the target is coldfire m5208 and it doesnt really matter what
optimisation setting you choose.

[Bug c/49934] gcc 4.6.1 messes up code

[andi-gcc at firstfloor dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49934

Andi Kleen <andi-gcc at firstfloor dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andi-gcc at firstfloor dot
                   |                            |org

--- Comment #3 from Andi Kleen <andi-gcc at firstfloor dot org> 2011-10-30 16:06:12 UTC ---
My guess is that "FPGA_UART" is not declared volatile

[Bug c/49934] gcc 4.6.1 messes up code

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49934

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-10 15:06:34 UTC ---
No response from reporter.