<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/143247>143247</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang generates incorrect code when storing to memory location 0x1 for target avr-none
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          tomtor
      </td>
    </tr>
</table>

<pre>
    sample code:

```
#define PA      0x1 // Bad
//#define PA    0x2 // Good

char *const PORT = (char *const) PA;

extern void nil(short);

void bug()
{
 short s= 0;
 
  while (1) {
    s++;
    *PORT = *PORT | 0x80;
 nil((s & 0xF) + 1);
  }
}
```

compiled with clang build from git yesterday:

`clang -O2 -target avr-none -mmcu=attiny402 -S bug.c`

generates an incorrect store (uses s which changes in each loop iteration instead of constant 0x1):

```
bug: ; @bug
; %bb.0:                                ; %entry
        push r16
        push    r17
        ldi     r26, 0
        ldi     r27, 0
.LBB0_1:                                ; %while.cond
 ; =>This Inner Loop Header: Depth=1
        ld      r24, X+
        ori     r24, -128
        movw    r16, r26
        andi    r26, 15
        andi    r27, 0
        st      X+, r24
        movw    r24, r26
        call    nil
        movw    r26, r16
        rjmp .LBB0_1
```

using `#define PA    0x2`

generates correct code:

```
bug:                                    ; @bug
; %bb.0: ; %entry
        push    r16
        push    r17
 ldi     r24, 0
        ldi     r25, 0
.LBB0_1: ; %while.cond
                                        ; =>This Inner Loop Header: Depth=1
        sbi     2, 7
        adiw    r24, 1
 movw    r16, r24
        andi    r24, 15
        andi    r25, 0
 adiw    r24, 1
        call    nil
        movw    r24, r16
        rjmp .LBB0_1

```




</pre>
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