[sdcc-devel] [ sdcc-Bugs-2740884 ] Incorrect assignment in array of structs

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Bugs item #2740884, was opened at 2009-04-07 16:37
Message generated for change (Comment added) made by wek_
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https://sourceforge.net/tracker/?func=detail&atid=100599&aid=2740884&group_id=599

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Category: mcs51(8051) target
Group: known bugs
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Frank Cornett (fcornett)
Assigned to: Nobody/Anonymous (nobody)
Summary: Incorrect assignment in array of structs

Initial Comment:
Code:
#include "dp8051.h" //Define 8051 ports

typedef struct{
    unsigned char Fail;
    unsigned char Route;
    unsigned char xor;
    unsigned char RX_invert;
} DT_SERDES_PORT;

__xdata DT_SERDES_PORT doors[3];

void main(void){

        unsigned char door;

        for (door = 0x01; door <= 0x02; door++){ doors[door].Route = 0x24; }
        for (door = 0x01; door <= 0x02; door++){
                P2 = 0xAA;//Set 8051 ports to trigger display in Verilog
                P1 = doors[door].Route;
                P0 = door;
        }
        P3 = 0xA5;//Trigger simulation finish
}

This code is compiled and executed with a Verilog simulation of an 8051 processor.  The output is:
P0, P1, P2 = 01, 24, aa
P0, P1, P2 = 02, 00, aa
Note that the second element in the doors array is not assigned correctly.  This behavior appears to be associated with loop reversal, since setting the compiler option --noloopreverse results in the following output:
P0, P1, P2 = 01, 24, aa
P0, P1, P2 = 02, 24, aa
I've also observed that if the two for loops are combined into a single loop, the correct assignment occurs.
  Please refer to the attached tarball for more details.

Thanks,
Frank Cornett
Cray Inc.

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Comment By: wek (wek_)
Date: 2009-06-07 16:00

Message:
Robert,

once you are in it, please check out and fix also the inadequate tests for
case INC_OP: and case DEC_OP: just a few lines below the case for PTR_OP
you have just patched.

The regression test function could include perhaps the following function:
void bar(void) {
  char i;
  for (i = 1; i <= 2; i++)
    doors[i].Route++;
}

Jan Waclawek


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Comment By: Robert Larice (rlar)
Date: 2009-06-07 15:27

Message:
I propose the following patch to fix this
  
https://sourceforge.net/tracker/?func=detail&aid=2802510&group_id=599&atid=300599

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=100599&aid=2740884&group_id=599