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/** bug2729218.c
*/
#include <testfwk.h>
/*
sdcc appears to compile the following file incorrectly. I have attached
the C source code, and the generated assembly code, with some comments
that explain the bug.
The basic problem is that a memory location is post-incremented, but
the register variable that shadows that memory location is NOT
increment, and this incorrect value is used in later calculations.
I compiled it with these options:
sdcc -mmcs51 --model-small --std-sdcc99 --code-loc 0xf000 -c bug.c
Here is the "sdcc -v" output:
SDCC : mcs51/gbz80/z80/avr/ds390/pic16/pic14/TININative/xa51/ds400/hc08 2.9.1 #5422 (Apr 3 2009) (UNIX)
*/
struct iglobals
{
unsigned char rx_byte;
unsigned char input_cnt;
};
#if !defined(__SDCC_sm83) && !defined(__SDCC_pdk14) && !defined(__SDCC_f8)
#define ig (*(__idata struct iglobals *) 0xf0)
#else
struct iglobals ig;
#endif
unsigned char count;
unsigned char
do_command(void)
{
// In the following statement, the post-increment is saved in
// memory, but not in the value stored in the r7 register
count = ig.input_cnt++;
// In the following statement, the value of "input_cnt" stored in
// the r7 register is used, but it is wrong (never incremented).
return ig.input_cnt;
}
void testBug(void)
{
#ifdef __SDCC
ig.rx_byte = 0;
ig.input_cnt = 1;
ASSERT (do_command() == 2);
ASSERT (ig.input_cnt == 2);
ASSERT (count == 1);
#endif
}
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