mirror of
https://github.com/cc65/cc65.git
synced 2024-08-16 12:29:03 +00:00
Only the low bytes are compared. Originally, signed 16-bit compares were optimized into signed 8-bit compares. But, the sign bits are in the high bytes; and, they're equal. Therefore, the low bytes always must be compared as unsigned numbers. Fixes #1348.
55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
/* bug #1348, wrongly optimized integer promotion in comparison */
|
|
|
|
#include <stdio.h>
|
|
|
|
static const int notrandtab[] = {
|
|
0xffff, 0x7fff, 0x3fff, 0x1fff,
|
|
0x0fff, 0x07ff, 0x03ff, 0x01ff,
|
|
0x00ff, 0x007f, 0x003f, 0x001f,
|
|
0x000f, 0x0007, 0x0003, 0x0001
|
|
};
|
|
|
|
static unsigned char notrandcount = 0;
|
|
|
|
static int notrand(void)
|
|
{
|
|
return notrandtab[notrandcount & 0x0f];
|
|
}
|
|
|
|
static unsigned char n1, n2;
|
|
static unsigned char i, ii, s;
|
|
static unsigned char err = 0;
|
|
|
|
static const unsigned char cmptab[] = {
|
|
0xff, 0x7f, 0x3f, 0x1f,
|
|
0x0f, 0x07, 0x03, 0x01,
|
|
0x80, 0x40, 0x20, 0x10,
|
|
0x08, 0x04, 0x02, 0x01
|
|
};
|
|
|
|
int main(void)
|
|
{
|
|
for (ii = 0; ii < 16; ++ii) {
|
|
s = cmptab[ii];
|
|
for (i = 0; i < 16; ++i) {
|
|
n1 = n2 = 0;
|
|
if ((notrand() & 0xff) > s) {
|
|
n1 = 1;
|
|
}
|
|
if ((notrand() & 0xffu) > s) {
|
|
n2 = 1;
|
|
}
|
|
printf("%5d > %3d %u(%02x) %u(%02x) %s\n",
|
|
notrandtab[i], s,
|
|
n1, (notrand() & 0xff),
|
|
n2, (notrand() & 0xffu),
|
|
n1 == n2 ? "=" : "!=");
|
|
if (n1 != n2) {
|
|
err = 1;
|
|
}
|
|
notrandcount++;
|
|
}
|
|
}
|
|
return err;
|
|
}
|