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Better code for compares

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git-svn-id: svn://svn.cc65.org/cc65/trunk@1150 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz 2002-02-12 20:40:05 +00:00
parent 0de448df64
commit 08443d5e7a
1 changed files with 120 additions and 62 deletions
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122
src/cc65/codegen.c
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@ -3344,6 +3344,8 @@ void g_lt (unsigned flags, unsigned long val)
/* Give a warning in some special cases */
if ((flags & CF_UNSIGNED) && val == 0) {
Warning ("Condition is never true");
AddCodeLine ("jsr return0");
return;
}
/* Look at the type */
@ -3370,15 +3372,31 @@ void g_lt (unsigned flags, unsigned long val)
AddCodeLine ("jsr boollt");
return;
}
/* Direct code only for unsigned data types */
if (flags & CF_UNSIGNED) {
unsigned L = GetLocalLabel();
/* Unsigned compare */
/* If the low byte is zero, we must only test the high
* byte. Or, citing Piotr Fusik:
* Another interpretation: the code is effectively:
* if (ax >= 0xAB00) goto L2;
* It's equivalent to:
* if ((ax >> 8) >= 0xAB) goto L2;
*/
AddCodeLine ("cpx #$%02X", (unsigned char)(val >> 8));
if ((val & 0xFF) != 0) {
unsigned L = GetLocalLabel();
AddCodeLine ("bne %s", LocalLabelName (L));
AddCodeLine ("cmp #$%02X", (unsigned char)val);
g_defcodelabel (L);
}
AddCodeLine ("jsr boolult");
return;
} else {
/* Signed compare */
if ((val & 0xFF) == 0) {
AddCodeLine ("cpx #$%02X", (unsigned char)(val >> 8));
AddCodeLine ("jsr boollt");
return;
}
}
break;
@ -3426,26 +3444,30 @@ void g_le (unsigned flags, unsigned long val)
*/
if (flags & CF_CONST) {
/* <= is not very effective on the 6502, so try to convert
* it into < if the value is in a valid range.
*/
/* Look at the type */
switch (flags & CF_TYPE) {
case CF_CHAR:
if (flags & CF_FORCECHAR) {
if (flags & CF_UNSIGNED) {
/* Unsigned compare */
if (val < 255) {
AddCodeLine ("cmp #$%02X", (unsigned char)val+1);
/* Use < instead of <= because the former gives
* better code on the 6502 than the latter.
*/
AddCodeLine ("cmp #$%02X", (unsigned char)(val+1));
AddCodeLine ("jsr boolult");
} else {
AddCodeLine ("cmp #$%02X", (unsigned char)val);
AddCodeLine ("jsr boolule");
}
} else {
/* Signed compare */
if (val < 127) {
AddCodeLine ("cmp #$%02X", (unsigned char)val+1);
/* Use < instead of <= because the former gives
* better code on the 6502 than the latter.
*/
AddCodeLine ("cmp #$%02X", (unsigned char)(val+1));
AddCodeLine ("jsr boollt");
} else {
AddCodeLine ("cmp #$%02X", (unsigned char)val);
@ -3458,18 +3480,27 @@ void g_le (unsigned flags, unsigned long val)
case CF_INT:
if (flags & CF_UNSIGNED) {
unsigned L = GetLocalLabel();
const char* Name = "boolule";
/* Unsigned compare */
if (val < 65535) {
++val;
Name = "boolult";
}
/* Use < instead of <= because the former gives
* better code on the 6502 than the latter.
*/
g_lt (flags, val+1);
} else {
unsigned L = GetLocalLabel();
AddCodeLine ("cpx #$%02X", (unsigned char)(val >> 8));
AddCodeLine ("bne %s", LocalLabelName (L));
AddCodeLine ("cmp #$%02X", (unsigned char)val);
g_defcodelabel (L);
AddCodeLine ("jsr %s", Name);
AddCodeLine ("jsr %s", "boolule");
}
return;
} else {
/* Signed compare */
if (val < 32767) {
g_lt (flags, val+1);
return;
}
}
break;
@ -3509,25 +3540,24 @@ void g_gt (unsigned flags, unsigned long val)
*/
if (flags & CF_CONST) {
/* > is not very effective on the 6502, so try to convert
* it into >= if the value is in a valid range.
*/
/* Look at the type */
switch (flags & CF_TYPE) {
case CF_CHAR:
if (flags & CF_FORCECHAR) {
if (flags & CF_UNSIGNED) {
/* If we have a compare > 0, we will replace it by
* != 0 here, since both are identical but the latter
* is easier to optimize.
*/
if (val == 0) {
/* If we have a compare > 0, we will replace it by
* != 0 here, since both are identical but the
* latter is easier to optimize.
*/
AddCodeLine ("cmp #$%02X", (unsigned char)val);
AddCodeLine ("jsr boolne");
} else if (val < 255) {
AddCodeLine ("cmp #$%02X", (unsigned char)val+1);
/* Use >= instead of > because the former gives
* better code on the 6502 than the latter.
*/
AddCodeLine ("cmp #$%02X", (unsigned char)(val+1));
AddCodeLine ("jsr booluge");
} else {
AddCodeLine ("cmp #$%02X", (unsigned char)val);
@ -3535,7 +3565,10 @@ void g_gt (unsigned flags, unsigned long val)
}
} else {
if (val < 127) {
AddCodeLine ("cmp #$%02X", (unsigned char)val+1);
/* Use >= instead of > because the former gives
* better code on the 6502 than the latter.
*/
AddCodeLine ("cmp #$%02X", (unsigned char)(val+1));
AddCodeLine ("jsr boolge");
} else {
AddCodeLine ("cmp #$%02X", (unsigned char)val);
@ -3548,28 +3581,35 @@ void g_gt (unsigned flags, unsigned long val)
case CF_INT:
if (flags & CF_UNSIGNED) {
/* Unsigned compare */
if (val == 0) {
/* If we have a compare > 0, we will replace it by
* != 0 here, since both are identical but the latter
* is easier to optimize.
*/
if (val == 0) {
AddCodeLine ("stx tmp1");
AddCodeLine ("ora tmp1");
AddCodeLine ("jsr boolne");
} else if (val < 65535U) {
/* Use >= instead of > because the former gives better
* code on the 6502 than the latter.
*/
g_ge (flags, val+1);
} else {
unsigned L = GetLocalLabel();
const char* Name = "boolugt";
if (val < 65535) {
++val;
Name = "booluge";
}
AddCodeLine ("cpx #$%02X", (unsigned char)(val >> 8));
AddCodeLine ("bne %s", LocalLabelName (L));
AddCodeLine ("cmp #$%02X", (unsigned char)val);
g_defcodelabel (L);
AddCodeLine ("jsr %s", Name);
AddCodeLine ("jsr %s", "boolugt");
}
return;
} else {
/* Signed compare */
if (val < 32767) {
g_ge (flags, val+1);
return;
}
}
break;
@ -3612,6 +3652,8 @@ void g_ge (unsigned flags, unsigned long val)
/* Give a warning in some special cases */
if ((flags & CF_UNSIGNED) && val == 0) {
Warning ("Condition is always true");
AddCodeLine ("jsr return1");
return;
}
/* Look at the type */
@ -3640,13 +3682,29 @@ void g_ge (unsigned flags, unsigned long val)
}
/* Direct code only for unsigned data types */
if (flags & CF_UNSIGNED) {
unsigned L = GetLocalLabel();
/* If the low byte is zero, we must only test the high
* byte. Or, citing Piotr Fusik:
* Another interpretation: the code is effectively:
* if (ax >= 0xAB00) goto L2;
* It's equivalent to:
* if ((ax >> 8) >= 0xAB) goto L2;
*/
AddCodeLine ("cpx #$%02X", (unsigned char)(val >> 8));
if ((val & 0xFF) != 0) {
unsigned L = GetLocalLabel();
AddCodeLine ("bne %s", LocalLabelName (L));
AddCodeLine ("cmp #$%02X", (unsigned char)val);
g_defcodelabel (L);
}
AddCodeLine ("jsr booluge");
return;
} else {
/* Signed compare */
if ((val & 0xFF) == 0) {
AddCodeLine ("cpx #$%02X", (unsigned char) (val >> 8));
AddCodeLine ("jsr boolge");
return;
}
}
break;