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Optimize multiplication by zero

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This commit is contained in:
Colin Leroy-Mira 2023-11-05 21:03:06 +01:00
parent fe115fb621
commit cff611711b
2 changed files with 14 additions and 1 deletions
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14
src/cc65/codegen.c
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@ -2726,7 +2726,12 @@ void g_mul (unsigned flags, unsigned long val)
if (flags & CF_FORCECHAR) {
/* Handle some special cases */
switch (val) {
case 0:
AddCodeLine ("lda #$00");
return;
case 1:
/* Nothing to do */
return;
case 3:
AddCodeLine ("sta tmp1");
AddCodeLine ("asl a");
@ -2764,6 +2769,13 @@ void g_mul (unsigned flags, unsigned long val)
case CF_INT:
switch (val) {
case 0:
AddCodeLine ("lda #$00");
AddCodeLine ("tax");
return;
case 1:
/* Nothing to do */
return;
case 3:
AddCodeLine ("jsr mulax3");
return;

1
test/val/mult1.c
View File

@ -55,6 +55,7 @@ void m3(unsigned char uc)
/* testing literal multiply with same source and destination */
vuc = uc;
uc2 = 0;
uc1 = vuc; uc1 = uc1*0; if( uc1 != 0 ) failures++;
uc1 = vuc; uc1 = uc1*1; if( uc1 != (uc2+=TESTLIT) ) failures++;
uc1 = vuc; uc1 = uc1*2; if( uc1 != (uc2+=TESTLIT) ) failures++;
uc1 = vuc; uc1 = uc1*3; if( uc1 != (uc2+=TESTLIT) ) failures++;