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opt: constprop also 'cond && 0'

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We didn't handle constants in logical expressions when they weren't
the first operand.  Some reordering in the loop structure is enough
to handle them.
This commit is contained in:
Michael Matz 2016-09-26 21:21:42 +02:00
parent ca435dc2e3
commit fb933ae0eb
2 changed files with 113 additions and 62 deletions
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136
tccgen.c
View File

@ -4909,37 +4909,43 @@ static void expr_land(void)
{
expr_or();
if (tok == TOK_LAND) {
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb, cti;
ctb.t = VT_BOOL;
cti.t = VT_INT;
next();
gen_cast(&ctb);
if (vtop->c.i) {
vpop();
expr_land();
gen_cast(&ctb);
} else {
int saved_nocode_wanted = nocode_wanted;
nocode_wanted = 1;
expr_land();
vpop();
nocode_wanted = saved_nocode_wanted;
}
gen_cast(&cti);
} else {
int t = 0;
save_regs(1);
for(;;) {
t = gvtst(1, t);
if (tok != TOK_LAND) {
vseti(VT_JMPI, t);
break;
}
next();
expr_or();
}
}
int t = 0;
for(;;) {
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb;
ctb.t = VT_BOOL;
gen_cast(&ctb);
if (vtop->c.i) {
vpop();
} else {
int saved_nocode_wanted = nocode_wanted;
nocode_wanted = 1;
while (tok == TOK_LAND) {
next();
expr_or();
vpop();
}
if (t)
gsym(t);
nocode_wanted = saved_nocode_wanted;
gen_cast(&int_type);
break;
}
} else {
if (!t)
save_regs(1);
t = gvtst(1, t);
}
if (tok != TOK_LAND) {
if (t)
vseti(VT_JMPI, t);
else
vpushi(1);
break;
}
next();
expr_or();
}
}
}
@ -4947,37 +4953,43 @@ static void expr_lor(void)
{
expr_land();
if (tok == TOK_LOR) {
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb, cti;
ctb.t = VT_BOOL;
cti.t = VT_INT;
next();
gen_cast(&ctb);
if (vtop->c.i) {
int saved_nocode_wanted = nocode_wanted;
nocode_wanted = 1;
expr_lor();
vpop();
nocode_wanted = saved_nocode_wanted;
} else {
vpop();
expr_lor();
gen_cast(&ctb);
}
gen_cast(&cti);
} else {
int t = 0;
save_regs(1);
for(;;) {
t = gvtst(0, t);
if (tok != TOK_LOR) {
vseti(VT_JMP, t);
break;
}
next();
expr_land();
}
}
int t = 0;
for(;;) {
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb;
ctb.t = VT_BOOL;
gen_cast(&ctb);
if (!vtop->c.i) {
vpop();
} else {
int saved_nocode_wanted = nocode_wanted;
nocode_wanted = 1;
while (tok == TOK_LOR) {
next();
expr_land();
vpop();
}
if (t)
gsym(t);
nocode_wanted = saved_nocode_wanted;
gen_cast(&int_type);
break;
}
} else {
if (!t)
save_regs(1);
t = gvtst(0, t);
}
if (tok != TOK_LOR) {
if (t)
vseti(VT_JMP, t);
else
vpushi(0);
break;
}
next();
expr_land();
}
}
}

39
tests/tcctest.c
View File

@ -1232,6 +1232,38 @@ void optimize_out(void)
printf("ool6:%d\n", defined_function());
goto breakhere;
}
/* Test that constants in logical && are optimized: */
i = 0 && undefined_function();
i = defined_function() && 0 && undefined_function();
if (0 && undefined_function())
undefined_function();
if (defined_function() && 0)
undefined_function();
if (0 && 0)
undefined_function();
if (defined_function() && 0 && undefined_function())
undefined_function();
/* The same for || : */
i = 1 || undefined_function();
i = defined_function() || 1 || undefined_function();
if (1 || undefined_function())
;
else
undefined_function();
if (defined_function() || 1)
;
else
undefined_function();
if (1 || 1)
;
else
undefined_function();
if (defined_function() || 1 || undefined_function())
;
else
undefined_function();
if (1)
return;
printf ("oor:%d\n", undefined_function());
@ -2544,6 +2576,13 @@ void sizeof_test(void)
/* And as direct sizeof argument (as unary expression): */
printf("sizeof (struct {short i; short j;}){4,5} = %d\n",
sizeof (struct {short i; short j;}){4,5} );
/* sizeof(x && y) should be sizeof(int), even if constant
evaluating is possible. */
printf("sizeof(t && 0) = %d\n", sizeof(t && 0));
printf("sizeof(1 && 1) = %d\n", sizeof(1 && 1));
printf("sizeof(t || 1) = %d\n", sizeof(t || 1));
printf("sizeof(0 || 0) = %d\n", sizeof(0 || 0));
}
void typeof_test(void)