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Improve constant propagation with "&&" and "||".

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This commit is contained in:
Edmund Grimley Evans 2015-11-20 23:33:49 +00:00
parent c7067aeb84
commit 3ff77a1d6f
3 changed files with 58 additions and 52 deletions
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1
TODO
View File

@ -68,7 +68,6 @@ Not critical:
to suppress VT_LOCAL and use a base register instead).
- interactive mode / integrated debugger
- fix preprocessor symbol redefinition
- better constant opt (&&, ||, ?:)
- add portable byte code generator and interpreter for other
unsupported architectures.
- C++: variable declaration in for, minimal 'class' support.

103
tccgen.c
View File

@ -4453,80 +4453,83 @@ static void expr_or(void)
}
}
/* XXX: fix this mess */
static void expr_land_const(void)
{
expr_or();
while (tok == TOK_LAND) {
next();
expr_or();
gen_op(TOK_LAND);
}
}
/* XXX: fix this mess */
static void expr_lor_const(void)
{
expr_land_const();
while (tok == TOK_LOR) {
next();
expr_land_const();
gen_op(TOK_LOR);
}
}
/* only used if non constant */
static void expr_land(void)
{
int t;
expr_or();
if (tok == TOK_LAND) {
t = 0;
save_regs(1);
for(;;) {
t = gvtst(1, t);
if (tok != TOK_LAND) {
vseti(VT_JMPI, t);
break;
}
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb, cti;
ctb.t = VT_BOOL;
cti.t = VT_INT;
next();
expr_or();
gen_cast(&ctb);
if (vtop->c.i) {
vpop();
expr_land();
gen_cast(&ctb);
} else {
expr_land();
vpop();
}
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();
}
}
}
}
static void expr_lor(void)
{
int t;
expr_land();
if (tok == TOK_LOR) {
t = 0;
save_regs(1);
for(;;) {
t = gvtst(0, t);
if (tok != TOK_LOR) {
vseti(VT_JMP, t);
break;
}
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
CType ctb, cti;
ctb.t = VT_BOOL;
cti.t = VT_INT;
next();
expr_land();
gen_cast(&ctb);
if (vtop->c.i) {
expr_lor();
vpop();
} 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();
}
}
}
}
/* XXX: better constant handling */
static void expr_cond(void)
{
int tt, u, r1, r2, rc, t1, t2, bt1, bt2;
SValue sv;
CType type, type1, type2;
if (const_wanted)
expr_lor_const();
else
expr_lor();
expr_lor();
if (tok == '?') {
next();
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {

6
tests/tests2/78_vla_label.c
View File

@ -17,9 +17,13 @@ void f2(void)
{
goto start;
{
int a[1 ? 1 : 1]; /* not a variable-length array */
int a[1 && 1]; /* not a variable-length array */
int b[1 || 1]; /* not a variable-length array */
int c[1 ? 1 : 1]; /* not a variable-length array */
start:
a[0] = 0;
b[0] = 0;
c[0] = 0;
}
}