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-rw-r--r--parse.c66
-rw-r--r--test.c6
2 files changed, 48 insertions, 24 deletions
diff --git a/parse.c b/parse.c
index 77d263a..20e517f 100644
--- a/parse.c
+++ b/parse.c
@@ -950,8 +950,18 @@ commaexpr(struct parser *pr)
/*********/
static union ref expraddr(struct function *, const struct expr *);
-static union ref exprvalue(struct function *, const struct expr *);
+static union ref compileexpr(struct function *, const struct expr *, bool discard);
+static inline union ref
+exprvalue(struct function *fn, const struct expr *ex)
+{
+ return compileexpr(fn, ex, /*discard*/ 0);
+}
+static inline void
+expreffects(struct function *fn, const struct expr *ex)
+{
+ compileexpr(fn, ex, /*discard*/ 1);
+}
static void
@@ -1012,7 +1022,7 @@ expraddr(struct function *fn, const struct expr *ex)
structcopy(fn, r, &ex->sub[1]);
return r;
case ESEQ:
- (void)exprvalue(fn, &ex->sub[0]);
+ expreffects(fn, &ex->sub[0]);
return expraddr(fn, &ex->sub[1]);
case ECALL:
assert(isagg(ex->ty));
@@ -1162,7 +1172,7 @@ condjump(struct function *fn, const struct expr *ex, struct block *tr, struct bl
struct block *next, *next2;
Loop:
while (ex->t == ESEQ) {
- (void)exprvalue(fn, &ex->sub[0]);
+ expreffects(fn, &ex->sub[0]);
ex = &ex->sub[1];
}
if (ex->t == ELOGAND) {
@@ -1215,7 +1225,7 @@ condexprrec(struct function *fn, const struct expr *ex, struct condphis *phis,
struct block *tr, *fl, *next;
union ref r;
while (ex->t == ESEQ) {
- (void)exprvalue(fn, &ex->sub[0]);
+ expreffects(fn, &ex->sub[0]);
ex = &ex->sub[1];
}
if (ex->t == ELOGAND) {
@@ -1308,7 +1318,7 @@ condexprvalue(struct function *fn, const struct expr *ex)
}
static union ref
-exprvalue(struct function *fn, const struct expr *ex)
+compileexpr(struct function *fn, const struct expr *ex, bool discard)
{
union type ty;
union ref r, q;
@@ -1321,31 +1331,38 @@ exprvalue(struct function *fn, const struct expr *ex)
sub = ex->sub;
if (ex->ty.t != TYVOID && !isscalar(ex->ty))
+ /* fn & array designators evaluate to their address; so do aggregates for the purpose of code generation */
return expraddr(fn, ex);
switch (ex->t) {
case ENUMLIT:
+ if (discard) return NOREF;
if (isflt(ex->ty))
return mkfltcon(fn, cls, ex->f);
return mkintcon(fn, cls, ex->i);
case ESYM:
+ if (discard && !(ex->qual & QVOLATILE)) return NOREF;
return genload(fn, ex->ty, expraddr(fn, ex));
case EGETF:
+ if (discard && !(ex->qual & QVOLATILE)) return NOREF;
return genload(fn, ex->ty, expraddr(fn, ex));
case ECAST:
if (ex->ty.t == TYVOID) {
- (void)exprvalue(fn, sub);
+ expreffects(fn, sub);
return NOREF;
}
/* fallthru */
case EPLUS:
- return cvt(fn, ex->ty.t, sub->ty.t, exprvalue(fn, sub));
+ r = compileexpr(fn, sub, discard);
+ if (discard) return NOREF;
+ return cvt(fn, ex->ty.t, sub->ty.t, r);
case ENEG:
ins.op = Oneg;
goto Unary;
case ECOMPL:
ins.op = Onot;
Unary:
- ins.l = exprvalue(fn, sub);
+ ins.l = compileexpr(fn, sub, discard);
+ if (discard) return NOREF;
ins.l = cvt(fn, ex->ty.t, sub->ty.t, ins.l);
ins.cls = cls;
return addinstr(fn, ins);
@@ -1353,13 +1370,17 @@ exprvalue(struct function *fn, const struct expr *ex)
for (; sub->t == ELOGNOT; ex = sub, sub = sub->sub)
swp ^= 1;
ins.op = Oequ + swp;
- ins.l = exprvalue(fn, sub);
+ ins.l = compileexpr(fn, sub, discard);
+ if (discard) return NOREF;
ins.l = cvt(fn, ex->ty.t, sub->ty.t, ins.l);
ins.r = mkintcon(fn, cls, 0);
ins.cls = cls;
return addinstr(fn, ins);
case EDEREF:
- return genload(fn, ex->ty, exprvalue(fn, sub));
+ discard &= (ex->qual & QVOLATILE) == 0;
+ r = compileexpr(fn, sub, discard);
+ if (discard) return NOREF;
+ return genload(fn, ex->ty, r);
case EADDROF:
return expraddr(fn, sub);
case EMUL:
@@ -1392,8 +1413,9 @@ exprvalue(struct function *fn, const struct expr *ex)
case EADD:
ins.op = Oadd;
BinArith:
- ins.l = exprvalue(fn, &sub[0]);
- ins.r = exprvalue(fn, &sub[1]);
+ ins.l = compileexpr(fn, &sub[0], discard);
+ ins.r = compileexpr(fn, &sub[1], discard);
+ if (discard) return NOREF;
if (ins.op == Osub && isptrcvt(sub[0].ty) && isptrcvt(sub[1].ty)) {
/* ptr - ptr */
return genptrdiff(fn, typesize(typechild(sub[0].ty)), ins.l, ins.r);
@@ -1432,6 +1454,7 @@ exprvalue(struct function *fn, const struct expr *ex)
ins.r = mkref(RICON, 1);
q = addinstr(fn, ins);
genstore(fn, sub->ty, r, q);
+ if (discard) return NOREF;
return narrow(fn, cls, ex->ty.t, q);
case EEQU:
ins.op = Oequ;
@@ -1457,9 +1480,10 @@ exprvalue(struct function *fn, const struct expr *ex)
if (!ty.t) ty.t = TYPTR;
if (isunsigned(ty) && in_range(ins.op, Olth, Olte))
ins.op += Oulth - Olth;
- ins.l = exprvalue(fn, &sub[0^swp]);
+ ins.l = compileexpr(fn, &sub[0^swp], discard);
+ ins.r = compileexpr(fn, &sub[1^swp], discard);
+ if (discard) return NOREF;
ins.l = cvt(fn, ty.t, sub[0^swp].ty.t, ins.l);
- ins.r = exprvalue(fn, &sub[1^swp]);
ins.r = cvt(fn, ty.t, sub[1^swp].ty.t, ins.r);
ins.cls = cls;
return addinstr(fn, ins);
@@ -1468,6 +1492,7 @@ exprvalue(struct function *fn, const struct expr *ex)
r = expraddr(fn, &sub[0]);
q = cvt(fn, sub[0].ty.t, sub[1].ty.t, exprvalue(fn, &sub[1]));
genstore(fn, ex->ty, r, q);
+ if (discard) return NOREF;
return narrow(fn, cls, sub[0].ty.t, q);
case ESETMUL:
ins.op = isunsigned(ex->ty) ? Oumul : Omul;
@@ -1513,19 +1538,20 @@ exprvalue(struct function *fn, const struct expr *ex)
q = genptroff(fn, ins.op, typesize(typechild(ex->ty)), ins.l, sub[1].ty.t, ins.r);
}
genstore(fn, ex->ty, r, q);
+ if (discard) return NOREF;
return narrow(fn, cls, ex->ty.t, q);
case ECALL:
return compilecall(fn, ex);
case ECOND:
if (ex->ty.t == TYVOID) {
struct block *tr, *fl, *end;
- condjump(fn, &ex->sub[0], tr = newblk(fn), fl = newblk(fn));
+ condjump(fn, &sub[0], tr = newblk(fn), fl = newblk(fn));
useblk(fn, tr);
- (void)exprvalue(fn, &ex->sub[1]);
+ expreffects(fn, &sub[1]);
end = newblk(fn);
putbranch(fn, end);
useblk(fn, fl);
- (void)exprvalue(fn, &ex->sub[2]);
+ expreffects(fn, &sub[2]);
putbranch(fn, end);
useblk(fn, end);
return NOREF;
@@ -1535,8 +1561,8 @@ exprvalue(struct function *fn, const struct expr *ex)
case ELOGIOR:
return condexprvalue(fn, ex);
case ESEQ:
- (void)exprvalue(fn, &sub[0]);
- return exprvalue(fn, &sub[1]);
+ expreffects(fn, &sub[0]);
+ return compileexpr(fn, &sub[1], discard);
default: assert(!"nyi expr");
}
}
@@ -1669,7 +1695,7 @@ stmt(struct parser *pr, struct function *fn)
default:
ex = commaexpr(pr);
stmtterm(pr);
- EMITS exprvalue(fn, &ex);
+ EMITS expreffects(fn, &ex);
break;
}
freearena(pr->exarena);
diff --git a/test.c b/test.c
index e061b2b..b89942a 100644
--- a/test.c
+++ b/test.c
@@ -56,11 +56,9 @@ struct f2 f2test(struct f2 *r) {
return *r;
}
-void memset(char *p, int c, unsigned long n)
+void memset(volatile char *p, int c, unsigned long n)
{
- if (n) do {
- *p++ = c;
- } while (--n);
+ if (n) do *p++ = c; while (--n);
}
generated by cgit v1.2.3 (git 2.39.1) at 2026-05-02 01:30:19 +0000