qbe: Handle K&R function definition argument promotion

Parameters for K&R function definitions that are affected by default
argument promotion are passed as their promoted type, so need to be
converted back before storing into memory allocated for the parameter.

3 files changed, 173 insertions, 143 deletions

diff --git a/qbe.c b/qbe.c
index 1cd1a6c..f342723 100644
--- a/qbe.c
+++ b/qbe.c
@@ -376,6 +376,142 @@ funcload(struct func *f, struct type *t, struct lvalue lval)
 	return funcbits(f, t, v, lval.bits);
 }
 
+/* TODO: move these conversions to QBE */
+static struct value *
+utof(struct func *f, struct repr *r, struct value *v)
+{
+	struct value *odd, *big, *phi[5] = {0}, *join;
+
+	if (v->repr->base == 'w') {
+		v = funcinst(f, IEXTUW, &i64, v);
+		return funcinst(f, ISLTOF, r, v);
+	}
+
+	phi[0] = mkblock("utof_small");
+	phi[2] = mkblock("utof_big");
+	join = mkblock("utof_join");
+
+	big = funcinst(f, ICSLTL, &i32, v, mkintconst(&i64, 0));
+	funcjnz(f, big, phi[2], phi[0]);
+
+	funclabel(f, phi[0]);
+	phi[1] = funcinst(f, ISLTOF, r, v);
+	funcjmp(f, join);
+
+	funclabel(f, phi[2]);
+	odd = funcinst(f, IAND, &i64, v, mkintconst(&i64, 1));
+	v = funcinst(f, ISHR, &i64, v, mkintconst(&i64, 1));
+	v = funcinst(f, IOR, &i64, v, odd);  /* round to odd */
+	v = funcinst(f, ISLTOF, r, v);
+	phi[3] = funcinst(f, IADD, r, v, v);
+
+	funclabel(f, join);
+	return funcinstn(f, IPHI, r, phi);
+}
+
+static struct value *
+ftou(struct func *f, struct repr *r, struct value *v)
+{
+	struct value *big, *phi[5] = {0}, *join, *maxflt, *maxint;
+	enum instkind op = v->repr->base == 's' ? ISTOSI : IDTOSI;
+
+	if (r->base == 'w') {
+		v = funcinst(f, op, &i64, v);
+		return funcinst(f, ICOPY, r, v);
+	}
+
+	phi[0] = mkblock("ftou_small");
+	phi[2] = mkblock("ftou_big");
+	join = mkblock("ftou_join");
+
+	maxflt = mkfltconst(v->repr, 0x1p63);
+	maxint = mkintconst(&i64, 1ull<<63);
+
+	big = funcinst(f, v->repr->base == 's' ? ICGES : ICGED, &i32, v, maxflt);
+	funcjnz(f, big, phi[2], phi[0]);
+
+	funclabel(f, phi[0]);
+	phi[1] = funcinst(f, op, r, v);
+	funcjmp(f, join);
+
+	funclabel(f, phi[2]);
+	v = funcinst(f, ISUB, v->repr, v, maxflt);
+	v = funcinst(f, op, r, v);
+	phi[3] = funcinst(f, IXOR, r, v, maxint);
+
+	funclabel(f, join);
+	return funcinstn(f, IPHI, r, phi);
+}
+
+static struct value *
+extend(struct func *f, struct type *t, struct value *v)
+{
+	enum instkind op;
+
+	switch (t->size) {
+	case 1: op = t->basic.issigned ? IEXTSB : IEXTUB; break;
+	case 2: op = t->basic.issigned ? IEXTSH : IEXTUH; break;
+	default: return v;
+	}
+	return funcinst(f, op, &i32, v);
+}
+
+static struct value *
+convert(struct func *f, struct type *dst, struct type *src, struct value *l)
+{
+	enum instkind op;
+	struct value *r = NULL;
+
+	if (src->kind == TYPEPOINTER)
+		src = &typeulong;
+	if (dst->kind == TYPEPOINTER)
+		dst = &typeulong;
+	if (dst->kind == TYPEVOID)
+		return NULL;
+	if (!(src->prop & PROPREAL) || !(dst->prop & PROPREAL))
+		fatal("internal error; unsupported conversion");
+	if (dst->kind == TYPEBOOL) {
+		l = extend(f, src, l);
+		r = mkintconst(src->repr, 0);
+		if (src->prop & PROPINT)
+			op = src->size == 8 ? ICNEL : ICNEW;
+		else
+			op = src->size == 8 ? ICNED : ICNES;
+	} else if (dst->prop & PROPINT) {
+		if (src->prop & PROPINT) {
+			if (dst->size <= src->size) {
+				op = ICOPY;
+			} else {
+				switch (src->size) {
+				case 4: op = src->basic.issigned ? IEXTSW : IEXTUW; break;
+				case 2: op = src->basic.issigned ? IEXTSH : IEXTUH; break;
+				case 1: op = src->basic.issigned ? IEXTSB : IEXTUB; break;
+				default: fatal("internal error; unknown int conversion");
+				}
+			}
+		} else {
+			if (!dst->basic.issigned)
+				return ftou(f, dst->repr, l);
+			op = src->size == 8 ? IDTOSI : ISTOSI;
+		}
+	} else {
+		if (src->prop & PROPINT) {
+			if (!src->basic.issigned)
+				return utof(f, dst->repr, l);
+			op = src->size == 8 ? ISLTOF : ISWTOF;
+		} else {
+			if (src->size < dst->size)
+				op = IEXTS;
+			else if (src->size > dst->size)
+				op = ITRUNCD;
+			else
+				op = ICOPY;
+		}
+	}
+
+	return funcinst(f, op, dst->repr, l, r);
+}
+
 /*
 XXX: If a function declared without a prototype is declared with a
 parameter affected by default argument promotion, we need to emit a QBE
@@ -388,6 +524,8 @@ mkfunc(struct decl *decl, char *name, struct type *t, struct scope *s)
 	struct func *f;
 	struct param *p;
 	struct decl *d;
+	struct type *pt;
+	struct value *v;
 
 	f = xmalloc(sizeof(*f));
 	f->decl = decl;
@@ -402,19 +540,19 @@ mkfunc(struct decl *decl, char *name, struct type *t, struct scope *s)
 	for (p = t->func.params; p; p = p->next) {
 		if (!p->name)
 			error(&tok.loc, "parameter name omitted in function definition");
-		if (!t->func.isprototype && !typecompatible(p->type, typepromote(p->type, -1)))
-			error(&tok.loc, "old-style function definition with parameter type incompatible with promoted type is not yet supported");
-		emittype(p->type);
-		d = mkdecl(DECLOBJECT, p->type, p->qual, LINKNONE);
+		pt = t->func.isprototype ? p->type : typepromote(p->type, -1);
+		emittype(pt);
 		p->value = xmalloc(sizeof(*p->value));
-		functemp(f, p->value, p->type->repr);
+		functemp(f, p->value, pt->repr);
+		d = mkdecl(DECLOBJECT, p->type, p->qual, LINKNONE);
 		if (p->type->repr->abi.id) {
 			d->value = xmalloc(sizeof(*d->value));
 			*d->value = *p->value;
 			d->value->repr = &iptr;
 		} else {
+			v = typecompatible(p->type, pt) ? p->value : convert(f, pt, p->type, p->value);
 			funcinit(f, d, NULL);
-			funcstore(f, p->type, QUALNONE, (struct lvalue){d->value}, p->value);
+			funcstore(f, p->type, QUALNONE, (struct lvalue){d->value}, v);
 		}
 		scopeputdecl(s, p->name, d);
 	}
@@ -551,142 +689,6 @@ funclval(struct func *f, struct expr *e)
 	return lval;
 }
 
-/* TODO: move these conversions to QBE */
-static struct value *
-utof(struct func *f, struct repr *r, struct value *v)
-{
-	struct value *odd, *big, *phi[5] = {0}, *join;
-
-	if (v->repr->base == 'w') {
-		v = funcinst(f, IEXTUW, &i64, v);
-		return funcinst(f, ISLTOF, r, v);
-	}
-
-	phi[0] = mkblock("utof_small");
-	phi[2] = mkblock("utof_big");
-	join = mkblock("utof_join");
-
-	big = funcinst(f, ICSLTL, &i32, v, mkintconst(&i64, 0));
-	funcjnz(f, big, phi[2], phi[0]);
-
-	funclabel(f, phi[0]);
-	phi[1] = funcinst(f, ISLTOF, r, v);
-	funcjmp(f, join);
-
-	funclabel(f, phi[2]);
-	odd = funcinst(f, IAND, &i64, v, mkintconst(&i64, 1));
-	v = funcinst(f, ISHR, &i64, v, mkintconst(&i64, 1));
-	v = funcinst(f, IOR, &i64, v, odd);  /* round to odd */
-	v = funcinst(f, ISLTOF, r, v);
-	phi[3] = funcinst(f, IADD, r, v, v);
-
-	funclabel(f, join);
-	return funcinstn(f, IPHI, r, phi);
-}
-
-static struct value *
-ftou(struct func *f, struct repr *r, struct value *v)
-{
-	struct value *big, *phi[5] = {0}, *join, *maxflt, *maxint;
-	enum instkind op = v->repr->base == 's' ? ISTOSI : IDTOSI;
-
-	if (r->base == 'w') {
-		v = funcinst(f, op, &i64, v);
-		return funcinst(f, ICOPY, r, v);
-	}
-
-	phi[0] = mkblock("ftou_small");
-	phi[2] = mkblock("ftou_big");
-	join = mkblock("ftou_join");
-
-	maxflt = mkfltconst(v->repr, 0x1p63);
-	maxint = mkintconst(&i64, 1ull<<63);
-
-	big = funcinst(f, v->repr->base == 's' ? ICGES : ICGED, &i32, v, maxflt);
-	funcjnz(f, big, phi[2], phi[0]);
-
-	funclabel(f, phi[0]);
-	phi[1] = funcinst(f, op, r, v);
-	funcjmp(f, join);
-
-	funclabel(f, phi[2]);
-	v = funcinst(f, ISUB, v->repr, v, maxflt);
-	v = funcinst(f, op, r, v);
-	phi[3] = funcinst(f, IXOR, r, v, maxint);
-
-	funclabel(f, join);
-	return funcinstn(f, IPHI, r, phi);
-}
-
-static struct value *
-extend(struct func *f, struct type *t, struct value *v)
-{
-	enum instkind op;
-
-	switch (t->size) {
-	case 1: op = t->basic.issigned ? IEXTSB : IEXTUB; break;
-	case 2: op = t->basic.issigned ? IEXTSH : IEXTUH; break;
-	default: return v;
-	}
-	return funcinst(f, op, &i32, v);
-}
-
-static struct value *
-convert(struct func *f, struct type *dst, struct type *src, struct value *l)
-{
-	enum instkind op;
-	struct value *r = NULL;
-
-	if (src->kind == TYPEPOINTER)
-		src = &typeulong;
-	if (dst->kind == TYPEPOINTER)
-		dst = &typeulong;
-	if (dst->kind == TYPEVOID)
-		return NULL;
-	if (!(src->prop & PROPREAL) || !(dst->prop & PROPREAL))
-		fatal("internal error; unsupported conversion");
-	if (dst->kind == TYPEBOOL) {
-		l = extend(f, src, l);
-		r = mkintconst(src->repr, 0);
-		if (src->prop & PROPINT)
-			op = src->size == 8 ? ICNEL : ICNEW;
-		else
-			op = src->size == 8 ? ICNED : ICNES;
-	} else if (dst->prop & PROPINT) {
-		if (src->prop & PROPINT) {
-			if (dst->size <= src->size) {
-				op = ICOPY;
-			} else {
-				switch (src->size) {
-				case 4: op = src->basic.issigned ? IEXTSW : IEXTUW; break;
-				case 2: op = src->basic.issigned ? IEXTSH : IEXTUH; break;
-				case 1: op = src->basic.issigned ? IEXTSB : IEXTUB; break;
-				default: fatal("internal error; unknown int conversion");
-				}
-			}
-		} else {
-			if (!dst->basic.issigned)
-				return ftou(f, dst->repr, l);
-			op = src->size == 8 ? IDTOSI : ISTOSI;
-		}
-	} else {
-		if (src->prop & PROPINT) {
-			if (!src->basic.issigned)
-				return utof(f, dst->repr, l);
-			op = src->size == 8 ? ISLTOF : ISWTOF;
-		} else {
-			if (src->size < dst->size)
-				op = IEXTS;
-			else if (src->size > dst->size)
-				op = ITRUNCD;
-			else
-				op = ICOPY;
-		}
-	}
-
-	return funcinst(f, op, dst->repr, l, r);
-}
-
 struct value *
 funcexpr(struct func *f, struct expr *e)
 {
@@ -1204,7 +1206,7 @@ emitfunc(struct func *f, bool global)
 	for (p = f->type->func.params; p; p = p->next) {
 		if (p != f->type->func.params)
 			fputs(", ", stdout);
-		emitrepr(p->type->repr, true, false);
+		emitrepr(p->value->repr, true, false);
 		putchar(' ');
 		emitvalue(p->value);
 	}
diff --git a/test/kr-function-argument-promotion.c b/test/kr-function-argument-promotion.c
new file mode 100644
index 0000000..7592da1
--- /dev/null
+++ b/test/kr-function-argument-promotion.c
@@ -0,0 +1,10 @@
+int f(c)
+	unsigned char c;
+{
+	return c;
+}
+
+int main(void)
+{
+	return f(0x100);
+}
diff --git a/test/kr-function-argument-promotion.qbe b/test/kr-function-argument-promotion.qbe
new file mode 100644
index 0000000..6d2f2b8
--- /dev/null
+++ b/test/kr-function-argument-promotion.qbe
@@ -0,0 +1,18 @@
+export
+function w $f(w %.1) {
+@start.1
+	%.2 =w extub %.1
+	%.3 =l alloc4 1
+	storeb %.2, %.3
+@body.2
+	%.4 =w loadub %.3
+	%.5 =w extub %.4
+	ret %.5
+}
+export
+function w $main() {
+@start.3
+@body.4
+	%.1 =w call $f(w 256)
+	ret %.1
+}