shithub: scc

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ref: bcedb21933bb5b585d6e65bd17eb2aaadf5f95a6
parent: 2490562f2017eaf5097cfa6cd8353b986959b453
author: Roberto E. Vargas Caballero <k0ga@shike2.com>
date: Thu Nov 4 10:51:16 EDT 2021 

cc2/qbe: Use sethi numbers in all of assign ops

Before this commit only normal and abbreviation assign operators
were using the Sethi complexity numbers to drive the code
generation. This commit unifies all the operators and apply the
Sethi numbers to all the operators.


--- a/src/cmd/cc/cc2/target/qbe/cgen.c
+++ b/src/cmd/cc/cc2/target/qbe/cgen.c
@@ -235,32 +235,6 @@
 }
 
 static Node *
-assign(Type *tp, Node *to, Node *from)
-{
-	int op;
-
-	switch (tp->size) {
-	case 1:
-		op = ASSTB;
-		break;
-	case 2:
-		op = ASSTH;
-		break;
-	case 4:
-		op = (tp->flags & FLOATF) ? ASSTS : ASSTW;
-		break;
-	case 8:
-		op = (tp->flags & FLOATF) ? ASSTD : ASSTL;
-		break;
-	default:
-		op = ASSTM;
-		break;
-	}
-	code(op, to, from, NULL);
-	return from;
-}
-
-static Node *
 copy(Type *tp, Node *to, Node *from)
 {
 	int op;
@@ -450,7 +424,70 @@
 	}
 }
 
+static int
+assignop(Type *tp)
+{
+	switch (tp->size) {
+	case 1:
+		return ASSTB;
+	case 2:
+		return ASSTH;
+	case 4:
+		return (tp->flags & FLOATF) ? ASSTS : ASSTW;
+	case 8:
+		return (tp->flags & FLOATF) ? ASSTD : ASSTL;
+	default:
+		return ASSTM;
+	}
+}
+
 static Node *
+assign(Node *np)
+{
+	Node *tmp, aux;
+	Node *l = np->left, *r = np->right;
+	int op;
+
+	switch (np->u.subop) {
+	case OINC:
+		op = OADD;
+		goto post_oper;
+	case ODEC:
+		op = OSUB;
+	post_oper:
+		tmp = rhs(l);
+		aux.op = op;
+		aux.left = tmp;
+		aux.right = r;
+		aux.type = np->type;
+		r = complex(&aux);
+		break;
+	default:
+		/* assign abbreviation */
+		aux.type = np->type;
+		aux.op = np->u.subop;
+		aux.right = np->right;
+		aux.left = np->left;
+		r = rhs(complex(&aux));
+	case 0:
+		op = 0;
+		break;
+	}
+
+	if (l->complex >= r->complex) {
+		l = lhs(l);
+		r = rhs(r);
+	} else {
+		r = rhs(r);
+		l = lhs(l);
+	}
+
+	code(assignop(&np->type), l, r, NULL);
+
+	return (op == 0) ? r : tmp;
+}
+
+static Node *
 rhs(Node *np)
 {
 	Node *tmp, aux1, aux2, aux3;
@@ -552,43 +589,7 @@
 	case OCAST:
 		return cast(tp, rhs(l));
 	case OASSIG:
-		switch (np->u.subop) {
-		case OINC:
-			op = OADD;
-			goto post_oper;
-		case ODEC:
-			op = OSUB;
-		post_oper:
-			tmp = rhs(l);
-
-			aux1.op = op;
-			aux1.left = tmp;
-			aux1.right = r;
-			aux1.type = np->type;
-			r = &aux1;
-
-			r = rhs(r);
-			l = lhs(l);
-			assign(tp, l, r);
-
-			return tmp;
-		default:
-			aux2.type = np->type;
-			aux2.op = np->u.subop;
-			aux2.right = np->right;
-			aux2.left = np->left;
-			r = rhs(&aux2);
-		case 0:
-			if (l->complex >= r->complex) {
-				l = lhs(l);
-				r = rhs(r);
-			} else {
-				r = rhs(r);
-				l = lhs(l);
-			}
-
-			return assign(tp, l, r);
-		}
+		return assign(np);
 	case OASK:
 		return ternary(np);
 	case OCOMMA: