shithub: scc

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Add idempotent optimization

- and ~ operands are idempotent.

--- a/cc1/expr.c

+++ b/cc1/expr.c

@@ -130,11 +130,13 @@

 	switch (BTYPE(np)) {

 	case INT:

 	case FLOAT:

+		if (op == ONEG && np->op == ONEG)

+			return np->left;

 		if (op == OADD)

 			return np;

 		return simplify(op, np->type, np, NULL);

 	default:

-		error("unary operator requires integer operand");

+		error("unary operator requires numerical operand");

 	}

 }

@@ -144,6 +146,8 @@

 	np = eval(np);

 	if (BTYPE(np) != INT)

 		error("unary operator requires integer operand");

+	if (op == OCPL && np->op == OCPL)

+		return np->left;

 	return simplify(op, np->type, np, NULL);

 }