ack/lang/cem/cemcom/l_lint.c

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Header$ */
/*	Lint main routines	*/

#include	"lint.h"

#ifdef	LINT

#include	<alloc.h>	/* for st_free */
#include	"arith.h"	/* definition arith */
#include	"label.h"	/* definition label */
#include	"expr.h"
#include	"idf.h"
#include	"def.h"
#include	"code.h"	/* RVAL etc */
#include	"LLlex.h"
#include	"Lpars.h"
#include	"stack.h"
#include	"type.h"
#include	"level.h"
#include	"nofloat.h"
#include	"l_lint.h"
#include	"l_state.h"
#include	"l_outdef.h"

extern char options[128];
extern char *symbol2str();

struct expr_state *lint_expr();

lint_init()
{
/* Allocate some memory for the global stack_bottom
 * and some other initializations
 */

	extern struct lint_stack_entry stack_bottom;

	stack_bottom.ls_current = new_state();
}

pre_lint_expr(expr, val, used)
	struct expr *expr;
{
/* Introduced to dispose the returned expression states */

	register struct expr_state *esp;

	esp = lint_expr(expr, val, used);
	free_expr_states(esp);
}

free_expr_states(esp)
	register struct expr_state *esp;
{
	register struct expr_state *esp2;

	while (esp) {
		esp2 = esp;
		esp = esp->next;
		free_expr_state(esp2);
	}
}

struct expr_state *
lint_expr(expr, val, used)
	register struct expr *expr;
{
/* Main function to process an expression tree.
 * It returns a structure containing information about which variables
 * are set and which are used in the expression.
 * In addition it sets 'used' and 'set' fields of the corresponding
 * variables in the current state.
 * If the value of an operation without side-effects is not used,
 * a warning is given.
 */
	struct expr_state *esp1 = 0, *esp2 = 0;

	if (used == IGNORED) {
		expr_ignored(expr);
	}

	switch (expr->ex_class) {
	case Value:
		switch (expr->VL_CLASS) {
		case Const:
		case Label:
			return(0);

		case Name:
		{
			register struct idf *idf = expr->VL_IDF;

			if (!idf || !idf->id_def)
				return(0);

			if (	val == LVAL
			||	(	val == RVAL
				&&	expr->ex_type->tp_fund == POINTER
				&&	!expr->ex_lvalue
				)
			) {
				change_state(idf, SET);
				idf->id_def->df_file =
					Salloc(dot.tk_file,
						strlen(dot.tk_file) + 1);
				idf->id_def->df_line = dot.tk_line;
			}
			if (val == RVAL) {
				change_state(idf, USED);
				add_expr_state(expr->EX_VALUE, USED, &esp1);
			}
			return(esp1);
		}

		default:
			crash("(lint_expr) bad value class\n");
			/* NOTREACHED */
		}

	case Oper:
	{
		register int oper = expr->OP_OPER;
		register struct expr *left = expr->OP_LEFT;
		register struct expr *right = expr->OP_RIGHT;

		switch (oper) {
		case '=':
		case PLUSAB:
		case MINAB:
		case TIMESAB:
		case DIVAB:
		case MODAB:
		case LEFTAB:
		case RIGHTAB:
		case ANDAB:
		case XORAB:
		case ORAB:
			lint_conversion(oper, right->ex_type, left->ex_type);
			/* for cases like i += l; */
			esp1 = lint_expr(right, RVAL, USED);
			if (oper != '=') {
				/* i += 1; is interpreted as i = i + 1; */
				esp2 = lint_expr(left, RVAL, USED);
				check_and_merge(&esp1, esp2, oper);
			}
			esp2 = lint_expr(left, LVAL, USED);
			/* for cases like i = i + 1; and i not set, this
			** order is essential
			*/
			check_and_merge(&esp1, esp2, oper);
			if (	left->ex_class == Value
			&&	left->VL_CLASS == Name
			) {
				add_expr_state(left->EX_VALUE, SET, &esp1);
			}
			return(esp1);

		case POSTINCR:
		case POSTDECR:
		case PLUSPLUS:
		case MINMIN:
			/* i++; is parsed as i = i + 1;
			 * This isn't quite correct :
			 * The first statement doesn't USE i,
			 * the second does.
			 */
			esp1 = lint_expr(left, RVAL, USED);
			esp2 = lint_expr(left, LVAL, USED);
			check_and_merge(&esp1, esp2, oper);
			if (	left->ex_class == Value
			&&	left->VL_CLASS == Name
			) {
				add_expr_state(left->EX_VALUE, SET, &esp1);
				add_expr_state(left->EX_VALUE, USED, &esp1);
			}
			return(esp1);

		case '-':
		case '*':
			if (left == 0)	/* unary */
				return(lint_expr(right, RVAL, USED));
			esp1 = lint_expr(left, RVAL, USED);
			esp2 = lint_expr(right, RVAL, USED);
			check_and_merge(&esp1, esp2, oper);
			return(esp1);

		case '(':
			if (right != 0) {
				/* function call with parameters */
				register struct expr *ex = right;

				while (	ex->ex_class == Oper
				&&	ex->OP_OPER == PARCOMMA
				) {
					esp2 = lint_expr(ex->OP_RIGHT, RVAL,
							 USED);
					check_and_merge(&esp1, esp2, oper);
					ex = ex->OP_LEFT;
				}
				esp2 = lint_expr(ex, RVAL, USED);
				check_and_merge(&esp1, esp2, oper);
			}
			if (	left->ex_class == Value
			&&	left->VL_CLASS == Name
			) {
				fill_outcall(expr,
					expr->ex_type->tp_fund == VOID ?
					VOIDED : used
				);
				outcall();
				left->VL_IDF->id_def->df_used = 1;
			}
			else {
				esp2 = lint_expr(left, val, USED);
				check_and_merge(&esp1, esp2, oper);
			}
			return(esp1);

		case '.':
			return(lint_expr(left, val, USED));

		case ARROW:
			return(lint_expr(left, RVAL, USED));

		case '~':
		case '!':
			return(lint_expr(right, RVAL, USED));

		case '?':
			esp1 = lint_expr(left, RVAL, USED);
			esp2 = lint_expr(right->OP_LEFT, RVAL, USED);
			check_and_merge(&esp1, esp2, 0);
			esp2 = lint_expr(right->OP_RIGHT, RVAL, USED);
			check_and_merge(&esp1, esp2, 0);
			return(esp1);

		case INT2INT:
		case INT2FLOAT:
		case FLOAT2INT:
		case FLOAT2FLOAT:
			lint_conversion(oper, right->ex_type, left->ex_type);
			return(lint_expr(right, RVAL, USED));

		case '<':
		case '>':
		case LESSEQ:
		case GREATEREQ:
		case EQUAL:
		case NOTEQUAL:
			lint_relop(left, right, oper);
			lint_relop(right, left, 
				oper == '<' ? '>' :
				oper == '>' ? '<' :
				oper == LESSEQ ? GREATEREQ :
				oper == GREATEREQ ? LESSEQ :
				oper
			);
			/*FALLTHROUGH*/
		case '+':
		case '/':
		case '%':
		case ',':
		case LEFT:
		case RIGHT:
		case '&':
		case '|':
		case '^':
		case OR:
		case AND:
			esp1 = lint_expr(left, RVAL,
						oper == ',' ? IGNORED : USED);
			esp2 = lint_expr(right, RVAL,
						oper == ',' ? used : USED);
			if (oper == OR || oper == AND || oper == ',')
				check_and_merge(&esp1, esp2, 0);
			else
				check_and_merge(&esp1, esp2, oper);
			return(esp1);

		default:
			return(0);	/* for initcomma */
		}
	}

	default:
		return(0);
	}
}

expr_ignored(expr)
	struct expr *expr;
{
	switch (expr->ex_class) {
	case Oper:
		switch (expr->OP_OPER) {
		case '=':
		case TIMESAB:
		case DIVAB:
		case MODAB:
		case LEFTAB:
		case RIGHTAB:
		case ANDAB:
		case XORAB:
		case ORAB:
		case AND:			/* doubtful but useful */
		case OR:			/* doubtful but useful */
		case '(':
		case '?':
		case ',':
			break;

		case PLUSAB:
		case MINAB:
		case POSTINCR:
		case POSTDECR:
		case PLUSPLUS:
		case MINMIN:
			/* may hide the operator * */
			if (	/* operation on a pointer */
				expr->OP_TYPE->tp_fund == POINTER
			&&	/* the result is dereferenced, e.g. *p++; */
				expr->ex_type == expr->OP_TYPE->tp_up
			) {
				hwarning("result of * ignored");
			}
			break;

		default:
			hwarning("result of %s ignored",
						symbol2str(expr->OP_OPER));
			break;
		}
		break;

	case Value:
		hwarning("identifier as statement");
		break;

	case String:
	case Float:
		hwarning("constant as statement");
		break;
	}
}

#endif	LINT