view lwasm/pass6.c @ 505:59b8c8b15bd4

Add integer shifts and fix code template errors for mul/div/mod One needs to remove stuff from the stack after putting it there. Actually do that in the code output for multiplication, division, and modulus. Add integer shifting code output which is optimized for constant shift counts but calls a routine for non-constant shift counts. Shifting by a negative amount is a no-op. Shifting by more than the size of an integer results in 0 (for left shifts) or -1 (for right shifts). Both negative shift counts and shift counts larger than the base type are undefined in the C standard so this behaviour is allowed.
author William Astle <lost@l-w.ca>
date Sat, 26 Oct 2019 22:01:55 -0600
parents 58cafa61ab40
children
line wrap: on
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/*
pass6.c

Copyright © 2010 William Astle

This file is part of LWTOOLS.

LWTOOLS is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.

You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdio.h>
#include <string.h>

#include <lw_alloc.h>
#include <lw_string.h>

#include "lwasm.h"
#include "instab.h"

/*
Finalize Pass

Reduce all expressions in a final pass.

Observation:

Everything should reduce as far as it is going to in a single pass
because all line addresses are now constant (or section-base offset)
*/

static int exprok_aux(lw_expr_t e, void *priv)
{
	asmstate_t *as = priv;
	
	if (lw_expr_istype(e, lw_expr_type_int))
		return 0;
	
	if (as -> output_format == OUTPUT_OBJ || as -> output_format == OUTPUT_LWMOD)
	{
		if (lw_expr_istype(e, lw_expr_type_oper))
			return 0;
		if (lw_expr_istype(e, lw_expr_type_special) && (as -> output_format == OUTPUT_OBJ || as -> output_format == OUTPUT_LWMOD))
		{
			int t;
			t = lw_expr_specint(e);
			if (t == lwasm_expr_secbase || t == lwasm_expr_syment || t == lwasm_expr_import)
				return 0;
		}
	}
	
	return 1;
}

static int exprok(asmstate_t *as, lw_expr_t e)
{
	if (lw_expr_testterms(e, exprok_aux, as))
		return 0;
	return 1;
}


void do_pass6(asmstate_t *as)
{
	line_t *cl;
	struct line_expr_s *le;

	for (cl = as -> line_head; cl; cl = cl -> next)
	{
		as -> cl = cl;
		for (le = cl -> exprs; le; le = le -> next)
		{
			lwasm_reduce_expr(as, le -> expr);
			if (!exprok(as, le -> expr))
			{
				lwasm_register_error2(as, cl, E_EXPRESSION_BAD, "%s", lw_expr_print(le -> expr));
			}
		}
	}
}