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Fix bug in like terms collection in expression simplification
Like term collection would lose the actual "variable" part of the term if
the second term collected happened to have no coefficient. This would cause
the expression to take the value of the calculated coefficient which is
obviously wrong.
Thanks to hider <stego@satx.rr.com> for reporting the bug and providing a
proper test case.
Observation: this bug has been present since the first pre-release of
lwtools 3.0 when the algebraic expression system was introduced. Apparently
people tend not to create expressions that trigger the like terms handler.
The specific conditions require the symbol to be undefined and the second
operand to the addition has to have no coefficient so it's likely a fairly
rare scenario. Still, it is somewhat surprising that nobody tripped on it
before now.
author | William Astle <lost@l-w.ca> |
---|---|
date | Mon, 23 Jan 2017 22:58:36 -0700 |
parents | 3aad0ff3c3be |
children |
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#!/bin/sh # # Copyright 2009 by William Astle <lost@l-w.ca> # #This file is part of LWASM. # #LWASM 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/>. # this was based somewhat on the "as" script from gcc6809 #echo "LWASM-as $0 $*" show_version () { cat <<END LWASM (GNU assembler frontend) 2.3 This program is free software; you may redistribute it under the terms of the GNU General Public License. This program has absolutely no warranty. END } fatal_error () { echo $* 1>&2 exit 1 } # Assume nothing. input_file= output_file= list_file= options= # Parse the command-line options. See the GNU 'as' man page for # an explanation of all these options. Our goal is to translate # them into lwasm form. while [ "$1" != "" ]; do arg=$1; shift case $arg in -m6809) true ;; -gn) # Generate NoICE debug symbols # ignored - no output formats support debugging symbols ;; -gs) # Generate SDCC debug symbols # ignored - no output formats supprt debugging symbols ;; # --globalize-symbols) # # Make all symbols global # # lwasm does not support globalizing everything by default # ;; -m*) fatal_error "invalid CPU option '$arg'" ;; --) fatal_error "standard input not supported" ;; -a*) list_file=${arg#${arg%=*}} list_file=${list_file#=} options="$options -l$list_file" ;; -I*) #include_file=${arg#-I} #echo "warning: include path '$include_file' ignored" ;; -MD) fatal_error "assembler option '$arg' not supported" ;; -o) output_file=$1; shift ;; --defsym) options="${options} -D$1"; shift ;; -v|-version) show_version ;; --version) show_version exit 0 ;; -D|-f|-K|--traditional-format|-w|-x|-Z|-W|--no-warn) # These options are accepted but ignored by GNU as. true ;; -Qy) # "identify in output" - ignore true ;; -*) echo "as (m6809): unrecognized option $arg" exit 1 ;; *) input_file=$arg ;; esac done # Complain if no input files given. We don't support redirecting # from standard input. if [ "x$input_file" = "x" ]; then fatal_error "no input file specified" fi # Invoke the real (lwasm) assembler. # The -o option specifies the output file name # --obj creates object files # --pragma=undefextern causes undefined symbols to be assumed external # --pragma=cescapes allows C escape syntax in strings #echo lwasm -o "$output_file" $options --obj --pragma=undefextern --pragma=cescapes $input_file # pragma=newsource allows preprocessed asm files with macro expansion to assemble properly even # when the preprocessor interproses extra spaces lwasm -o "$output_file" $options --obj --pragma=undefextern --pragma=cescapes --pragma=importundefexport --pragma=newsource $input_file rc=$? # OK, see if the assembler succeeded or not. # If it failed, the source is copied to /tmp/as6809_error.s # so that it can be inspected. GCC will normally delete any # temporary .s files that it generates. This makes debugging # the compiler easier. # # lwasm does not create an output file if it errors out but it also doesn't # remove an existing file if it fails so we remove it anyway... if [ "$rc" != "0" ]; then cp -p $input_file /tmp/as6809_error.s rm -f $output_file $list_file exit $rc fi # we don't need anything fancy here since lwasm supports specifying output # file names....