xref: /plan9-contrib/sys/src/cmd/spin/main.c (revision de2caf28f9ba1a56e70be94a699435d36eb50311)

/***** spin: main.c *****/

/*
 * This file is part of the public release of Spin. It is subject to the
 * terms in the LICENSE file that is included in this source directory.
 * Tool documentation is available at http://spinroot.com
 */

#include <stdlib.h>
#include <assert.h>
#include "spin.h"
#include "version.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <time.h>
#ifdef PC
 #include <io.h>
#else
 #include <unistd.h>
#endif
#include "y.tab.h"

extern int	DstepStart, lineno, tl_terse;
extern FILE	*yyin, *yyout, *tl_out;
extern Symbol	*context;
extern char	*claimproc;
extern void	repro_src(void);
extern void	qhide(int);
extern char	CurScope[MAXSCOPESZ];
extern short	has_provided, has_code, has_ltl, has_accept;
extern int	realread, buzzed;
extern void	ana_src(int, int);
extern void	putprelude(void);

static void	add_comptime(char *);
static void	add_runtime(char *);

Symbol	*Fname, *oFname;

int	Etimeouts;	/* nr timeouts in program */
int	Ntimeouts;	/* nr timeouts in never claim */
int	analyze, columns, dumptab, has_remote, has_remvar;
int	interactive, jumpsteps, m_loss, nr_errs, cutoff;
int	s_trail, ntrail, verbose, xspin, notabs, rvopt;
int	no_print, no_wrapup, Caccess, limited_vis, like_java;
int	separate;	/* separate compilation */
int	export_ast;	/* pangen5.c */
int	norecompile;	/* main.c */
int	old_scope_rules;	/* use pre 5.3.0 rules */
int	old_priority_rules;	/* use pre 6.2.0 rules */
int	product, Strict;
short	replay;

int	merger = 1, deadvar = 1, implied_semis = 1;
int	ccache = 0; /* oyvind teig: 5.2.0 case caching off by default */

static int preprocessonly, SeedUsed, itsr, itsr_n, sw_or_bt;
static int seedy;	/* be verbose about chosen seed */
static int inlineonly;	/* show inlined code */
static int dataflow = 1;

#if 0
meaning of flags on verbose:
	1	-g global variable values
	2	-l local variable values
	4	-p all process actions
	8	-r receives
	16	-s sends
	32	-v verbose
	64	-w very verbose
#endif

static char	Operator[] = "operator: ";
static char	Keyword[]  = "keyword: ";
static char	Function[] = "function-name: ";
static char	**add_ltl  = (char **) 0;
static char	**ltl_file = (char **) 0;
static char	**nvr_file = (char **) 0;
static char	*ltl_claims = (char *) 0;
static char	*pan_runtime = "";
static char	*pan_comptime = "";
static char	*formula = NULL;
static FILE	*fd_ltl = (FILE *) 0;
static char	*PreArg[64];
static int	PreCnt = 0;
static char	out1[64];

char	**trailfilename;	/* new option 'k' */

void	explain(int);

#ifndef CPP
	/* to use visual C++:
		#define CPP	"cl -E/E"
	   or call spin as:	spin -P"CL -E/E"

	   on OS2:
		#define CPP	"icc -E/Pd+ -E/Q+"
	   or call spin as:	spin -P"icc -E/Pd+ -E/Q+"
	   make sure the -E arg is always at the end,
	   in each case, because the command line
	   can later be truncated at that point
	*/
 #if 1
	#define CPP	"gcc -std=gnu99 -Wformat-overflow=0 -E -x c"
	/* if gcc-4 is available, this setting is modified below */
 #else
	#if defined(PC) || defined(MAC)
		#define CPP	"gcc -std=gnu99 -E -x c"
	#else
		#ifdef SOLARIS
			#define CPP	"/usr/ccs/lib/cpp"
		#else
			#define CPP	"cpp"	/* sometimes: "/lib/cpp" */
		#endif
	#endif
 #endif
#endif

static char	PreProc[512];
extern int	depth; /* at least some steps were made */

int
WhatSeed(void)
{
	return SeedUsed;
}

void
final_fiddle(void)
{	char *has_a, *has_l, *has_f;

	/* no -a or -l but has_accept: add -a */
	/* no -a or -l in pan_runtime: add -DSAFETY to pan_comptime */
	/* -a or -l but no -f then add -DNOFAIR */

	has_a = strstr(pan_runtime, "-a");
	has_l = strstr(pan_runtime, "-l");
	has_f = strstr(pan_runtime, "-f");

	if (!has_l && !has_a && strstr(pan_comptime, "-DNP"))
	{	add_runtime("-l");
		has_l = strstr(pan_runtime, "-l");
	}

	if (!has_a && !has_l
	&&  !strstr(pan_comptime, "-DSAFETY"))
	{	if (has_accept
		&& !strstr(pan_comptime, "-DBFS")
		&& !strstr(pan_comptime, "-DNOCLAIM"))
		{	add_runtime("-a");
			has_a = pan_runtime;
		} else
		{	add_comptime("-DSAFETY");
	}	}

	if ((has_a || has_l) && !has_f
	&&  !strstr(pan_comptime, "-DNOFAIR"))
	{	add_comptime("-DNOFAIR");
	}
}

static int
change_param(char *t, char *what, int range, int bottom)
{	char *ptr;
	int v;

	assert(range < 1000 && range > 0);
	if ((ptr = strstr(t, what)) != NULL)
	{	ptr += strlen(what);
		if (!isdigit((int) *ptr))
		{	return 0;
		}
		v = atoi(ptr) + 1;	/* was: v = (atoi(ptr)+1)%range */
		if (v >= range)
		{	v = bottom;
		}
		if (v >= 100)
		{	*ptr++ = '0' + (v/100); v %= 100;
			*ptr++ = '0' + (v/10);
			*ptr   = '0' + (v%10);
		} else if (v >= 10)
		{	*ptr++ = '0' + (v/10);
			*ptr++ = '0' + (v%10);
			*ptr   = ' ';
		} else
		{	*ptr++ = '0' + v;
			*ptr++ = ' ';
			*ptr   = ' ';
	}	}
	return 1;
}

static void
change_rs(char *t)
{	char *ptr;
	int cnt = 0;
	long v;

	if ((ptr = strstr(t, "-RS")) != NULL)
	{	ptr += 3;
		/* room for at least 10 digits */
		v = Rand()%1000000000L;
		while (v/10 > 0)
		{	*ptr++ = '0' + v%10;
			v /= 10;
			cnt++;
		}
		*ptr++ = '0' + v;
		cnt++;
		while (cnt++ < 10)
		{	*ptr++ = ' ';
	}	}
}

int
omit_str(char *in, char *s)
{	char *ptr = strstr(in, s);
	int i, nr = -1;

	if (ptr)
	{	for (i = 0; i < (int) strlen(s); i++)
		{	*ptr++ = ' ';
		}
		if (isdigit((int) *ptr))
		{	nr = atoi(ptr);
			while (isdigit((int) *ptr))
			{	*ptr++ = ' ';
	}	}	}
	return nr;
}

void
string_trim(char *t)
{	int n = strlen(t) - 1;

	while (n > 0 && t[n] == ' ')
	{	t[n--] = '\0';
	}
}

int
e_system(int v, const char *s)
{	static int count = 1;

	/* v == 0 : checks to find non-linked version of gcc */
	/* v == 1 : all other commands */
	/* v == 2 : preprocessing the promela input */

	if (v == 1)
	{	if (verbose&(32|64))	/* -v or -w */
		{	printf("cmd%02d: %s\n", count++, s);
			fflush(stdout);
		}
		if (verbose&64)		/* only -w */
		{	return 0;	/* suppress the call to system(s) */
	}	}
	return system(s);
}

void
alldone(int estatus)
{	char *ptr;
#if defined(WIN32) || defined(WIN64)
	struct _stat x;
#else
	struct stat x;
#endif
	if (preprocessonly == 0 &&  strlen(out1) > 0)
	{	(void) unlink((const char *) out1);
	}

	(void) unlink(TMP_FILE1);
	(void) unlink(TMP_FILE2);

	if (!buzzed && seedy && !analyze && !export_ast
	&& !s_trail && !preprocessonly && depth > 0)
	{	printf("seed used: %d\n", SeedUsed);
	}

	if (!buzzed && xspin && (analyze || s_trail))
	{	if (estatus)
		{	printf("spin: %d error(s) - aborting\n",
				estatus);
		} else
		{	printf("Exit-Status 0\n");
	}	}

	if (buzzed && replay && !has_code && !estatus)
	{	extern QH *qh_lst;
		QH *j;
		int i;

		pan_runtime = (char *) emalloc(2048);	/* more than enough */
		sprintf(pan_runtime, "-n%d ", SeedUsed);
		if (jumpsteps)
		{	sprintf(&pan_runtime[strlen(pan_runtime)], "-j%d ", jumpsteps);
		}
		if (trailfilename)
		{	sprintf(&pan_runtime[strlen(pan_runtime)], "-k%s ", *trailfilename);
		}
		if (cutoff)
		{	sprintf(&pan_runtime[strlen(pan_runtime)], "-u%d ", cutoff);
		}
		for (i = 1; i <= PreCnt; i++)
		{	strcat(pan_runtime, PreArg[i]);
			strcat(pan_runtime, " ");
		}
		for (j = qh_lst; j; j = j->nxt)
		{	sprintf(&pan_runtime[strlen(pan_runtime)], "-q%d ", j->n);
		}
		if (strcmp(PreProc, CPP) != 0)
		{	sprintf(&pan_runtime[strlen(pan_runtime)], "\"-P%s\" ", PreProc);
		}
		/* -oN options 1..5 are ignored in simulations */
		if (old_priority_rules) strcat(pan_runtime, "-o6 ");
		if (!implied_semis)  strcat(pan_runtime, "-o7 ");
		if (no_print)        strcat(pan_runtime, "-b ");
		if (no_wrapup)       strcat(pan_runtime, "-B ");
		if (columns == 1)    strcat(pan_runtime, "-c ");
		if (columns == 2)    strcat(pan_runtime, "-M ");
		if (seedy == 1)      strcat(pan_runtime, "-h ");
		if (like_java == 1)  strcat(pan_runtime, "-J ");
		if (old_scope_rules) strcat(pan_runtime, "-O ");
		if (notabs)          strcat(pan_runtime, "-T ");
		if (verbose&1)       strcat(pan_runtime, "-g ");
		if (verbose&2)       strcat(pan_runtime, "-l ");
		if (verbose&4)       strcat(pan_runtime, "-p ");
		if (verbose&8)       strcat(pan_runtime, "-r ");
		if (verbose&16)      strcat(pan_runtime, "-s ");
		if (verbose&32)      strcat(pan_runtime, "-v ");
		if (verbose&64)      strcat(pan_runtime, "-w ");
		if (m_loss)          strcat(pan_runtime, "-m ");

		char *tmp = (char *) emalloc(strlen("spin -t") +
				strlen(pan_runtime) + strlen(Fname->name) + 8);

		sprintf(tmp, "spin -t %s %s", pan_runtime, Fname->name);
		estatus = e_system(1, tmp);	/* replay */
		exit(estatus);	/* replay without c_code */
	}

	if (buzzed && (!replay || has_code) && !estatus)
	{	char *tmp, *tmp2 = NULL, *P_X;
		char *C_X = (buzzed == 2) ? "-O" : "";

		if (replay && strlen(pan_comptime) == 0)
		{
#if defined(WIN32) || defined(WIN64)
			P_X = "pan";
#else
			P_X = "./pan";
#endif
			if (stat(P_X, (struct stat *)&x) < 0)
			{	goto recompile;	/* no executable pan for replay */
			}
			tmp = (char *) emalloc(8 + strlen(P_X) + strlen(pan_runtime) +4);
			/* the final +4 is too allow adding " &" in some cases */
			sprintf(tmp, "%s %s", P_X, pan_runtime);
			goto runit;
		}
#if defined(WIN32) || defined(WIN64)
		P_X = "-o pan pan.c && pan";
#else
		P_X = "-o pan pan.c && ./pan";
#endif
		/* swarm and biterate randomization additions */
		if (!replay && itsr)	/* iterative search refinement */
		{	if (!strstr(pan_comptime, "-DBITSTATE"))
			{	add_comptime("-DBITSTATE");
			}
			if (!strstr(pan_comptime, "-DPUTPID"))
			{	add_comptime("-DPUTPID");
			}
			if (!strstr(pan_comptime, "-DT_RAND")
			&&  !strstr(pan_comptime, "-DT_REVERSE"))
			{	add_runtime("-T0  ");	/* controls t_reverse */
			}
			if (!strstr(pan_runtime, "-P")	/* runtime flag */
			||   pan_runtime[2] < '0'
			||   pan_runtime[2] > '1') /* no -P0 or -P1 */
			{	add_runtime("-P0  ");	/* controls p_reverse */
			}
			if (!strstr(pan_runtime, "-w"))
			{	add_runtime("-w18 ");	/* -w18 = 256K */
			} else
			{	char nv[32];
				int x;
				x = omit_str(pan_runtime, "-w");
				if (x >= 0)
				{	sprintf(nv, "-w%d  ", x);
					add_runtime(nv); /* added spaces */
			}	}
			if (!strstr(pan_runtime, "-h"))
			{	add_runtime("-h0  ");	/* 0..499 */
				/* leave 2 spaces for increments up to -h499 */
			} else if (!strstr(pan_runtime, "-hash"))
			{	char nv[32];
				int x;
				x = omit_str(pan_runtime, "-h");
				if (x >= 0)
				{	sprintf(nv, "-h%d  ", x%500);
					add_runtime(nv); /* added spaces */
			}	}
			if (!strstr(pan_runtime, "-k"))
			{	add_runtime("-k1  ");	/* 1..3 */
			} else
			{	char nv[32];
				int x;
				x = omit_str(pan_runtime, "-k");
				if (x >= 0)
				{	sprintf(nv, "-k%d  ", x%4);
					add_runtime(nv); /* added spaces */
			}	}
			if (strstr(pan_runtime, "-p_rotate"))
			{	char nv[32];
				int x;
				x = omit_str(pan_runtime, "-p_rotate");
				if (x < 0)
				{	x = 0;
				}
				sprintf(nv, "-p_rotate%d  ", x%256);
				add_runtime(nv); /* added spaces */
			} else if (strstr(pan_runtime, "-p_permute") == 0)
			{	add_runtime("-p_rotate0  ");
			}
			if (strstr(pan_runtime, "-RS"))
			{	(void) omit_str(pan_runtime, "-RS");
			}
			/* need room for at least 10 digits */
			add_runtime("-RS1234567890 ");
			change_rs(pan_runtime);
		}
recompile:
		if (strstr(PreProc, "cpp"))	/* unix/linux */
		{	strcpy(PreProc, "gcc");	/* need compiler */
		} else if ((tmp = strstr(PreProc, "-E")) != NULL)
		{	*tmp = '\0'; /* strip preprocessing flags */
		}

		final_fiddle();
		tmp = (char *) emalloc(8 +	/* account for alignment */
				strlen(PreProc) +
				strlen(C_X) +
				strlen(pan_comptime) +
				strlen(P_X) +
				strlen(pan_runtime) +
				strlen(" -p_reverse & "));
		tmp2 = tmp;

		/* P_X ends with " && ./pan " */
		sprintf(tmp, "%s %s %s %s %s",
			PreProc, C_X, pan_comptime, P_X, pan_runtime);

		if (!replay)
		{	if (itsr < 0)		/* swarm only */
			{	strcat(tmp, " &"); /* after ./pan */
				itsr = -itsr;	/* now same as biterate */
			}
			/* do compilation first
			 * split cc command from run command
			 * leave cc in tmp, and set tmp2 to run
			 */
			if ((ptr = strstr(tmp, " && ")) != NULL)
			{	tmp2 = ptr + 4;	/* first run */
				*ptr = '\0';
		}	}

		if (has_ltl)
		{	(void) unlink("_spin_nvr.tmp");
		}

		if (!norecompile)
		{	/* make sure that if compilation fails we do not continue */
#ifdef PC
			(void) unlink("./pan.exe");
#else
			(void) unlink("./pan");
#endif
		}
runit:
		if (norecompile && tmp != tmp2)
		{	estatus = 0;
		} else
		{	estatus = e_system(1, tmp);	/* compile or run */
		}
		if (replay || estatus < 0)
		{	goto skipahead;
		}
		/* !replay */
		if (itsr == 0 && !sw_or_bt)			/* single run */
		{	estatus = e_system(1, tmp2);
		} else if (itsr > 0)	/* iterative search refinement */
		{	int is_swarm = 0;
			if (tmp2 != tmp)	/* swarm: did only compilation so far */
			{	tmp = tmp2;	/* now we point to the run command */
				estatus = e_system(1, tmp);	/* first run */
				itsr--;
			}
			itsr--;			/* count down */

			/* the following are added back randomly later */
			(void) omit_str(tmp, "-p_reverse");	/* replaced by spaces */
			(void) omit_str(tmp, "-p_normal");

			if (strstr(tmp, " &") != NULL)
			{	(void) omit_str(tmp, " &");
				is_swarm = 1;
			}

			/* increase -w every itsr_n-th run */
			if ((itsr_n > 0 && (itsr == 0 || (itsr%itsr_n) != 0))
			||  (change_param(tmp, "-w", 36, 18) >= 0))	/* max 4G bit statespace */
			{	(void) change_param(tmp, "-h", 500, 0);	/* hash function 0.499 */
				(void) change_param(tmp, "-p_rotate", 256, 0); /* if defined */
				(void) change_param(tmp, "-k", 4, 1);	/* nr bits per state 0->1,2,3 */
				(void) change_param(tmp, "-T", 2, 0);	/* with or without t_reverse*/
				(void) change_param(tmp, "-P", 2, 0);	/* -P 0..1 != p_reverse */
				change_rs(tmp);			/* change random seed */
				string_trim(tmp);
				if (rand()%5 == 0)		/* 20% of all runs */
				{	strcat(tmp, " -p_reverse ");
					/* at end, so this overrides -p_rotateN, if there */
					/* but -P0..1 disable this in 50% of the cases */
					/* so its really activated in 10% of all runs */
				} else if (rand()%6 == 0) /* override p_rotate and p_reverse */
				{	strcat(tmp, " -p_normal ");
				}
				if (is_swarm)
				{	strcat(tmp, " &");
				}
				goto runit;
		}	}
skipahead:
		(void) unlink("pan.b");
		(void) unlink("pan.c");
		(void) unlink("pan.h");
		(void) unlink("pan.m");
		(void) unlink("pan.p");
		(void) unlink("pan.t");
	}
	exit(estatus);
}
#if 0
	-P0	normal active process creation
	-P1	reversed order for *active* process creation != p_reverse

	-T0	normal transition exploration
	-T1	reversed order of transition exploration

	-DP_RAND	(random starting point +- -DP_REVERSE)
	-DPERMUTED	(also enables -p_rotateN and -p_reverse)
	-DP_REVERSE	(same as -DPERMUTED with -p_reverse, but 7% faster)

	-DT_RAND	(random starting point -- optionally with -T0..1)
	-DT_REVERSE	(superseded by -T0..1 options)

	 -hash generates new hash polynomial for -h0

	permutation modes:
	 -permuted (adds -DPERMUTED) -- this is also the default with -swarm
	 -t_reverse (same as -T1)
	 -p_reverse (similar to -P1)
	 -p_rotateN
	 -p_normal

	less useful would be (since there is less non-determinism in transitions):
		-t_rotateN -- a controlled version of -DT_RAND

	compiling with -DPERMUTED enables a number of new runtime options,
	that -swarmN,M will also exploit:
		-p_permute (default)
		-p_rotateN
		-p_reverse
#endif

void
preprocess(char *a, char *b, int a_tmp)
{	char precmd[1024], cmd[2048];
	int i;
#ifdef PC
	/* gcc is sometimes a symbolic link to gcc-4
	   that does not work well in cygwin, so we try
	   to use the actual executable that is used.
	   the code below assumes we are on a cygwin-like system
	 */
	if (strncmp(PreProc, "gcc ", strlen("gcc ")) == 0)
	{	if (e_system(0, "gcc-4 --version > pan.pre 2>&1") == 0)
		{	strcpy(PreProc, "gcc-4 -std=gnu99 -Wformat-overflow=0 -E -x c");
		} else if (e_system(0, "gcc-3 --version > pan.pre 2>&1") == 0)
		{	strcpy(PreProc, "gcc-3 -std=gnu99 -Wformat-overflow=0 -E -x c");
	}	}
#endif

	assert(strlen(PreProc) < sizeof(precmd));
	strcpy(precmd, PreProc);
	for (i = 1; i <= PreCnt; i++)
	{	strcat(precmd, " ");
		strcat(precmd, PreArg[i]);
	}
	if (strlen(precmd) > sizeof(precmd))
	{	fprintf(stdout, "spin: too many -D args, aborting\n");
		alldone(1);
	}
	sprintf(cmd, "%s \"%s\" > \"%s\"", precmd, a, b);
	if (e_system(2, (const char *)cmd))	/* preprocessing step */
	{	(void) unlink((const char *) b);
		if (a_tmp) (void) unlink((const char *) a);
		fprintf(stdout, "spin: preprocessing failed %s\n", cmd);
		alldone(1); /* no return, error exit */
	}
	if (a_tmp) (void) unlink((const char *) a);
}

void
usage(void)
{
	printf("use: spin [-option] ... [-option] file\n");
	printf("\tNote: file must always be the last argument\n");
	printf("\t-A apply slicing algorithm\n");
	printf("\t-a generate a verifier in pan.c\n");
	printf("\t-B no final state details in simulations\n");
	printf("\t-b don't execute printfs in simulation\n");
	printf("\t-C print channel access info (combine with -g etc.)\n");
	printf("\t-c columnated -s -r simulation output\n");
	printf("\t-d produce symbol-table information\n");
	printf("\t-Dyyy pass -Dyyy to the preprocessor\n");
	printf("\t-Eyyy pass yyy to the preprocessor\n");
	printf("\t-e compute synchronous product of multiple never claims (modified by -L)\n");
	printf("\t-f \"..formula..\"  translate LTL ");
	printf("into never claim\n");
	printf("\t-F file  like -f, but with the LTL formula stored in a 1-line file\n");
	printf("\t-g print all global variables\n");
	printf("\t-h at end of run, print value of seed for random nr generator used\n");
	printf("\t-i interactive (random simulation)\n");
	printf("\t-I show result of inlining and preprocessing\n");
	printf("\t-J reverse eval order of nested unlesses\n");
	printf("\t-jN skip the first N steps ");
	printf("in simulation trail\n");
	printf("\t-k fname use the trailfile stored in file fname, see also -t\n");
	printf("\t-L when using -e, use strict language intersection\n");
	printf("\t-l print all local variables\n");
	printf("\t-M generate msc-flow in tcl/tk format\n");
	printf("\t-m lose msgs sent to full queues\n");
	printf("\t-N fname use never claim stored in file fname\n");
	printf("\t-nN seed for random nr generator\n");
	printf("\t-O use old scope rules (pre 5.3.0)\n");
	printf("\t-o1 turn off dataflow-optimizations in verifier\n");
	printf("\t-o2 don't hide write-only variables in verifier\n");
	printf("\t-o3 turn off statement merging in verifier\n");
	printf("\t-o4 turn on rendezvous optiomizations in verifier\n");
	printf("\t-o5 turn on case caching (reduces size of pan.m, but affects reachability reports)\n");
	printf("\t-o6 revert to the old rules for interpreting priority tags (pre version 6.2)\n");
	printf("\t-o7 revert to the old rules for semi-colon usage (pre version 6.3)\n");
	printf("\t-Pxxx use xxx for preprocessing\n");
	printf("\t-p print all statements\n");
	printf("\t-pp pretty-print (reformat) stdin, write stdout\n");
	printf("\t-qN suppress io for queue N in printouts\n");
	printf("\t-r print receive events\n");
	printf("\t-replay  replay an error trail-file found earlier\n");
	printf("\t	if the model contains embedded c-code, the ./pan executable is used\n");
	printf("\t	otherwise spin itself is used to replay the trailfile\n");
	printf("\t	note that pan recognizes different runtime options than spin itself\n");
	printf("\t-run  (or -search) generate a verifier, and compile and run it\n");
	printf("\t      options before -search are interpreted by spin to parse the input\n");
	printf("\t      options following a -search are used to compile and run the verifier pan\n");
	printf("\t	    valid options that can follow a -search argument include:\n");
	printf("\t	    -bfs	perform a breadth-first search\n");
	printf("\t	    -bfspar	perform a parallel breadth-first search\n");
	printf("\t	    -dfspar	perform a parallel depth-first search, same as -DNCORE=4\n");
	printf("\t	    -bcs	use the bounded-context-switching algorithm\n");
	printf("\t	    -bitstate	or -bit, use bitstate storage\n");
	printf("\t	    -biterateN,M use bitstate with iterative search refinement (-w18..-w35)\n");
	printf("\t			perform N randomized runs and increment -w every M runs\n");
	printf("\t			default value for N is 10, default for M is 1\n");
	printf("\t			(use N,N to keep -w fixed for all runs)\n");
	printf("\t			(add -w to see which commands will be executed)\n");
	printf("\t			(add -W if ./pan exists and need not be recompiled)\n");
	printf("\t	    -swarmN,M like -biterate, but running all iterations in parallel\n");
	printf("\t	    -link file.c  link executable pan to file.c\n");
	printf("\t	    -collapse	use collapse state compression\n");
	printf("\t	    -noreduce	do not use partial order reduction\n");
	printf("\t	    -hc  	use hash-compact storage\n");
	printf("\t	    -noclaim	ignore all ltl and never claims\n");
	printf("\t	    -p_permute	use process scheduling order random permutation\n");
	printf("\t	    -p_rotateN	use process scheduling order rotation by N\n");
	printf("\t	    -p_reverse	use process scheduling order reversal\n");
	printf("\t	    -rhash      randomly pick one of the -p_... options\n");
	printf("\t	    -ltl p	verify the ltl property named p\n");
	printf("\t	    -safety	compile for safety properties only\n");
	printf("\t	    -i	    	use the dfs iterative shortening algorithm\n");
	printf("\t	    -a	    	search for acceptance cycles\n");
	printf("\t	    -l	    	search for non-progress cycles\n");
	printf("\t	similarly, a -D... parameter can be specified to modify the compilation\n");
	printf("\t	and any valid runtime pan argument can be specified for the verification\n");
	printf("\t-S1 and -S2 separate pan source for claim and model\n");
	printf("\t-s print send events\n");
	printf("\t-T do not indent printf output\n");
	printf("\t-t[N] follow [Nth] simulation trail, see also -k\n");
	printf("\t-Uyyy pass -Uyyy to the preprocessor\n");
	printf("\t-uN stop a simulation run after N steps\n");
	printf("\t-v verbose, more warnings\n");
	printf("\t-w very verbose (when combined with -l or -g)\n");
	printf("\t-[XYZ] reserved for use by xspin interface\n");
	printf("\t-V print version number and exit\n");
	alldone(1);
}

int
optimizations(int nr)
{
	switch (nr) {
	case '1':
		dataflow = 1 - dataflow; /* dataflow */
		if (verbose&32)
		printf("spin: dataflow optimizations turned %s\n",
			dataflow?"on":"off");
		break;
	case '2':
		/* dead variable elimination */
		deadvar = 1 - deadvar;
		if (verbose&32)
		printf("spin: dead variable elimination turned %s\n",
			deadvar?"on":"off");
		break;
	case '3':
		/* statement merging */
		merger = 1 - merger;
		if (verbose&32)
		printf("spin: statement merging turned %s\n",
			merger?"on":"off");
		break;

	case '4':
		/* rv optimization */
		rvopt = 1 - rvopt;
		if (verbose&32)
		printf("spin: rendezvous optimization turned %s\n",
			rvopt?"on":"off");
		break;
	case '5':
		/* case caching */
		ccache = 1 - ccache;
		if (verbose&32)
		printf("spin: case caching turned %s\n",
			ccache?"on":"off");
		break;
	case '6':
		old_priority_rules = 1;
		if (verbose&32)
		printf("spin: using old priority rules (pre version 6.2)\n");
		return 0; /* no break */
	case '7':
		implied_semis = 0;
		if (verbose&32)
		printf("spin: no implied semi-colons (pre version 6.3)\n");
		return 0; /* no break */
	default:
		printf("spin: bad or missing parameter on -o\n");
		usage();
		break;
	}
	return 1;
}

static void
add_comptime(char *s)
{	char *tmp;

	if (!s || strstr(pan_comptime, s))
	{	return;
	}

	tmp = (char *) emalloc(strlen(pan_comptime)+strlen(s)+2);
	sprintf(tmp, "%s %s", pan_comptime, s);
	pan_comptime = tmp;
}

static struct {
	char *ifsee, *thendo;
	int keeparg;
} pats[] = {
	{ "-bfspar",	"-DBFS_PAR",	0 },
	{ "-bfs",	"-DBFS",	0 },
	{ "-bcs",	"-DBCS",	0 },
	{ "-bitstate",	"-DBITSTATE",	0 },
	{ "-bit",	"-DBITSTATE",	0 },
	{ "-hc",	"-DHC4",	0 },
	{ "-collapse",	"-DCOLLAPSE",	0 },
	{ "-noclaim",	"-DNOCLAIM",	0 },
	{ "-noreduce",	"-DNOREDUCE",	0 },
	{ "-np",	"-DNP",		0 },
	{ "-permuted",	"-DPERMUTED",	0 },
	{ "-p_permute", "-DPERMUTED",	1 },
	{ "-p_rotate",	"-DPERMUTED",	1 },
	{ "-p_reverse",	"-DPERMUTED",	1 },
	{ "-rhash",	"-DPERMUTED",	1 },
	{ "-safety",	"-DSAFETY",	0 },
	{ "-i",		"-DREACH",	1 },
	{ "-l",		"-DNP",		1 },
	{ 0, 0 }
};

static void
set_itsr_n(char *s)	/* e.g., -swarm12,3 */
{	char *tmp;

	if ((tmp = strchr(s, ',')) != NULL)
	{	tmp++;
		if (*tmp != '\0' && isdigit((int) *tmp))
		{	itsr_n = atoi(tmp);
			if (itsr_n < 2)
			{	itsr_n = 0;
	}	}	}
}

static void
add_runtime(char *s)
{	char *tmp;
	int i;

	if (strncmp(s, "-biterate", strlen("-biterate")) == 0)
	{	itsr = 10;	/* default nr of sequential iterations */
		sw_or_bt = 1;
		if (isdigit((int) s[9]))
		{	itsr = atoi(&s[9]);
			if (itsr < 1)
			{	itsr = 1;
			}
			set_itsr_n(s);
		}
		return;
	}
	if (strncmp(s, "-swarm", strlen("-swarm")) == 0)
	{	itsr = -10;	/* parallel iterations */
		sw_or_bt = 1;
		if (isdigit((int) s[6]))
		{	itsr = atoi(&s[6]);
			if (itsr < 1)
			{	itsr = 1;
			}
			itsr = -itsr;
			set_itsr_n(s);
		}
		return;
	}

	for (i = 0; pats[i].ifsee; i++)
	{	if (strncmp(s, pats[i].ifsee, strlen(pats[i].ifsee)) == 0)
		{	add_comptime(pats[i].thendo);
			if (pats[i].keeparg)
			{	break;
			}
			return;
	}	}
	if (strncmp(s, "-dfspar", strlen("-dfspar")) == 0)
	{	add_comptime("-DNCORE=4");
		return;
	}

	tmp = (char *) emalloc(strlen(pan_runtime)+strlen(s)+2);
	sprintf(tmp, "%s %s", pan_runtime, s);
	pan_runtime = tmp;
}

ssize_t
getline(char **lineptr, size_t *n, FILE *stream)
{	static char buffer[8192];

	*lineptr = (char *) &buffer;

	if (!fgets(buffer, sizeof(buffer), stream))
	{	return 0;
	}
	return 1;
}

int
main(int argc, char *argv[])
{	Symbol *s;
	int T = (int) time((time_t *)0);
	int usedopts = 0;

	yyin  = stdin;
	yyout = stdout;
	tl_out = stdout;
	strcpy(CurScope, "_");

	assert(strlen(CPP) < sizeof(PreProc));
	strcpy(PreProc, CPP);

	/* unused flags: y, z, G, L, Q, R, W */
	while (argc > 1 && argv[1][0] == '-')
	{	switch (argv[1][1]) {
		case 'A': export_ast = 1; break;
		case 'a': analyze = 1; break;
		case 'B': no_wrapup = 1; break;
		case 'b': no_print = 1; break;
		case 'C': Caccess = 1; break;
		case 'c': columns = 1; break;
		case 'D': PreArg[++PreCnt] = (char *) &argv[1][0];
			  break;	/* define */
		case 'd': dumptab =  1; break;
		case 'E': PreArg[++PreCnt] = (char *) &argv[1][2];
			  break;
		case 'e': product++; break; /* see also 'L' */
		case 'F': ltl_file = (char **) (argv+2);
			  argc--; argv++; break;
		case 'f': add_ltl = (char **) argv;
			  argc--; argv++; break;
		case 'g': verbose +=  1; break;
		case 'h': seedy = 1; break;
		case 'i': interactive = 1; break;
		case 'I': inlineonly = 1; break;
		case 'J': like_java = 1; break;
		case 'j': jumpsteps = atoi(&argv[1][2]); break;
		case 'k': s_trail = 1;
			  trailfilename = (char **) (argv+2);
			  argc--; argv++; break;
		case 'L': Strict++; break; /* modified -e */
		case 'l': verbose +=  2; break;
		case 'M': columns = 2; break;
		case 'm': m_loss   =  1; break;
		case 'N': nvr_file = (char **) (argv+2);
			  argc--; argv++; break;
		case 'n': T = atoi(&argv[1][2]); tl_terse = 1; break;
		case 'O': old_scope_rules = 1; break;
		case 'o': usedopts += optimizations(argv[1][2]); break;
		case 'P': assert(strlen((const char *) &argv[1][2]) < sizeof(PreProc));
			  strcpy(PreProc, (const char *) &argv[1][2]);
			  break;
		case 'p': if (argv[1][2] == 'p')
			  {	pretty_print();
				alldone(0);
			  }
			  verbose +=  4; break;
		case 'q': if (isdigit((int) argv[1][2]))
				qhide(atoi(&argv[1][2]));
			  break;
		case 'r':
			  if (strcmp(&argv[1][1], "run") == 0)
			  {	Srand((unsigned int) T);
samecase:			if (buzzed != 0)
				{ fatal("cannot combine -x with -run -replay or -search", (char *)0);
				}
				buzzed  = 2;
				analyze = 1;
				argc--; argv++;
				/* process all remaining arguments, except -w/-W, as relating to pan: */
				while (argc > 1 && argv[1][0] == '-')
				{ switch (argv[1][1]) {
				  case 'D': /* eg -DNP */
			/*	  case 'E': conflicts with runtime arg */
				  case 'O': /* eg -O2 */
				  case 'U': /* to undefine a macro */
					add_comptime(argv[1]);
					break;
#if 0
				  case 'w': /* conflicts with bitstate runtime arg */
					verbose += 64;
					break;
#endif
				  case 'W':
					norecompile = 1;
					break;
				  case 'l':
					if (strcmp(&argv[1][1], "ltl") == 0)
					{	add_runtime("-N");
						argc--; argv++;
						add_runtime(argv[1]); /* prop name */
						break;
					}
					if (strcmp(&argv[1][1], "link") == 0)
					{	argc--; argv++;
						add_comptime(argv[1]);
						break;
					}
					/* else fall through */
				  default:
					add_runtime(argv[1]); /* -bfs etc. */
					break;
				  }
				  argc--; argv++;
				}
				argc++; argv--;
			  } else if (strcmp(&argv[1][1], "replay") == 0)
			  {	replay = 1;
				add_runtime("-r");
				goto samecase;
			  } else
			  {	verbose +=  8;
			  }
			  break;
		case 'S': separate = atoi(&argv[1][2]); /* S1 or S2 */
			  /* generate code for separate compilation */
			  analyze = 1; break;
		case 's':
			  if (strcmp(&argv[1][1], "simulate") == 0)
			  {	break; /* ignore */
			  }
			  if (strcmp(&argv[1][1], "search") == 0)
			  {	goto samecase;
			  }
			  verbose += 16; break;
		case 'T': notabs = 1; break;
		case 't': s_trail  =  1;
			  if (isdigit((int)argv[1][2]))
			  {	ntrail = atoi(&argv[1][2]);
			  }
			  break;
		case 'U': PreArg[++PreCnt] = (char *) &argv[1][0];
			  break;	/* undefine */
		case 'u': cutoff = atoi(&argv[1][2]); break;
		case 'v': verbose += 32; break;
		case 'V': printf("%s\n", SpinVersion);
			  alldone(0);
			  break;
		case 'w': verbose += 64; break;
		case 'W': norecompile = 1; break;	/* 6.4.7: for swarm/biterate */
		case 'x': /* internal - reserved use */
			  if (buzzed != 0)
			  {	fatal("cannot combine -x with -run -search or -replay", (char *)0);
			  }
			  buzzed = 1;	/* implies also -a -o3 */
			  pan_runtime = "-d";
			  analyze = 1;
			  usedopts += optimizations('3');
			  break;
		case 'X': xspin = notabs = 1;
#ifndef PC
			  signal(SIGPIPE, alldone); /* not posix... */
#endif
			  break;
		case 'Y': limited_vis = 1; break;	/* used by xspin */
		case 'Z': preprocessonly = 1; break;	/* used by xspin */

		default : usage(); break;
		}
		argc--; argv++;
	}

	if (columns == 2 && !cutoff)
	{	cutoff = 1024;
	}

	if (usedopts && !analyze)
		printf("spin: warning -o[1..5] option ignored in simulations\n");

	if (ltl_file)
	{	add_ltl = ltl_file-2; add_ltl[1][1] = 'f';
		if (!(tl_out = fopen(*ltl_file, "r")))
		{	printf("spin: cannot open %s\n", *ltl_file);
			alldone(1);
		}
		size_t linebuffsize = 0;
		ssize_t length = getline(&formula, &linebuffsize, tl_out);
		if (!formula || !length)
		{	printf("spin: cannot read %s\n", *ltl_file);
		}
		fclose(tl_out);
		tl_out = stdout;
		*ltl_file = formula;
	}
	if (argc > 1)
	{	FILE *fd = stdout;
		char cmd[512], out2[512];

		/* must remain in current dir */
		strcpy(out1, "pan.pre");

		if (add_ltl || nvr_file)
		{	assert(strlen(argv[1]) < sizeof(out2));
			sprintf(out2, "%s.nvr", argv[1]);
			if ((fd = fopen(out2, MFLAGS)) == NULL)
			{	printf("spin: cannot create tmp file %s\n",
					out2);
				alldone(1);
			}
			fprintf(fd, "#include \"%s\"\n", argv[1]);
		}

		if (add_ltl)
		{	tl_out = fd;
			nr_errs = tl_main(2, add_ltl);
			fclose(fd);
			preprocess(out2, out1, 1);
		} else if (nvr_file)
		{	fprintf(fd, "#include \"%s\"\n", *nvr_file);
			fclose(fd);
			preprocess(out2, out1, 1);
		} else
		{	preprocess(argv[1], out1, 0);
		}

		if (preprocessonly)
		{	alldone(0);
		}

		if (!(yyin = fopen(out1, "r")))
		{	printf("spin: cannot open %s\n", out1);
			alldone(1);
		}

		assert(strlen(argv[1])+1 < sizeof(cmd));

		if (strncmp(argv[1], "progress", (size_t) 8) == 0
		||  strncmp(argv[1], "accept", (size_t) 6) == 0)
		{	sprintf(cmd, "_%s", argv[1]);
		} else
		{	strcpy(cmd, argv[1]);
		}
		oFname = Fname = lookup(cmd);
		if (oFname->name[0] == '\"')
		{	int i = (int) strlen(oFname->name);
			oFname->name[i-1] = '\0';
			oFname = lookup(&oFname->name[1]);
		}
	} else
	{	oFname = Fname = lookup("<stdin>");
		if (add_ltl)
		{	if (argc > 0)
				exit(tl_main(2, add_ltl));
			printf("spin: missing argument to -f\n");
			alldone(1);
		}
		printf("%s\n", SpinVersion);
		fprintf(stderr, "spin: error, no filename specified\n");
		fflush(stdout);
		alldone(1);
	}
	if (columns == 2)
	{	if (xspin || (verbose & (1|4|8|16|32)))
		{	printf("spin: -c precludes all flags except -t\n");
			alldone(1);
		}
		putprelude();
	}
	if (columns && !(verbose&8) && !(verbose&16))
	{	verbose += (8+16);
	}
	if (columns == 2 && limited_vis)
	{	verbose += (1+4);
	}

	Srand((unsigned int) T);	/* defined in run.c */
	SeedUsed = T;
	s = lookup("_");	s->type = PREDEF; /* write-only global var */
	s = lookup("_p");	s->type = PREDEF;
	s = lookup("_pid");	s->type = PREDEF;
	s = lookup("_last");	s->type = PREDEF;
	s = lookup("_nr_pr");	s->type = PREDEF; /* new 3.3.10 */
	s = lookup("_priority"); s->type = PREDEF; /* new 6.2.0 */

	yyparse();
	fclose(yyin);

	if (ltl_claims)
	{	Symbol *r;
		fclose(fd_ltl);
		if (!(yyin = fopen(ltl_claims, "r")))
		{	fatal("cannot open %s", ltl_claims);
		}
		r = oFname;
		oFname = Fname = lookup(ltl_claims);
		lineno = 0;
		yyparse();
		fclose(yyin);
		oFname = Fname = r;
		if (0)
		{	(void) unlink(ltl_claims);
	}	}

	loose_ends();

	if (inlineonly)
	{	repro_src();
		return 0;
	}

	chanaccess();
	if (!Caccess)
	{	if (has_provided && merger)
		{	merger = 0;	/* cannot use statement merging in this case */
		}
		if (!s_trail && (dataflow || merger) && (!replay || has_code))
		{	ana_src(dataflow, merger);
		}
		sched();
		alldone(nr_errs);
	}

	return 0;
}

void
ltl_list(char *nm, char *fm)
{
	if (s_trail
	||  analyze
	||  dumptab)	/* when generating pan.c or replaying a trace */
	{	if (!ltl_claims)
		{	ltl_claims = "_spin_nvr.tmp";
			if ((fd_ltl = fopen(ltl_claims, MFLAGS)) == NULL)
			{	fatal("cannot open tmp file %s", ltl_claims);
			}
			tl_out = fd_ltl;
		}
		add_ltl = (char **) emalloc(5 * sizeof(char *));
		add_ltl[1] = "-c";
		add_ltl[2] = nm;
		add_ltl[3] = "-f";
		add_ltl[4] = (char *) emalloc(strlen(fm)+4);
		strcpy(add_ltl[4], "!(");
		strcat(add_ltl[4], fm);
		strcat(add_ltl[4], ")");
		/* add_ltl[4] = fm; */
		nr_errs += tl_main(4, add_ltl);

		fflush(tl_out);
		/* should read this file after the main file is read */
	}
}

void
non_fatal(char *s1, char *s2)
{	extern char yytext[];

	printf("spin: %s:%d, Error: ",
		Fname?Fname->name:(oFname?oFname->name:"nofilename"), lineno);
#if 1
	printf(s1, s2); /* avoids a gcc warning */
#else
	if (s2)
		printf(s1, s2);
	else
		printf(s1);
#endif
	if (strlen(yytext)>1)
		printf(" near '%s'", yytext);
	printf("\n");
	nr_errs++;
}

void
fatal(char *s1, char *s2)
{
	non_fatal(s1, s2);
	(void) unlink("pan.b");
	(void) unlink("pan.c");
	(void) unlink("pan.h");
	(void) unlink("pan.m");
	(void) unlink("pan.t");
	(void) unlink("pan.p");
	(void) unlink("pan.pre");
	if (!(verbose&32))
	{	(void) unlink("_spin_nvr.tmp");
	}
	alldone(1);
}

char *
emalloc(size_t n)
{	char *tmp;
	static unsigned long cnt = 0;

	if (n == 0)
		return NULL;	/* robert shelton 10/20/06 */

	if (!(tmp = (char *) malloc(n)))
	{	printf("spin: allocated %ld Gb, wanted %d bytes more\n",
			cnt/(1024*1024*1024), (int) n);
		fatal("not enough memory", (char *)0);
	}
	cnt += (unsigned long) n;
	memset(tmp, 0, n);
	return tmp;
}

void
trapwonly(Lextok *n /* , char *unused */)
{	short i;

	if (!n)
	{	fatal("unexpected error,", (char *) 0);
	}

	i = (n->sym)?n->sym->type:0;

	/* printf("%s	realread %d type %d\n", n->sym?n->sym->name:"--", realread, i); */

	if (realread
	&& (i == MTYPE
	||  i == BIT
	||  i == BYTE
	||  i == SHORT
	||  i == INT
	||  i == UNSIGNED))
	{	n->sym->hidden |= 128;	/* var is read at least once */
	}
}

void
setaccess(Symbol *sp, Symbol *what, int cnt, int t)
{	Access *a;

	for (a = sp->access; a; a = a->lnk)
		if (a->who == context
		&&  a->what == what
		&&  a->cnt == cnt
		&&  a->typ == t)
			return;

	a = (Access *) emalloc(sizeof(Access));
	a->who = context;
	a->what = what;
	a->cnt = cnt;
	a->typ = t;
	a->lnk = sp->access;
	sp->access = a;
}

Lextok *
nn(Lextok *s, int t, Lextok *ll, Lextok *rl)
{	Lextok *n = (Lextok *) emalloc(sizeof(Lextok));
	static int warn_nn = 0;

	n->uiid = is_inline();	/* record origin of the statement */
	n->ntyp = (unsigned short) t;
	if (s && s->fn)
	{	n->ln = s->ln;
		n->fn = s->fn;
	} else if (rl && rl->fn)
	{	n->ln = rl->ln;
		n->fn = rl->fn;
	} else if (ll && ll->fn)
	{	n->ln = ll->ln;
		n->fn = ll->fn;
	} else
	{	n->ln = lineno;
		n->fn = Fname;
	}
	if (s) n->sym  = s->sym;
	n->lft  = ll;
	n->rgt  = rl;
	n->indstep = DstepStart;

	if (t == TIMEOUT) Etimeouts++;

	if (!context) return n;

	if (t == 'r' || t == 's')
		setaccess(n->sym, ZS, 0, t);
	if (t == 'R')
		setaccess(n->sym, ZS, 0, 'P');

	if (context->name == claimproc)
	{	int forbidden = separate;
		switch (t) {
		case ASGN:
			printf("spin: Warning, never claim has side-effect\n");
			break;
		case 'r': case 's':
			non_fatal("never claim contains i/o stmnts",(char *)0);
			break;
		case TIMEOUT:
			/* never claim polls timeout */
			if (Ntimeouts && Etimeouts)
				forbidden = 0;
			Ntimeouts++; Etimeouts--;
			break;
		case LEN: case EMPTY: case FULL:
		case 'R': case NFULL: case NEMPTY:
			/* status becomes non-exclusive */
			if (n->sym && !(n->sym->xu&XX))
			{	n->sym->xu |= XX;
				if (separate == 2) {
				printf("spin: warning, make sure that the S1 model\n");
				printf("      also polls channel '%s' in its claim\n",
				n->sym->name);
			}	}
			forbidden = 0;
			break;
		case 'c':
			AST_track(n, 0);	/* register as a slice criterion */
			/* fall thru */
		default:
			forbidden = 0;
			break;
		}
		if (forbidden)
		{	printf("spin: never, saw "); explain(t); printf("\n");
			fatal("incompatible with separate compilation",(char *)0);
		}
	} else if ((t == ENABLED || t == PC_VAL) && !(warn_nn&t))
	{	printf("spin: Warning, using %s outside never claim\n",
			(t == ENABLED)?"enabled()":"pc_value()");
		warn_nn |= t;
	} else if (t == NONPROGRESS)
	{	fatal("spin: Error, using np_ outside never claim\n", (char *)0);
	}
	return n;
}

Lextok *
rem_lab(Symbol *a, Lextok *b, Symbol *c)	/* proctype name, pid, label name */
{	Lextok *tmp1, *tmp2, *tmp3;

	has_remote++;
	c->type = LABEL;	/* refered to in global context here */
	fix_dest(c, a);		/* in case target of rem_lab is jump */
	tmp1 = nn(ZN, '?',   b, ZN); tmp1->sym = a;
	tmp1 = nn(ZN, 'p', tmp1, ZN);
	tmp1->sym = lookup("_p");
	tmp2 = nn(ZN, NAME,  ZN, ZN); tmp2->sym = a;
	tmp3 = nn(ZN, 'q', tmp2, ZN); tmp3->sym = c;
	return nn(ZN, EQ, tmp1, tmp3);
#if 0
	      .---------------EQ-------.
	     /                          \
	   'p' -sym-> _p               'q' -sym-> c (label name)
	   /                           /
	 '?' -sym-> a (proctype)     NAME -sym-> a (proctype name)
	 /
	b (pid expr)
#endif
}

Lextok *
rem_var(Symbol *a, Lextok *b, Symbol *c, Lextok *ndx)
{	Lextok *tmp1;

	has_remote++;
	has_remvar++;
	dataflow = 0;	/* turn off dead variable resets 4.2.5 */
	merger   = 0;	/* turn off statement merging for locals 6.4.9 */
	tmp1 = nn(ZN, '?', b, ZN); tmp1->sym = a;
	tmp1 = nn(ZN, 'p', tmp1, ndx);
	tmp1->sym = c;
	return tmp1;
#if 0
	cannot refer to struct elements
	only to scalars and arrays

	    'p' -sym-> c (variable name)
	    / \______  possible arrayindex on c
	   /
	 '?' -sym-> a (proctype)
	 /
	b (pid expr)
#endif
}

void
explain(int n)
{	FILE *fd = stdout;
	switch (n) {
	default:	if (n > 0 && n < 256)
				fprintf(fd, "'%c' = ", n);
			fprintf(fd, "%d", n);
			break;
	case '\b':	fprintf(fd, "\\b"); break;
	case '\t':	fprintf(fd, "\\t"); break;
	case '\f':	fprintf(fd, "\\f"); break;
	case '\n':	fprintf(fd, "\\n"); break;
	case '\r':	fprintf(fd, "\\r"); break;
	case 'c':	fprintf(fd, "condition"); break;
	case 's':	fprintf(fd, "send"); break;
	case 'r':	fprintf(fd, "recv"); break;
	case 'R':	fprintf(fd, "recv poll %s", Operator); break;
	case '@':	fprintf(fd, "@"); break;
	case '?':	fprintf(fd, "(x->y:z)"); break;
#if 1
	case NEXT:	fprintf(fd, "X"); break;
	case ALWAYS:	fprintf(fd, "[]"); break;
	case EVENTUALLY: fprintf(fd, "<>"); break;
	case IMPLIES:	fprintf(fd, "->"); break;
	case EQUIV:	fprintf(fd, "<->"); break;
	case UNTIL:	fprintf(fd, "U"); break;
	case WEAK_UNTIL: fprintf(fd, "W"); break;
	case IN: fprintf(fd, "%sin", Keyword); break;
#endif
	case ACTIVE:	fprintf(fd, "%sactive",	Keyword); break;
	case AND:	fprintf(fd, "%s&&",	Operator); break;
	case ASGN:	fprintf(fd, "%s=",	Operator); break;
	case ASSERT:	fprintf(fd, "%sassert",	Function); break;
	case ATOMIC:	fprintf(fd, "%satomic",	Keyword); break;
	case BREAK:	fprintf(fd, "%sbreak",	Keyword); break;
	case C_CODE:	fprintf(fd, "%sc_code",	Keyword); break;
	case C_DECL:	fprintf(fd, "%sc_decl",	Keyword); break;
	case C_EXPR:	fprintf(fd, "%sc_expr",	Keyword); break;
	case C_STATE:	fprintf(fd, "%sc_state",Keyword); break;
	case C_TRACK:	fprintf(fd, "%sc_track",Keyword); break;
	case CLAIM:	fprintf(fd, "%snever",	Keyword); break;
	case CONST:	fprintf(fd, "a constant"); break;
	case DECR:	fprintf(fd, "%s--",	Operator); break;
	case D_STEP:	fprintf(fd, "%sd_step",	Keyword); break;
	case D_PROCTYPE: fprintf(fd, "%sd_proctype", Keyword); break;
	case DO:	fprintf(fd, "%sdo",	Keyword); break;
	case DOT:	fprintf(fd, "."); break;
	case ELSE:	fprintf(fd, "%selse",	Keyword); break;
	case EMPTY:	fprintf(fd, "%sempty",	Function); break;
	case ENABLED:	fprintf(fd, "%senabled",Function); break;
	case EQ:	fprintf(fd, "%s==",	Operator); break;
	case EVAL:	fprintf(fd, "%seval",	Function); break;
	case FI:	fprintf(fd, "%sfi",	Keyword); break;
	case FULL:	fprintf(fd, "%sfull",	Function); break;
	case GE:	fprintf(fd, "%s>=",	Operator); break;
	case GET_P:	fprintf(fd, "%sget_priority",Function); break;
	case GOTO:	fprintf(fd, "%sgoto",	Keyword); break;
	case GT:	fprintf(fd, "%s>",	Operator); break;
	case HIDDEN:	fprintf(fd, "%shidden",	Keyword); break;
	case IF:	fprintf(fd, "%sif",	Keyword); break;
	case INCR:	fprintf(fd, "%s++",	Operator); break;
	case INAME:	fprintf(fd, "inline name"); break;
	case INLINE:	fprintf(fd, "%sinline",	Keyword); break;
	case INIT:	fprintf(fd, "%sinit",	Keyword); break;
	case ISLOCAL:	fprintf(fd, "%slocal",  Keyword); break;
	case LABEL:	fprintf(fd, "a label-name"); break;
	case LE:	fprintf(fd, "%s<=",	Operator); break;
	case LEN:	fprintf(fd, "%slen",	Function); break;
	case LSHIFT:	fprintf(fd, "%s<<",	Operator); break;
	case LT:	fprintf(fd, "%s<",	Operator); break;
	case MTYPE:	fprintf(fd, "%smtype",	Keyword); break;
	case NAME:	fprintf(fd, "an identifier"); break;
	case NE:	fprintf(fd, "%s!=",	Operator); break;
	case NEG:	fprintf(fd, "%s! (not)",Operator); break;
	case NEMPTY:	fprintf(fd, "%snempty",	Function); break;
	case NFULL:	fprintf(fd, "%snfull",	Function); break;
	case NON_ATOMIC: fprintf(fd, "sub-sequence"); break;
	case NONPROGRESS: fprintf(fd, "%snp_",	Function); break;
	case OD:	fprintf(fd, "%sod",	Keyword); break;
	case OF:	fprintf(fd, "%sof",	Keyword); break;
	case OR:	fprintf(fd, "%s||",	Operator); break;
	case O_SND:	fprintf(fd, "%s!!",	Operator); break;
	case PC_VAL:	fprintf(fd, "%spc_value",Function); break;
	case PNAME:	fprintf(fd, "process name"); break;
	case PRINT:	fprintf(fd, "%sprintf",	Function); break;
	case PRINTM:	fprintf(fd, "%sprintm",	Function); break;
	case PRIORITY:	fprintf(fd, "%spriority", Keyword); break;
	case PROCTYPE:	fprintf(fd, "%sproctype",Keyword); break;
	case PROVIDED:	fprintf(fd, "%sprovided",Keyword); break;
	case RCV:	fprintf(fd, "%s?",	Operator); break;
	case R_RCV:	fprintf(fd, "%s??",	Operator); break;
	case RSHIFT:	fprintf(fd, "%s>>",	Operator); break;
	case RUN:	fprintf(fd, "%srun",	Operator); break;
	case SEP:	fprintf(fd, "token: ::"); break;
	case SEMI:	fprintf(fd, ";"); break;
	case ARROW:	fprintf(fd, "->"); break;
	case SET_P:	fprintf(fd, "%sset_priority",Function); break;
	case SHOW:	fprintf(fd, "%sshow", Keyword); break;
	case SND:	fprintf(fd, "%s!",	Operator); break;
	case STRING:	fprintf(fd, "a string"); break;
	case TRACE:	fprintf(fd, "%strace", Keyword); break;
	case TIMEOUT:	fprintf(fd, "%stimeout",Keyword); break;
	case TYPE:	fprintf(fd, "data typename"); break;
	case TYPEDEF:	fprintf(fd, "%stypedef",Keyword); break;
	case XU:	fprintf(fd, "%sx[rs]",	Keyword); break;
	case UMIN:	fprintf(fd, "%s- (unary minus)", Operator); break;
	case UNAME:	fprintf(fd, "a typename"); break;
	case UNLESS:	fprintf(fd, "%sunless",	Keyword); break;
	}
}