From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Tue,  1 Dec 2009 13:41:32 -0500
To: 9fans@9fans.net
Message-ID: <dc10137c2661c11595d2aa2ca370ba45@brasstown.quanstro.net>
In-Reply-To: <<a4d2df97e4d97d460ae33ca0800a4060@terzarima.net>>
References: <<a4d2df97e4d97d460ae33ca0800a4060@terzarima.net>>
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Subject: Re: [9fans] compiler double bug.
Topicbox-Message-UUID: a63debc0-ead5-11e9-9d60-3106f5b1d025

On Tue Dec  1 11:58:47 EST 2009, forsyth@terzarima.net wrote:
> i hadn't noticed the changed example.
> it's removing the cast, which probably isn't right, although
> in that particular case it's probably better
> that it should trap (because the result is wrong).
> what is the actual code in awk that's equivalent to that sequence?
>

all these fault:

minooka; awk 'BEGIN {
	s = "01234567890";
	printf "%x\n", 4215866817.
	g = 1.					# delayed fpe
	printf "%08x", 4215866817.
	print substr(s, 4215866817., 1)
	s = substr(s, 1, 4215866817.)
	g= 1.					# delayed fpe
	printf utf(4215866817.);
	g= 1.					# delayed fpe
}'

a (not-so-elegant) fix follows.

- erik

proto.h:92,98 - /n/dump/2009/1129/sys/src/cmd/awk/proto.h:92,97
  extern	void	funnyvar(Cell *, const char *);
  extern	char	*setsval(Cell *, const char *);
  extern	double	getfval(Cell *);
- extern	unsigned long	getival(Cell *, unsigned long, unsigned long);
  extern	char	*getsval(Cell *);
  extern	char	*getpssval(Cell *);     /* for print */
  extern	char	*tostring(const char *);
diff: can't stat /n/dump/2009/1129/sys/src/cmd/awk/trans.c
run.c:50,57 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:50,55
  }
  */

- #define	Imax	ULONG_MAX
-
  /* do we really need these? */
  /* #ifdef _NFILE */
  /* #ifndef FOPEN_MAX */
run.c:355,361 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:353,359
  	case EXIT:
  		if (a[0] != NULL) {
  			y = execute(a[0]);
- 			errorflag = getfval(y) != 0.;
+ 			errorflag = (int) getfval(y);
  			tempfree(y);
  		}
  		longjmp(env, 1);
run.c:752,765 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:750,770
  		setsval(x, "");
  		return(x);
  	}
- 	m = getival(y, 1, k);	/* 1 <= m <= k */
+ 	m = (int) getfval(y);
+ 	if (m <= 0)
+ 		m = 1;
+ 	else if (m > k)
+ 		m = k;
  	tempfree(y);
  	if (a[2] != 0) {
- 		n = getival(z, 0, k-m);
- 				/* n <= 0 <= k-m */
+ 		n = (int) getfval(z);
  		tempfree(z);
  	} else
  		n = k - 1;
+ 	if (n < 0)
+ 		n = 0;
+ 	else if (n > k - m)
+ 		n = k - m;
  	   dprintf( ("substr: m=%d, n=%d, s=%s\n", m, n, s) );
  	y = gettemp();
  	temp = s[n+m-1];	/* with thanks to John Linderman */
run.c:804,810 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:809,815
  	char *p, *t;
  	const char *os;
  	Cell *x;
- 	int flag = 0, n, ch;
+ 	int flag = 0, n;
  	int fmtwd; /* format width */
  	int fmtsz = recsize;
  	char *buf = *pbuf;
run.c:838,844 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:843,849
  			if (*s == '*') {
  				x = execute(a);
  				a = a->nnext;
- 				sprintf(t-1, "%d", fmtwd=getival(x, Imax, Imax));
+ 				sprintf(t-1, "%d", fmtwd=(int) getfval(x));
  				if (fmtwd < 0)
  					fmtwd = -fmtwd;
  				adjbuf(&buf, &bufsize, fmtwd+1+p-buf, recsize, &p, "format");
run.c:894,901 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:900,907
  			sprintf(p, "%s", t);
  			break;
  		case 'f':	sprintf(p, fmt, getfval(x)); break;
- 		case 'd':	sprintf(p, fmt, getival(x, Imax, Imax)); break;
- 		case 'u':	sprintf(p, fmt, getival(x, Imax, Imax)); break;
+ 		case 'd':	sprintf(p, fmt, (long) getfval(x)); break;
+ 		case 'u':	sprintf(p, fmt, (int) getfval(x)); break;
  		case 's':
  			t = getsval(x);
  			n = strlen(t);
run.c:907,915 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:913,920
  			break;
  		case 'c':
  			if (isnum(x)) {
- 				ch = getival(x, Imax, Imax);
- 				if (ch)
- 					sprintf(p, fmt, ch);
+ 				if (getfval(x))
+ 					sprintf(p, fmt, (int) getfval(x));
  				else {
  					*p++ = '\0'; /* explicit null byte */
  					*p = '\0';   /* next output will start here */
  Awkfloat
  strtonum(Cell *x)
  {
run.c:1566,1579 - /n/dump/2009/1129/sys/src/cmd/awk/run.c:1583,1589
  			u = fflush(fp);
  		break;
  	case FUTF:
- 		r = getival(x, Imax, Imax);
- 		if(r < 0)
- 			r = -r;
- 		if(r > Runemax){
- 			WARNING("utf argument out-of-range %g", getfval(x));
- 			r = Runeerror;
- 		}
- 		wc = r;
+ 		wc = (int)getfval(x);
  		mbc[wctomb(mbc, wc)] = 0;
  		tempfree(x);
  		x = gettemp();