🚀 go-pugleaf

The following code sequence fails on the Motorola 88K when compiled
with gcc 2.2.2 with options "-O -g -funsigned-char"; it has not been
tested without "-g -funsigned-char".  Without "-O" the code sequence
executes as expected.  If fail_msg is declared static the code
sequence executes as expected.

	volatile char	*fail_msg ;

	if (setjmp (regexpfail)) {
		sprintf (msg, "%s\n (%s)", fail_msg, regexp_errmsg) ;
		WriteErr (5, "EvalINDEX", msg, DO_PRINT_UNIT) ;
		operand[0].val.value.integer_value = 0 ;
	} else {
		fail_msg = "Incorrectly formed search argument." ;
		regbuff = CompileRegexp (srch) ;
		fail_msg = "Error occurred while searching." ;
		if (regexec (regbuff, src->chars) == 0)
		.
		.
		.
	}

The functions CompileRegexp and regexec both longjmp to regexpfail
when they encounter errors.  When this code is compiled with the
"-O" option, it appears that the first store to fail_msg is deleted;
if the longjmp is executed from CompileRegexp, the value in fail_msg
is not a pointer to the specified string.  This violates the specifi-
cation that "at every sequence point the value of the object in storage
shall agree with that prescribed by the abstract machine" (describing
an object with a type that includes the volatile type specifier) in
our copy of the July 9, 1986, Draft Proposed American National Standard
for Information Systems -- Programming Language C (3.5.2.4, const and
volatile).  Unfortunately, we do not have anything later than the 1986
draft; I offer my apologies if this statement has disappeared.
--
Darrell Tangman -- darrell@galois.NSCF.org
National Mathematics Center / National Science Center Foundation, Inc.
P.O. Box 15577, Augusta, GA, USA, 30919-1577