Path: utzoo!telly!ddsw1!mcdchg!rutgers!tut.cis.ohio-state.edu!MOOSE.CITA.UTORONTO.CA!trq
From: trq@MOOSE.CITA.UTORONTO.CA (Tom Quinn)
Newsgroups: gnu.gcc.bug
Subject: bug in m68k gcc 1.32
Message-ID: <8901162313.AA10017@moose.cita.utoronto.ca>
Date: 16 Jan 89 23:13:23 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 114

gcc with the "-O -fomit-frame-pointer" flags compiles the following
code into something which loses track of the stack pointer, and
therefore, returns to never-neverland.  This is gcc version 1.32 on a
Sun 3/50 running SunOS 3.5.

Tom Quinn                 Canadian Institute for Theoretical Astrophysics
trq@moose.cita.utoronto.ca
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The compile:
gcc -S -g -v -O -fomit-frame-pointer -c history.c
gcc version 1.32
 /usr/local/lib/gcc-cpp -v -undef -D__GNUC__ -Dmc68000 -Dsun -Dunix -D__mc68000_
_ -D__sun__ -D__unix__ -D__OPTIMIZE__ -D__HAVE_68881__ -Dmc68020 history.c /tmp/cca28687.cpp
GNU CPP version 1.32
 /usr/local/lib/gcc-cc1 /tmp/cca28687.cpp -quiet -dumpbase history.c -fomit-frame-pointer -g -O -version -o history.s
GNU C version 1.32 (68k, MIT syntax) compiled by GNU C version 1.32.

The offending assembler:
	.stabd 68,0,31
	clrl sp@-
	movel a2,sp@-
	jbsr _edit_line
	movel d0,d1
	moveq #14,d3
	cmpl d1,d3
	jeq L15
	jlt L25
	moveq #13,d3
	cmpl d1,d3
	jeq L6
	addqw #8,sp   ### this should be before the above jumps.
	jra L21
L25:
	moveq #16,d3
	cmpl d1,d3
	jeq L17
	jra L21

The code:
------------------------------------------------------------------------
extern	struct	_iobuf {
	int	_cnt;
	unsigned char *_ptr;
	unsigned char *_base;
	int	_bufsiz;
	short	_flag;
	char	_file;		 
} _iob[];
extern	char	_ctype_[];
typedef struct {
   char line[82	];			 
   int num;				 
} HISTORY;
static char search_str[40] = "";	 
static HISTORY **hist;			 
extern int interrupt;			 
static int hindex,			 
	   hlev,			 
	   hsize;			 
char *
edit_hist()
{
   char *current,			 
   	*strcpy(),
        *strncpy();
   int i,
       index = 0;			 
   current = hist[hindex%hsize]->line;	 
   erase_str(current,82				);
   for(;;) {
      switch(i = edit_line(current,(char **)0 )) {
       case 13  :			 
	 interrupt = 0;
	 search_str[0] = '\0';		 
	 printf("\n");
	 for(i = strlen(current) - 1;i >= 0 && current[i] != '\0';i--) {
	    if(!((_ctype_+1)[current[i]]&010 ) ) break;
	    current[i] = '\0';
	 }
	 if(i < 0) {			 
	    break;
	 }
	 if(hindex == 0 || strcmp(hist[hindex%hsize]->line,
				 hist[(hindex - 1)%hsize]->line) != 0) {
	    hist[hindex++%hsize]->num = hlev++;
	 }
	 return(current);
       case 14  :			 
	 if(index > 0) {
	    index--;
	 }
	 erase_str(current,82				);
	 (void)strcpy(current,hist[(hsize + hindex - index)%hsize]->line);
	 break;
       case 16 :			 
	 if(index <= hsize - 1 &&	 
	       (index == 0 || hist[(hsize + hindex - index)%hsize]->num > 0)) {
	    index++;
	 }
	 erase_str(current,82				);
	 if(hist[(hsize + hindex - index)%hsize]->num > 0) {
	    (void)strcpy(current,hist[(hsize + hindex - index)%hsize]->line);
	 }
	 break;
       default:
	 (--((&_iob[1]) )->_cnt>=0? (int)(*((&_iob[1]) )->_ptr++=(unsigned char)((7 ))):_flsbuf((unsigned char)((7 )),(&_iob[1]) ))  ;
	 break;
      }
      (void)fflush((&_iob[1]) );
   }
}