🚀 go-pugleaf

You've probably had several reports + fixes to this bug - but here is my
contribution anyway.

Simon Cooper
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GnuEmacs-Version:	18.55

C-Compiler:		Gcc 1.37
Debugger:		Gdb 3.4
Machine:		Sun 4/60  (SPARCstation 1)

Operating-System:	SunOs 4.0.3_EXPORT

Bug-Description:

./temacs bombs out with a "Bus error" in function "staticpro".  This bug is
not attributable to Gcc - it generates correct code for the information given.
Other compilers may fall over.

When GDB is being used to debug ./temacs the following line is returned
(marked with =>)

--- 667,682 --- file: alloc.c -------------------------------------------------
char staticvec1[NSTATICS * sizeof (Lisp_Object *)] = {0};

int staticidx = 0;

#define staticvec ((Lisp_Object **) staticvec1)

/* Put an entry in staticvec, pointing at the variable whose address is given */

void
staticpro (varaddress)
     Lisp_Object *varaddress;
{
=>staticvec[staticidx++] = varaddress;
  if (staticidx >= NSTATICS)
    abort ();
}
-------------------------------------------------------------------------------

staticvec is declared as a "char" rather than a "Lisp_Object *" and as such
can be skewed across a word boundary.  A (Lisp_Object *) is of size word.
This is bad news since a Sparc cannot write a word across a word boundary =>
staticvec needs to be word aligned.  GCC produces the following code
(disassembled via GDB) where <staticvec1> can be seen to have been allocated
an odd address 0x10d069 (thus causing word mis-alignment).

Starting program: /export/local/src/GnuEmacs-18.55/src/temacs -batch inc-vers

Program received signal 10, Bus error
0x31460 in staticpro (varaddress=(int *) 0x11e5d8) (alloc.c line 679)
(gdb) disass
Dump of assembler code from 0x31440 to 0x31480:
0x31440 <staticpro>:	save %sp, -112, %sp
0x31444 <staticpro+4>:	sethi %hi(0x10d000), %g1
0x31448 <staticpro+8>:	ld [%g1+0x38c], %o0	! 0x10d38c <staticidx>
0x3144c <staticpro+12>:	add %o0, 1, %o1
0x31450 <staticpro+16>:	st %o1, [%g1+0x38c]
0x31454 <staticpro+20>:	sethi %hi(0x10d000), %o2
0x31458 <staticpro+24>:	or %o2, 0x69, %o2	! 0x10d069 <staticvec1>
0x3145c <staticpro+28>:	sll %o0, 2, %o0
0x31460 <staticpro+32>:	st %i0, [%o2+%o0]
0x31464 <staticpro+36>:	cmp %o1, 0xc7
0x31468 <staticpro+40>:	ble 0x31478 <staticpro+56>
0x3146c <staticpro+44>:	nop 
0x31470 <staticpro+48>:	call 0xc8e30 <abort>
0x31474 <staticpro+52>:	nop 
0x31478 <staticpro+56>:	ret 
0x3147c <staticpro+60>:	restore 
End of assembler dump.
(gdb) 


Fix:

Give the compiler enough information to align the array correctly.

*** alloc.c.~1~	Mon Feb 13 10:23:35 1989
--- alloc.c	Thu May 17 05:28:13 1990
***************
*** 664,670 ****
  
  #define NSTATICS 200
  
! char staticvec1[NSTATICS * sizeof (Lisp_Object *)] = {0};
  
  int staticidx = 0;
  
--- 664,670 ----
  
  #define NSTATICS 200
  
! Lisp_Object *staticvec1[NSTATICS * sizeof (Lisp_Object *)] = {0};
  
  int staticidx = 0;