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From: trq@moose.cita.toronto.edu (Tom Quinn)
Newsgroups: gnu.gcc.bug
Subject: structure passing bug in sparc gcc 1.28
Message-ID: <8809272214.AA01712@moose.cita.toronto.edu>
Date: 27 Sep 88 22:14:09 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 77

The following code demonstrates a bug in gcc v1.28 on sparc when
passing structure values to a function.  Two of the parameter passing
registers get smashed while the end of the structure is being put onto
the stack.

This is on a Sun4/110 running SunOS 4.0

The compile:
gcc -g -v -S  -sun4 -c  control2.c
gcc version 1.28
 /usr/local/lib/gcc-cpp -v -undef -D__GNU__ -D__GNUC__ -Dsparc -Dsun -Dunix control2.c /tmp/cca20015.cpp
GNU CPP version 1.28
 /usr/local/lib/gcc-cc1 /tmp/cca20015.cpp -quiet -dumpbase control2.c -g -version -o control2.s
GNU C version 1.28 (sparc) compiled by GNU C version 1.28.

The code:
------------------------------------------------------------
typedef struct {
   char descrip[80],		 
	*name;				 
   float *vec;				 
   int dimen;				 
} VECTOR;   
typedef union yystype {			 
   char charval[80];
   int intval;
};
extern union yystype  yylval;
   static char data_file[80];	 
union yystype 	yylval;			 
int
yyparse()
{
  register union yystype  *yyvsp;
  union yystype  yyvsa[200 ];	 
  union yystype  *yyvs = yyvsa;	 
  yyvsp = yyvs;
  *++yyvsp = yylval;
{
	    VECTOR temp;
	    if(read_row(data_file,yyvsp[0].intval,&temp) == 0) {
	       copy_vector(yyvsp[-1].charval,temp);
	    }
	 ;
}
}
--------------------------------------------------------------

The offending assembler:
.stabn 68,0,25,LM6
LM6:
	sub %sp,72,%sp
	add %l0,-80,%l1
	set -16120,%o0
	add %fp,%o0,%o0
	ld [%o0],%o1		<<<First 4 bytes of structure
	ld [%o0+4],%o2		<<<Second 4 bytes of structure
	ld [%o0+8],%o3
	ld [%o0+12],%o4
	ld [%o0+16],%o5
	set 68,%o1		<<< OUCH!!
	add %sp,76,%o2		<<< OOFF!!
	
Lm1:				<<< Loop to shove the rest onto the stack
	ld [%o0+%o1],%g1
	subcc %o1,4,%o1
	bge Lm1
	st %g1,[%o2+%o1]
	mov %l1,%o0
	call _copy_vector,0
	nop

Tom Quinn                 Canadian Institute for Theoretical Astrophysics
trq@moose.cita.toronto.edu
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