optimization/8726: GCC 3.2.1 miscompiles Samba 2.2.7 on 32-bit sparc

Paul Eggert eggert@twinsun.com
Tue Nov 26 17:31:00 GMT 2002


>Number:         8726
>Category:       optimization
>Synopsis:       GCC 3.2.1 -O2 miscompiles Samba 2.2.7 on 32-bit sparc
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 26 17:06:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Paul Eggert.
>Release:        3.2.1
>Organization:
Twin Sun, Inc.
>Environment:
System: SunOS sic.twinsun.com 5.8 Generic_108528-17 sun4u sparc SUNW,UltraSPARC-IIi-Engine
Architecture: sun4

	
host: sparc-sun-solaris2.8
build: sparc-sun-solaris2.8
target: sparc-sun-solaris2.8
configured with: ../gcc-3.2.1/configure --disable-nls --enable-languages=c,c++ --prefix=/opt/reb/lib/gcc/gcc-3.2.1 --with-system-zlib
>Description:
	Samba 2.2.7 (32-bit sparc) mishandles 64-bit file locks because
	GCC 3.2.1 miscompiles the file-locking code.  I have narrowed
	down the problem to a simple test case enclosed below.
>How-To-Repeat:
	Compile and run the following program with "gcc -O2 t.i; ./a.out".
	a.out will exit with nonzero status; it should exit with zero status.

# 1 "t.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "t.c"
int fcntl_lock(int fd, int op, long long offset, long long count, int type);

int vfswrap_lock(char *fsp, int fd, int op, long long offset, long long count, int type)
{
  int result;
  result = fcntl_lock(fd, op, offset, count,type);
  return result;
}

int fcntl_lock(int fd, int op, long long offset, long long count, int type)
{
  return type;
}

int
main (void)
{
  return vfswrap_lock (0, 1, 2, 3, 4, 5) != 5;
}


The problem can be found in the assembly code for vfswrap_lock.
The "st" followed by the "ldd" puts garbage into the "type" argument.

vfswrap_lock:
	!#PROLOGUE# 0
	add	%sp, -48, %sp
	!#PROLOGUE# 1
	mov	%o1, %o0
	mov	%o2, %o1
	mov	%o3, %o2
	st	%o5, [%sp+136]
	mov	%o4, %o3
	ldd	[%sp+136], %o4
	sethi	%hi(fcntl_lock), %g1
	jmpl	%g1 + %lo(fcntl_lock), %g0
	 sub	%sp, -48, %sp

>Fix:
	A workaround is to not compile with -O2.
>Release-Note:
>Audit-Trail:
>Unformatted:



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