Avoid gcc warning on sparc solaris 9

["Pedro Alves" <pedro_alves at portugalmail dot pt>]

Hi,

Building HEAD on a native gdb on sparc solaris 9 with gcc 3.4.6 stops due to:

gcc -c -g -O2    -I. -I../../src/gdb -I../../src/gdb/config
-DLOCALEDIR="\"/usr/local/share/locale\"" -DHAVE_CONFIG_H
-I../../src/gdb/../include/opcode -I../../src/gdb/../readline/..
-I../bfd -I../../src/gdb/../bfd -I../../src/gdb/../include -I./../intl
 -DMI_OUT=1 -DTUI=1 -I/usr/local/include -Wall
-Wdeclaration-after-statement -Wpointer-arith -Wformat-nonliteral
-Wno-unused -Wno-switch -Wno-char-subscripts -Werror
../../src/gdb/sol-thread.c
../../src/gdb/sol-thread.c: In function `sol_thread_fetch_registers':
../../src/gdb/sol-thread.c:533: warning: dereferencing type-punned
pointer will break strict-aliasing rules
make: *** [sol-thread.o] Error 1

gcc -v
Reading specs from /usr/local/lib/gcc/sparc-sun-solaris2.9/3.4.6/specs
Configured with: ../configure --with-as=/usr/ccs/bin/as
--with-ld=/usr/ccs/bin/ld --enable-shared --enable-languages=c,c++,f77
Thread model: posix
gcc version 3.4.6

uname -a
SunOS ol154 5.9 Generic_117171-13 sun4u sparc SUNW,Sun-Fire-480R Solaris

The attached patch gets me going.

config/sparc/nm-sol2.h has these, so it looks safe on sparc:

#define GDB_GREGSET_T prgregset_t
#define GDB_FPREGSET_T prfpregset_t

Here's a simplified preprocessed output of sol-thread.c:

typedef prgregset_t gdb_gregset_t;
typedef prfpregset_t gdb_fpregset_t;

extern void supply_gregset (struct regcache *regcache,
       const gdb_gregset_t *gregs);

extern void supply_fpregset (struct regcache *regcache,
        const gdb_fpregset_t *fpregs);

static void
sol_thread_fetch_registers (struct regcache *regcache, int regnum)
{
  prgregset_t gregset;
  prfpregset_t fpregset;

  supply_gregset (regcache, (const gdb_gregset_t *) &gregset);
  supply_fpregset (regcache, (const gdb_fpregset_t *) &fpregset);
}

But I'm not sure it's correct, since the i386 sparc config files don't set
GDB_{G|FP}REGSET, so they should be defaulting to:

gregset.h:

#ifndef GDB_GREGSET_T
#define GDB_GREGSET_T gregset_t
#endif

#ifndef GDB_FPREGSET_T
#define GDB_FPREGSET_T fpregset_t
#endif

I ran the testsuite on it, and this is what I got:

                === gdb Summary ===

# of expected passes            10898
# of unexpected failures        81
# of unexpected successes       2
# of expected failures          47
# of known failures             42
# of unresolved testcases       3
# of untested testcases         8
# of unsupported tests          25

2007-10-23  Pedro Alves  <pedro_alves@portugalmail.pt>

	* sol-thread.c (sol_thread_fetch_registers): Avoid alias warning.
	Add assertion to verify correct size of gdb_gregset_t and
	gdb_fpregset_t.

---
 gdb/sol-thread.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Index: src/gdb/sol-thread.c
===================================================================
--- src.orig/gdb/sol-thread.c	2007-10-23 15:14:44.529038000 +0100
+++ src/gdb/sol-thread.c	2007-10-23 15:15:49.819263000 +0100
@@ -484,6 +484,10 @@ sol_thread_fetch_registers (struct regca
   td_err_e val;
   prgregset_t gregset;
   prfpregset_t fpregset;
+
+  gdb_assert (sizeof (prgregset_t) == sizeof (gdb_gregset_t));
+  gdb_assert (sizeof (prfpregset_t) == sizeof (gdb_fpregset_t));
+
 #if 0
   int xregsize;
   caddr_t xregset;
@@ -530,8 +534,8 @@ sol_thread_fetch_registers (struct regca
      calling the td routines because the td routines call ps_lget*
      which affect the values stored in the registers array.  */
 
-  supply_gregset (regcache, (const gdb_gregset_t *) &gregset);
-  supply_fpregset (regcache, (const gdb_fpregset_t *) &fpregset);
+  supply_gregset (regcache, (const gdb_gregset_t *) (void *) &gregset);
+  supply_fpregset (regcache, (const gdb_fpregset_t *) (void *) &fpregset);
 
 #if 0
   /* FIXME: libthread_db doesn't seem to handle this right.  */