Avoid gcc warning on sparc solaris 9

Pedro Alves
2007-10-23T16:24:23Z

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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

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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. */