[PATCH] Clear *VAL in regcache_raw_read_unsigned

[Yao Qi <qiyaoltc@gmail.com>]

We have function regcache_raw_read_unsigned defined in both GDB and
GDBserver, so that it is used in common like this,

  ULONGEST value;
  status = regcache_raw_read_unsigned (regcache, regnum, &value);

'value' is correctly set in GDB side, but may not be correctly set
in GDBserver, because &value is passed in regcache_raw_read_unsigned
but collect_register may only set part of the whole variable.  In my
test, I see the top half of 'value' is garbage.  This patch fixes this
problem by clearing *VAL before calling collect_register.

Regression tests are still running.  I'll push it in if there is no
regression in tests.

gdb/gdbserver:

2016-02-09  Yao Qi  <yao.qi@linaro.org>

	* regcache.c (regcache_raw_read_unsigned): Clear *VAL.
---
 gdb/gdbserver/regcache.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gdb/gdbserver/regcache.c b/gdb/gdbserver/regcache.c
index 6a737ea..2af8e24 100644
--- a/gdb/gdbserver/regcache.c
+++ b/gdb/gdbserver/regcache.c
@@ -440,6 +440,7 @@ regcache_raw_read_unsigned (struct regcache *regcache, int regnum,
             "%d bytes."),
           (int) sizeof (ULONGEST));
 
+  *val = 0;
   collect_register (regcache, regnum, val);
 
   return REG_VALID;
-- 
1.9.1