[PATCH] Retrieve segment registers on Windows amd64

[Jon TURNEY <jon.turney@dronecode.org.uk>]

For amd64, CONTEXT_FULL does not contain CONTEXT_SEGMENTS, which seems to be
needed to retrieve all the segment registers.  Add it explicitly, with a little
de-cruftification.

The value of the segment registers isn't terribly useful on amd64, but at least
this makes the output of 'info registers' correct.

before:

(gdb)  i r cs ss ds es fs gs
cs             0x33     51
ss             0x2b     43
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0

after:

(gdb) i r cs ss ds es fs gs
cs             0x33     51
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x53     83
gs             0x2b     43

gdb/ChangeLog

2015-02-19  Jon TURNEY  <jon.turney@dronecode.org.uk>

	* windows-nat.c (CONTEXT_DEBUGGER_DR): Add CONTEXT_SEGMENTS.
---
 gdb/windows-nat.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 9c2dca1..ec11822 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -130,7 +130,6 @@ static CONTEXT saved_context;	/* Containes the saved context from a
 enum
   {
     FLAG_TRACE_BIT = 0x100,
-    CONTEXT_DEBUGGER = (CONTEXT_FULL | CONTEXT_FLOATING_POINT)
   };
 #endif
 
@@ -140,8 +139,8 @@ enum
 #define CONTEXT_EXTENDED_REGISTERS 0
 #endif
 
-#define CONTEXT_DEBUGGER_DR CONTEXT_DEBUGGER | CONTEXT_DEBUG_REGISTERS \
-	| CONTEXT_EXTENDED_REGISTERS
+#define CONTEXT_DEBUGGER_DR CONTEXT_FULL | CONTEXT_FLOATING_POINT \
+        | CONTEXT_SEGMENTS | CONTEXT_DEBUG_REGISTERS | CONTEXT_EXTENDED_REGISTERS
 
 static uintptr_t dr[8];
 static int debug_registers_changed;
-- 
2.1.4