PR gdb/10565

	* value.c (value_primitive_field): Do not save value_offset for
	bitfields.
	(unpack_bits_as_long): Do not read an entire ULONGEST.

	testsuite/
	PR gdb/10565

	* gdb.base/bitfields.c (struct container, container): New.
	(main): Initialize it and call break5.
	* gdb.base/bitfields.exp (bitfield_at_offset): New test.

5 files changed, 61 insertions, 4 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8f534a7..4cd1e53 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2009-08-28  Daniel Jacobowitz  <dan@codesourcery.com>
+
+	PR gdb/10565
+
+	* value.c (value_primitive_field): Do not save value_offset for
+	bitfields.
+	(unpack_bits_as_long): Do not read an entire ULONGEST.
+
 2009-08-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	Support constant DW_AT_data_member_location by GCC PR debug/40659.
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index a07ed2a..0d10281 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2009-08-28  Daniel Jacobowitz  <dan@codesourcery.com>
+
+	PR gdb/10565
+
+	* gdb.base/bitfields.c (struct container, container): New.
+	(main): Initialize it and call break5.
+	* gdb.base/bitfields.exp (bitfield_at_offset): New test.
+
 2009-08-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	Support constant DW_AT_data_member_location by GCC PR debug/40659.
diff --git a/gdb/testsuite/gdb.base/bitfields.c b/gdb/testsuite/gdb.base/bitfields.c
index bd411f7..3b5e42c 100644
--- a/gdb/testsuite/gdb.base/bitfields.c
+++ b/gdb/testsuite/gdb.base/bitfields.c
@@ -63,6 +63,12 @@ void break10 ()
 {
 }
 
+struct container
+{
+  struct fields one;
+  struct fields two;
+} container;
+
 /* This is used by bitfields.exp to determine if the target understands
    signed bitfields.  */
 int i;
@@ -190,5 +196,10 @@ int main ()
   flags.s3 = 0;
   flags.s9 = 0;
 
+  /* Bitfields at a non-zero offset in a containing structure.  */
+  container.one.u3 = 5;
+  container.two.u3 = 3;
+  break5 ();
+
   return 0;
 }
diff --git a/gdb/testsuite/gdb.base/bitfields.exp b/gdb/testsuite/gdb.base/bitfields.exp
index 31e8b01..659785e 100644
--- a/gdb/testsuite/gdb.base/bitfields.exp
+++ b/gdb/testsuite/gdb.base/bitfields.exp
@@ -233,6 +233,26 @@ proc bitfield_signedness {} {
     gdb_stop_suppressing_tests;
 }
 
+# Test bitfields at non-zero offsets in a struct.
+
+proc bitfield_at_offset {} {
+    global decimal
+    global hex
+    global gdb_prompt
+    global srcfile
+
+    gdb_breakpoint break5
+    if [gdb_test "cont" "Break.*break5 \\(\\) at .*$srcfile:$decimal.*" "continuing to break5"] {
+	return
+    }
+
+    set one ".*uc = 0 .*, s1 = 0, u1 = 0, s2 = 0, u2 = 0, s3 = 0, u3 = 5, s9 = 0, u9 = 0, sc = 0.*"
+    set two ".*uc = 0 .*, s1 = 0, u1 = 0, s2 = 0, u2 = 0, s3 = 0, u3 = 3, s9 = 0, u9 = 0, sc = 0.*"
+    gdb_test "print container" "$one$two" "distinct bitfields in container"
+    gdb_test "print container.one.u3" ".* = 5"
+    gdb_test "print container.two.u3" ".* = 3"
+}
+
 gdb_start
 gdb_reinitialize_dir $srcdir/$subdir
 gdb_load ${binfile}
@@ -264,3 +284,5 @@ if [istarget "mips-idt-*"] then {
     gdb_load ${binfile}
 }
 bitfield_signedness
+
+bitfield_at_offset
diff --git a/gdb/value.c b/gdb/value.c
index 330ab15..f26e16c 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -1878,7 +1878,7 @@ value_primitive_field (struct value *arg1, int offset,
 	v->bitpos = bitpos % container_bitsize;
       else
 	v->bitpos = bitpos % 8;
-      v->offset = value_offset (arg1) + value_embedded_offset (arg1)
+      v->offset = value_embedded_offset (arg1)
 	+ (bitpos - v->bitpos) / 8;
       v->parent = arg1;
       value_incref (v->parent);
@@ -2031,15 +2031,23 @@ unpack_bits_as_long (struct type *field_type, const gdb_byte *valaddr,
   ULONGEST val;
   ULONGEST valmask;
   int lsbcount;
+  int bytes_read;
 
-  val = extract_unsigned_integer (valaddr + bitpos / 8,
-				  sizeof (val), byte_order);
+  /* Read the minimum number of bytes required; there may not be
+     enough bytes to read an entire ULONGEST.  */
   CHECK_TYPEDEF (field_type);
+  if (bitsize)
+    bytes_read = ((bitpos % 8) + bitsize + 7) / 8;
+  else
+    bytes_read = TYPE_LENGTH (field_type);
+
+  val = extract_unsigned_integer (valaddr + bitpos / 8,
+				  bytes_read, byte_order);
 
   /* Extract bits.  See comment above. */
 
   if (gdbarch_bits_big_endian (get_type_arch (field_type)))
-    lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
+    lsbcount = (bytes_read * 8 - bitpos % 8 - bitsize);
   else
     lsbcount = (bitpos % 8);
   val >>= lsbcount;