commit 23f945bf8cebf348154aff43782de2e1977e9230
Author: Andreas Arnez <arnez@linux.vnet.ibm.com>
Date:   Tue Jun 13 15:20:31 2017 +0200

    Fix bit-/byte-offset mismatch in parameter to read_value_memory
    
    The function read_value_memory accepts a parameter embedded_offset and
    expects it to represent the byte offset into the given value.  However,
    the only invocation with a possibly non-zero embedded_offset happens in
    read_pieced_value, where a bit offset is passed instead.
    
    Adjust the implementation of read_value_memory to meet the caller's
    expectation.  This implicitly fixes the invocation in read_pieced_value.
    
    gdb/ChangeLog:
    
            * valops.c (read_value_memory): Change embedded_offset to
            represent a bit offset instead of a byte offset.
            * value.h (read_value_memory): Adjust comment.

### a/gdb/ChangeLog
### b/gdb/ChangeLog
## -1,5 +1,11 @@
 2017-06-13  Andreas Arnez  <arnez@linux.vnet.ibm.com>
 
+	* valops.c (read_value_memory): Change embedded_offset to
+	represent a bit offset instead of a byte offset.
+	* value.h (read_value_memory): Adjust comment.
+
+2017-06-13  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+
 	* dwarf2loc.c (read_pieced_value): Remove unnecessary variables
 	dest_offset_bits and source_offset_bits.
 	(write_pieced_value): Likewise.
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -958,7 +958,7 @@ value_at_lazy (struct type *type, CORE_ADDR addr)
 }
 
 void
-read_value_memory (struct value *val, LONGEST embedded_offset,
+read_value_memory (struct value *val, LONGEST bit_offset,
 		   int stack, CORE_ADDR memaddr,
 		   gdb_byte *buffer, size_t length)
 {
@@ -984,8 +984,9 @@ read_value_memory (struct value *val, LONGEST embedded_offset,
       if (status == TARGET_XFER_OK)
 	/* nothing */;
       else if (status == TARGET_XFER_UNAVAILABLE)
-	mark_value_bytes_unavailable (val, embedded_offset + xfered_total,
-				      xfered_partial);
+	mark_value_bits_unavailable (val, (xfered_total * HOST_CHAR_BIT
+					   + bit_offset),
+				     xfered_partial * HOST_CHAR_BIT);
       else if (status == TARGET_XFER_EOF)
 	memory_error (TARGET_XFER_E_IO, memaddr + xfered_total);
       else
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -581,12 +581,11 @@ extern int value_contents_eq (const struct value *val1, LONGEST offset1,
 
 /* Read LENGTH addressable memory units starting at MEMADDR into BUFFER,
    which is (or will be copied to) VAL's contents buffer offset by
-   EMBEDDED_OFFSET (that is, to &VAL->contents[EMBEDDED_OFFSET]).
-   Marks value contents ranges as unavailable if the corresponding
-   memory is likewise unavailable.  STACK indicates whether the memory
-   is known to be stack memory.  */
+   BIT_OFFSET bits.  Marks value contents ranges as unavailable if
+   the corresponding memory is likewise unavailable.  STACK indicates
+   whether the memory is known to be stack memory.  */
 
-extern void read_value_memory (struct value *val, LONGEST embedded_offset,
+extern void read_value_memory (struct value *val, LONGEST bit_offset,
 			       int stack, CORE_ADDR memaddr,
 			       gdb_byte *buffer, size_t length);