[binutils-gdb] write_pieced_value: Fix buffer offset for memory pieces

[Andreas Arnez <arnez at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=07c9ca3bd8e6f83bcec49c922b52422c538f60f7

commit 07c9ca3bd8e6f83bcec49c922b52422c538f60f7
Author: Andreas Arnez <arnez@linux.vnet.ibm.com>
Date:   Tue Jun 13 15:20:28 2017 +0200

    write_pieced_value: Fix buffer offset for memory pieces
    
    In write_pieced_value, when transferring the data to target memory via a
    buffer, the bit offset within the target value is not reduced to its
    sub-byte fraction before using it as a bit offset into the buffer.  This
    is fixed.
    
    gdb/ChangeLog:
    
    	* dwarf2loc.c (write_pieced_value): In DWARF_VALUE_MEMORY,
    	truncate full bytes from dest_offset_bits before using it as an
    	offset into the buffer.

Diff:
---
 gdb/ChangeLog   | 6 ++++++
 gdb/dwarf2loc.c | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ee4c9d8..296d187 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2017-06-13  Andreas Arnez  <arnez@linux.vnet.ibm.com>
 
+	* dwarf2loc.c (write_pieced_value): In DWARF_VALUE_MEMORY,
+	truncate full bytes from dest_offset_bits before using it as an
+	offset into the buffer.
+
+2017-06-13  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+
 	* dwarf2loc.c (write_pieced_value): Include transfer size in
 	byte-wise check.
 
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 2849dad..67a123f 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -2058,7 +2058,7 @@ write_pieced_value (struct value *to, struct value *from)
 	      read_memory (p->v.mem.addr + dest_offset, buffer.data (), 1);
 	      read_memory (p->v.mem.addr + dest_offset + this_size - 1,
 			   &buffer[this_size - 1], 1);
-	      copy_bitwise (buffer.data (), dest_offset_bits,
+	      copy_bitwise (buffer.data (), dest_offset_bits % 8,
 			    contents, source_offset_bits,
 			    this_size_bits,
 			    bits_big_endian);