[binutils-gdb] msp430: Set DWARF2_ADDR_SIZE to 4.

[Kevin Buettner <kevinb at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3d8efabf21cfeb2f6244fadcf915da4c7f51ed6f

commit 3d8efabf21cfeb2f6244fadcf915da4c7f51ed6f
Author: Kevin Buettner <kevinb@redhat.com>
Date:   Wed Jan 27 12:44:38 2016 -0700

    msp430: Set DWARF2_ADDR_SIZE to 4.
    
    This change makes gas's notion of the msp430 dwarf2 address size match
    that of gcc and gdb.  This is needed so that the format of addresses
    generated for DW_LNE_set_address in .debug_line will match the address
    size for the compilation unit.
    
    In gcc/config/msp430/msp430.h, it's set to 4:
    
      #define	DWARF2_ADDR_SIZE			4
    
    Likewise in gdb/msp430-tdep.c:
    
      set_gdbarch_dwarf2_addr_size (gdbarch, 4);
    
    (As far as I can tell, however, GDB doesn't use this value when decoding
    .debug_line.  Instead, GDB uses the Pointer Size from the compilation
    unit.)
    
    readelf is able to seamlessly handle mismatches between these various
    sizes by using the size of the DW_LNE_set_address instruction to
    determine the address size.  Another way to fix this problem is to
    make GDB behave in a similar manner.  In my opinion, GDB should detect
    and inform the user about these mismatches; it's not clear to me if
    it's correct for GDB to go ahead and read the address anyway when a
    size mismatch is detected.
    
    Without this change, addresses in .debug_line are encoded in two bytes
    for some multilibs.  When GDB reads the address for
    DW_LNE_set_address, it uses the pointer size provided by the CU.  When
    these values don't match, GDB reads the wrong number of bytes.  In the
    cases that I've looked at, GDB is reading 4 bytes from a 2 byte
    container, which results in a garbage address.  GDB discards lines
    which have a bogus address; the end result is that GDB records no line
    number information for CUs which have a mismatch between the address
    size (from the CU) and the format of the address used by
    DW_LNE_set_address.
    
    gas/ChangeLog:
    
    	* config/tc-msp430.h (DWARF2_ADDR_SIZE): Set to 4.

Diff:
---
 gas/ChangeLog          | 4 ++++
 gas/config/tc-msp430.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 10a72d2..56146c7 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,7 @@
+2016-02-03  Kevin Buettner  <kevinb@redhat.com>
+
+    	* config/tc-msp430.h (DWARF2_ADDR_SIZE): Set to 4.
+
 2016-02-03  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* NEWS: Mention new command line option -mfence-as-lock-add=yes
diff --git a/gas/config/tc-msp430.h b/gas/config/tc-msp430.h
index 4a02452..86c9117 100644
--- a/gas/config/tc-msp430.h
+++ b/gas/config/tc-msp430.h
@@ -171,3 +171,5 @@ extern bfd_boolean msp430_allow_local_subtract (expressionS *, expressionS *, se
 #define DWARF2_USE_FIXED_ADVANCE_PC 1
 
 #define TC_LINKRELAX_FIXUP(seg) ((seg->flags & SEC_CODE) || (seg->flags & SEC_DEBUGGING))
+
+#define DWARF2_ADDR_SIZE(bfd) 4