cp-valprint.c, always pass valaddr == value->contents to val_print & co

[Pedro Alves <pedro at codesourcery dot com>]

Following up on <http://sourceware.org/ml/gdb-patches/2010-10/msg00127.html>,

This cp-valprint.c code path violates the
"always pass valaddr == value->contents to val_print & co" assertion I
mentioned adding before.  Ensuring that's always true allows:

 - querying the passed in value for metadata about the
   contents/valaddr+embedded_offset we're handling.
 - at some point in the future actually getting rid of the valaddr parameter.

Tested on x86_64-linux and applied.

-- 
Pedro Alves

2011-01-25  Pedro Alves  <pedro@codesourcery.com>

	gdb/
	* cp-valprint.c (cp_print_value): Treat the 'skip' local as
	boolean.  Make sure to always pass a value that matches the
	contents buffer to callees.  Preserve `address' for following
	iterations.
	* value.c (value_contents_for_printing_const): New.
	(value_address): Constify value argument.
	* value.h (value_contents_for_printing_const): Declare.
	(value_address): Constify value argument.

---
 gdb/cp-valprint.c |   35 +++++++++++++++++++++++------------
 gdb/value.c       |    9 ++++++++-
 gdb/value.h       |    8 +++++++-
 3 files changed, 38 insertions(+), 14 deletions(-)

Index: src/gdb/cp-valprint.c
===================================================================
--- src.orig/gdb/cp-valprint.c	2011-01-25 09:09:07.000000000 +0000
+++ src/gdb/cp-valprint.c	2011-01-25 13:05:13.107639996 +0000
@@ -488,6 +488,7 @@ cp_print_value (struct type *type, struc
       struct type *baseclass = check_typedef (TYPE_BASECLASS (type, i));
       char *basename = TYPE_NAME (baseclass);
       const gdb_byte *base_valaddr;
+      const struct value *base_val;
 
       if (BASETYPE_VIA_VIRTUAL (type, i))
 	{
@@ -509,7 +510,7 @@ cp_print_value (struct type *type, struc
 
       boffset = baseclass_offset (type, i, valaddr + offset,
 				  address + offset);
-      skip = ((boffset == -1) || (boffset + offset) < 0) ? 1 : -1;
+      skip = ((boffset == -1) || (boffset + offset) < 0);
 
       if (BASETYPE_VIA_VIRTUAL (type, i))
 	{
@@ -525,20 +526,28 @@ cp_print_value (struct type *type, struc
 		 large.  */
 	      gdb_byte *buf = alloca (TYPE_LENGTH (baseclass));
 
-	      base_valaddr = buf;
 	      if (target_read_memory (address + boffset, buf,
 				      TYPE_LENGTH (baseclass)) != 0)
 		skip = 1;
-	      address = address + boffset;
+	      base_val = value_from_contents_and_address (baseclass,
+							  buf,
+							  address + boffset);
 	      thisoffset = 0;
 	      boffset = 0;
 	      thistype = baseclass;
+	      base_valaddr = value_contents_for_printing_const (base_val);
 	    }
 	  else
-	    base_valaddr = valaddr;
+	    {
+	      base_valaddr = valaddr;
+	      base_val = val;
+	    }
 	}
       else
-	base_valaddr = valaddr;
+	{
+	  base_valaddr = valaddr;
+	  base_val = val;
+	}
 
       /* Now do the printing.  */
       if (options->pretty)
@@ -553,7 +562,7 @@ cp_print_value (struct type *type, struc
       fputs_filtered ("> = ", stream);
 
 
-      if (skip >= 1)
+      if (skip)
 	fprintf_filtered (stream, "<invalid address>");
       else
 	{
@@ -564,15 +573,17 @@ cp_print_value (struct type *type, struc
 	  if (!options->raw)
 	    result = apply_val_pretty_printer (baseclass, base_valaddr,
 					       thisoffset + boffset,
-					       address,
-					       stream, recurse,
-					       val, options,
-					       current_language);
+					       value_address (base_val),
+					       stream, recurse, base_val,
+					       options, current_language);
+
+
 	  	  
 	  if (!result)
 	    cp_print_value_fields (baseclass, thistype, base_valaddr,
-				   thisoffset + boffset, address,
-				   stream, recurse, val, options,
+				   thisoffset + boffset,
+				   value_address (base_val),
+				   stream, recurse, base_val, options,
 				   ((struct type **)
 				    obstack_base (&dont_print_vb_obstack)),
 				   0);
Index: src/gdb/value.c
===================================================================
--- src.orig/gdb/value.c	2011-01-24 21:32:37.000000000 +0000
+++ src/gdb/value.c	2011-01-25 13:08:23.447639990 +0000
@@ -435,6 +435,13 @@ value_contents_for_printing (struct valu
 }
 
 const gdb_byte *
+value_contents_for_printing_const (const struct value *value)
+{
+  gdb_assert (!value->lazy);
+  return value->contents;
+}
+
+const gdb_byte *
 value_contents_all (struct value *value)
 {
   const gdb_byte *result = value_contents_for_printing (value);
@@ -596,7 +603,7 @@ deprecated_value_lval_hack (struct value
 }
 
 CORE_ADDR
-value_address (struct value *value)
+value_address (const struct value *value)
 {
   if (value->lval == lval_internalvar
       || value->lval == lval_internalvar_component)
Index: src/gdb/value.h
===================================================================
--- src.orig/gdb/value.h	2011-01-24 21:32:37.000000000 +0000
+++ src/gdb/value.h	2011-01-25 15:17:06.517639989 +0000
@@ -273,6 +273,12 @@ extern const gdb_byte *value_contents_al
    plan to check the validity manually.  */
 extern const gdb_byte *value_contents_for_printing (struct value *value);
 
+/* Like value_contents_for_printing, but accepts a constant value
+   pointer.  Unlike value_contents_for_printing however, the pointed
+   value must _not_ be lazy.  */
+extern const gdb_byte *
+  value_contents_for_printing_const (const struct value *value);
+
 extern int value_fetch_lazy (struct value *val);
 extern int value_contents_equal (struct value *val1, struct value *val2);
 
@@ -308,7 +314,7 @@ extern enum lval_type *deprecated_value_
    lval == lval_register, return the byte offset into the registers
    structure.  Otherwise, return 0.  The returned address
    includes the offset, if any.  */
-extern CORE_ADDR value_address (struct value *);
+extern CORE_ADDR value_address (const struct value *);
 
 /* Like value_address, except the result does not include value's
    offset.  */