binutils/

	* NEWS: Mention change in linker script expression evaluation.
ld/
	* ld.texinfo (Expression Section): Detail expression evaluation.
	(Builtin Functions <ADDR>): Correct.
	(Builtin Functions <LOADADDR>): Don't mention LOADADDR normally
	the same as ADDR.
	(Builtin Functions <SEGMENT_START>): Typo fix.
	* ldexp.c (new_number): New function.
	(make_abs, exp_get_abs_int): Cope with NULL expld.result.section.
	(fold_unary <'~', '!', '-'>): Don't make_abs.
	(fold_binary): Simplify result section logic.  Return NULL section
	for logical ops.
	(fold_binary <SEGMENT_START>): Use new_rel_from_abs to set value to
	a consistent result.
	(fold_name <SIZEOF_HEADERS>): Return new_number, not new_abs.
	(fold_name <DEFINED, SIZEOF, ALIGNOF, LENGTH, CONSTANT>): Likewise.
	(fold_name <NAME>): No need to handle absolute symbols differently
	from relative ones.
	(fold_name <ORIGIN>): Don't return valid result when
	lang_first_phase_enum.  Return new_rel_from_abs, not new_abs.
	(exp_fold_tree_1 <etree_value>): Return new_number, not new_rel.
	(exp_fold_tree_1): Ajust for NULL expld.result.section.  When assigning
	a plain number to dot, assume the value is relative to expld.section.
	Make terms not in an output section, absolute.
	* ldlang.c (print_assignment): Fix style nit.
	(lang_size_sections_1): Cope with NULL expld.result.section.
	(lang_do_assignments_1): Likewise.
ld/testsuite/
	* ld-scripts/memory.t: Remove ORIGIN fudge.

6 files changed, 220 insertions, 124 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 30cb4eb..e0873ae 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,31 @@
+2010-08-19  Alan Modra  <amodra@gmail.com>
+
+	* ld.texinfo (Expression Section): Detail expression evaluation.
+	(Builtin Functions <ADDR>): Correct.
+	(Builtin Functions <LOADADDR>): Don't mention LOADADDR normally
+	the same as ADDR.
+	(Builtin Functions <SEGMENT_START>): Typo fix.
+	* ldexp.c (new_number): New function.
+	(make_abs, exp_get_abs_int): Cope with NULL expld.result.section.
+	(fold_unary <'~', '!', '-'>): Don't make_abs.
+	(fold_binary): Simplify result section logic.  Return NULL section
+	for logical ops.
+	(fold_binary <SEGMENT_START>): Use new_rel_from_abs to set value to
+	a consistent result.
+	(fold_name <SIZEOF_HEADERS>): Return new_number, not new_abs.
+	(fold_name <DEFINED, SIZEOF, ALIGNOF, LENGTH, CONSTANT>): Likewise.
+	(fold_name <NAME>): No need to handle absolute symbols differently
+	from relative ones.
+	(fold_name <ORIGIN>): Don't return valid result when
+	lang_first_phase_enum.  Return new_rel_from_abs, not new_abs.
+	(exp_fold_tree_1 <etree_value>): Return new_number, not new_rel.
+	(exp_fold_tree_1): Ajust for NULL expld.result.section.  When assigning
+	a plain number to dot, assume the value is relative to expld.section.
+	Make terms not in an output section, absolute.
+	* ldlang.c (print_assignment): Fix style nit.
+	(lang_size_sections_1): Cope with NULL expld.result.section.
+	(lang_do_assignments_1): Likewise.
+
 2010-08-12  Alan Modra  <amodra@gmail.com>
 
 	* ldexp.c (new_rel): Remove "str".  Update all call sites.
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 8928350..7470c53 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -5447,23 +5447,82 @@ address}.
 @cindex absolute and relocatable symbols
 @cindex relocatable and absolute symbols
 @cindex symbols, relocatable and absolute
-When the linker evaluates an expression, the result is either absolute
-or relative to some section.  A relative expression is expressed as a
-fixed offset from the base of a section.
+Addresses and symbols may be section relative, or absolute.  A section
+relative symbol is relocatable.  If you request relocatable output
+using the @samp{-r} option, a further link operation may change the
+value of a section relative symbol.  On the other hand, an absolute
+symbol will retain the same value throughout any further link
+operations.
+
+Some terms in linker expressions are addresses.  This is true of all
+symbols and for builtin functions that return an address, such as
+@code{ADDR}, @code{LOADADDR}, @code{ORIGIN} and @code{SEGMENT_START}.
+Other terms are simply numbers, or are builtin functions that return a
+non-address value, such as @code{LENGTH}.
+
+When the linker evaluates an expression, the result depends on where
+the expression is located in a linker script.  Expressions appearing
+outside an output section definitions are evaluated with all terms
+first being converted to absolute addresses before applying operators,
+and evaluate to an absolute address result.  Expressions appearing
+inside an output section definition are evaluated with more complex
+rules, but the aim is to treat terms as relative addresses and produce
+a relative address result.  In particular, an assignment of a number
+to a symbol results in a symbol relative to the output section with an
+offset given by the number.  So, in the following simple example,
 
-The position of the expression within the linker script determines
-whether it is absolute or relative.  An expression which appears within
-an output section definition is relative to the base of the output
-section.  An expression which appears elsewhere will be absolute.
+@smallexample
+@group
+SECTIONS
+  @{
+    . = 0x100;
+    __executable_start = 0x100;
+    .data :
+    @{
+      . = 0x10;
+      __data_start = 0x10;
+      *(.data)
+    @}
+    @dots{}
+  @}
+@end group
+@end smallexample
 
-A symbol set to a relative expression will be relocatable if you request
-relocatable output using the @samp{-r} option.  That means that a
-further link operation may change the value of the symbol.  The symbol's
-section will be the section of the relative expression.
+both @code{.} and @code{__executable_start} are set to the absolute
+address 0x100 in the first two assignments, then both @code{.} and
+@code{__data_start} are set to 0x10 relative to the @code{.data}
+section in the second two assignments.
 
-A symbol set to an absolute expression will retain the same value
-through any further link operation.  The symbol will be absolute, and
-will not have any particular associated section.
+For expressions appearing inside an output section definition
+involving numbers, relative addresses and absolute addresses, ld
+follows these rules to evaluate terms:
+
+@itemize @bullet
+@item
+Unary operations on a relative address, and binary operations on two
+relative addresses in the same section or between one relative address
+and a number, apply the operator to the offset part of the address(es).
+@item
+Unary operations on an absolute address, and binary operations on one
+or more absolute addresses or on two relative addresses not in the
+same section, first convert any non-absolute term to an absolute
+address before applying the operator.
+@end itemize
+
+The result section of each sub-expression is as follows:
+
+@itemize @bullet
+@item
+An operation involving only numbers results in a number.
+@item
+The result of comparisons, @samp{&&} and @samp{||} is also a number.
+@item
+The result of other operations on relative addresses (after above
+conversions) is a relative address in the same section as the operand(s).
+@item
+The result of other operations on absolute addresses (after above
+conversions) is an absolute address.
+@end itemize
 
 You can use the builtin function @code{ABSOLUTE} to force an expression
 to be absolute when it would otherwise be relative.  For example, to
@@ -5479,6 +5538,9 @@ SECTIONS
 If @samp{ABSOLUTE} were not used, @samp{_edata} would be relative to the
 @samp{.data} section.
 
+Using @code{LOADADDR} also forces an expression absolute, since this
+particular builtin function returns an absolute address.
+
 @node Builtin Functions
 @subsection Builtin Functions
 @cindex functions in expressions
@@ -5497,10 +5559,12 @@ normally section relative.  @xref{Expression Section}.
 @item ADDR(@var{section})
 @kindex ADDR(@var{section})
 @cindex section address in expression
-Return the absolute address (the VMA) of the named @var{section}.  Your
+Return the address (VMA) of the named @var{section}.  Your
 script must previously have defined the location of that section.  In
-the following example, @code{symbol_1} and @code{symbol_2} are assigned
-identical values:
+the following example, @code{start_of_output_1}, @code{symbol_1} and
+@code{symbol_2} are assigned equivalent values, except that
+@code{symbol_1} will be relative to the @code{.output1} section while
+the other two will be absolute:
 @smallexample
 @group
 SECTIONS @{ @dots{}
@@ -5664,9 +5728,7 @@ Return the length of the memory region named @var{memory}.
 @item LOADADDR(@var{section})
 @kindex LOADADDR(@var{section})
 @cindex section load address in expression
-Return the absolute LMA of the named @var{section}.  This is normally
-the same as @code{ADDR}, but it may be different if the @code{AT}
-attribute is used in the output section definition (@pxref{Output
+Return the absolute LMA of the named @var{section}.  (@pxref{Output
 Section LMA}).
 
 @kindex MAX
@@ -5696,7 +5758,7 @@ value has been given for this segment (with a command-line @samp{-T}
 option) that value will be returned; otherwise the value will be
 @var{default}.  At present, the @samp{-T} command-line option can only
 be used to set the base address for the ``text'', ``data'', and
-``bss'' sections, but you use @code{SEGMENT_START} with any segment
+``bss'' sections, but you can use @code{SEGMENT_START} with any segment
 name.
 
 @item SIZEOF(@var{section})
diff --git a/ld/ldexp.c b/ld/ldexp.c
index 050227d..0549f19 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -138,7 +138,8 @@ exp_print_token (token_code_type code, int infix_p)
 static void
 make_abs (void)
 {
-  expld.result.value += expld.result.section->vma;
+  if (expld.result.section != NULL)
+    expld.result.value += expld.result.section->vma;
   expld.result.section = bfd_abs_section_ptr;
 }
 
@@ -190,6 +191,15 @@ exp_relop (asection *section, bfd_vma value)
 }
 
 static void
+new_number (bfd_vma value)
+{
+  expld.result.valid_p = TRUE;
+  expld.result.value = value;
+  expld.result.str = NULL;
+  expld.result.section = NULL;
+}
+
+static void
 new_rel (bfd_vma value, asection *section)
 {
   expld.result.valid_p = TRUE;
@@ -227,17 +237,14 @@ fold_unary (etree_type *tree)
 	  break;
 
 	case '~':
-	  make_abs ();
 	  expld.result.value = ~expld.result.value;
 	  break;
 
 	case '!':
-	  make_abs ();
 	  expld.result.value = !expld.result.value;
 	  break;
 
 	case '-':
-	  make_abs ();
 	  expld.result.value = -expld.result.value;
 	  break;
 
@@ -293,6 +300,7 @@ fold_binary (etree_type *tree)
     {
       const char *segment_name;
       segment_type *seg;
+
       /* Check to see if the user has overridden the default
 	 value.  */
       segment_name = tree->binary.rhs->name.name;
@@ -305,9 +313,7 @@ fold_binary (etree_type *tree)
 	      einfo (_("%P: warning: address of `%s' isn't multiple of maximum page size\n"),
 		     segment_name);
 	    seg->used = TRUE;
-	    expld.result.value = seg->value;
-	    expld.result.str = NULL;
-	    expld.result.section = expld.section;
+	    new_rel_from_abs (seg->value);
 	    break;
 	  }
       return;
@@ -319,32 +325,20 @@ fold_binary (etree_type *tree)
 
   if (expld.result.valid_p)
     {
-      /* If the values are from different sections, or this is an
-	 absolute expression, make both the source arguments
-	 absolute.  However, adding or subtracting an absolute
-	 value from a relative value is meaningful, and is an
-	 exception.  */
-      if (expld.section != bfd_abs_section_ptr
-	  && lhs.section == bfd_abs_section_ptr
-	  && tree->type.node_code == '+')
+      if (lhs.section != expld.result.section)
 	{
-	  /* Keep the section of the rhs term.  */
-	  expld.result.value = lhs.value + expld.result.value;
-	  return;
-	}
-      else if (expld.section != bfd_abs_section_ptr
-	       && expld.result.section == bfd_abs_section_ptr
-	       && (tree->type.node_code == '+'
-		   || tree->type.node_code == '-'))
-	{
-	  /* Keep the section of the lhs term.  */
-	  expld.result.section = lhs.section;
-	}
-      else if (expld.result.section != lhs.section
-	       || expld.section == bfd_abs_section_ptr)
-	{
-	  make_abs ();
-	  lhs.value += lhs.section->vma;
+	  /* If the values are from different sections, and neither is
+	     just a number, make both the source arguments absolute.  */
+	  if (expld.result.section != NULL
+	      && lhs.section != NULL)
+	    {
+	      make_abs ();
+	      lhs.value += lhs.section->vma;
+	    }
+
+	  /* If the rhs is just a number, keep the lhs section.  */
+	  else if (expld.result.section == NULL)
+	    expld.result.section = lhs.section;
 	}
 
       switch (tree->type.node_code)
@@ -366,26 +360,32 @@ fold_binary (etree_type *tree)
 	  break;
 
 #define BOP(x, y) \
-	    case x:							\
-	      expld.result.value = lhs.value y expld.result.value;	\
-	      break;
+	case x:							\
+	  expld.result.value = lhs.value y expld.result.value;	\
+	  break;
+
+#define BOPN(x, y) \
+	case x:							\
+	  expld.result.value = lhs.value y expld.result.value;	\
+	  expld.result.section = NULL;				\
+	  break;
 
 	  BOP ('+', +);
 	  BOP ('*', *);
 	  BOP ('-', -);
 	  BOP (LSHIFT, <<);
 	  BOP (RSHIFT, >>);
-	  BOP (EQ, ==);
-	  BOP (NE, !=);
-	  BOP ('<', <);
-	  BOP ('>', >);
-	  BOP (LE, <=);
-	  BOP (GE, >=);
 	  BOP ('&', &);
 	  BOP ('^', ^);
 	  BOP ('|', |);
-	  BOP (ANDAND, &&);
-	  BOP (OROR, ||);
+	  BOPN (EQ, ==);
+	  BOPN (NE, !=);
+	  BOPN ('<', <);
+	  BOPN ('>', >);
+	  BOPN (LE, <=);
+	  BOPN (GE, >=);
+	  BOPN (ANDAND, &&);
+	  BOPN (OROR, ||);
 
 	case MAX_K:
 	  if (lhs.value > expld.result.value)
@@ -499,7 +499,7 @@ fold_name (etree_type *tree)
 	     The bfd function may cache incorrect data.  */
 	  if (expld.phase != lang_mark_phase_enum)
 	    hdr_size = bfd_sizeof_headers (link_info.output_bfd, &link_info);
-	  new_abs (hdr_size);
+	  new_number (hdr_size);
 	}
       break;
 
@@ -516,14 +516,12 @@ fold_name (etree_type *tree)
 					    &link_info,
 					    tree->name.name,
 					    FALSE, FALSE, TRUE);
-	  expld.result.value = (h != NULL
-				&& (h->type == bfd_link_hash_defined
-				    || h->type == bfd_link_hash_defweak
-				    || h->type == bfd_link_hash_common)
-				&& (def_iteration == lang_statement_iteration
-				    || def_iteration == -1));
-	  expld.result.section = expld.section;
-	  expld.result.valid_p = TRUE;
+	  new_number (h != NULL
+		      && (h->type == bfd_link_hash_defined
+			  || h->type == bfd_link_hash_defweak
+			  || h->type == bfd_link_hash_common)
+		      && (def_iteration == lang_statement_iteration
+			  || def_iteration == -1));
 	}
       break;
 
@@ -545,24 +543,19 @@ fold_name (etree_type *tree)
 	  else if (h->type == bfd_link_hash_defined
 		   || h->type == bfd_link_hash_defweak)
 	    {
-	      if (bfd_is_abs_section (h->u.def.section))
-		new_abs (h->u.def.value);
-	      else
-		{
-		  asection *output_section;
+	      asection *output_section;
 
-		  output_section = h->u.def.section->output_section;
-		  if (output_section == NULL)
-		    {
-		      if (expld.phase != lang_mark_phase_enum)
-			einfo (_("%X%S: unresolvable symbol `%s'"
-				 " referenced in expression\n"),
-			       tree->name.name);
-		    }
-		  else
-		    new_rel (h->u.def.value + h->u.def.section->output_offset,
-			     output_section);
+	      output_section = h->u.def.section->output_section;
+	      if (output_section == NULL)
+		{
+		  if (expld.phase != lang_mark_phase_enum)
+		    einfo (_("%X%S: unresolvable symbol `%s'"
+			     " referenced in expression\n"),
+			   tree->name.name);
 		}
+	      else
+		new_rel (h->u.def.value + h->u.def.section->output_offset,
+			 output_section);
 	    }
 	  else if (expld.phase == lang_final_phase_enum
 		   || expld.assigning_to_dot)
@@ -633,7 +626,7 @@ fold_name (etree_type *tree)
 	      if (expld.phase == lang_final_phase_enum)
 		einfo (_("%F%S: undefined section `%s' referenced in expression\n"),
 		       tree->name.name);
-	      new_abs (0);
+	      new_number (0);
 	    }
 	  else if (os->processed_vma)
 	    {
@@ -645,7 +638,7 @@ fold_name (etree_type *tree)
 	      else
 		val = (bfd_vma)1 << os->bfd_section->alignment_power;
 	      
-	      new_abs (val);
+	      new_number (val);
 	    }
 	}
       break;
@@ -656,7 +649,7 @@ fold_name (etree_type *tree)
         
         mem = lang_memory_region_lookup (tree->name.name, FALSE);  
         if (mem != NULL) 
-          new_abs (mem->length);
+          new_number (mem->length);
         else          
           einfo (_("%F%S: undefined MEMORY region `%s'"
 		   " referenced in expression\n"), tree->name.name);
@@ -664,23 +657,24 @@ fold_name (etree_type *tree)
       break;
 
     case ORIGIN:
-      {
-        lang_memory_region_type *mem;
+      if (expld.phase != lang_first_phase_enum)
+	{
+	  lang_memory_region_type *mem;
         
-        mem = lang_memory_region_lookup (tree->name.name, FALSE);  
-        if (mem != NULL) 
-          new_abs (mem->origin);
-        else          
-          einfo (_("%F%S: undefined MEMORY region `%s'"
-		   " referenced in expression\n"), tree->name.name);
-      }
+	  mem = lang_memory_region_lookup (tree->name.name, FALSE);  
+	  if (mem != NULL) 
+	    new_rel_from_abs (mem->origin);
+	  else          
+	    einfo (_("%F%S: undefined MEMORY region `%s'"
+		     " referenced in expression\n"), tree->name.name);
+	}
       break;
 
     case CONSTANT:
       if (strcmp (tree->name.name, "MAXPAGESIZE") == 0)
-	new_abs (config.maxpagesize);
+	new_number (config.maxpagesize);
       else if (strcmp (tree->name.name, "COMMONPAGESIZE") == 0)
-	new_abs (config.commonpagesize);
+	new_number (config.commonpagesize);
       else
 	einfo (_("%F%S: unknown constant `%s' referenced in expression\n"),
 	       tree->name.name);
@@ -704,7 +698,7 @@ exp_fold_tree_1 (etree_type *tree)
   switch (tree->type.node_class)
     {
     case etree_value:
-      new_rel (tree->value.value, expld.section);
+      new_number (tree->value.value);
       expld.result.str = tree->value.str;
       break;
 
@@ -767,7 +761,11 @@ exp_fold_tree_1 (etree_type *tree)
 		{
 		  bfd_vma nextdot;
 
-		  nextdot = expld.result.value + expld.result.section->vma;
+		  nextdot = expld.result.value;
+		  if (expld.result.section != NULL)
+		    nextdot += expld.result.section->vma;
+		  else
+		    nextdot += expld.section->vma;
 		  if (nextdot < expld.dot
 		      && expld.section != bfd_abs_section_ptr)
 		    einfo (_("%F%S cannot move location counter backwards"
@@ -818,6 +816,8 @@ exp_fold_tree_1 (etree_type *tree)
 	      lang_update_definedness (tree->assign.dst, h);
 	      h->type = bfd_link_hash_defined;
 	      h->u.def.value = expld.result.value;
+	      if (expld.result.section == NULL)
+		expld.result.section = expld.section;
 	      h->u.def.section = expld.result.section;
 	      if (tree->type.node_class == etree_provide)
 		tree->type.node_class = etree_provided;
@@ -856,6 +856,12 @@ exp_fold_tree_1 (etree_type *tree)
       memset (&expld.result, 0, sizeof (expld.result));
       break;
     }
+
+  /* Any value not inside an output section statement is an
+     absolute value.  */
+  if (expld.result.valid_p
+      && expld.section == bfd_abs_section_ptr)
+    make_abs ();
 }
 
 void
@@ -1186,7 +1192,8 @@ exp_get_abs_int (etree_type *tree, int def, char *name)
 
       if (expld.result.valid_p)
 	{
-	  expld.result.value += expld.result.section->vma;
+	  if (expld.result.section != NULL)
+	    expld.result.value += expld.result.section->vma;
 	  return expld.result.value;
 	}
       else if (name != NULL && expld.phase != lang_mark_phase_enum)
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 41ab2ee..2b9971a 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -3916,7 +3916,7 @@ print_assignment (lang_assignment_statement_type *assignment,
 	{
 	  value = expld.result.value;
 
-	  if (expld.result.section)
+	  if (expld.result.section != NULL)
 	    value += expld.result.section->vma;
 
 	  minfo ("0x%V", value);
@@ -3933,7 +3933,7 @@ print_assignment (lang_assignment_statement_type *assignment,
 	    {
 	      value = h->u.def.value;
 
-	      if (expld.result.section)
+	      if (expld.result.section != NULL)
 		value += expld.result.section->vma;
 
 	      minfo ("[0x%V]", value);
@@ -4718,7 +4718,11 @@ lang_size_sections_1
 		exp_fold_tree (os->addr_tree, bfd_abs_section_ptr, &dot);
 
 		if (expld.result.valid_p)
-		  dot = expld.result.value + expld.result.section->vma;
+		  {
+		    dot = expld.result.value;
+		    if (expld.result.section != NULL)
+		      dot += expld.result.section->vma;
+		  }
 		else if (expld.phase != lang_mark_phase_enum)
 		  einfo (_("%F%S: non constant or forward reference"
 			   " address expression for section %s\n"),
@@ -5397,8 +5401,11 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 	case lang_data_statement_enum:
 	  exp_fold_tree (s->data_statement.exp, bfd_abs_section_ptr, &dot);
 	  if (expld.result.valid_p)
-	    s->data_statement.value = (expld.result.value
-				       + expld.result.section->vma);
+	    {
+	      s->data_statement.value = expld.result.value;
+	      if (expld.result.section != NULL)
+		s->data_statement.value += expld.result.section->vma;
+	    }
 	  else
 	    einfo (_("%F%P: invalid data statement\n"));
 	  {
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index c15a44e..dd7ee77 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2010-08-19  Alan Modra  <amodra@gmail.com>
+
+	* ld-scripts/memory.t: Remove ORIGIN fudge.
+
 2010-08-13  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/11913
diff --git a/ld/testsuite/ld-scripts/memory.t b/ld/testsuite/ld-scripts/memory.t
index 6623b28..129bd7c 100644
--- a/ld/testsuite/ld-scripts/memory.t
+++ b/ld/testsuite/ld-scripts/memory.t
@@ -15,19 +15,7 @@ SECTIONS
   . = 0;
   .text :
   {
-    /* The value returned by the ORIGIN operator is a constant.
-       However it is being assigned to a symbol declared within
-       a section.  Therefore the symbol is section-relative and
-       its value will include the offset of that section from
-       the start of memory.  ie the declaration:
-          text_start = ORIGIN (TEXTMEM);
-       here will result in text_start having a value of 0x200.
-       Hence we need to subtract the absolute value of the
-       location counter at this point in order to give text_start
-       a value that is truely absolute, and which coincidentally
-       will allow the tests in script.exp to work.  */
- 	
-    text_start = ORIGIN(TEXTMEM) - ABSOLUTE (.);
+    text_start = ORIGIN (TEXTMEM);
     *(.text)
     *(.pr)
     text_end = .;