Re: PATCH: Fix empty sections with alignment

["H. J. Lu" <hjl@lucon.org>]

On Tue, Sep 27, 2005 at 08:04:05AM -0700, H. J. Lu wrote:
> > 
> > Instead, I think we need some linker script construct that allows us to
> > increase the alignment of an output section over that specified by its
> > input sections, other than using ALIGN() as the address.  Perhaps an
> > ALIGN() after the semicolon.  lang_enter_output_section_statement
> > already supports an output section alignment.
> 
> I will look into it.
> 

Here is the patch to allow ALIGN to be used to force output section
alignment.


H.J.
----
2005-09-27  H.J. Lu  <hongjiu.lu@intel.com>

	* ld.texinfo (ALIGN): Document it as forcing output section
	alignment.

	* ldgram.y (ALIGN): Support it for forcing output section
	alignment.

--- ld/ld.texinfo.align	2005-09-26 13:12:55.000000000 -0700
+++ ld/ld.texinfo	2005-09-27 10:11:16.000000000 -0700
@@ -3067,7 +3067,7 @@ The full description of an output sectio
 @smallexample
 @group
 @var{section} [@var{address}] [(@var{type})] :
-  [AT(@var{lma})] [SUBALIGN(@var{subsection_align})]
+  [AT(@var{lma})] [ALIGN(@var{section_align})] [SUBALIGN(@var{subsection_align})]
   @{
     @var{output-section-command}
     @var{output-section-command}
@@ -3643,7 +3643,7 @@ like this:
 @smallexample
 @group
 @var{section} [@var{address}] [(@var{type})] :
-  [AT(@var{lma})] [SUBALIGN(@var{subsection_align})]
+  [AT(@var{lma})] [ALIGN(@var{section_align})] [SUBALIGN(@var{subsection_align})]
   @{
     @var{output-section-command}
     @var{output-section-command}
@@ -3658,6 +3658,7 @@ remaining section attributes.
 @menu
 * Output Section Type::		Output section type
 * Output Section LMA::		Output section LMA
+* Forced Output Alignment::	Forced Output Alignment
 * Forced Input Alignment::	Forced Input Alignment
 * Output Section Region::	Output section region
 * Output Section Phdr::		Output section phdr
@@ -3771,6 +3772,15 @@ for (dst = &_bstart; dst< &_bend; dst++)
 @end group
 @end smallexample
 
+@node Forced Output Alignment
+@subsubsection Forced Output Alignment
+@kindex ALIGN(@var{section_align})
+@cindex forcing output section alignment
+@cindex output section alignment
+You can force an output section alignment by using ALIGN.  The value
+specified overrides any alignment given by input sections, whether
+larger or smaller.
+
 @node Forced Input Alignment
 @subsubsection Forced Input Alignment
 @kindex SUBALIGN(@var{subsection_align})
--- ld/ldgram.y.align	2005-09-26 13:12:55.000000000 -0700
+++ ld/ldgram.y	2005-09-27 10:04:14.000000000 -0700
@@ -92,7 +92,7 @@ static int error_index;
 }
 
 %type <etree> exp opt_exp_with_type mustbe_exp opt_at phdr_type phdr_val
-%type <etree> opt_exp_without_type opt_subalign
+%type <etree> opt_exp_without_type opt_subalign opt_align
 %type <fill> fill_opt fill_exp
 %type <name_list> exclude_name_list
 %type <wildcard_list> file_NAME_list
@@ -892,6 +892,11 @@ opt_at:
 	|	{ $$ = 0; }
 	;
 
+opt_align:
+		ALIGN_K '(' exp ')' { $$ = $3; }
+	|	{ $$ = 0; }
+	;
+
 opt_subalign:
 		SUBALIGN '(' exp ')' { $$ = $3; }
 	|	{ $$ = 0; }
@@ -907,20 +912,21 @@ sect_constraint:
 section:	NAME 		{ ldlex_expression(); }
 		opt_exp_with_type
 		opt_at
+		opt_align
 		opt_subalign	{ ldlex_popstate (); ldlex_script (); }
 		sect_constraint
 		'{'
 			{
 			  lang_enter_output_section_statement($1, $3,
 							      sectype,
-							      0, $5, $4, $7);
+							      $5, $6, $4, $8);
 			}
 		statement_list_opt
  		'}' { ldlex_popstate (); ldlex_expression (); }
 		memspec_opt memspec_at_opt phdr_opt fill_opt
 		{
 		  ldlex_popstate ();
-		  lang_leave_output_section_statement ($16, $13, $15, $14);
+		  lang_leave_output_section_statement ($17, $14, $16, $15);
 		}
 		opt_comma
 		{}