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Removing empty sections
- From: Alan Modra <amodra at bigpond dot net dot au>
- To: binutils at sources dot redhat dot com
- Date: Fri, 10 Jun 2005 10:06:00 +0930
- Subject: Removing empty sections
See http://sources.redhat.com/bugzilla/show_bug.cgi?id=797
ld/
* scripttempt/elf.sc (.bss): Align tail in a way that allows
empty section pruning.
ld/testsuite/
* ld-scripts/empty-aligned.t: Adjust alignment expressions so
that no .text? section is kept. Also check setting vma and
lma.
* ld-scripts/empty-aligned.d: Update.
Index: ld/scripttempl/elf.sc
===================================================================
RCS file: /cvs/src/src/ld/scripttempl/elf.sc,v
retrieving revision 1.58
diff -u -p -r1.58 elf.sc
--- ld/scripttempl/elf.sc 29 May 2005 23:16:09 -0000 1.58
+++ ld/scripttempl/elf.sc 10 Jun 2005 00:29:49 -0000
@@ -398,7 +398,7 @@ cat <<EOF
/* Align here to ensure that the .bss section occupies space up to
_end. Align after .bss to ensure correct alignment even if the
.bss section disappears because there are no input sections. */
- ${RELOCATING+. = ALIGN(${ALIGNMENT});}
+ ${RELOCATING+. = ALIGN(. != 0 ? ${ALIGNMENT} : 1);}
}
${OTHER_BSS_SECTIONS}
${RELOCATING+. = ALIGN(${ALIGNMENT});}
Index: ld/testsuite/ld-scripts/empty-aligned.d
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-scripts/empty-aligned.d,v
retrieving revision 1.2
diff -u -p -r1.2 empty-aligned.d
--- ld/testsuite/ld-scripts/empty-aligned.d 9 Jun 2005 02:06:58 -0000 1.2
+++ ld/testsuite/ld-scripts/empty-aligned.d 10 Jun 2005 00:29:49 -0000
@@ -6,9 +6,7 @@
Program Headers:
+Type +Offset +VirtAddr +PhysAddr +FileSiz +MemSiz +Flg +Align
+LOAD +0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ [RWE ]+ +0x[0-9a-f]+
- +LOAD +0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ 0x[0-9a-f]+ [RWE ]+ +0x[0-9a-f]+
Section to Segment mapping:
+Segment Sections\.\.\.
- +00.*\.text.*\.text2.*
- +01.*.data.*
+ +00.*\.text.*\.data.*
Index: ld/testsuite/ld-scripts/empty-aligned.t
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-scripts/empty-aligned.t,v
retrieving revision 1.1
diff -u -p -r1.1 empty-aligned.t
--- ld/testsuite/ld-scripts/empty-aligned.t 17 May 2005 16:42:54 -0000 1.1
+++ ld/testsuite/ld-scripts/empty-aligned.t 10 Jun 2005 00:29:49 -0000
@@ -1,15 +1,29 @@
SECTIONS
{
.text : { *(.text) }
- .text2 :
+ /* Alignment at beginning shouldn't result in empty section being kept. */
+ .text1 ALIGN (4096) :
{
- . = ALIGN(4096);
- *(.text2)
+ *(.text1)
}
- .text3 :
+ /* Same for alignment at beginning and end. */
+ .text2 ALIGN (4096) :
{
- *(.text3)
- . = ALIGN(4096);
+ *(.text2)
+ . = ALIGN (4096);
+ }
+ /* Same for alignment just at end, although we need to be careful in
+ the expression used to align. */
+ .text3 :
+ {
+ *(.text3)
+ . = ALIGN (. != 0 ? 4096 : 1);
+ }
+ /* Same when setting vma and lma. This also shouldn't result in
+ .text3 being kept. */
+ .text4 ADDR (.text3) + SIZEOF (.text3) + 8192 : AT (LOADADDR (.text3))
+ {
+ *(.text4)
}
.data : { *(.data) }
.bss : { *(.bss) }
--
Alan Modra
IBM OzLabs - Linux Technology Centre