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Strip global symbol defined in discarded section

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When a global symbol is defined in COMDAT group, we shouldn't leave an
undefined symbol in symbol table when the symbol section is discarded
unless there is a reference to the symbol outside of COMDAT group.

bfd/

	PR ld/17550
	* elf-bfd.h (elf_link_hash_entry): Update comments for indx,
	documenting that indx == -3 if symbol is defined in a discarded
	section.
	* elflink.c (elf_link_add_object_symbols): Set indx to -3 if
	symbol is defined in a discarded section.
	(elf_link_output_extsym): Strip a global symbol defined in a
	discarded section.

ld/

	PR ld/17550
	* testsuite/ld-elf/pr17550-1.s: New file.
	* testsuite/ld-elf/pr17550-2.s: Likewise.
	* testsuite/ld-elf/pr17550-3.s: Likewise.
	* testsuite/ld-elf/pr17550-4.s: Likewise.
	* testsuite/ld-elf/pr17550a.d: Likewise.
	* testsuite/ld-elf/pr17550b.d: Likewise.
	* testsuite/ld-elf/pr17550c.d: Likewise.
	* testsuite/ld-elf/pr17550d.d: Likewise.
This commit is contained in:
H.J. Lu 2016-05-06 09:46:34 -07:00
parent 030e823caf
commit 97196564c7
12 changed files with 131 additions and 1 deletions
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11
bfd/ChangeLog
View File

@ -1,3 +1,14 @@
2016-05-06 H.J. Lu <hongjiu.lu@intel.com>
PR ld/17550
* elf-bfd.h (elf_link_hash_entry): Update comments for indx,
documenting that indx == -3 if symbol is defined in a discarded
section.
* elflink.c (elf_link_add_object_symbols): Set indx to -3 if
symbol is defined in a discarded section.
(elf_link_output_extsym): Strip a global symbol defined in a
discarded section.
2016-05-06 H.J. Lu <hongjiu.lu@intel.com>
* elf32-i386.c (elf_backend_add_symbol_hook): Defined for Intel

3
bfd/elf-bfd.h
View File

@ -124,7 +124,8 @@ struct elf_link_hash_entry
struct bfd_link_hash_entry root;
/* Symbol index in output file. This is initialized to -1. It is
set to -2 if the symbol is used by a reloc. */
set to -2 if the symbol is used by a reloc. It is set to -3 if
this symbol is defined in a discarded section. */
long indx;
/* Symbol index as a dynamic symbol. Initialized to -1, and remains

12
bfd/elflink.c
View File

@ -4082,6 +4082,7 @@ error_free_dyn:
bfd_boolean old_weak;
bfd_boolean override;
bfd_boolean common;
bfd_boolean discarded;
unsigned int old_alignment;
bfd *old_bfd;
bfd_boolean matched;
@ -4092,6 +4093,7 @@ error_free_dyn:
sec = NULL;
value = isym->st_value;
common = bed->common_definition (isym);
discarded = FALSE;
bind = ELF_ST_BIND (isym->st_info);
switch (bind)
@ -4142,6 +4144,7 @@ error_free_dyn:
/* Symbols from discarded section are undefined. We keep
its visibility. */
sec = bfd_und_section_ptr;
discarded = TRUE;
isym->st_shndx = SHN_UNDEF;
}
else if ((abfd->flags & (EXEC_P | DYNAMIC)) != 0)
@ -4385,6 +4388,11 @@ error_free_dyn:
|| h->root.type == bfd_link_hash_warning)
h = (struct elf_link_hash_entry *) h->root.u.i.link;
/* Setting the index to -3 tells elf_link_output_extsym that
this symbol is defined in a discarded section. */
if (discarded)
h->indx = -3;
*sym_hash = h;
new_weak = (flags & BSF_WEAK) != 0;
@ -9201,6 +9209,10 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
return FALSE;
}
}
/* Strip a global symbol defined in a discarded section. */
if (h->indx == -3)
return TRUE;
}
/* We should also warn if a forced local symbol is referenced from

12
ld/ChangeLog
View File

@ -1,3 +1,15 @@
2016-05-06 H.J. Lu <hongjiu.lu@intel.com>
PR ld/17550
* testsuite/ld-elf/pr17550-1.s: New file.
* testsuite/ld-elf/pr17550-2.s: Likewise.
* testsuite/ld-elf/pr17550-3.s: Likewise.
* testsuite/ld-elf/pr17550-4.s: Likewise.
* testsuite/ld-elf/pr17550a.d: Likewise.
* testsuite/ld-elf/pr17550b.d: Likewise.
* testsuite/ld-elf/pr17550c.d: Likewise.
* testsuite/ld-elf/pr17550d.d: Likewise.
2016-05-06 Senthil Kumar Selvaraj <senthil_kumar.selvaraj@atmel.com>
* ld/testsuite/ld-srec/srec.exp: Mark test as XFAIL for AVR.

9
ld/testsuite/ld-elf/pr17550-1.s Normal file
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@ -0,0 +1,9 @@
.section .data,"awG",%progbits,foo_group,comdat
.dc.a x_alias
.type x, %object
.p2align 2
.size x, 4
x:
.zero 4
.globl x_alias
.set x_alias,x

6
ld/testsuite/ld-elf/pr17550-2.s Normal file
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@ -0,0 +1,6 @@
.section .data,"awG",%progbits,foo_group,comdat
.type x, %object
.p2align 2
.size x, 4
x:
.zero 4

14
ld/testsuite/ld-elf/pr17550-3.s Normal file
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@ -0,0 +1,14 @@
.data
.dc.a y
.section .data,"awG",%progbits,foo_group,comdat
.type y, %object
.size y, 4
y:
.zero 4
.globl x
.type x, %object
.size x, 4
x:
.zero 4
.globl x_alias
.set x_alias,x

15
ld/testsuite/ld-elf/pr17550-4.s Normal file
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@ -0,0 +1,15 @@
.data
.dc.a y
.section .data,"awG",%progbits,foo_group,comdat
.globl y
.type y, %object
.size y, 4
y:
.zero 4
.globl x
.type x, %object
.size x, 4
x:
.zero 4
.globl x_alias
.set x_alias,x

14
ld/testsuite/ld-elf/pr17550a.d Normal file
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@ -0,0 +1,14 @@
#source: pr17550-1.s
#source: pr17550-2.s
#ld: -r
#readelf: -s --wide
#notarget: alpha-*-* cr16-*-* crx-*-* d30v-*-* dlx-*-* i960-*-* pj*-*-*
# Disabled on alpha because alpha has a different .set directive.
# cr16 and crx use non-standard scripts with memory regions, which don't
# play well with comdat group sections under ld -r. Generic linker
# targets don't support comdat group sections.
#failif
#...
+[0-9]+: +[0-9a-f]+ +0 +OBJECT +GLOBAL +DEFAULT +UND x_alias
#...

14
ld/testsuite/ld-elf/pr17550b.d Normal file
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@ -0,0 +1,14 @@
#source: pr17550-2.s
#source: pr17550-1.s
#ld: -r
#readelf: -s --wide
#notarget: alpha-*-* cr16-*-* crx-*-* d30v-*-* dlx-*-* i960-*-* pj*-*-*
# Disabled on alpha because alpha has a different .set directive.
# cr16 and crx use non-standard scripts with memory regions, which don't
# play well with comdat group sections under ld -r. Generic linker
# targets don't support comdat group sections.
#failif
#...
+[0-9]+: +[0-9a-f]+ +0 +OBJECT +GLOBAL +DEFAULT +UND x_alias
#...

9
ld/testsuite/ld-elf/pr17550c.d Normal file
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@ -0,0 +1,9 @@
#source: pr17550-2.s
#source: pr17550-3.s
#ld: -r
#error: .*: defined in discarded section `\.data\[foo_group\]'
#notarget: alpha-*-* cr16-*-* crx-*-* d30v-*-* dlx-*-* i960-*-* pj*-*-*
# Disabled on alpha because alpha has a different .set directive.
# cr16 and crx use non-standard scripts with memory regions, which don't
# play well with comdat group sections under ld -r. Generic linker
# targets don't support comdat group sections.

13
ld/testsuite/ld-elf/pr17550d.d Normal file
View File

@ -0,0 +1,13 @@
#source: pr17550-2.s
#source: pr17550-4.s
#ld: -r
#readelf: -s --wide
#notarget: alpha-*-* cr16-*-* crx-*-* d30v-*-* dlx-*-* i960-*-* pj*-*-*
# Disabled on alpha because alpha has a different .set directive.
# cr16 and crx use non-standard scripts with memory regions, which don't
# play well with comdat group sections under ld -r. Generic linker
# targets don't support comdat group sections.
#...
+[0-9]+: +[0-9a-f]+ +0 +OBJECT +GLOBAL +DEFAULT +UND y
#pass