Use a symbol flag bit to mark linker defined symbols

Alan Modra amodra@gmail.com
Tue Dec 23 12:50:00 GMT 2014


Trying to use the SEC_LINKER_CREATED section flag to determine whether
a symbol is linker defined fails to work on targets like alpha that
define special SEC_COMMON sections.  These might contain symbols that
originated in an object file.

The following patch fixes this problem, introduced here:
https://sourceware.org/ml/binutils/2014-06/msg00070.html

include/
	* bfdlink.h (struct bfd_link_hash_entry): Comment non_ir_ref.  Add
	linker_def.
bfd/
	* elflink.c (_bfd_elf_define_linkage_sym): Set linker_def.
	* linker.c (_bfd_generic_link_add_one_symbol): Clear linker_def
	for CDEF, DEF, DEFW, COM.
ld/
	* ldexp.c (exp_fold_tree_1 <etree_provide>): Test linker_def.
ld/testsuite/
	* ld-powerpc/sdabase.s,
	* ld-powerpc/sdabase.t,
	* ld-powerpc/sdabase.d: New test.
	* ld-powerpc/sdabase2.t,
	* ld-powerpc/sdabase2.d: New test.
	* ld-powerpc/powerpc.exp: Run them.

diff --git a/bfd/elflink.c b/bfd/elflink.c
index b701fa0..16421cf 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -85,6 +85,7 @@ _bfd_elf_define_linkage_sym (bfd *abfd,
   h = (struct elf_link_hash_entry *) bh;
   h->def_regular = 1;
   h->non_elf = 0;
+  h->root.linker_def = 1;
   h->type = STT_OBJECT;
   if (ELF_ST_VISIBILITY (h->other) != STV_INTERNAL)
     h->other = (h->other & ~ELF_ST_VISIBILITY (-1)) | STV_HIDDEN;
diff --git a/bfd/linker.c b/bfd/linker.c
index abdf5b0..9223810 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -1560,6 +1560,7 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
 	      h->type = bfd_link_hash_defined;
 	    h->u.def.section = section;
 	    h->u.def.value = value;
+	    h->linker_def = 0;
 
 	    /* If we have been asked to, we act like collect2 and
 	       identify all functions that might be global
@@ -1659,6 +1660,7 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
 	    }
 	  else
 	    h->u.c.p->section = section;
+	  h->linker_def = 0;
 	  break;
 
 	case REF:
diff --git a/include/bfdlink.h b/include/bfdlink.h
index f3181ba..48c91da 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -91,8 +91,14 @@ struct bfd_link_hash_entry
   /* Type of this entry.  */
   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 
+  /* Symbol is referenced in a normal object file, as distict from a LTO
+     IR object file.  */
   unsigned int non_ir_ref : 1;
 
+  /* Symbol is a built-in define.  These will be overridden by PROVIDE
+     in a linker script.  */
+  unsigned int linker_def : 1;
+
   /* A union of information depending upon the type.  */
   union
     {
diff --git a/ld/ldexp.c b/ld/ldexp.c
index 8615869..b4af893 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -1072,9 +1072,7 @@ exp_fold_tree_1 (etree_type *tree)
 	      if (h == NULL
 		  || !(h->type == bfd_link_hash_new
 		       || h->type == bfd_link_hash_undefined
-		       || (h->type == bfd_link_hash_defined
-			   && (h->u.def.section->flags
-			       & SEC_LINKER_CREATED) != 0)))
+		       || h->linker_def))
 		{
 		  /* Do nothing.  The symbol was never referenced, or
 		     was defined in some object file.  Undefined weak
 2014-12-19  Matthew Fortune  <matthew.fortune@imgtec.com>
diff --git a/ld/testsuite/ld-powerpc/powerpc.exp b/ld/testsuite/ld-powerpc/powerpc.exp
index 599b980..645236d 100644
--- a/ld/testsuite/ld-powerpc/powerpc.exp
+++ b/ld/testsuite/ld-powerpc/powerpc.exp
@@ -289,6 +289,8 @@ if { [istarget "powerpc*-eabi*"] } {
 }
 
 run_dump_test "plt1"
+run_dump_test "sdabase"
+run_dump_test "sdabase2"
 
 run_dump_test "attr-gnu-4-00"
 run_dump_test "attr-gnu-4-01"
diff --git a/ld/testsuite/ld-powerpc/sdabase.d b/ld/testsuite/ld-powerpc/sdabase.d
new file mode 100644
index 0000000..c54f750
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/sdabase.d
@@ -0,0 +1,10 @@
+#source: sdabase.s
+#as: -a32
+#ld: -melf32ppc -T sdabase.t
+#objdump: -s
+#target: powerpc*-*-*
+
+.*:     file format .*
+
+Contents of section \.sdata:
+ 0400 (00008400|00840000) (00000400|00040000) .*
diff --git a/ld/testsuite/ld-powerpc/sdabase.s b/ld/testsuite/ld-powerpc/sdabase.s
new file mode 100644
index 0000000..8c85688
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/sdabase.s
@@ -0,0 +1,9 @@
+	.text
+	.globl _start
+_start:
+
+	.section .sdata,"aw",@progbits
+	.globl my_sdata
+my_sdata:
+	.dc.a	_SDA_BASE_
+	.dc.a	my_sdata
diff --git a/ld/testsuite/ld-powerpc/sdabase.t b/ld/testsuite/ld-powerpc/sdabase.t
new file mode 100644
index 0000000..2486962
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/sdabase.t
@@ -0,0 +1,6 @@
+SECTIONS
+{
+  .text 0x100 : { *(.text) }
+  .sdata 0x400 : { *(.sdata) }
+  /DISCARD/ : { *(*) }
+}
diff --git a/ld/testsuite/ld-powerpc/sdabase2.d b/ld/testsuite/ld-powerpc/sdabase2.d
new file mode 100644
index 0000000..a0da6f5
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/sdabase2.d
@@ -0,0 +1,10 @@
+#source: sdabase.s
+#as: -a32
+#ld: -melf32ppc -T sdabase2.t
+#objdump: -s
+#target: powerpc*-*-*
+
+.*:     file format .*
+
+Contents of section \.sdata:
+ 0400 (00000400|00040000) (00000400|00040000) .*
diff --git a/ld/testsuite/ld-powerpc/sdabase2.t b/ld/testsuite/ld-powerpc/sdabase2.t
new file mode 100644
index 0000000..2a8f5d0
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/sdabase2.t
@@ -0,0 +1,6 @@
+SECTIONS
+{
+  .text 0x100 : { *(.text) }
+  .sdata 0x400 : { PROVIDE (_SDA_BASE_ = .); *(.sdata) }
+  /DISCARD/ : { *(*) }
+}

-- 
Alan Modra
Australia Development Lab, IBM



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