ld/elf: Ignore section symbols when matching linkonce with comdat

When deciding if a single member comdat group section in file FOO should
be discarded by a linkonce section in file BAR, we check if 2 sections
define the same set of local and global symbols.  When only one of the
files doesn't contain the unused section symbols in the symbol table,
such as object files generated by clang or GNU assembler with

commit d1bcae833b32f1408485ce69f844dcd7ded093a8
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Jan 7 06:42:00 2021 -0800

    ELF: Don't generate unused section symbols

the check will fail since one file has the extra unused section symbols.
We should ignore both undefined and section symbols in the symbol table
when making such a decision.

bfd/

	PR ld/27193
	* elflink.c (elf_create_symbuf): Also ignore section symbols.

ld/

	PR ld/27193
	* testsuite/ld-i386/i386.exp: Run PR ld/27193 test.
	* testsuite/ld-i386/pr27193.dd: New file.
	* testsuite/ld-i386/pr27193a.o.bz2: Likewise.
	* testsuite/ld-i386/pr27193b.s: Likewise.

7 files changed, 36 insertions, 1 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index dbb240a..b947c51 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2021-01-17  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/27193
+	* elflink.c (elf_create_symbuf): Also ignore section symbols.
+
 2021-01-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/23169
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 8794864..59a6080 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -8126,8 +8126,12 @@ elf_create_symbuf (size_t symcount, Elf_Internal_Sym *isymbuf)
   if (indbuf == NULL)
     return NULL;
 
+  /* NB: When checking if 2 sections define the same set of local and
+     global symbols, ignore both undefined and section symbols in the
+     symbol table.  */
   for (ind = indbuf, i = 0; i < symcount; i++)
-    if (isymbuf[i].st_shndx != SHN_UNDEF)
+    if (isymbuf[i].st_shndx != SHN_UNDEF
+	&& ELF_ST_TYPE (isymbuf[i].st_info) != STT_SECTION)
       *ind++ = &isymbuf[i];
   indbufend = ind;
 
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 6b602d6..92fa8a4 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,11 @@
+2021-01-17  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/27193
+	* testsuite/ld-i386/i386.exp: Run PR ld/27193 test.
+	* testsuite/ld-i386/pr27193.dd: New file.
+	* testsuite/ld-i386/pr27193a.o.bz2: Likewise.
+	* testsuite/ld-i386/pr27193b.s: Likewise.
+
 2021-01-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR binutils/23460
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index f3e62a4..0be6b86 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -245,6 +245,11 @@ set i386tests {
      "-melf_i386 -shared -Bsymbolic -z notext" ""
      "--32 -mx86-used-note=yes"
      { pr19827a.S }  {{readelf {-rW} pr19827.rd}} "pr19827.so"}
+    {"Build pr27193.so"
+     "-melf_i386 -shared" ""
+     "--32"
+     { pr27193a.o.bz2 pr27193b.s }
+     {{objdump {-dw} pr27193.dd}} "pr27193.so"}
 }
 
 proc iamcu_tests {} {
diff --git a/ld/testsuite/ld-i386/pr27193.dd b/ld/testsuite/ld-i386/pr27193.dd
new file mode 100644
index 0000000..7d1e799
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr27193.dd
@@ -0,0 +1,5 @@
+#...
+0+[a-f0-9]+ <__x86.get_pc_thunk.bx>:
+ +[a-f0-9]+:	8b 1c 24             	mov    \(%esp\),%ebx
+ +[a-f0-9]+:	c3                   	ret    
+#pass
diff --git a/ld/testsuite/ld-i386/pr27193a.o.bz2 b/ld/testsuite/ld-i386/pr27193a.o.bz2
new file mode 100644
index 0000000..365899d
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr27193a.o.bz2
diff --git a/ld/testsuite/ld-i386/pr27193b.s b/ld/testsuite/ld-i386/pr27193b.s
new file mode 100644
index 0000000..9b27a6f
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr27193b.s
@@ -0,0 +1,8 @@
+	 .section .text.__x86.get_pc_thunk.bx,"axG",%progbits,__x86.get_pc_thunk.bx,comdat
+        .globl  __x86.get_pc_thunk.bx
+        .hidden __x86.get_pc_thunk.bx
+        .type   __x86.get_pc_thunk.bx, %function
+	.p2align 4
+__x86.get_pc_thunk.bx:
+	mov	(%esp),%ebx
+	ret