Re: PATCH: PR ld/14272: Mark the plugin symbol undefined

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Feb 05, 2015 at 09:10:32PM -0800, H.J. Lu wrote:
> On Thu, Feb 5, 2015 at 8:06 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> > On Thu, Feb 5, 2015 at 5:52 PM, Alan Modra <amodra@gmail.com> wrote:
> >> On Thu, Feb 05, 2015 at 05:06:38PM -0800, H.J. Lu wrote:
> >>> On Thu, Feb 5, 2015 at 4:59 PM, Alan Modra <amodra@gmail.com> wrote:
> >>> > On Wed, Feb 04, 2015 at 04:36:16AM -0800, H.J. Lu wrote:
> >>> >> On Wed, Feb 4, 2015 at 3:08 AM, Alan Modra <amodra@gmail.com> wrote:
> >>> >> > On Tue, Feb 03, 2015 at 09:06:47AM -0800, H.J. Lu wrote:
> >>> >> >>       PR ld/12365
> >>> >> >>       * ld-plugin/pr12365a.c: New file.
> >>> >> >>       * ld-plugin/pr12365b.c: Likewise.
> >>> >> >>       * ld-plugin/pr12365c.c: Likewise.
> >>> >> >
> >>> >> > The testcase fails when using gcc-5.  Also, gcc-5 objects don't seem
> >>> >> > exercise your _bfd_elf_fix_symbol_flags code.  I presume you need an
> >>> >> > older version of gcc, with lto bugs, to need those hacks.  Is that
> >>> >> > true?  Can you write a testcase that does exercise your
> >>> >> > _bfd_elf_fix_symbol_flags code?
> >>> >>
> >>> >> The -flto-partition default was changed.  I checked in this patch
> >>> >> to pass -flto-partition=none to the PR ld/12365 test.
> >>> >
> >>> > The test fails when using gcc-4.7.2 on powerpc64-linux.  Please fix it.
> >>>
> >>> Does it fail with gcc 4.8?  What is the error message?
> >>
> >> No error message.  The link succeeds.  Similarly with gcc-4.9 and
> >
> > The test is very sensitive to LTO partition.  Also
> 
> The test is also sensitive to LTO IR order.  I am testing this patch.
> 
> > #define ASMNAME(cname)  ASMNAME2 (__USER_LABEL_PREFIX__, cname)
> > #define ASMNAME2(prefix, cname) STRING (prefix) cname
> > #define STRING(x)    #x
> >
> > typedef __SIZE_TYPE__ size_t;
> > extern void abort (void);
> > extern void *memcpy (void *, const void *, size_t)
> >   __asm (ASMNAME ("my_memcpy"));
> >
> > doesn't work for all platforms.  I will keep digging.
> >
> 
> I will also limit this test to x86 for now until we find a way to make it
> work for other platforms.
> 

It turns out that existing tests show PR ld/12365. The "plugin claimfile
resolve symbol" and "plugin claimfile replace symbol" tests expect

`func' referenced in section `.text.startup' of tmpdir/main.o: defined
in discarded section `.text' of tmpdir/func.o (symbol from plugin)

Since plugin never provides func, the error message should be

tmpdir/main.o: In function `main':
main.c:(.text.startup+0x15): undefined reference to `func'

I am checking in this patch to move the plugin symbol marking from
_bfd_elf_fix_symbol_flags to elf_link_input_bfd.  I kept the PR ld/12365
test and limited to x86 targets.


H.J.
---
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f12a610..1220455 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2015-02-06  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/12365
+	PR ld/14272
+	* elflink.c (_bfd_elf_fix_symbol_flags): Revert the last change.
+	(elf_link_input_bfd): Mark the plugin symbol undefined if it is
+	referenced from a non-IR file.
+
 2015-02-06  Nick Clifton  <nickc@redhat.com>
 
 	PR binutils/17512
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 604cfb6..e8c4ad4 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -2423,20 +2423,6 @@ _bfd_elf_fix_symbol_flags (struct elf_link_hash_entry *h,
     }
   else
     {
-      /* If a plugin symbol is referenced from a non-IR file, mark
-         the symbol as undefined, except for symbol for linker
-	 created section.  */
-      if (h->root.non_ir_ref
-	  && (h->root.type == bfd_link_hash_defined
-	      || h->root.type == bfd_link_hash_defweak)
-	  && (h->root.u.def.section->flags & SEC_LINKER_CREATED) == 0
-	  && h->root.u.def.section->owner != NULL
-	  && (h->root.u.def.section->owner->flags & BFD_PLUGIN) != 0)
-	{
-	  h->root.type = bfd_link_hash_undefined;
-	  h->root.u.undef.abfd = h->root.u.def.section->owner;
-	}
-
       /* Unfortunately, NON_ELF is only correct if the symbol
 	 was first seen in a non-ELF file.  Fortunately, if the symbol
 	 was first seen in an ELF file, we're probably OK unless the
@@ -9807,6 +9793,22 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 
 		  s_type = h->type;
 
+		  /* If a plugin symbol is referenced from a non-IR file,
+		     mark the symbol as undefined, except for symbol for
+		     linker created section.  */
+		  if (h->root.non_ir_ref
+		      && (h->root.type == bfd_link_hash_defined
+			  || h->root.type == bfd_link_hash_defweak)
+		      && (h->root.u.def.section->flags
+			  & SEC_LINKER_CREATED) == 0
+		      && h->root.u.def.section->owner != NULL
+		      && (h->root.u.def.section->owner->flags
+			  & BFD_PLUGIN) != 0)
+		    {
+		      h->root.type = bfd_link_hash_undefined;
+		      h->root.u.undef.abfd = h->root.u.def.section->owner;
+		    }
+
 		  ps = NULL;
 		  if (h->root.type == bfd_link_hash_defined
 		      || h->root.type == bfd_link_hash_defweak)
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index 1041bd1..075016b 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2015-02-06  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/12365
+	PR ld/14272
+	* ld-plugin/lto.exp: Run the PR ld/12365 test only for x86 targets.
+	* ld-plugin/plugin-7.d: Updated.
+	* ld-plugin/plugin-8.d: Likewise.
+
 2015-02-04  H.J. Lu  <hongjiu.lu@intel.com>
 
 	*  ld-plugin/lto.exp: Pass -flto-partition=none to the PR
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 065e1bb..6d9500b 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -383,12 +383,23 @@ if {![string match "" $catch_output]} {
 
 if { [at_least_gcc_version 4 7] } {
     # Check expected LTO linker errors.
-    set testname "PR ld/12365"
-    set exec_output [run_host_cmd "$CC" "-O2 -flto -flto-partition=none -fuse-linker-plugin tmpdir/pr12365a.o tmpdir/pr12365b.o tmpdir/pr12365c.o"]
-    if { [ regexp "undefined reference to `my_bcopy'" $exec_output ] } {
-	pass $testname
-    } {
-	fail $testname
+    # Since the asm symbol name hack in pr12365b.c doesn't work on all
+    # targets, run PR ld/12365 tests only for known targets.
+    if { ([istarget "i?86-*-elf*"]
+	   || (([istarget "i?86-*-linux*"] || [istarget "i?86-*-gnu*"])
+		&& ![istarget "*-*-*aout*"]
+		&& ![istarget "*-*-*oldld*"])
+	   || [istarget "i?86-*-nacl*"]
+	   || [istarget "x86_64-*-nacl*"]
+	   || [istarget "x86_64-*-linux*"]
+	   || [istarget "amd64-*-linux*"]) } {
+	set testname "PR ld/12365"
+	set exec_output [run_host_cmd "$CC" "-O2 -flto -flto-partition=none -fuse-linker-plugin tmpdir/pr12365a.o tmpdir/pr12365b.o tmpdir/pr12365c.o"]
+	if { [ regexp "undefined reference to `my_bcopy'" $exec_output ] } {
+	    pass $testname
+	} {
+	    fail $testname
+	}
     }
     set testname "PR ld/12942 (3)"
     set exec_output [run_host_cmd "$CXX" "-O2 -flto -fuse-linker-plugin tmpdir/pr12942b.o tmpdir/pr12942a.o"]
diff --git a/ld/testsuite/ld-plugin/plugin-7.d b/ld/testsuite/ld-plugin/plugin-7.d
index 28a7036..d1c159c 100644
--- a/ld/testsuite/ld-plugin/plugin-7.d
+++ b/ld/testsuite/ld-plugin/plugin-7.d
@@ -28,6 +28,7 @@ hook called: claim_file tmpdir/func.o \[@0/.* CLAIMED
 hook called: claim_file tmpdir/text.o \[@0/.* not claimed
 #...
 hook called: all symbols read.
-`_?func' referenced in section `\.text.*' of tmpdir/main.o: defined in discarded section .*
+tmpdir/main.o: In function `main':
+.*main.c.*: undefined reference to `func'
 hook called: cleanup.
 #...
diff --git a/ld/testsuite/ld-plugin/plugin-8.d b/ld/testsuite/ld-plugin/plugin-8.d
index 8170b54..2c7a15b 100644
--- a/ld/testsuite/ld-plugin/plugin-8.d
+++ b/ld/testsuite/ld-plugin/plugin-8.d
@@ -32,6 +32,7 @@ hook called: claim_file tmpdir/text.o \[@0/.* not claimed
 hook called: all symbols read.
 Sym: '_?func' Resolution: LDPR_PREVAILING_DEF
 Sym: '_?func2' Resolution: LDPR_PREVAILING_DEF_IRONLY
-`_?func' referenced in section `\.text.*' of tmpdir/main.o: defined in discarded section .*
+tmpdir/main.o: In function `main':
+.*main.c.*: undefined reference to `func'
 hook called: cleanup.
 #...