Allow pie links to create PLT entries

[Sriraman Tallam]

Hi,

    Here is a simple example that fails to link with -pie but which
should work just fine without having to use -fPIE.

foo.cc
======
int extern_func();
int main()
{
  extern_func();
  return 0;
}

bar.cc
=====
int extern_func()
{
  return 1;
}

$ g++ -fPIC -shared bar.cc -o libbar.so
$ g++ foo.cc -lbar -pie

ld: error: foo.o: requires dynamic R_X86_64_PC32 reloc against
'_Z11extern_funcv' which may overflow at runtime; recompile with -fPIC

It fails because the linker disallows creating a PLT for
R_X86_64_PC32 reloc when it is perfectly fine to do so.  Note that I
could have recompiled foo.cc with -fPIE or -fPIC but I still think
this can be allowed.  With support for copy relocations in pie in gold
and with this support, the cases where we would need to use -fPIE to
get working pie links is smaller.  This would help us link non-PIE
objects into pie executables.


Attached patch to fix this. I have only tested this patch on X86_64.

Please review.

Thanks
Sri
-------------- next part --------------
	* symtab.h (needs_plt_entry): Allow pie links to generate PLT
	entries.
	(needs_dynamic_reloc): Remove check for position independence
	when disallowing dynamic relocation for PLT entry.

diff --git a/gold/symtab.h b/gold/symtab.h
index aa0cb68..7de5e99 100644
--- a/gold/symtab.h
+++ b/gold/symtab.h
@@ -639,10 +639,8 @@ class Symbol
     if (!this->is_func())
       return false;
 
-    // If we're doing a static link or a -pie link, we don't create
-    // PLT entries.
-    if (parameters->doing_static_link()
-	|| parameters->options().pie())
+    // If we're doing a static link we don't create PLT entries.
+    if (parameters->doing_static_link())
       return false;
 
     // We need a PLT entry if the function is defined in a dynamic
@@ -706,10 +704,9 @@ class Symbol
     if ((flags & FUNCTION_CALL) && this->has_plt_offset())
       return false;
 
-    // A reference to any PLT entry in a non-position-independent executable
-    // does not need a dynamic relocation.
+    // A reference to any PLT entry in an executable does not need a dynamic
+    // relocation.
     if (!(flags & FUNC_DESC_ABI)
-	&& !parameters->options().output_is_position_independent()
         && this->has_plt_offset())
       return false;