Skip PLT for function pointer initialization

We use its PLT entry to initialize function pointer at run-time.  If
there is no other usage for the PLT entry, we can generate run-time
function pointer relocations in read-write section, which can be
resolved by dynamic linker, to initialize function pointers.  It avoids
the extra indirect branch overhead in PLT.

bfd/

	PR ld/18900
	* elf32-i386.c (elf_i386_link_hash_entry): Add
	func_pointer_refcount.
	(elf_i386_link_hash_newfunc): Clear func_pointer_refcount.
	(elf_i386_get_local_sym_hash): Likewise.
	(elf_i386_copy_indirect_symbol): Also copy
	func_pointer_refcount.
	(elf_i386_check_relocs): Increment func_pointer_refcount.
	(elf_i386_gc_sweep_hook): Decrement func_pointer_refcount.
	(elf_i386_allocate_dynrelocs): Don't create the PLT entry if
	there are only function pointer relocations which can be
	resolved at run-time.  Keep dynanamic relocations for run-time
	function pointer initialization.
	(elf_i386_relocate_section): Copy dynamic function pointer
	relocations.
	* elf64-x86-64.c (elf_x86_64_link_hash_entry): Add
	func_pointer_refcount.
	(elf_x86_64_link_hash_newfunc): Clear func_pointer_refcount.
	(elf_x86_64_get_local_sym_hash): Likewise.
	(elf_x86_64_copy_indirect_symbol): Also copy
	func_pointer_refcount.
	(elf_x86_64_check_relocs): Increment func_pointer_refcount.
	(elf_x86_64_gc_sweep_hook): Decrement func_pointer_refcount.
	(elf_x86_64_allocate_dynrelocs): Don't create the PLT entry if
	there are only function pointer relocations which can be
	resolved at run-time.  Keep dynanamic relocations for run-time
	function pointer initialization.
	(elf_x86_64_relocate_section): Copy dynamic function pointer
	relocations.

ld/testsuite/

	PR ld/18900
	* ld-i386/i386.exp: Run tests for PR ld/18900.
	* ld-x86-64/x86-64.exp: Likewise.
	* ld-i386/pr18900.out: New file.
	* ld-i386/pr18900a.c: Likewise.
	* ld-i386/pr18900a.c: Likewise.
	* ld-i386/pr18900a.rd: Likewise.
	* ld-i386/pr18900b.c: Likewise.
	* ld-i386/pr18900b.rd: Likewise.
	* ld-i386/pr18900c.c: Likewise.
	* ld-x86-64/pr18900.out: Likewise.
	* ld-x86-64/pr18900a.c: Likewise.
	* ld-x86-64/pr18900a.rd: Likewise.
	* ld-x86-64/pr18900b.c: Likewise.
	* ld-x86-64/pr18900b.rd: Likewise.
	* ld-x86-64/pr18900c.c: Likewise.
	* ld-x86-64/mpx3.dd: Updated.

16 files changed, 199 insertions, 16 deletions

diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index 7650cda..0241c08 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,23 @@
+2015-09-01  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/18900
+	* ld-i386/i386.exp: Run tests for PR ld/18900.
+	* ld-x86-64/x86-64.exp: Likewise.
+	* ld-i386/pr18900.out: New file.
+	* ld-i386/pr18900a.c: Likewise.
+	* ld-i386/pr18900a.c: Likewise.
+	* ld-i386/pr18900a.rd: Likewise.
+	* ld-i386/pr18900b.c: Likewise.
+	* ld-i386/pr18900b.rd: Likewise.
+	* ld-i386/pr18900c.c: Likewise.
+	* ld-x86-64/pr18900.out: Likewise.
+	* ld-x86-64/pr18900a.c: Likewise.
+	* ld-x86-64/pr18900a.rd: Likewise.
+	* ld-x86-64/pr18900b.c: Likewise.
+	* ld-x86-64/pr18900b.rd: Likewise.
+	* ld-x86-64/pr18900c.c: Likewise.
+	* ld-x86-64/mpx3.dd: Updated.
+
 2015-08-27  Alan Modra  <amodra@gmail.com>
 
 	* ld-powerpc/relocsort.s, * ld-powerpc/relocsort.d: New test.
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index 47911a6..6213dbe 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -466,6 +466,30 @@ if { [isnative]
 	    {{readelf {-Wr} pr17827.rd}} \
 	    "pr17827" \
 	] \
+	[list \
+	    "Build pr18900.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    { pr18900a.c } \
+	    "" \
+	    "pr18900.so" \
+	] \
+	[list \
+	    "Build pr18900a" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    {{readelf {-Wrd} pr18900a.rd}} \
+	    "pr18900a" \
+	] \
+	[list \
+	    "Build pr18900b" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    {{readelf {-Wrd} pr18900b.rd}} \
+	    "pr18900b" \
+	] \
     ]
 
     run_ld_link_exec_tests [] [list \
@@ -520,6 +544,14 @@ if { [isnative]
 	    "pr17689ver" \
 	    "pr17689.out" \
 	] \
+	[list \
+	    "Run pr18900" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    "pr18900" \
+	    "pr18900.out" \
+	] \
     ]
 }
 
diff --git a/ld/testsuite/ld-i386/pr18900.out b/ld/testsuite/ld-i386/pr18900.out
new file mode 100644
index 0000000..b462a5a
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900.out
@@ -0,0 +1,4 @@
+OK
+OK
+OK
+OK
diff --git a/ld/testsuite/ld-i386/pr18900a.c b/ld/testsuite/ld-i386/pr18900a.c
new file mode 100644
index 0000000..fa2fc06
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900a.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+void
+foo (void)
+{
+  printf ("OK\n");
+}
+
+void *
+bar (void)
+{
+  foo ();
+  return &foo;
+}
diff --git a/ld/testsuite/ld-i386/pr18900a.rd b/ld/testsuite/ld-i386/pr18900a.rd
new file mode 100644
index 0000000..0731396
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900a.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+.*\(TEXTREL\).*
+#...
diff --git a/ld/testsuite/ld-i386/pr18900b.c b/ld/testsuite/ld-i386/pr18900b.c
new file mode 100644
index 0000000..e666305
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900b.c
@@ -0,0 +1,22 @@
+extern void abort (void);
+extern void foo (void);
+extern void *bar (void);
+
+typedef void (*func_p) (void);
+
+extern const func_p p1;
+
+func_p p2 = &foo;
+func_p p3 = &foo;
+
+int
+main ()
+{
+  void *p = bar ();
+  p1 ();
+  p2 ();
+  p3 ();
+  if (p != p1)
+    abort ();
+  return 0;
+}
diff --git a/ld/testsuite/ld-i386/pr18900b.rd b/ld/testsuite/ld-i386/pr18900b.rd
new file mode 100644
index 0000000..e256a70
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900b.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+[0-9a-f ]+R_386_JUMP_SLOT[0-9a-f ]+foo
+#...
diff --git a/ld/testsuite/ld-i386/pr18900c.c b/ld/testsuite/ld-i386/pr18900c.c
new file mode 100644
index 0000000..b37ca16
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr18900c.c
@@ -0,0 +1,5 @@
+extern void foo (void);
+
+typedef void (*func_p) (void);
+
+func_p p1 = &foo;
diff --git a/ld/testsuite/ld-x86-64/mpx3.dd b/ld/testsuite/ld-x86-64/mpx3.dd
index 2a8356d..eb529f4 100644
--- a/ld/testsuite/ld-x86-64/mpx3.dd
+++ b/ld/testsuite/ld-x86-64/mpx3.dd
@@ -3,33 +3,26 @@
 
 Disassembly of section .plt:
 
-0+400290 <.plt>:
-[  	]*[a-f0-9]+:	ff 35 6a 01 20 00    	pushq  0x20016a\(%rip\)        # 600400 <_GLOBAL_OFFSET_TABLE_\+0x8>
-[  	]*[a-f0-9]+:	f2 ff 25 6b 01 20 00 	bnd jmpq \*0x20016b\(%rip\)        # 600408 <_GLOBAL_OFFSET_TABLE_\+0x10>
+0+[a-f0-9]+ <.plt>:
+[  	]*[a-f0-9]+:	ff ([0-9a-f]{2} ){5}   	pushq  0x[a-f0-9]+\(%rip\)        # [a-f0-9]+ <_GLOBAL_OFFSET_TABLE_\+0x8>
+[  	]*[a-f0-9]+:	f2 ff ([0-9a-f]{2} ){5}	bnd jmpq \*0x[a-f0-9]+\(%rip\)        # [a-f0-9]+ <_GLOBAL_OFFSET_TABLE_\+0x10>
 [  	]*[a-f0-9]+:	0f 1f 00             	nopl   \(%rax\)
 [  	]*[a-f0-9]+:	68 00 00 00 00       	pushq  \$0x0
-[  	]*[a-f0-9]+:	f2 e9 e5 ff ff ff    	bnd jmpq 400290 <call1@plt-0x30>
-[  	]*[a-f0-9]+:	0f 1f 44 00 00       	nopl   0x0\(%rax,%rax,1\)
-[  	]*[a-f0-9]+:	68 01 00 00 00       	pushq  \$0x1
-[  	]*[a-f0-9]+:	f2 e9 d5 ff ff ff    	bnd jmpq 400290 <call1@plt-0x30>
+[  	]*[a-f0-9]+:	f2 e9 ([0-9a-f]{2} ){4}   	bnd jmpq [a-f0-9]+ <call1@plt-0x20>
 [  	]*[a-f0-9]+:	0f 1f 44 00 00       	nopl   0x0\(%rax,%rax,1\)
 
 Disassembly of section .plt.bnd:
 
-0+4002c0 <call1@plt>:
-[  	]*[a-f0-9]+:	f2 ff 25 49 01 20 00 	bnd jmpq \*0x200149\(%rip\)        # 600410 <_GLOBAL_OFFSET_TABLE_\+0x18>
-[  	]*[a-f0-9]+:	90                   	nop
-
-0+4002c8 <call2@plt>:
-[  	]*[a-f0-9]+:	f2 ff 25 49 01 20 00 	bnd jmpq \*0x200149\(%rip\)        # 600418 <_GLOBAL_OFFSET_TABLE_\+0x20>
+0+[a-f0-9]+ <call1@plt>:
+[  	]*[a-f0-9]+:	f2 ff ([0-9a-f]{2} ){5}	bnd jmpq \*0x[a-f0-9]+\(%rip\)        # [a-f0-9]+ <_GLOBAL_OFFSET_TABLE_\+0x18>
 [  	]*[a-f0-9]+:	90                   	nop
 
 Disassembly of section .text:
 
-0+4002d0 <_start>:
-[  	]*[a-f0-9]+:	bf c0 02 40 00       	mov    \$0x4002c0,%edi
+0+[a-f0-9]+ <_start>:
+[  	]*[a-f0-9]+:	bf ([0-9a-f]{2} ){4}      	mov    \$0x[a-f0-9]+,%edi
 [  	]*[a-f0-9]+:	f2 ff d7             	bnd callq \*%rdi
-[  	]*[a-f0-9]+:	48 8b 3d 41 01 20 00 	mov    0x200141\(%rip\),%rdi        # 600420 <func>
+[  	]*[a-f0-9]+:	48 8b ([0-9a-f]{2} ){5}	mov    0x[a-f0-9]+\(%rip\),%rdi        # [a-f0-9]+ <func>
 [  	]*[a-f0-9]+:	f2 ff d7             	bnd callq \*%rdi
 [  	]*[a-f0-9]+:	c3                   	retq   
 #pass
diff --git a/ld/testsuite/ld-x86-64/pr18900.out b/ld/testsuite/ld-x86-64/pr18900.out
new file mode 100644
index 0000000..b462a5a
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900.out
@@ -0,0 +1,4 @@
+OK
+OK
+OK
+OK
diff --git a/ld/testsuite/ld-x86-64/pr18900a.c b/ld/testsuite/ld-x86-64/pr18900a.c
new file mode 100644
index 0000000..fa2fc06
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900a.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+void
+foo (void)
+{
+  printf ("OK\n");
+}
+
+void *
+bar (void)
+{
+  foo ();
+  return &foo;
+}
diff --git a/ld/testsuite/ld-x86-64/pr18900a.rd b/ld/testsuite/ld-x86-64/pr18900a.rd
new file mode 100644
index 0000000..0731396
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900a.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+.*\(TEXTREL\).*
+#...
diff --git a/ld/testsuite/ld-x86-64/pr18900b.c b/ld/testsuite/ld-x86-64/pr18900b.c
new file mode 100644
index 0000000..e666305
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900b.c
@@ -0,0 +1,22 @@
+extern void abort (void);
+extern void foo (void);
+extern void *bar (void);
+
+typedef void (*func_p) (void);
+
+extern const func_p p1;
+
+func_p p2 = &foo;
+func_p p3 = &foo;
+
+int
+main ()
+{
+  void *p = bar ();
+  p1 ();
+  p2 ();
+  p3 ();
+  if (p != p1)
+    abort ();
+  return 0;
+}
diff --git a/ld/testsuite/ld-x86-64/pr18900b.rd b/ld/testsuite/ld-x86-64/pr18900b.rd
new file mode 100644
index 0000000..7e46c85
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900b.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+[0-9a-f ]+R_X86_64_JUMP_SLOT[0-9a-f ]+foo \+ 0
+#...
diff --git a/ld/testsuite/ld-x86-64/pr18900c.c b/ld/testsuite/ld-x86-64/pr18900c.c
new file mode 100644
index 0000000..b37ca16
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr18900c.c
@@ -0,0 +1,5 @@
+extern void foo (void);
+
+typedef void (*func_p) (void);
+
+func_p p1 = &foo;
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 5409dff..6320999 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -476,6 +476,30 @@ if { [isnative] && [which $CC] != 0 } {
 	    {{readelf {-Wr} pr17827.rd}} \
 	    "pr17827" \
 	] \
+	[list \
+	    "Build pr18900.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    { pr18900a.c } \
+	    "" \
+	    "pr18900.so" \
+	] \
+	[list \
+	    "Build pr18900a" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    {{readelf {-Wrd} pr18900a.rd}} \
+	    "pr18900a" \
+	] \
+	[list \
+	    "Build pr18900b" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    {{readelf {-Wrd} pr18900b.rd}} \
+	    "pr18900b" \
+	] \
     ]
 
     run_ld_link_exec_tests [] [list \
@@ -522,6 +546,14 @@ if { [isnative] && [which $CC] != 0 } {
 	    "pr17689now" \
 	    "pr17689.out" \
 	] \
+	[list \
+	    "Run pr18900" \
+	    "tmpdir/pr18900.so" \
+	    "" \
+	    { pr18900b.c pr18900c.c } \
+	    "pr18900" \
+	    "pr18900.out" \
+	] \
     ]
 
     if { [istarget "x86_64-*-linux*"] \