Allocate the first .plt entry space only if needed

Commit dd7e64d45b may optimize out
i386/x86-64 JUMP_SLOT relocation.  If there is no JUMP_SLOT relocation
left, we don't need to the first .plt entry.  This patch allocates
space for the first .plt entry only if we also reserve space for a PLT
slot for JUMP_SLOT relocation.

bfd/

	* elf32-i386.c (elf_i386_allocate_dynrelocs): Allocate space
	for the first .plt entry only if needed.
	* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): Likewise.

ld/testsuite/

	* ld-i386/i386.exp: Run pltgot-1 for Linux targets.
	* ld-x86-64/x86-64.exp: Likewise.
	* ld-i386/pltgot-1.d: New file.
	* ld-i386/pltgot-1.s: Likewise.
	* ld-x86-64/pltgot-1.d: Likewise.
	* ld-x86-64/pltgot-1.s: Likewise.

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2015-05-12  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* elf32-i386.c (elf_i386_allocate_dynrelocs): Allocate space
+	for the first .plt entry only if needed.
+	* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): Likewise.
+
 2015-05-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* Makefile.am (ALL_MACHINES): Add cpu-iamcu.lo.

bfd/elf32-i386.c

@@ -2338,15 +2338,16 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	  asection *s = htab->elf.splt;
 	  asection *got_s = htab->plt_got;
 
-	  /* If this is the first .plt entry, make room for the special
-	     first entry.  */
-	  if (s->size == 0)
-	    s->size = plt_entry_size;
-
 	  if (use_plt_got)
 	    eh->plt_got.offset = got_s->size;
 	  else
-	    h->plt.offset = s->size;
+	    {
+	      /* If this is the first .plt entry, make room for the
+		 special first entry.  */
+	      if (s->size == 0)
+		s->size = plt_entry_size;
+	      h->plt.offset = s->size;
+	    }
 
 	  /* If this symbol is not defined in a regular file, and we are
 	     not generating a shared library, then set the symbol to this

bfd/elf64-x86-64.c

@@ -2558,15 +2558,14 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
 	  asection *bnd_s = htab->plt_bnd;
 	  asection *got_s = htab->plt_got;
 
-	  /* If this is the first .plt entry, make room for the special
-	     first entry.  */
-	  if (s->size == 0)
-	    s->size = plt_entry_size;
-
 	  if (use_plt_got)
 	    eh->plt_got.offset = got_s->size;
 	  else
 	    {
+	      /* If this is the first .plt entry, make room for the
+		 special first entry.  */
+	      if (s->size == 0)
+		s->size = plt_entry_size;
 	      h->plt.offset = s->size;
 	      if (bnd_s)
 		eh->plt_bnd.offset = bnd_s->size;

ld/testsuite/ChangeLog

@@ -1,3 +1,12 @@
+2015-05-12  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* ld-i386/i386.exp: Run pltgot-1 for Linux targets.
+	* ld-x86-64/x86-64.exp: Likewise.
+	* ld-i386/pltgot-1.d: New file.
+	* ld-i386/pltgot-1.s: Likewise.
+	* ld-x86-64/pltgot-1.d: Likewise.
+	* ld-x86-64/pltgot-1.s: Likewise.
+
 2015-05-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* ld-i386/i386.exp (iamcu_tests): Run iamcu-4.

ld/testsuite/ld-i386/i386.exp

@@ -493,3 +493,11 @@ if { [isnative]
 	] \
     ]
 }
+
+if { !([istarget "i?86-*-linux*"]
+       || [istarget "x86_64-*-linux*"]) } {
+    return
+}
+
+# Linux only tests
+run_dump_test "pltgot-1"

ld/testsuite/ld-i386/pltgot-1.d

@@ -0,0 +1,8 @@
+#ld: -shared -melf_i386
+#readelf: -S --wide
+#as: --32
+
+#failif
+#...
+ +\[ [0-9]+\] \.plt +PROGBITS +.*
+#...

ld/testsuite/ld-i386/pltgot-1.s

@@ -0,0 +1,6 @@
+	.text
+	.globl	plt	
+	.type	plt, @function
+plt:
+	call   *puts@GOT(%ebx)
+	jmp	puts@PLT

ld/testsuite/ld-x86-64/pltgot-1.d

@@ -0,0 +1,8 @@
+#ld: -shared -melf_x86_64
+#readelf: -S --wide
+#as: --64
+
+#failif
+#...
+ +\[ [0-9]+\] \.plt +PROGBITS +.*
+#...

ld/testsuite/ld-x86-64/pltgot-1.s

@@ -0,0 +1,6 @@
+	.text
+	.globl	plt	
+	.type	plt, @function
+plt:
+	call   *puts@GOTPCREL(%rip)
+	jmp	puts@PLT

ld/testsuite/ld-x86-64/x86-64.exp

@@ -549,3 +549,4 @@ if { ![istarget "x86_64-*-linux*"]} {
 
 # Linux only tests
 run_dump_test "pr17618"
+run_dump_test "pltgot-1"