Optimize R_386_GOT32/R_386_GOT32X only if addend is 0

Linker can't optimize R_386_GOT32 and R_386_GOT32X relocations if addend
isn't 0.  It isn't valid to convert

movl	foo@GOT+1(%ecx), %eax

to

leal	foo@GOTOFF+1(%ecx), %eax

nor to convert

movq	foo@GOTPCREL+1(%rip), %rax

to

leaq	foo(%rip), %rax

for x86-64.  We should check if addend is 0 before optimizing R_386_GOT32
and R_386_GOT32X relocations.  Testcases are added for i386 and x86-64.

bfd/

	* elf32-i386.c (elf_i386_convert_load): Skip if addend isn't 0.
	(elf_i386_relocate_section): Skip R_386_GOT32X optimization if
	addend isn't 0.

ld/testsuite/

	* ld-i386/i386.exp: Run mov2a, mov2b and mov3.
	* ld-i386/mov2.s: New file.
	* ld-i386/mov2a.d: Likewise.
	* ld-i386/mov2b.d: Likewise.
	* ld-i386/mov3.d: Likewise.
	* ld-i386/mov3.s: Likewise.
	* ld-x86-64/mov2.s: Likewise.
	* ld-x86-64/mov2a.d: Likewise.
	* ld-x86-64/mov2b.d: Likewise.
	* ld-x86-64/mov2c.d: Likewise.
	* ld-x86-64/mov2d.d: Likewise.
	* ld-x86-64/x86-64.exp: Run mov2a, mov2b, mov2c and mov2d.

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2015-12-04  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* elf32-i386.c (elf_i386_convert_load): Skip if addend isn't 0.
+	(elf_i386_relocate_section): Skip R_386_GOT32X optimization if
+	addend isn't 0.
+
 2015-12-04  Tristan Gingold  <gingold@adacore.com>
 
 	* elf.c (rewrite_elf_program_header): Remove useless loop.

bfd/elf32-i386.c

@@ -2820,6 +2820,11 @@ elf_i386_convert_load (bfd *abfd, asection *sec,
       if (roff < 2)
 	continue;
 
+      /* Addend for R_386_GOT32 and R_386_GOT32X relocations must be 0.  */
+      addend = bfd_get_32 (abfd, contents + roff);
+      if (addend != 0)
+	continue;
+
       modrm = bfd_get_8 (abfd, contents + roff - 1);
       baseless = (modrm & 0xc7) == 0x5;
 
@@ -2913,11 +2918,6 @@ elf_i386_convert_load (bfd *abfd, asection *sec,
 	    {
 	      /* The function is locally defined.   */
 convert_branch:
-	      addend = bfd_get_32 (abfd, contents + roff);
-	      /* Addend for R_386_GOT32X relocation must be 0.  */
-	      if (addend != 0)
-		continue;
-
 	      /* Convert R_386_GOT32X to R_386_PC32.  */
 	      if (modrm == 0x15 || (modrm & 0xf8) == 0x90)
 		{
@@ -3007,11 +3007,6 @@ convert_load:
 		}
 	      else
 		{
-		  /* Addend for R_386_GOT32X relocation must be 0.  */
-		  addend = bfd_get_32 (abfd, contents + roff);
-		  if (addend != 0)
-		    continue;
-
 		  if (opcode == 0x85)
 		    {
 		      /* Convert "test %reg1, foo@GOT(%reg2)" to
@@ -3998,8 +3993,11 @@ elf_i386_relocate_section (bfd *output_bfd,
 		 branch to direct branch.  It is OK to convert adc,
 		 add, and, cmp, or, sbb, sub, test, xor only when PIC
 		 is false.   */
-	      unsigned int opcode;
+	      unsigned int opcode, addend;
-	      opcode = bfd_get_8 (abfd, contents + rel->r_offset - 2);
+	      addend = bfd_get_32 (input_bfd, contents + rel->r_offset);
+	      if (addend != 0)
+		goto r_386_got32;
+	      opcode = bfd_get_8 (input_bfd, contents + rel->r_offset - 2);
 	      if (opcode != 0x8b && opcode != 0xff)
 		goto r_386_got32;
 	    }
@@ -4031,7 +4029,7 @@ elf_i386_relocate_section (bfd *output_bfd,
 	      /* If not PIC, add the .got.plt section address for
 		 baseless addressing.  */
 	      unsigned int modrm;
-	      modrm = bfd_get_8 (abfd, contents + rel->r_offset - 1);
+	      modrm = bfd_get_8 (input_bfd, contents + rel->r_offset - 1);
 	      if ((modrm & 0xc7) == 0x5)
 		relocation += offplt;
 	    }

ld/testsuite/ChangeLog

@@ -1,3 +1,16 @@
+2015-12-04  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* ld-i386/i386.exp: Run mov2a and mov2b.
+	* ld-i386/mov2.s: New file.
+	* ld-i386/mov2a.d: Likewise.
+	* ld-i386/mov2b.d: Likewise.
+	* ld-x86-64/mov2.s: Likewise.
+	* ld-x86-64/mov2a.d: Likewise.
+	* ld-x86-64/mov2b.d: Likewise.
+	* ld-x86-64/mov2c.d: Likewise.
+	* ld-x86-64/mov2d.d: Likewise.
+	* ld-x86-64/x86-64.exp: Run mov2a, mov2b, mov2c and mov2d.
+
 2015-12-01  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/19319

ld/testsuite/ld-i386/i386.exp

@@ -293,6 +293,9 @@ run_dump_test "lea1e"
 run_dump_test "lea1f"
 run_dump_test "mov1a"
 run_dump_test "mov1b"
+run_dump_test "mov2a"
+run_dump_test "mov2b"
+run_dump_test "mov3"
 run_dump_test "branch1"
 run_dump_test "call1"
 run_dump_test "call2"

ld/testsuite/ld-i386/mov2.s

@@ -0,0 +1,15 @@
+	.section	my_section,"aw",@progbits
+	.long	0x12345678
+	.text
+	.globl	foo
+	.type	foo, @function
+foo:
+	ret
+	.size	foo, .-foo
+	.globl	_start
+	.type	_start, @function
+_start:
+	movl	foo@GOT+1(%ecx), %eax
+	movl	__start_my_section@GOT+1(%ecx), %eax
+	movl	__stop_my_section@GOT+1(%ecx), %eax
+	.size	_start, .-_start

ld/testsuite/ld-i386/mov2a.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --32
+#ld: -shared -melf_i386
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+#pass

ld/testsuite/ld-i386/mov2b.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --32
+#ld: -pie -melf_i386
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+[ 	]*[a-f0-9]+:	8b 81 ([0-9a-f]{2} ){4} *	mov    -0x[a-f0-9]+\(%ecx\),%eax
+#pass

ld/testsuite/ld-i386/mov3.d

@@ -0,0 +1,14 @@
+#as: --32
+#ld: -melf_i386
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\,%eax
+[ 	]*[a-f0-9]+:	8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\,%eax
+[ 	]*[a-f0-9]+:	8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\,%eax
+#pass

ld/testsuite/ld-i386/mov3.s

@@ -0,0 +1,15 @@
+	.section	my_section,"aw",@progbits
+	.long	0x12345678
+	.text
+	.globl	foo
+	.type	foo, @function
+foo:
+	ret
+	.size	foo, .-foo
+	.globl	_start
+	.type	_start, @function
+_start:
+	movl	foo@GOT+1, %eax
+	movl	__start_my_section@GOT+1, %eax
+	movl	__stop_my_section@GOT+1, %eax
+	.size	_start, .-_start

ld/testsuite/ld-x86-64/mov2.s

@@ -0,0 +1,15 @@
+	.section	my_section,"aw",@progbits
+	.long	0x12345678
+	.text
+	.globl	foo
+	.type	foo, @function
+foo:
+	ret
+	.size	foo, .-foo
+	.globl	_start
+	.type	_start, @function
+_start:
+	movq	foo@GOTPCREL+1(%rip), %rax
+	movq	__start_my_section@GOTPCREL+1(%rip), %rax
+	movq	__stop_my_section@GOTPCREL+1(%rip), %rax
+	.size	_start, .-_start

ld/testsuite/ld-x86-64/mov2a.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --64
+#ld: -shared -melf_x86_64
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+#pass

ld/testsuite/ld-x86-64/mov2b.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --64
+#ld: -pie -melf_x86_64
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+#pass

ld/testsuite/ld-x86-64/mov2c.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --x32
+#ld: -shared -melf32_x86_64
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+#pass

ld/testsuite/ld-x86-64/mov2d.d

@@ -0,0 +1,15 @@
+#source: mov2.s
+#as: --x32
+#ld: -pie -melf32_x86_64
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+#...
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+[ 	]*[a-f0-9]+:	48 8b 05 ([0-9a-f]{2} ){4} *	mov    0x[a-f0-9]+\(%rip\),%rax        # [a-f0-9]+ <_DYNAMIC\+0x[a-f0-9]+>
+#pass

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

@@ -321,6 +321,10 @@ run_dump_test "mov1a"
 run_dump_test "mov1b"
 run_dump_test "mov1c"
 run_dump_test "mov1d"
+run_dump_test "mov2a"
+run_dump_test "mov2b"
+run_dump_test "mov2c"
+run_dump_test "mov2d"
 run_dump_test "load1a"
 run_dump_test "load1b"
 run_dump_test "load1c"