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[PATCH] Fix IA-32 gas _GLOBAL_OFFSET_TABLE_ handling bugs (take 2)


On Fri, Aug 02, 2002 at 01:01:03PM -0700, Roland McGrath wrote:
> Please add some test cases that don't use . and arithmetic, such as:
> 
> 	addl $_GLOBAL_OFFSET_TABLE_,%eax
> 	addl $_GLOBAL_OFFSET_TABLE_,%ebx
> 
> This is what GCC actually produced that bit me.

I've added a bunch of these tests below.
Ok to commit then?
Daniel, can this make it into 2.13?

2002-08-03  Jakub Jelinek  <jakub@redhat.com>

	* config/tc-i386.c (output_insn): Save frag_now and frag_now_fix ()
	at start of insn, pass it to output_disp and output_imm.
	(output_disp): Added arguments.  If _GLOBAL_OFFSET_TABLE_ is seen
	in displacement for R_386_32 reloc, use R_386_GOTPC and compute
	properly addend.
	(output_imm): Added arguments.  Compute properly addend for
	R_386_GOTPC.
	(md_apply_fix3): Remove R_386_GOTPC handling.
	* testsuite/gas/i386/gotpc.s: New.
	* testsuite/gas/i386/gotpc.d: New.
	* testsuite/gas/i386/i386.exp: Add gotpc test.

--- gas/config/tc-i386.c.jj	2002-07-18 11:35:39.000000000 +0200
+++ gas/config/tc-i386.c	2002-08-02 21:13:18.000000000 +0200
@@ -104,8 +104,10 @@ static void output_insn PARAMS ((void));
 static void output_branch PARAMS ((void));
 static void output_jump PARAMS ((void));
 static void output_interseg_jump PARAMS ((void));
-static void output_imm PARAMS ((void));
-static void output_disp PARAMS ((void));
+static void output_imm PARAMS ((fragS *insn_start_frag,
+				offsetT insn_start_off));
+static void output_disp PARAMS ((fragS *insn_start_frag,
+				 offsetT insn_start_off));
 #ifndef I386COFF
 static void s_bss PARAMS ((int));
 #endif
@@ -3101,14 +3103,21 @@ output_interseg_jump ()
   md_number_to_chars (p + size, (valueT) i.op[0].imms->X_add_number, 2);
 }
 
+
 static void
 output_insn ()
 {
+  fragS *insn_start_frag;
+  offsetT insn_start_off;
+
   /* Tie dwarf2 debug info to the address at the start of the insn.
      We can't do this after the insn has been output as the current
      frag may have been closed off.  eg. by frag_var.  */
   dwarf2_emit_insn (0);
 
+  insn_start_frag = frag_now;
+  insn_start_off = frag_now_fix ();
+
   /* Output jumps.  */
   if (i.tm.opcode_modifier & Jump)
     output_branch ();
@@ -3179,10 +3188,10 @@ output_insn ()
 	}
 
       if (i.disp_operands)
-	output_disp ();
+	output_disp (insn_start_frag, insn_start_off);
 
       if (i.imm_operands)
-	output_imm ();
+	output_imm (insn_start_frag, insn_start_off);
     }
 
 #ifdef DEBUG386
@@ -3194,7 +3203,9 @@ output_insn ()
 }
 
 static void
-output_disp ()
+output_disp (insn_start_frag, insn_start_off)
+    fragS *insn_start_frag;
+    offsetT insn_start_off;
 {
   char *p;
   unsigned int n;
@@ -3224,6 +3235,7 @@ output_disp ()
 	    }
 	  else
 	    {
+	      RELOC_ENUM reloc_type;
 	      int size = 4;
 	      int sign = 0;
 	      int pcrel = (i.flags[n] & Operand_PCrel) != 0;
@@ -3266,16 +3278,50 @@ output_disp ()
 		}
 
 	      p = frag_more (size);
+	      reloc_type = reloc (size, pcrel, sign, i.reloc[n]);
+#ifdef BFD_ASSEMBLER
+	      if (reloc_type == BFD_RELOC_32
+		  && GOT_symbol
+		  && GOT_symbol == i.op[n].disps->X_add_symbol
+		  && (i.op[n].disps->X_op == O_symbol
+		      || (i.op[n].disps->X_op == O_add
+			  && ((symbol_get_value_expression
+			       (i.op[n].disps->X_op_symbol)->X_op)
+			      == O_subtract))))
+		{
+		  offsetT add;
+
+		  if (insn_start_frag == frag_now)
+		    add = (p - frag_now->fr_literal) - insn_start_off;
+		  else
+		    {
+		      fragS *fr;
+
+		      add = insn_start_frag->fr_fix - insn_start_off;
+		      for (fr = insn_start_frag->fr_next;
+			   fr && fr != frag_now; fr = fr->fr_next)
+			add += fr->fr_fix;
+		      add += p - frag_now->fr_literal;
+		    }
+
+		  /* We don't support dynamic linking on x86-64 yet.  */
+		  if (flag_code == CODE_64BIT)
+		    abort ();
+		  reloc_type = BFD_RELOC_386_GOTPC;
+		  i.op[n].disps->X_add_number += add;
+		}
+#endif
 	      fix_new_exp (frag_now, p - frag_now->fr_literal, size,
-			   i.op[n].disps, pcrel,
-			   reloc (size, pcrel, sign, i.reloc[n]));
+			   i.op[n].disps, pcrel, reloc_type);
 	    }
 	}
     }
 }
 
 static void
-output_imm ()
+output_imm (insn_start_frag, insn_start_off)
+    fragS *insn_start_frag;
+    offsetT insn_start_off;
 {
   char *p;
   unsigned int n;
@@ -3328,6 +3374,48 @@ output_imm ()
 	      p = frag_more (size);
 	      reloc_type = reloc (size, 0, sign, i.reloc[n]);
 #ifdef BFD_ASSEMBLER
+	      /*   This is tough to explain.  We end up with this one if we
+	       * have operands that look like
+	       * "_GLOBAL_OFFSET_TABLE_+[.-.L284]".  The goal here is to
+	       * obtain the absolute address of the GOT, and it is strongly
+	       * preferable from a performance point of view to avoid using
+	       * a runtime relocation for this.  The actual sequence of
+	       * instructions often look something like:
+	       *
+	       *	call	.L66
+	       * .L66:
+	       *	popl	%ebx
+	       *	addl	$_GLOBAL_OFFSET_TABLE_+[.-.L66],%ebx
+	       *
+	       *   The call and pop essentially return the absolute address
+	       * of the label .L66 and store it in %ebx.  The linker itself
+	       * will ultimately change the first operand of the addl so
+	       * that %ebx points to the GOT, but to keep things simple, the
+	       * .o file must have this operand set so that it generates not
+	       * the absolute address of .L66, but the absolute address of
+	       * itself.  This allows the linker itself simply treat a GOTPC
+	       * relocation as asking for a pcrel offset to the GOT to be
+	       * added in, and the addend of the relocation is stored in the
+	       * operand field for the instruction itself.
+	       *
+	       *   Our job here is to fix the operand so that it would add
+	       * the correct offset so that %ebx would point to itself.  The
+	       * thing that is tricky is that .-.L66 will point to the
+	       * beginning of the instruction, so we need to further modify
+	       * the operand so that it will point to itself.  There are
+	       * other cases where you have something like:
+	       *
+	       *	.long	$_GLOBAL_OFFSET_TABLE_+[.-.L66]
+	       *
+	       * and here no correction would be required.  Internally in
+	       * the assembler we treat operands of this form as not being
+	       * pcrel since the '.' is explicitly mentioned, and I wonder
+	       * whether it would simplify matters to do it this way.  Who
+	       * knows.  In earlier versions of the PIC patches, the
+	       * pcrel_adjust field was used to store the correction, but
+	       * since the expression is not pcrel, I felt it would be
+	       * confusing to do it this way.  */
+
 	      if (reloc_type == BFD_RELOC_32
 		  && GOT_symbol
 		  && GOT_symbol == i.op[n].imms->X_add_symbol
@@ -3337,11 +3425,26 @@ output_imm ()
 			       (i.op[n].imms->X_op_symbol)->X_op)
 			      == O_subtract))))
 		{
+		  offsetT add;
+
+		  if (insn_start_frag == frag_now)
+		    add = (p - frag_now->fr_literal) - insn_start_off;
+		  else
+		    {
+		      fragS *fr;
+
+		      add = insn_start_frag->fr_fix - insn_start_off;
+		      for (fr = insn_start_frag->fr_next;
+			   fr && fr != frag_now; fr = fr->fr_next)
+			add += fr->fr_fix;
+		      add += p - frag_now->fr_literal;
+		    }
+
 		  /* We don't support dynamic linking on x86-64 yet.  */
 		  if (flag_code == CODE_64BIT)
 		    abort ();
 		  reloc_type = BFD_RELOC_386_GOTPC;
-		  i.op[n].imms->X_add_number += 3;
+		  i.op[n].imms->X_add_number += add;
 		}
 #endif
 	      fix_new_exp (frag_now, p - frag_now->fr_literal, size,
@@ -4542,48 +4645,6 @@ md_apply_fix3 (fixP, valP, seg)
 	   runtime we merely add the offset to the actual PLT entry.  */
 	value = -4;
 	break;
-      case BFD_RELOC_386_GOTPC:
-
-/*   This is tough to explain.  We end up with this one if we have
- * operands that look like "_GLOBAL_OFFSET_TABLE_+[.-.L284]".  The goal
- * here is to obtain the absolute address of the GOT, and it is strongly
- * preferable from a performance point of view to avoid using a runtime
- * relocation for this.  The actual sequence of instructions often look
- * something like:
- *
- *	call	.L66
- * .L66:
- *	popl	%ebx
- *	addl	$_GLOBAL_OFFSET_TABLE_+[.-.L66],%ebx
- *
- *   The call and pop essentially return the absolute address of
- * the label .L66 and store it in %ebx.  The linker itself will
- * ultimately change the first operand of the addl so that %ebx points to
- * the GOT, but to keep things simple, the .o file must have this operand
- * set so that it generates not the absolute address of .L66, but the
- * absolute address of itself.  This allows the linker itself simply
- * treat a GOTPC relocation as asking for a pcrel offset to the GOT to be
- * added in, and the addend of the relocation is stored in the operand
- * field for the instruction itself.
- *
- *   Our job here is to fix the operand so that it would add the correct
- * offset so that %ebx would point to itself.  The thing that is tricky is
- * that .-.L66 will point to the beginning of the instruction, so we need
- * to further modify the operand so that it will point to itself.
- * There are other cases where you have something like:
- *
- *	.long	$_GLOBAL_OFFSET_TABLE_+[.-.L66]
- *
- * and here no correction would be required.  Internally in the assembler
- * we treat operands of this form as not being pcrel since the '.' is
- * explicitly mentioned, and I wonder whether it would simplify matters
- * to do it this way.  Who knows.  In earlier versions of the PIC patches,
- * the pcrel_adjust field was used to store the correction, but since the
- * expression is not pcrel, I felt it would be confusing to do it this
- * way.  */
-
-	value -= 1;
-	break;
       case BFD_RELOC_386_GOT32:
       case BFD_RELOC_386_TLS_GD:
       case BFD_RELOC_386_TLS_LDM:
--- gas/testsuite/gas/i386/gotpc.s.jj	2002-08-02 21:17:57.000000000 +0200
+++ gas/testsuite/gas/i386/gotpc.s	2002-08-03 22:55:47.000000000 +0200
@@ -0,0 +1,40 @@
+	.text
+test:
+	addl $_GLOBAL_OFFSET_TABLE_+[.-test], %eax
+	addl $_GLOBAL_OFFSET_TABLE_+[.-test], %ebx
+	addl $_GLOBAL_OFFSET_TABLE_, %eax
+	addl $_GLOBAL_OFFSET_TABLE_, %ebx
+	leal _GLOBAL_OFFSET_TABLE+[.-test](%eax), %ebx
+	leal _GLOBAL_OFFSET_TABLE+[.-test](%ebx), %eax
+	leal _GLOBAL_OFFSET_TABLE+[.-test](%eax), %eax
+	leal _GLOBAL_OFFSET_TABLE+[.-test](%ebx), %ebx
+	subl $_GLOBAL_OFFSET_TABLE_+[.-test], %eax
+	subl $_GLOBAL_OFFSET_TABLE_+[.-test], %ebx
+	subl $_GLOBAL_OFFSET_TABLE_, %eax
+	subl $_GLOBAL_OFFSET_TABLE_, %ebx
+	orl $_GLOBAL_OFFSET_TABLE_+[.-test], %eax
+	orl $_GLOBAL_OFFSET_TABLE_+[.-test], %ebx
+	orl $_GLOBAL_OFFSET_TABLE_, %eax
+	orl $_GLOBAL_OFFSET_TABLE_, %ebx
+	movl $_GLOBAL_OFFSET_TABLE_+[.-test], %eax
+	movl $_GLOBAL_OFFSET_TABLE_+[.-test], %ebx
+	movl $_GLOBAL_OFFSET_TABLE_, %eax
+	movl $_GLOBAL_OFFSET_TABLE_, %ebx
+	movl $_GLOBAL_OFFSET_TABLE_+[.-test], foo
+	movl $_GLOBAL_OFFSET_TABLE_+[.-test], %gs:foo
+	gs; movl $_GLOBAL_OFFSET_TABLE_+[.-test], foo
+	movl $_GLOBAL_OFFSET_TABLE_+[.-test], _GLOBAL_OFFSET_TABLE_
+	movl _GLOBAL_OFFSET_TABLE_+[.-test], %eax
+	movl _GLOBAL_OFFSET_TABLE_+[.-test], %ebx
+	movl %eax, _GLOBAL_OFFSET_TABLE_+[.-test]
+	movl %ebx, _GLOBAL_OFFSET_TABLE_+[.-test]
+	movl %eax, %gs:_GLOBAL_OFFSET_TABLE_+[.-test]
+	movl %ebx, %gs:_GLOBAL_OFFSET_TABLE_+[.-test]
+	gs; movl %eax, _GLOBAL_OFFSET_TABLE_+[.-test]
+	gs; movl %ebx, _GLOBAL_OFFSET_TABLE_+[.-test]
+	leal _GLOBAL_OFFSET_TABLE_@GOTOFF(%ebx), %eax
+	leal _GLOBAL_OFFSET_TABLE_@GOTOFF(%ebx), %ebx
+	movl _GLOBAL_OFFSET_TABLE_@GOTOFF(%ebx), %eax
+	movl _GLOBAL_OFFSET_TABLE_@GOTOFF(%ebx), %ebx
+	.long _GLOBAL_OFFSET_TABLE_+[.-test]
+	.long _GLOBAL_OFFSET_TABLE_@GOTOFF
--- gas/testsuite/gas/i386/gotpc.d.jj	2002-08-02 21:18:43.000000000 +0200
+++ gas/testsuite/gas/i386/gotpc.d	2002-08-03 23:05:43.000000000 +0200
@@ -0,0 +1,52 @@
+#objdump: -drw
+#name: i386 gotpc
+
+.*: +file format .*
+
+Disassembly of section .text:
+
+0+000 <test>:
+   0:	05 01 00 00 00 [ 	]*add    \$0x1,%eax	1: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+   5:	81 c3 07 00 00 00 [ 	]*add    \$0x7,%ebx	7: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+   b:	05 01 00 00 00 [ 	]*add    \$0x1,%eax	c: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  10:	81 c3 02 00 00 00 [ 	]*add    \$0x2,%ebx	12: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  16:	8d 98 16 00 00 00 [ 	]*lea    0x16\(%eax\),%ebx	18: (R_386_)?(dir)?32	_GLOBAL_OFFSET_TABLE
+  1c:	8d 83 1c 00 00 00 [ 	]*lea    0x1c\(%ebx\),%eax	1e: (R_386_)?(dir)?32	_GLOBAL_OFFSET_TABLE
+  22:	8d 80 22 00 00 00 [ 	]*lea    0x22\(%eax\),%eax	24: (R_386_)?(dir)?32	_GLOBAL_OFFSET_TABLE
+  28:	8d 9b 28 00 00 00 [ 	]*lea    0x28\(%ebx\),%ebx	2a: (R_386_)?(dir)?32	_GLOBAL_OFFSET_TABLE
+  2e:	2d 2f 00 00 00 [ 	]*sub    \$0x2f,%eax	2f: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  33:	81 eb 35 00 00 00 [ 	]*sub    \$0x35,%ebx	35: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  39:	2d 01 00 00 00 [ 	]*sub    \$0x1,%eax	3a: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  3e:	81 eb 02 00 00 00 [ 	]*sub    \$0x2,%ebx	40: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  44:	0d 45 00 00 00 [ 	]*or     \$0x45,%eax	45: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  49:	81 cb 4b 00 00 00 [ 	]*or     \$0x4b,%ebx	4b: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  4f:	0d 01 00 00 00 [ 	]*or     \$0x1,%eax	50: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  54:	81 cb 02 00 00 00 [ 	]*or     \$0x2,%ebx	56: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  5a:	b8 5b 00 00 00 [ 	]*mov    \$0x5b,%eax	5b: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  5f:	bb 60 00 00 00 [ 	]*mov    \$0x60,%ebx	60: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  64:	b8 01 00 00 00 [ 	]*mov    \$0x1,%eax	65: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  69:	bb 01 00 00 00 [ 	]*mov    \$0x1,%ebx	6a: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  6e:	c7 05 00 00 00 00 74 00 00 00 [ 	]*movl   \$0x74,0x0	70: (R_386_)?(dir)?32	foo
+[ 	]*74: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  78:	65 c7 05 00 00 00 00 7f 00 00 00 [ 	]*movl   \$0x7f,%gs:0x0	7b: (R_386_)?(dir)?32	foo
+[ 	]*7f: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  83:	65 c7 05 00 00 00 00 8a 00 00 00 [ 	]*movl   \$0x8a,%gs:0x0	86: (R_386_)?(dir)?32	foo
+[ 	]*8a: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  8e:	c7 05 02 00 00 00 94 00 00 00 [ 	]*movl   \$0x94,0x2	90: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+[ 	]*94: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  98:	a1 99 00 00 00 [ 	]*mov    0x99,%eax	99: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  9d:	8b 1d 9f 00 00 00 [ 	]*mov    0x9f,%ebx	9f: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  a3:	a3 a4 00 00 00 [ 	]*mov    %eax,0xa4	a4: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  a8:	89 1d aa 00 00 00 [ 	]*mov    %ebx,0xaa	aa: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  ae:	65 a3 b0 00 00 00 [ 	]*mov    %eax,%gs:0xb0	b0: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  b4:	65 89 1d b7 00 00 00 [ 	]*mov    %ebx,%gs:0xb7	b7: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  bb:	65 a3 bd 00 00 00 [ 	]*mov    %eax,%gs:0xbd	bd: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  c1:	65 89 1d c4 00 00 00 [ 	]*mov    %ebx,%gs:0xc4	c4: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  c8:	8d 83 00 00 00 00 [ 	]*lea    0x0\(%ebx\),%eax	ca: (R_386_)?GOTOFF	_GLOBAL_OFFSET_TABLE_
+  ce:	8d 9b 00 00 00 00 [ 	]*lea    0x0\(%ebx\),%ebx	d0: (R_386_)?GOTOFF	_GLOBAL_OFFSET_TABLE_
+  d4:	8b 83 00 00 00 00 [ 	]*mov    0x0\(%ebx\),%eax	d6: (R_386_)?GOTOFF	_GLOBAL_OFFSET_TABLE_
+  da:	8b 9b 00 00 00 00 [ 	]*mov    0x0\(%ebx\),%ebx	dc: (R_386_)?GOTOFF	_GLOBAL_OFFSET_TABLE_
+  e0:	e0 00 [ 	]*loopne e2 <test\+0xe2>	e0: (R_386_)?GOTPC	_GLOBAL_OFFSET_TABLE_
+  e2:	00 00 [ 	]*add    %al,\(%eax\)
+  e4:	00 00 [ 	]*add    %al,\(%eax\)	e4: (R_386_)?GOTOFF	_GLOBAL_OFFSET_TABLE_
+	...
--- gas/testsuite/gas/i386/i386.exp.jj	2002-07-18 11:35:39.000000000 +0200
+++ gas/testsuite/gas/i386/i386.exp	2002-08-02 21:57:46.000000000 +0200
@@ -53,6 +53,7 @@ if [expr ([istarget "i*86-*-*"] ||  [ist
     run_dump_test "jump"
     run_dump_test "ssemmx2"
     run_dump_test "sse2"
+    run_dump_test "gotpc"
 
     # PIC is only supported on ELF targets.
     if { ([istarget "*-*-elf*"] || [istarget "*-*-linux*"] )


	Jakub


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