[PATCH 1/3] x86-64: improve handling of branches to absolute addresses

[Jan Beulich]

There are two related problems here: The use of "addr32" on a direct
branch would, besides causing a warning, result in operands to be
permitted which mistakenly are refused without "addr32". Plus at some
point not too long ago I'm afraid it may have been me who regressed the
relocation addends emitted for such branches. Correct both problems,
adding a testcase to guard against regressing this again.
---
In principle things like "JECXZ <absolute>" should be permitted as well,
I think. Whether the destination is within reach can only be determined
by the linker. But that likely being a more intrusive change, I guess we
can leave this as is until someone really needs it to work.

If "ELF: emit symbol table when there are relocations" (submitted
earlier) goes in before this change, I'd be inclined to drop the label
again from the new testcase. The original lack of a label there was how
I noticed that other issue, so the testcase here could at once serve to
test that changed behavior as well.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -4975,7 +4975,9 @@ md_assemble (char *line)
   if (i.imm_operands)
     optimize_imm ();
 
-  if (i.disp_operands && !want_disp32 (current_templates->start))
+  if (i.disp_operands && !want_disp32 (current_templates->start)
+      && (!current_templates->start->opcode_modifier.jump
+	  || i.jumpabsolute || i.types[0].bitfield.baseindex))
     {
       for (j = 0; j < i.operands; ++j)
 	{
@@ -5985,7 +5987,9 @@ optimize_disp (void)
 	    /* Optimize 64-bit displacement to 32-bit for 64-bit BFD.  */
 	    if ((i.types[op].bitfield.disp32
 		 || (flag_code == CODE_64BIT
-		     && want_disp32 (current_templates->start)))
+		     && want_disp32 (current_templates->start)
+		     && (!current_templates->start->opcode_modifier.jump
+			 || i.jumpabsolute || i.types[op].bitfield.baseindex)))
 		&& fits_in_unsigned_long (op_disp))
 	      {
 		/* If this operand is at most 32 bits, convert
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -1314,6 +1314,7 @@ if [gas_64_check] then {
 	run_dump_test "x86-64-branch-3"
 	run_list_test "x86-64-branch-4" "-al -mintel64"
 	run_list_test "x86-64-branch-5" "-al"
+	run_dump_test "x86-64-branch-6"
 
 	run_dump_test "x86-64-rip-2"
 
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-branch-6.d
@@ -0,0 +1,21 @@
+#objdump: -r
+#name: x86-64 branch 6
+#warning_output: x86-64-branch-6.e
+
+.*: +file format .*
+
+RELOCATION RECORDS FOR \[\.text\]:
+OFFSET +TYPE +VALUE *
+0+01 R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+11 R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+0+21 R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+31 R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+0+07 R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+0c R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+17 R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+0+1c R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+0+27 R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+2c R_X86_64_PC32 +\*ABS\*\+0x000000008765431d
+0+37 R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+0+3c R_X86_64_PC32 +\*ABS\*\+0x000000087654320c
+#pass
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-branch-6.s
@@ -0,0 +1,18 @@
+	.text
+
+branch_6:
+	call	0x87654321
+	je	0x87654321
+	jmp	0x87654321
+
+	call	0x876543210
+	je	0x876543210
+	jmp	0x876543210
+
+	addr32 call	0x87654321
+	addr32 je	0x87654321
+	addr32 jmp	0x87654321
+
+	addr32 call	0x876543210
+	addr32 je	0x876543210
+	addr32 jmp	0x876543210
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-branch-6.e
@@ -0,0 +1,7 @@
+.*: Assembler messages:
+.*:12: Warning: skipping prefixes on `call'
+.*:13: Warning: skipping prefixes on `je'
+.*:14: Warning: skipping prefixes on `jmp'
+.*:16: Warning: skipping prefixes on `call'
+.*:17: Warning: skipping prefixes on `je'
+.*:18: Warning: skipping prefixes on `jmp'