[backport][2.25][aarch64]Don't create new frag for .inst directive when certain conditions fullfil

[Renlin Li <renlin dot li at arm dot com>]

Hi all,

This is a backport patch from the trunk introduced here: 
https://sourceware.org/ml/binutils/2015-03/msg00389.html

After the change, new frag is created for .inst directive, only during 
state transition in executable section. The same rule applies when 
handling normal instructions.

binutils, gas, ld regresstion test Okay.
Okay to commit?

Regards,
Renlin Li

Backport from mainline

2015-05-06  Renlin Li  <renlin.li@arm.com>

gas/ChangeLog
  * config/tc-aarch64.c (s_aarch64_inst): Align frag during state 
transition
  within executable section.
  (md_assemble): Likewise.

diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index ce2ba95..62a1a3f 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -1863,8 +1863,14 @@ s_aarch64_inst (int ignored ATTRIBUTE_UNUSED)
       return;
     }
 
-  if (!need_pass_2)
+  /* Sections are assumed to start aligned. In text section, there is no
+     MAP_DATA symbol pending. So we only align the address during
+     MAP_DATA --> MAP_INSN transition.
+     For other sections, this is not guaranteed.  */
+  enum mstate mapstate = seg_info (now_seg)->tc_segment_info_data.mapstate;
+  if (!need_pass_2 && (subseg_text_p (now_seg) && mapstate == MAP_DATA))
     frag_align_code (2, 0);
+
 #ifdef OBJ_ELF
   mapping_state (MAP_INSN);
 #endif
@@ -5571,6 +5577,14 @@ md_assemble (char *str)
 
   init_operand_error_report ();
 
+  /* Sections are assumed to start aligned. In text section, there is no
+     MAP_DATA symbol pending. So we only align the address during
+     MAP_DATA --> MAP_INSN transition.
+     For other sections, this is not guaranteed.  */
+  enum mstate mapstate = seg_info (now_seg)->tc_segment_info_data.mapstate;
+  if (!need_pass_2 && (subseg_text_p (now_seg) && mapstate == MAP_DATA))
+    frag_align_code (2, 0);
+
   saved_cond = inst.cond;
   reset_aarch64_instruction (&inst);
   inst.cond = saved_cond;