AArch64: Wire through instr_sequence

This patch introduces aarch64_instr_sequence which is a structure similar to IT
blocks on Arm in order to track instructions that introduce a constraint or
dependency on instruction 1..N positions away from the instruction that opened
the block.

The struct is also wired through to the locations that require it.

gas/

	* config/tc-aarch64.c (now_instr_sequence):
	(*insn_sequence, now_instr_sequence): New.
	(output_operand_error_record, do_encode): Add insn_sequence.
	(md_assemble): Update insn_sequence.
	(try_to_encode_as_unscaled_ldst, fix_mov_imm_insn, fix_insn):
	Pass insn_sequence.
	* config/tc-aarch64.h (struct aarch64_segment_info_type):
	Add insn_sequence.

include/

	* opcode/aarch64.h (struct aarch64_instr_sequence): New.
	(aarch64_opcode_encode): Use it.

opcodes/

	* aarch64-asm.c (aarch64_opcode_encode): Add insn_sequence.
	* aarch64-dis.c (insn_sequence): New.

3 files changed, 34 insertions, 8 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index d6a4380..68fc927 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,14 @@
+2018-10-03  Tamar Christina  <tamar.christina@arm.com>
+
+	* config/tc-aarch64.c (now_instr_sequence):
+	(*insn_sequence, now_instr_sequence): New.
+	(output_operand_error_record, do_encode): Add insn_sequence.
+	(md_assemble): Update insn_sequence.
+	(try_to_encode_as_unscaled_ldst, fix_mov_imm_insn, fix_insn):
+	Pass insn_sequence.
+	* config/tc-aarch64.h (struct aarch64_segment_info_type):
+	Add insn_sequence.
+
 2018-10-02  Palmer Dabbelt  <palmer@sifive.com>
 
 	* testsuite/gas/riscv/fence-tso.d: New file.
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index c77de21..206019b 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -55,6 +55,9 @@ static const aarch64_feature_set *march_cpu_opt = NULL;
 /* Constants for known architecture features.  */
 static const aarch64_feature_set cpu_default = CPU_DEFAULT;
 
+/* Currently active instruction sequence.  */
+static aarch64_instr_sequence *insn_sequence = NULL;
+
 #ifdef OBJ_ELF
 /* Pre-defined "_GLOBAL_OFFSET_TABLE_"	*/
 static symbolS *GOT_symbol;
@@ -146,6 +149,13 @@ static aarch64_instruction inst;
 static bfd_boolean parse_operands (char *, const aarch64_opcode *);
 static bfd_boolean programmer_friendly_fixup (aarch64_instruction *);
 
+#ifdef OBJ_ELF
+#  define now_instr_sequence seg_info \
+		(now_seg)->tc_segment_info_data.insn_sequence
+#else
+static struct aarch64_instr_sequence now_instr_sequence;
+#endif
+
 /* Diagnostics inline function utilities.
 
    These are lightweight utilities which should only be called by parse_operands
@@ -4661,7 +4671,7 @@ output_operand_error_record (const operand_error_record *record, char *str)
 	    && programmer_friendly_fixup (&inst);
 	  gas_assert (result);
 	  result = aarch64_opcode_encode (opcode, inst_base, &inst_base->value,
-					  NULL, NULL);
+					  NULL, NULL, insn_sequence);
 	  gas_assert (!result);
 
 	  /* Find the most matched qualifier sequence.  */
@@ -6738,7 +6748,7 @@ do_encode (const aarch64_opcode *opcode, aarch64_inst *instr,
   aarch64_operand_error error_info;
   memset (&error_info, '\0', sizeof (error_info));
   error_info.kind = AARCH64_OPDE_NIL;
-  if (aarch64_opcode_encode (opcode, instr, code, NULL, &error_info)
+  if (aarch64_opcode_encode (opcode, instr, code, NULL, &error_info, insn_sequence)
       && !error_info.non_fatal)
     return TRUE;
 
@@ -6784,6 +6794,9 @@ md_assemble (char *str)
       S_SET_SEGMENT (last_label_seen, now_seg);
     }
 
+  /* Update the current insn_sequence from the segment.  */
+  insn_sequence = &seg_info (now_seg)->tc_segment_info_data.insn_sequence;
+
   inst.reloc.type = BFD_RELOC_UNUSED;
 
   DEBUG_TRACE ("\n\n");
@@ -7376,7 +7389,8 @@ try_to_encode_as_unscaled_ldst (aarch64_inst *instr)
 
   DEBUG_TRACE ("Found LDURB entry to encode programmer-friendly LDRB");
 
-  if (!aarch64_opcode_encode (instr->opcode, instr, &instr->value, NULL, NULL))
+  if (!aarch64_opcode_encode (instr->opcode, instr, &instr->value, NULL, NULL,
+			      insn_sequence))
     return FALSE;
 
   return TRUE;
@@ -7410,7 +7424,7 @@ fix_mov_imm_insn (fixS *fixP, char *buf, aarch64_inst *instr, offsetT value)
       opcode = aarch64_get_opcode (OP_MOV_IMM_WIDE);
       aarch64_replace_opcode (instr, opcode);
       if (aarch64_opcode_encode (instr->opcode, instr,
-				 &instr->value, NULL, NULL))
+				 &instr->value, NULL, NULL, insn_sequence))
 	{
 	  put_aarch64_insn (buf, instr->value);
 	  return;
@@ -7419,7 +7433,7 @@ fix_mov_imm_insn (fixS *fixP, char *buf, aarch64_inst *instr, offsetT value)
       opcode = aarch64_get_opcode (OP_MOV_IMM_WIDEN);
       aarch64_replace_opcode (instr, opcode);
       if (aarch64_opcode_encode (instr->opcode, instr,
-				 &instr->value, NULL, NULL))
+				 &instr->value, NULL, NULL, insn_sequence))
 	{
 	  put_aarch64_insn (buf, instr->value);
 	  return;
@@ -7432,7 +7446,7 @@ fix_mov_imm_insn (fixS *fixP, char *buf, aarch64_inst *instr, offsetT value)
       opcode = aarch64_get_opcode (OP_MOV_IMM_LOG);
       aarch64_replace_opcode (instr, opcode);
       if (aarch64_opcode_encode (instr->opcode, instr,
-				 &instr->value, NULL, NULL))
+				 &instr->value, NULL, NULL, insn_sequence))
 	{
 	  put_aarch64_insn (buf, instr->value);
 	  return;
@@ -7543,7 +7557,7 @@ fix_insn (fixS *fixP, uint32_t flags, offsetT value)
       idx = aarch64_operand_index (new_inst->opcode->operands, opnd);
       new_inst->operands[idx].imm.value = value;
       if (aarch64_opcode_encode (new_inst->opcode, new_inst,
-				 &new_inst->value, NULL, NULL))
+				 &new_inst->value, NULL, NULL, insn_sequence))
 	put_aarch64_insn (buf, new_inst->value);
       else
 	as_bad_where (fixP->fx_file, fixP->fx_line,
@@ -7597,7 +7611,7 @@ fix_insn (fixS *fixP, uint32_t flags, offsetT value)
 
       /* Encode/fix-up.  */
       if (aarch64_opcode_encode (new_inst->opcode, new_inst,
-				 &new_inst->value, NULL, NULL))
+				 &new_inst->value, NULL, NULL, insn_sequence))
 	{
 	  put_aarch64_insn (buf, new_inst->value);
 	  break;
diff --git a/gas/config/tc-aarch64.h b/gas/config/tc-aarch64.h
index dd92521..cdf9883 100644
--- a/gas/config/tc-aarch64.h
+++ b/gas/config/tc-aarch64.h
@@ -183,6 +183,7 @@ struct aarch64_segment_info_type
 {
   enum mstate mapstate;
   unsigned int marked_pr_dependency;
+  aarch64_instr_sequence insn_sequence;
 };
 
 /* We want .cfi_* pseudo-ops for generating unwind info.  */