[PATCH 02/10] aarch64: Tweak insn sequence code

[PATCH 02/10] aarch64: Tweak insn sequence code

[Richard Sandiford]

libopcodes has some code to check constraints across sequences
of consecutive instructions.  It was added to support MOVPRFX
sequences but is going to be useful for the Armv8.8-A MOPS
feature as well.

Currently the structure has one field to record the instruction
that started a sequence and another to record the remaining
instructions in the sequence.  It's more convenient for the
MOPS code if we put the instructions into a single array instead.

No functional change intended.

Tested on aarch64-linux-gnu.  OK to install?

Richard


include/
	* opcode/aarch64.h (aarch64_instr_sequence): Replace num_insns
	and current_insns with num_added_insns and num_allocated_insns.

opcodes/
	* aarch64-opc.c (add_insn_to_sequence): New function.
	(init_insn_sequence): Update for new aarch64_instr_sequence layout.
	Add the first instruction to the inst array.
	(verify_constraints): Update for new aarch64_instr_sequence layout.
	Don't add the last instruction to the array.
---
 include/opcode/aarch64.h | 12 +++++-----
 opcodes/aarch64-opc.c    | 48 ++++++++++++++++++----------------------
 2 files changed, 27 insertions(+), 33 deletions(-)

diff --git a/include/opcode/aarch64.h b/include/opcode/aarch64.h
index 9448d3596f5..fa79aa9c25a 100644
--- a/include/opcode/aarch64.h
+++ b/include/opcode/aarch64.h
@@ -1290,15 +1290,13 @@ struct aarch64_operand_error
    dependencies for both assembler and disassembler.  */
 struct aarch64_instr_sequence
 {
-  /* The instruction that caused this sequence to be opened.  */
+  /* The instructions in the sequence, starting with the one that
+     caused it to be opened.  */
   aarch64_inst *instr;
-  /* The number of instructions the above instruction allows one to be kept in the
-     sequence before an automatic close is done.  */
-  int num_insns;
-  /* The instructions currently added to the sequence.  */
-  aarch64_inst **current_insns;
   /* The number of instructions already in the sequence.  */
-  int next_insn;
+  int num_added_insns;
+  /* The number of instructions allocated to the sequence.  */
+  int num_allocated_insns;
 };
 
 /* Encoding entrypoint.  */
diff --git a/opcodes/aarch64-opc.c b/opcodes/aarch64-opc.c
index b7076cdbf35..289df9e8848 100644
--- a/opcodes/aarch64-opc.c
+++ b/opcodes/aarch64-opc.c
@@ -5403,6 +5403,15 @@ verify_elem_sd (const struct aarch64_inst *inst, const aarch64_insn insn,
   return ERR_OK;
 }
 
+/* Add INST to the end of INSN_SEQUENCE.  */
+
+static void
+add_insn_to_sequence (const struct aarch64_inst *inst,
+		      aarch64_instr_sequence *insn_sequence)
+{
+  insn_sequence->instr[insn_sequence->num_added_insns++] = *inst;
+}
+
 /* Initialize an instruction sequence insn_sequence with the instruction INST.
    If INST is NULL the given insn_sequence is cleared and the sequence is left
    uninitialized.  */
@@ -5412,16 +5421,11 @@ init_insn_sequence (const struct aarch64_inst *inst,
 		    aarch64_instr_sequence *insn_sequence)
 {
   int num_req_entries = 0;
-  insn_sequence->next_insn = 0;
-  insn_sequence->num_insns = num_req_entries;
-  if (insn_sequence->instr)
-    XDELETE (insn_sequence->instr);
-  insn_sequence->instr = NULL;
 
-  if (inst)
+  if (insn_sequence->instr)
     {
-      insn_sequence->instr = XNEW (aarch64_inst);
-      memcpy (insn_sequence->instr, inst, sizeof (aarch64_inst));
+      XDELETE (insn_sequence->instr);
+      insn_sequence->instr = NULL;
     }
 
   /* Handle all the cases here.  May need to think of something smarter than
@@ -5430,16 +5434,13 @@ init_insn_sequence (const struct aarch64_inst *inst,
   if (inst && inst->opcode->constraints & C_SCAN_MOVPRFX)
     num_req_entries = 1;
 
-  if (insn_sequence->current_insns)
-    XDELETEVEC (insn_sequence->current_insns);
-  insn_sequence->current_insns = NULL;
+  insn_sequence->num_added_insns = 0;
+  insn_sequence->num_allocated_insns = num_req_entries;
 
   if (num_req_entries != 0)
     {
-      size_t size = num_req_entries * sizeof (aarch64_inst);
-      insn_sequence->current_insns
-	= (aarch64_inst**) XNEWVEC (aarch64_inst, num_req_entries);
-      memset (insn_sequence->current_insns, 0, size);
+      insn_sequence->instr = XCNEWVEC (aarch64_inst, num_req_entries);
+      add_insn_to_sequence (inst, insn_sequence);
     }
 }
 
@@ -5715,17 +5716,12 @@ verify_constraints (const struct aarch64_inst *inst,
 	}
 
     done:
-      /* Add the new instruction to the sequence.  */
-      memcpy (insn_sequence->current_insns + insn_sequence->next_insn++,
-	      inst, sizeof (aarch64_inst));
-
-      /* Check if sequence is now full.  */
-      if (insn_sequence->next_insn >= insn_sequence->num_insns)
-	{
-	  /* Sequence is full, but we don't have anything special to do for now,
-	     so clear and reset it.  */
-	  init_insn_sequence (NULL, insn_sequence);
-	}
+      if (insn_sequence->num_added_insns == insn_sequence->num_allocated_insns)
+	/* We've checked the last instruction in the sequence and so
+	   don't need the sequence any more.  */
+	init_insn_sequence (NULL, insn_sequence);
+      else
+	add_insn_to_sequence (inst, insn_sequence);
     }
 
   return res;
-- 
2.25.1

Re: [PATCH 02/10] aarch64: Tweak insn sequence code

[Nick Clifton]

Hi Richard,

> include/
> 	* opcode/aarch64.h (aarch64_instr_sequence): Replace num_insns
> 	and current_insns with num_added_insns and num_allocated_insns.
> 
> opcodes/
> 	* aarch64-opc.c (add_insn_to_sequence): New function.
> 	(init_insn_sequence): Update for new aarch64_instr_sequence layout.
> 	Add the first instruction to the inst array.
> 	(verify_constraints): Update for new aarch64_instr_sequence layout.
> 	Don't add the last instruction to the array.

Approved - please apply.

Cheers
   Nick