diff mbox series

[v1] aarch64: Preparatory Patch to place target independent and dependent changed code in one file

Message ID 7d7a82e6-c7a9-4af6-abeb-8cf7319e24dd@linux.ibm.com
State New
Headers show
Series [v1] aarch64: Preparatory Patch to place target independent and dependent changed code in one file | expand

Commit Message

Ajit Agarwal April 10, 2024, 10:07 a.m. UTC
Hello Alex/Richard:

All comments are addressed in this version-1 of the patch.

Common infrastructure of load store pair fusion is divded into target
independent and target dependent changed code.

Target independent code is the Generic code with pure virtual function
to interface betwwen target independent and dependent code.

Target dependent code is the implementation of pure virtual function for
aarch64 target and the call to target independent code.

Thanks & Regards
Ajit


aarch64: Place target independent and dependent changed code in one file

Common infrastructure of load store pair fusion is divided into target
independent and target dependent changed code.

Target independent code is the Generic code with pure virtual function
to interface betwwen target independent and dependent code.

Target dependent code is the implementation of pure virtual function for
aarch64 target and the call to target independent code.

2024-04-10  Ajit Kumar Agarwal  <aagarwa1@linux.ibm.com>

gcc/ChangeLog:

	* config/aarch64/aarch64-ldp-fusion.cc: Place target
	independent and dependent changed code.
---
 gcc/config/aarch64/aarch64-ldp-fusion.cc | 497 +++++++++++++++--------
 1 file changed, 337 insertions(+), 160 deletions(-)
diff mbox series

Patch

diff --git a/gcc/config/aarch64/aarch64-ldp-fusion.cc b/gcc/config/aarch64/aarch64-ldp-fusion.cc
index 365dcf48b22..03e8572ebfd 100644
--- a/gcc/config/aarch64/aarch64-ldp-fusion.cc
+++ b/gcc/config/aarch64/aarch64-ldp-fusion.cc
@@ -138,6 +138,198 @@  struct alt_base
   poly_int64 offset;
 };
 
+// Virtual base class for load/store walkers used in alias analysis.
+struct alias_walker
+{
+  virtual bool conflict_p (int &budget) const = 0;
+  virtual insn_info *insn () const = 0;
+  virtual bool valid () const = 0;
+  virtual void advance () = 0;
+};
+
+// Forward declaration to be used inside the aarch64_pair_fusion class.
+bool ldp_operand_mode_ok_p (machine_mode mode);
+rtx aarch64_destructure_load_pair (rtx regs[2], rtx pattern);
+rtx aarch64_destructure_store_pair (rtx regs[2], rtx pattern);
+rtx aarch64_gen_writeback_pair (rtx wb_effect, rtx pair_mem, rtx regs[2],
+			    bool load_p);
+enum class writeback{
+  WRITEBACK_PAIR_P,
+  WRITEBACK
+};
+
+struct pair_fusion {
+
+  pair_fusion ()
+  {
+    calculate_dominance_info (CDI_DOMINATORS);
+    df_analyze ();
+    crtl->ssa = new rtl_ssa::function_info (cfun);
+  };
+  // Return true if GPR is FP or SIMD accesses, passed
+  // with GPR reg_op rtx, machine mode and load_p.
+  virtual bool fpsimd_op_p (rtx, machine_mode, bool)
+  {
+    return false;
+  }
+  // Return true if pair operand mode is ok. Passed with
+  // machine mode.
+  virtual bool pair_operand_mode_ok_p (machine_mode mode) = 0;
+  // Return true if reg operand is ok, passed with load_p,
+  // reg_op rtx and machine mode.
+  virtual bool pair_reg_operand_ok_p (bool load_p, rtx reg_op,
+				      machine_mode mem_mode) = 0;
+  // Return alias check limit.
+  virtual int pair_mem_alias_check_limit () = 0;
+  // Return true if there is writeback opportunities. Passed
+  // with enum writeback.
+  virtual bool handle_writeback_opportunities (enum writeback wback) = 0 ;
+  // Return true if mem ok ldp stp policy model passed with
+  // rtx mem, load_p and machine mode.
+  virtual bool pair_mem_ok_with_policy (rtx first_mem, bool load_p,
+					machine_mode mode) = 0;
+  // Gen load store mem pair. Return load store rtx passed
+  // with arguments load store pattern, writeback rtx and
+  // load_p.
+  virtual rtx gen_mem_pair (rtx *pats, rtx writeback,
+			    bool load_p) = 0;
+  // Return true if memory writeback can be promoted, passed
+  // with insn, rtx pattern and load_p. load_p is set by this
+  // hook.
+  virtual bool pair_mem_promote_writeback_p (insn_info *, rtx, bool &)
+  {
+     return false;
+  }
+  // Return true if we track loads.
+  virtual bool track_loads_p ()
+  {
+    return true;
+  }
+  // Return true if we track stores.
+  virtual bool track_stores_p ()
+  {
+    return true;
+  }
+  // Return true if offset is out of range.
+  virtual bool pair_mem_out_of_range_p (HOST_WIDE_INT off) = 0;
+  // Return destructure pair. Passed with rtx reg, insn pattern
+  // and load_p.
+  virtual rtx gen_destructure_pair (rtx regs[2], rtx rti, bool load_p) = 0;
+  // Return writeback pair. Passed with rtx writeback effect, mem rtx
+  // regs rtx and load_p.
+  virtual rtx gen_writeback_pair (rtx wb_effect, rtx mem,
+				  rtx regs[2], bool load_p) = 0;
+  // Return true if offset is aligned and multiple of 32.
+  // Passed with offset and access_size to check multiple of 32.
+  virtual bool pair_offset_alignment_ok_p (poly_int64 offset,
+					   unsigned access_size) = 0;
+  void ldp_fusion_bb (bb_info *bb);
+  insn_info * find_trailing_add (insn_info *insns[2],
+				 const insn_range_info &pair_range,
+				 int initial_writeback,
+				 rtx *writeback_effect,
+				 def_info **add_def,
+				 def_info *base_def,
+				 poly_int64 initial_offset,
+				 unsigned access_size);
+  int get_viable_bases (insn_info *insns[2],
+			vec<base_cand> &base_cands,
+			rtx cand_mems[2],
+			unsigned access_size,
+			bool reversed);
+  void do_alias_analysis (insn_info *alias_hazards[4],
+			  alias_walker *walkers[4],
+			  bool load_p);
+  void run ();
+  ~pair_fusion()
+  {
+    if (crtl->ssa->perform_pending_updates ())
+      cleanup_cfg (0);
+
+    free_dominance_info (CDI_DOMINATORS);
+
+    delete crtl->ssa;
+    crtl->ssa = nullptr;
+  }
+};
+
+void
+pair_fusion::run ()
+{
+  if (!track_loads_p () && !track_stores_p ())
+    return;
+
+  for (auto bb : crtl->ssa->bbs ())
+    ldp_fusion_bb (bb);
+}
+
+struct aarch64_pair_fusion : public pair_fusion
+{
+  bool fpsimd_op_p (rtx reg_op, machine_mode mem_mode,
+		    bool load_p) override final
+  {
+    return reload_completed
+      ? (REG_P (reg_op) && FP_REGNUM_P (REGNO (reg_op)))
+      : (GET_MODE_CLASS (mem_mode) != MODE_INT
+	 && (load_p || !aarch64_const_zero_rtx_p (reg_op)));
+  }
+  bool pair_mem_promote_writeback_p (insn_info *insn, rtx pat, bool &load_p);
+  bool pair_mem_ok_with_policy (rtx first_mem, bool load_p,
+				machine_mode mode)
+  {
+    return aarch64_mem_ok_with_ldpstp_policy_model (first_mem,
+						     load_p,
+						     mode);
+  }
+  bool pair_operand_mode_ok_p (machine_mode mode)
+  {
+    return ldp_operand_mode_ok_p (mode);
+  }
+  rtx gen_mem_pair (rtx *pats, rtx writeback, bool load_p);
+  bool pair_reg_operand_ok_p (bool load_p, rtx reg_op,
+			      machine_mode mem_mode)
+  {
+    return (load_p
+	     ? aarch64_ldp_reg_operand (reg_op, mem_mode)
+	     : aarch64_stp_reg_operand (reg_op, mem_mode));
+  }
+  int pair_mem_alias_check_limit ()
+  {
+    return aarch64_ldp_alias_check_limit;
+  }
+  bool handle_writeback_opportunities (enum writeback wback)
+  {
+    if (wback == writeback::WRITEBACK_PAIR_P)
+      return aarch64_ldp_writeback > 1;
+    else
+      return aarch64_ldp_writeback;
+  }
+  bool track_loads_p ()
+  {
+    return
+      aarch64_tune_params.ldp_policy_model != AARCH64_LDP_STP_POLICY_NEVER;
+  }
+  bool track_stores_p ()
+  {
+    return
+      aarch64_tune_params.stp_policy_model != AARCH64_LDP_STP_POLICY_NEVER;
+  }
+  bool pair_mem_out_of_range_p (HOST_WIDE_INT off)
+  {
+    return (off < LDP_MIN_IMM || off > LDP_MAX_IMM);
+  }
+  rtx gen_writeback_pair (rtx wb_effect, rtx mem, rtx regs[2], bool load_p)
+  {
+    return aarch64_gen_writeback_pair (wb_effect, mem, regs, load_p);
+  }
+  rtx gen_destructure_pair (rtx regs[2], rtx rti, bool load_p);
+  bool pair_offset_alignment_ok_p (poly_int64 offset,
+				   unsigned access_size)
+  {
+    return multiple_p (offset, access_size);
+  }
+};
+
 // State used by the pass for a given basic block.
 struct ldp_bb_info
 {
@@ -160,8 +352,11 @@  struct ldp_bb_info
 
   static const size_t obstack_alignment = sizeof (void *);
   bb_info *m_bb;
+  pair_fusion *m_pass;
 
-  ldp_bb_info (bb_info *bb) : m_bb (bb), m_emitted_tombstone (false)
+  ldp_bb_info (bb_info *bb,
+		      pair_fusion *d) : m_bb (bb),
+		      m_pass (d), m_emitted_tombstone (false)
   {
     obstack_specify_allocation (&m_obstack, OBSTACK_CHUNK_SIZE,
 				obstack_alignment, obstack_chunk_alloc,
@@ -177,10 +372,28 @@  struct ldp_bb_info
 	bitmap_obstack_release (&m_bitmap_obstack);
       }
   }
-
   inline void track_access (insn_info *, bool load, rtx mem);
   inline void transform ();
   inline void cleanup_tombstones ();
+  inline void merge_pairs (insn_list_t &, insn_list_t &,
+		    bool load_p, unsigned access_size);
+  inline void transform_for_base (int load_size, access_group &group);
+
+  inline bool try_fuse_pair (bool load_p, unsigned access_size,
+			     insn_info *i1, insn_info *i2);
+
+  inline bool fuse_pair (bool load_p, unsigned access_size,
+		  int writeback,
+		  insn_info *i1, insn_info *i2,
+		  base_cand &base,
+		  const insn_range_info &move_range);
+
+  inline void track_tombstone (int uid);
+
+  inline bool track_via_mem_expr (insn_info *, rtx mem, lfs_fields lfs);
+
+  template<typename Map>
+    void traverse_base_map (Map &map);
 
 private:
   obstack m_obstack;
@@ -191,27 +404,60 @@  private:
   bool m_emitted_tombstone;
 
   inline splay_tree_node<access_record *> *node_alloc (access_record *);
+};
 
-  template<typename Map>
-  inline void traverse_base_map (Map &map);
-  inline void transform_for_base (int load_size, access_group &group);
-
-  inline void merge_pairs (insn_list_t &, insn_list_t &,
-			   bool load_p, unsigned access_size);
+bool
+aarch64_pair_fusion::pair_mem_promote_writeback_p (insn_info *insn, rtx pat,
+						   bool &load_p)
+{
+  if (reload_completed
+      && aarch64_ldp_writeback > 1
+      && GET_CODE (pat) == PARALLEL
+      && XVECLEN (pat, 0) == 2)
+    {
+      auto rti = insn->rtl ();
+      const auto attr = get_attr_ldpstp (rti);
+      if (attr == LDPSTP_NONE)
+	return false;
 
-  inline bool try_fuse_pair (bool load_p, unsigned access_size,
-			     insn_info *i1, insn_info *i2);
+      load_p = (attr == LDPSTP_LDP);
+      gcc_checking_assert (load_p || attr == LDPSTP_STP);
+      return true;
+    }
+  return false;
+}
 
-  inline bool fuse_pair (bool load_p, unsigned access_size,
-			 int writeback,
-			 insn_info *i1, insn_info *i2,
-			 base_cand &base,
-			 const insn_range_info &move_range);
+rtx
+aarch64_pair_fusion::gen_destructure_pair (rtx regs[2], rtx rti, bool load_p)
+{
+  if (load_p)
+    return aarch64_destructure_load_pair (regs, rti);
+  else
+    return aarch64_destructure_store_pair (regs, rti);
+}
 
-  inline void track_tombstone (int uid);
+rtx
+aarch64_pair_fusion::gen_mem_pair (rtx *pats,
+		  rtx writeback,
+		  bool load_p)
+  {
+    rtx pair_pat;
 
-  inline bool track_via_mem_expr (insn_info *, rtx mem, lfs_fields lfs);
-};
+    if (writeback)
+      {
+	auto patvec = gen_rtvec (3, writeback, pats[0], pats[1]);
+	return  gen_rtx_PARALLEL (VOIDmode, patvec);
+      }
+    else if (load_p)
+      return aarch64_gen_load_pair (XEXP (pats[0], 0),
+					XEXP (pats[1], 0),
+					XEXP (pats[0], 1));
+    else
+      return aarch64_gen_store_pair (XEXP (pats[0], 0),
+					 XEXP (pats[0], 1),
+					 XEXP (pats[1], 1));
+     return pair_pat;
+  }
 
 splay_tree_node<access_record *> *
 ldp_bb_info::node_alloc (access_record *access)
@@ -312,7 +558,7 @@  any_post_modify_p (rtx x)
 
 // Return true if we should consider forming ldp/stp insns from memory
 // accesses with operand mode MODE at this stage in compilation.
-static bool
+bool
 ldp_operand_mode_ok_p (machine_mode mode)
 {
   const bool allow_qregs
@@ -412,9 +658,10 @@  ldp_bb_info::track_via_mem_expr (insn_info *insn, rtx mem, lfs_fields lfs)
   const machine_mode mem_mode = GET_MODE (mem);
   const HOST_WIDE_INT mem_size = GET_MODE_SIZE (mem_mode).to_constant ();
 
-  // Punt on misaligned offsets.  LDP/STP instructions require offsets to be a
-  // multiple of the access size, and we believe that misaligned offsets on
-  // MEM_EXPR bases are likely to lead to misaligned offsets w.r.t. RTL bases.
+  // Punt on misaligned offsets.  Paired memory access instructions require
+  // offsets to be a multiple of the access size, and we believe that
+  // misaligned offsets on MEM_EXPR bases are likely to lead to misaligned
+  // offsets w.r.t. RTL bases.
   if (!multiple_p (offset, mem_size))
     return false;
 
@@ -438,10 +685,10 @@  ldp_bb_info::track_via_mem_expr (insn_info *insn, rtx mem, lfs_fields lfs)
 }
 
 // Main function to begin pair discovery.  Given a memory access INSN,
-// determine whether it could be a candidate for fusing into an ldp/stp,
-// and if so, track it in the appropriate data structure for this basic
-// block.  LOAD_P is true if the access is a load, and MEM is the mem
-// rtx that occurs in INSN.
+// determine whether it could be a candidate for fusing into a paired
+// access, and if so, track it in the appropriate data structure for
+// this basic block.  LOAD_P is true if the access is a load, and MEM
+//  is the mem rtx that occurs in INSN.
 void
 ldp_bb_info::track_access (insn_info *insn, bool load_p, rtx mem)
 {
@@ -449,35 +696,26 @@  ldp_bb_info::track_access (insn_info *insn, bool load_p, rtx mem)
   if (MEM_VOLATILE_P (mem))
     return;
 
-  // Ignore writeback accesses if the param says to do so.
-  if (!aarch64_ldp_writeback
+  // Ignore writeback accesses if the hook says to do so.
+  if (!m_pass->handle_writeback_opportunities (writeback::WRITEBACK)
       && GET_RTX_CLASS (GET_CODE (XEXP (mem, 0))) == RTX_AUTOINC)
     return;
 
   const machine_mode mem_mode = GET_MODE (mem);
-  if (!ldp_operand_mode_ok_p (mem_mode))
+  if (!m_pass->pair_operand_mode_ok_p (mem_mode))
     return;
 
   rtx reg_op = XEXP (PATTERN (insn->rtl ()), !load_p);
 
-  // Ignore the access if the register operand isn't suitable for ldp/stp.
-  if (load_p
-      ? !aarch64_ldp_reg_operand (reg_op, mem_mode)
-      : !aarch64_stp_reg_operand (reg_op, mem_mode))
+  if (!m_pass->pair_reg_operand_ok_p (load_p, reg_op, mem_mode))
     return;
-
   // We want to segregate FP/SIMD accesses from GPR accesses.
   //
   // Before RA, we use the modes, noting that stores of constant zero
   // operands use GPRs (even in non-integer modes).  After RA, we use
   // the hard register numbers.
-  const bool fpsimd_op_p
-    = reload_completed
-    ? (REG_P (reg_op) && FP_REGNUM_P (REGNO (reg_op)))
-    : (GET_MODE_CLASS (mem_mode) != MODE_INT
-       && (load_p || !aarch64_const_zero_rtx_p (reg_op)));
-
-  // Note ldp_operand_mode_ok_p already rejected VL modes.
+  const bool fpsimd_op_p = m_pass->fpsimd_op_p (reg_op, mem_mode, load_p);
+  // Note pair_operand_mode_ok_p already rejected VL modes.
   const HOST_WIDE_INT mem_size = GET_MODE_SIZE (mem_mode).to_constant ();
   const lfs_fields lfs = { load_p, fpsimd_op_p, mem_size };
 
@@ -506,8 +744,8 @@  ldp_bb_info::track_access (insn_info *insn, bool load_p, rtx mem)
   // elimination offset pre-RA, we should postpone forming pairs on such
   // accesses until after RA.
   //
-  // As it stands, addresses with offsets in range for LDR but not
-  // in range for LDP/STP are currently reloaded inefficiently,
+  // As it stands, addresses in range for an individual load/store but not
+  // for a paired access are currently reloaded inefficiently,
   // ending up with a separate base register for each pair.
   //
   // In theory LRA should make use of
@@ -519,8 +757,8 @@  ldp_bb_info::track_access (insn_info *insn, bool load_p, rtx mem)
   // that calls targetm.legitimize_address_displacement.
   //
   // So for now, it's better to punt when we can't be sure that the
-  // offset is in range for LDP/STP.  Out-of-range cases can then be
-  // handled after RA by the out-of-range LDP/STP peepholes.  Eventually, it
+  // offset is in range for paired access.  Out-of-range cases can then be
+  // handled after RA by the out-of-range PAIR MEM  peepholes.  Eventually, it
   // would be nice to handle known out-of-range opportunities in the
   // pass itself (for stack accesses, this would be in the post-RA pass).
   if (!reload_completed
@@ -573,8 +811,8 @@  ldp_bb_info::track_access (insn_info *insn, bool load_p, rtx mem)
 	gcc_unreachable (); // Base defs should be unique.
     }
 
-  // Punt on misaligned offsets.  LDP/STP require offsets to be a multiple of
-  // the access size.
+  // Punt on misaligned offsets.  Paired memory accesses require offsets
+  // to be a multiple of the access size.
   if (!multiple_p (mem_off, mem_size))
     return;
 
@@ -1207,8 +1445,8 @@  extract_writebacks (bool load_p, rtx pats[2], int changed)
 // base register.  If there is one, we choose the first such update after
 // PAIR_DST that is still in the same BB as our pair.  We return the new def in
 // *ADD_DEF and the resulting writeback effect in *WRITEBACK_EFFECT.
-static insn_info *
-find_trailing_add (insn_info *insns[2],
+insn_info *
+pair_fusion::find_trailing_add (insn_info *insns[2],
 		   const insn_range_info &pair_range,
 		   int initial_writeback,
 		   rtx *writeback_effect,
@@ -1286,7 +1524,7 @@  find_trailing_add (insn_info *insns[2],
 
   off_hwi /= access_size;
 
-  if (off_hwi < LDP_MIN_IMM || off_hwi > LDP_MAX_IMM)
+  if (pair_mem_out_of_range_p (off_hwi))
     return nullptr;
 
   auto dump_prefix = [&]()
@@ -1800,7 +2038,7 @@  ldp_bb_info::fuse_pair (bool load_p,
     {
       if (dump_file)
 	fprintf (dump_file,
-		 "  ldp: i%d has wb but subsequent i%d has non-wb "
+		 "  load pair: i%d has wb but subsequent i%d has non-wb "
 		 "update of base (r%d), dropping wb\n",
 		 insns[0]->uid (), insns[1]->uid (), base_regno);
       gcc_assert (writeback_effect);
@@ -1823,7 +2061,7 @@  ldp_bb_info::fuse_pair (bool load_p,
     }
 
   // If either of the original insns had writeback, but the resulting pair insn
-  // does not (can happen e.g. in the ldp edge case above, or if the writeback
+  // does not (can happen e.g. in the load pair edge case above, or if the writeback
   // effects cancel out), then drop the def(s) of the base register as
   // appropriate.
   //
@@ -1842,7 +2080,7 @@  ldp_bb_info::fuse_pair (bool load_p,
   // update of the base register and try and fold it in to make this into a
   // writeback pair.
   insn_info *trailing_add = nullptr;
-  if (aarch64_ldp_writeback > 1
+  if (m_pass->handle_writeback_opportunities (writeback::WRITEBACK_PAIR_P)
       && !writeback_effect
       && (!load_p || (!refers_to_regno_p (base_regno, base_regno + 1,
 					 XEXP (pats[0], 0), nullptr)
@@ -1850,7 +2088,7 @@  ldp_bb_info::fuse_pair (bool load_p,
 					     XEXP (pats[1], 0), nullptr))))
     {
       def_info *add_def;
-      trailing_add = find_trailing_add (insns, move_range, writeback,
+      trailing_add = m_pass->find_trailing_add (insns, move_range, writeback,
 					&writeback_effect,
 					&add_def, base.def, offsets[0],
 					access_size);
@@ -1863,14 +2101,14 @@  ldp_bb_info::fuse_pair (bool load_p,
     }
 
   // Now that we know what base mem we're going to use, check if it's OK
-  // with the ldp/stp policy.
+  // with the pair mem policy.
   rtx first_mem = XEXP (pats[0], load_p);
-  if (!aarch64_mem_ok_with_ldpstp_policy_model (first_mem,
-						load_p,
-						GET_MODE (first_mem)))
+  if (!m_pass->pair_mem_ok_with_policy (first_mem,
+			  load_p,
+			  GET_MODE (first_mem)))
     {
       if (dump_file)
-	fprintf (dump_file, "punting on pair (%d,%d), ldp/stp policy says no\n",
+	fprintf (dump_file, "punting on pair (%d,%d), pair mem  policy says no\n",
 		 i1->uid (), i2->uid ());
       return false;
     }
@@ -1878,21 +2116,10 @@  ldp_bb_info::fuse_pair (bool load_p,
   rtx reg_notes = combine_reg_notes (first, second, load_p);
 
   rtx pair_pat;
-  if (writeback_effect)
-    {
-      auto patvec = gen_rtvec (3, writeback_effect, pats[0], pats[1]);
-      pair_pat = gen_rtx_PARALLEL (VOIDmode, patvec);
-    }
-  else if (load_p)
-    pair_pat = aarch64_gen_load_pair (XEXP (pats[0], 0),
-				      XEXP (pats[1], 0),
-				      XEXP (pats[0], 1));
-  else
-    pair_pat = aarch64_gen_store_pair (XEXP (pats[0], 0),
-				       XEXP (pats[0], 1),
-				       XEXP (pats[1], 1));
 
+  pair_pat = m_pass->gen_mem_pair (pats, writeback_effect, load_p);
   insn_change *pair_change = nullptr;
+
   auto set_pair_pat = [pair_pat,reg_notes](insn_change *change) {
     rtx_insn *rti = change->insn ()->rtl ();
     validate_unshare_change (rti, &PATTERN (rti), pair_pat, true);
@@ -2133,15 +2360,6 @@  load_modified_by_store_p (insn_info *load,
   return false;
 }
 
-// Virtual base class for load/store walkers used in alias analysis.
-struct alias_walker
-{
-  virtual bool conflict_p (int &budget) const = 0;
-  virtual insn_info *insn () const = 0;
-  virtual bool valid () const = 0;
-  virtual void advance () = 0;
-};
-
 // Implement some common functionality used by both store_walker
 // and load_walker.
 template<bool reverse>
@@ -2259,13 +2477,13 @@  public:
 //
 // We try to maintain the invariant that if a walker becomes invalid, we
 // set its pointer to null.
-static void
-do_alias_analysis (insn_info *alias_hazards[4],
+void
+pair_fusion::do_alias_analysis (insn_info *alias_hazards[4],
 		   alias_walker *walkers[4],
 		   bool load_p)
 {
   const int n_walkers = 2 + (2 * !load_p);
-  int budget = aarch64_ldp_alias_check_limit;
+  int budget = pair_mem_alias_check_limit ();
 
   auto next_walker = [walkers,n_walkers](int current) -> int {
     for (int j = 1; j <= n_walkers; j++)
@@ -2350,8 +2568,8 @@  do_alias_analysis (insn_info *alias_hazards[4],
 //
 // Returns an integer where bit (1 << i) is set if INSNS[i] uses writeback
 // addressing.
-static int
-get_viable_bases (insn_info *insns[2],
+int
+pair_fusion::get_viable_bases (insn_info *insns[2],
 		  vec<base_cand> &base_cands,
 		  rtx cand_mems[2],
 		  unsigned access_size,
@@ -2397,7 +2615,7 @@  get_viable_bases (insn_info *insns[2],
       if (!is_lower)
 	base_off--;
 
-      if (base_off < LDP_MIN_IMM || base_off > LDP_MAX_IMM)
+      if (pair_mem_out_of_range_p (base_off))
 	continue;
 
       use_info *use = find_access (insns[i]->uses (), REGNO (base));
@@ -2454,7 +2672,7 @@  get_viable_bases (insn_info *insns[2],
 }
 
 // Given two adjacent memory accesses of the same size, I1 and I2, try
-// and see if we can merge them into a ldp or stp.
+// and see if we can merge them into a paired access load and store.
 //
 // ACCESS_SIZE gives the (common) size of a single access, LOAD_P is true
 // if the accesses are both loads, otherwise they are both stores.
@@ -2494,7 +2712,7 @@  ldp_bb_info::try_fuse_pair (bool load_p, unsigned access_size,
     {
       if (dump_file)
 	fprintf (dump_file,
-		 "punting on ldp due to reg conflcits (%d,%d)\n",
+		 "punting on pair mem load  due to reg conflcits (%d,%d)\n",
 		 insns[0]->uid (), insns[1]->uid ());
       return false;
     }
@@ -2512,7 +2730,7 @@  ldp_bb_info::try_fuse_pair (bool load_p, unsigned access_size,
 
   auto_vec<base_cand, 2> base_cands (2);
 
-  int writeback = get_viable_bases (insns, base_cands, cand_mems,
+  int writeback = m_pass->get_viable_bases (insns, base_cands, cand_mems,
 				    access_size, reversed);
   if (base_cands.is_empty ())
     {
@@ -2641,7 +2859,7 @@  ldp_bb_info::try_fuse_pair (bool load_p, unsigned access_size,
     walkers[1] = &backward_store_walker;
 
   if (load_p && (mem_defs[0] || mem_defs[1]))
-    do_alias_analysis (alias_hazards, walkers, load_p);
+    m_pass->do_alias_analysis (alias_hazards, walkers, load_p);
   else
     {
       // We want to find any loads hanging off the first store.
@@ -2650,7 +2868,7 @@  ldp_bb_info::try_fuse_pair (bool load_p, unsigned access_size,
       load_walker<true> backward_load_walker (mem_defs[1], insns[1], insns[0]);
       walkers[2] = &forward_load_walker;
       walkers[3] = &backward_load_walker;
-      do_alias_analysis (alias_hazards, walkers, load_p);
+      m_pass->do_alias_analysis (alias_hazards, walkers, load_p);
       // Now consolidate hazards back down.
       if (alias_hazards[2]
 	  && (!alias_hazards[0] || (*alias_hazards[2] < *alias_hazards[0])))
@@ -2891,7 +3109,7 @@  ldp_bb_info::merge_pairs (insn_list_t &left_list,
 // merge_pairs.
 void
 ldp_bb_info::transform_for_base (int encoded_lfs,
-				 access_group &group)
+					 access_group &group)
 {
   const auto lfs = decode_lfs (encoded_lfs);
   const unsigned access_size = lfs.size;
@@ -2903,7 +3121,9 @@  ldp_bb_info::transform_for_base (int encoded_lfs,
     {
       if (skip_next)
 	skip_next = false;
-      else if (known_eq (access.offset, prev_access->offset + access_size))
+      else if (m_pass->pair_offset_alignment_ok_p (prev_access->offset,
+						   access_size)
+	       && known_eq (access.offset, prev_access->offset + access_size))
 	{
 	  merge_pairs (prev_access->cand_insns,
 		       access.cand_insns,
@@ -2964,29 +3184,9 @@  ldp_bb_info::transform ()
   traverse_base_map (def_map);
 }
 
-static void
-ldp_fusion_init ()
-{
-  calculate_dominance_info (CDI_DOMINATORS);
-  df_analyze ();
-  crtl->ssa = new rtl_ssa::function_info (cfun);
-}
-
-static void
-ldp_fusion_destroy ()
-{
-  if (crtl->ssa->perform_pending_updates ())
-    cleanup_cfg (0);
-
-  free_dominance_info (CDI_DOMINATORS);
-
-  delete crtl->ssa;
-  crtl->ssa = nullptr;
-}
-
 // Given a load pair insn in PATTERN, unpack the insn, storing
 // the registers in REGS and returning the mem.
-static rtx
+rtx
 aarch64_destructure_load_pair (rtx regs[2], rtx pattern)
 {
   rtx mem = NULL_RTX;
@@ -3012,7 +3212,7 @@  aarch64_destructure_load_pair (rtx regs[2], rtx pattern)
 
 // Given a store pair insn in PATTERN, unpack the insn, storing
 // the register operands in REGS, and returning the mem.
-static rtx
+rtx
 aarch64_destructure_store_pair (rtx regs[2], rtx pattern)
 {
   rtx mem = XEXP (pattern, 0);
@@ -3030,7 +3230,7 @@  aarch64_destructure_store_pair (rtx regs[2], rtx pattern)
 //
 // This is used when promoting existing non-writeback pairs to writeback
 // variants.
-static rtx
+rtx
 aarch64_gen_writeback_pair (rtx wb_effect, rtx pair_mem, rtx regs[2],
 			    bool load_p)
 {
@@ -3068,22 +3268,13 @@  aarch64_gen_writeback_pair (rtx wb_effect, rtx pair_mem, rtx regs[2],
 // the base register which we can fold in to make this pair use
 // a writeback addressing mode.
 static void
-try_promote_writeback (insn_info *insn)
+try_promote_writeback (insn_info *insn, bool load_p, pair_fusion *pass)
 {
-  auto rti = insn->rtl ();
-  const auto attr = get_attr_ldpstp (rti);
-  if (attr == LDPSTP_NONE)
-    return;
-
-  bool load_p = (attr == LDPSTP_LDP);
-  gcc_checking_assert (load_p || attr == LDPSTP_STP);
-
   rtx regs[2];
   rtx mem = NULL_RTX;
-  if (load_p)
-    mem = aarch64_destructure_load_pair (regs, PATTERN (rti));
-  else
-    mem = aarch64_destructure_store_pair (regs, PATTERN (rti));
+
+  mem = pass->gen_destructure_pair (regs, PATTERN (insn->rtl ()), load_p);
+
   gcc_checking_assert (MEM_P (mem));
 
   poly_int64 offset;
@@ -3120,9 +3311,10 @@  try_promote_writeback (insn_info *insn)
   def_info *add_def;
   const insn_range_info pair_range (insn);
   insn_info *insns[2] = { nullptr, insn };
-  insn_info *trailing_add = find_trailing_add (insns, pair_range, 0, &wb_effect,
-					       &add_def, base_def, offset,
-					       access_size);
+  insn_info *trailing_add
+    = pass->find_trailing_add (insns, pair_range, 0, &wb_effect,
+			       &add_def, base_def, offset,
+			       access_size);
   if (!trailing_add)
     return;
 
@@ -3132,8 +3324,9 @@  try_promote_writeback (insn_info *insn)
   insn_change del_change (trailing_add, insn_change::DELETE);
   insn_change *changes[] = { &pair_change, &del_change };
 
-  rtx pair_pat = aarch64_gen_writeback_pair (wb_effect, mem, regs, load_p);
-  validate_unshare_change (rti, &PATTERN (rti), pair_pat, true);
+  rtx pair_pat = pass->gen_writeback_pair (wb_effect, mem, regs, load_p);
+
+  validate_unshare_change (insn->rtl(), &PATTERN (insn->rtl()), pair_pat, true);
 
   // The pair must gain the def of the base register from the add.
   pair_change.new_defs = insert_access (attempt,
@@ -3167,14 +3360,12 @@  try_promote_writeback (insn_info *insn)
 // for load/store candidates.  If running after RA, also try and promote
 // non-writeback pairs to use writeback addressing.  Then try to fuse
 // candidates into pairs.
-void ldp_fusion_bb (bb_info *bb)
+void pair_fusion::ldp_fusion_bb (bb_info *bb)
 {
-  const bool track_loads
-    = aarch64_tune_params.ldp_policy_model != AARCH64_LDP_STP_POLICY_NEVER;
-  const bool track_stores
-    = aarch64_tune_params.stp_policy_model != AARCH64_LDP_STP_POLICY_NEVER;
+  const bool track_loads = track_loads_p ();
+  const bool track_stores = track_stores_p ();
 
-  ldp_bb_info bb_state (bb);
+  ldp_bb_info bb_state (bb, this);
 
   for (auto insn : bb->nondebug_insns ())
     {
@@ -3184,11 +3375,9 @@  void ldp_fusion_bb (bb_info *bb)
 	continue;
 
       rtx pat = PATTERN (rti);
-      if (reload_completed
-	  && aarch64_ldp_writeback > 1
-	  && GET_CODE (pat) == PARALLEL
-	  && XVECLEN (pat, 0) == 2)
-	try_promote_writeback (insn);
+      bool load_p;
+      if (pair_mem_promote_writeback_p (insn, pat, load_p))
+	try_promote_writeback (insn, load_p, this);
 
       if (GET_CODE (pat) != SET)
 	continue;
@@ -3205,12 +3394,8 @@  void ldp_fusion_bb (bb_info *bb)
 
 void ldp_fusion ()
 {
-  ldp_fusion_init ();
-
-  for (auto bb : crtl->ssa->bbs ())
-    ldp_fusion_bb (bb);
-
-  ldp_fusion_destroy ();
+  aarch64_pair_fusion pass;
+  pass.run ();
 }
 
 namespace {
@@ -3242,14 +3427,6 @@  public:
       if (!optimize || optimize_debug)
 	return false;
 
-      // If the tuning policy says never to form ldps or stps, don't run
-      // the pass.
-      if ((aarch64_tune_params.ldp_policy_model
-	   == AARCH64_LDP_STP_POLICY_NEVER)
-	  && (aarch64_tune_params.stp_policy_model
-	      == AARCH64_LDP_STP_POLICY_NEVER))
-	return false;
-
       if (reload_completed)
 	return flag_aarch64_late_ldp_fusion;
       else