[RFC,4/9] Add TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT target macro

diff --git a/lra-constraints.c b/lra-constraints.c
index 1666380..7bdb288 100644
--- a/lra-constraints.c
+++ b/lra-constraints.c
@@ -3009,6 +3009,32 @@  process_address_1 (int nop, bool check_only_p,
 	      delete_insns_since (PREV_INSN (last_insn));
 	    }
 	}
+      /* Try if target can split displacement into legitimite new disp
+	 and offset.  If it's the case, we replace the last insn with
+	 insns for base + offset => new_reg and set new_reg + new disp
+	 to *ad.inner.  */
+      last_insn = get_last_insn ();
+      if ((set = single_set (last_insn)) != NULL_RTX
+	  && GET_CODE (SET_SRC (set)) == PLUS
+	  && REG_P (XEXP (SET_SRC (set), 0))
+	  && REGNO (XEXP (SET_SRC (set), 0)) < FIRST_PSEUDO_REGISTER
+	  && CONST_INT_P (XEXP (SET_SRC (set), 1)))
+	{
+	  rtx addend, disp = XEXP (SET_SRC (set), 1);
+	  if (targetm.legitimize_address_displacement (&disp, &addend,
+						       ad.mode))
+	    {
+	      rtx_insn *new_insns;
+	      start_sequence ();
+	      lra_emit_add (new_reg, XEXP (SET_SRC (set), 0), addend);
+	      new_insns = get_insns ();
+	      end_sequence ();
+	      new_reg = gen_rtx_PLUS (Pmode, new_reg, disp);
+	      delete_insns_since (PREV_INSN (last_insn));
+	      add_insn (new_insns);
+	      insns = get_insns ();
+	    }
+	}
       end_sequence ();
       emit_insn (insns);
       *ad.inner = new_reg;
diff --git a/target.def b/target.def
index b0c86b8..c21c9e3 100644
--- a/target.def
+++ b/target.def
@@ -5051,6 +5051,19 @@  can be used to avoid excessive spilling.",
  bool, (rtx subst),
  hook_bool_rtx_false)
 
+/* This target hook allows the backend to legitimize base plus
+   displacement addressing.  */
+DEFHOOK
+(legitimize_address_displacement,
+ "A target hook which returns @code{true} if *@var{disp} is\n\
+legitimezed to valid address displacement with subtracting *@var{offset}\n\
+at memory mode @var{mode}.\n\
+The default version of this target hook returns @code{false}.\n\
+This hook will benefit machines with limited base plus displacement\n\
+addressing.",
+ bool, (rtx *disp, rtx *offset, machine_mode mode),
+ default_legitimize_address_displacement)
+
 /* This target hook allows the backend to perform additional
    processing while initializing for variable expansion.  */
 DEFHOOK
diff --git a/targhooks.c b/targhooks.c
index 42fd82e..5e723b4 100644
--- a/targhooks.c
+++ b/targhooks.c
@@ -167,6 +167,14 @@  default_legitimize_address (rtx x, rtx orig_x ATTRIBUTE_UNUSED,
   return x;
 }
 
+bool
+default_legitimize_address_displacement (rtx *disp ATTRIBUTE_UNUSED,
+					 rtx *offset ATTRIBUTE_UNUSED,
+					 machine_mode mode ATTRIBUTE_UNUSED)
+{
+  return false;
+}
+
 rtx
 default_expand_builtin_saveregs (void)
 {
diff --git a/targhooks.h b/targhooks.h
index 9734220..26e4f5f 100644
--- a/targhooks.h
+++ b/targhooks.h
@@ -24,6 +24,8 @@  extern bool default_legitimate_address_p (machine_mode, rtx, bool);
 
 extern void default_external_libcall (rtx);
 extern rtx default_legitimize_address (rtx, rtx, machine_mode);
+extern bool default_legitimize_address_displacement (rtx *, rtx *,
+						     machine_mode);
 
 extern int default_unspec_may_trap_p (const_rtx, unsigned);
 extern machine_mode default_promote_function_mode (const_tree, machine_mode,
diff --git a/config/sh/sh.c b/config/sh/sh.c
index c445199..6f34b33 100644
--- a/config/sh/sh.c
+++ b/config/sh/sh.c
@@ -292,6 +292,7 @@  static bool sh_legitimate_address_p (machine_mode, rtx, bool);
 static rtx sh_legitimize_address (rtx, rtx, machine_mode);
 static rtx sh_delegitimize_address (rtx);
 static bool sh_cannot_substitute_mem_equiv_p (rtx);
+static bool sh_legitimize_address_displacement (rtx *, rtx *, machine_mode);
 static int shmedia_target_regs_stack_space (HARD_REG_SET *);
 static int shmedia_reserve_space_for_target_registers_p (int, HARD_REG_SET *);
 static int shmedia_target_regs_stack_adjust (HARD_REG_SET *);
@@ -634,6 +636,10 @@  static const struct attribute_spec sh_attribute_table[] =
 #undef TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P
 #define TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P sh_cannot_substitute_mem_equiv_p
 
+#undef TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT
+#define TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT \
+  sh_legitimize_address_displacement
+
 #undef TARGET_TRAMPOLINE_INIT
 #define TARGET_TRAMPOLINE_INIT		sh_trampoline_init
 #undef TARGET_TRAMPOLINE_ADJUST_ADDRESS
@@ -13236,6 +13242,29 @@  sh_cannot_substitute_mem_equiv_p (rtx)
   return true;
 }
 
+/* Return true if DISP can be legitimized.  */
+static bool
+sh_legitimize_address_displacement (rtx *disp, rtx *offs,
+				    machine_mode mode)
+{
+  if (TARGET_SHMEDIA)
+    return false;
+
+  if (((TARGET_SH4 || TARGET_SH2A_DOUBLE) && mode == DFmode)
+      || (TARGET_SH2E && mode == SFmode))
+    return false;
+
+  struct disp_adjust adj = sh_find_mov_disp_adjust (mode, INTVAL (*disp));
+  if (adj.offset_adjust != NULL_RTX && adj.mov_disp != NULL_RTX)
+    {
+      *disp = adj.mov_disp;
+      *offs = adj.offset_adjust;
+      return true;
+    }
+ 
+  return false;
+}
+
 static void
 sh_conditional_register_usage (void)
 {
diff --git a/doc/tm.texi.in b/doc/tm.texi.in
index a99cc72..20c0129 100644
--- a/doc/tm.texi.in
+++ b/doc/tm.texi.in
@@ -2483,6 +2483,8 @@  as below:
 
 @hook TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P
 
+@hook TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT
+
 @hook TARGET_SPILL_CLASS
 
 @hook TARGET_CSTORE_MODE