RFA: RL78:

[Nick Clifton <nickc at redhat dot com>]

Hi DJ,

  This patch contains two small improvements for the RL78 compiler:

  1. A peephole to match:

        movw    ax, !<function_name>
        movw    bc, ax
        call    bc

     with:

        movw    ax, !<function_name>
        call    ax

  2. A change to avoid pushing the frame pointer register in an
     interrupt handler if the handler never uses or corrupts the
     frame pointer.

  Tested with no regressions using an rx-elf toolchain.

  OK to apply ?

Cheers
  Nick

gcc/ChangeLog
2015-06-02  Nick Clifton  <nickc@redhat.com>

	* config/rl78/rl78-real.md: Add peepholes to avoid a register
	copy when calling a function.
	* config/rl78/rl78.c (need_to_save): Do not push the frame
	pointer in an interrupt handler prologue if it is never used.

Index: gcc/config/rl78/rl78-real.md
===================================================================
--- gcc/config/rl78/rl78-real.md	(revision 224011)
+++ gcc/config/rl78/rl78-real.md	(working copy)
@@ -342,6 +342,25 @@
   [(set (attr "update_Z") (const_string "clobber"))]
   )
 
+;; Peephole to match:
+;;
+;;	(set (reg1) (reg2))
+;;	(call (mem (reg1)))
+;;
+;;  and replace it with:
+;;
+;;	(call (mem (reg2)))
+
+(define_peephole2
+  [(set (match_operand:HI 0 "register_operand") (match_operand:HI 1 "register_operand"))
+   (call (mem:HI (match_dup 0))(const_int 0))
+  ]
+  "peep2_regno_dead_p (2, REGNO (operands[0]))
+   && REGNO (operands[1]) < 8"
+  [(call (mem:HI (match_dup 1))(const_int 0))
+  ]
+)
+
 (define_insn "*call_value_real"
   [(set (match_operand 0 "register_operand" "=v,v")
 	(call (match_operand:HI 1 "memory_operand" "Wab,Wca")
@@ -353,6 +372,25 @@
   [(set (attr "update_Z") (const_string "clobber"))]
   )
 
+;; Peephole to match:
+;;
+;;	(set (reg1) (reg2))
+;;	(set (reg3) (call (mem (reg1))))
+;;
+;;  and replace it with:
+;;
+;;	(set (reg3) (call (mem (reg2))))
+
+(define_peephole2
+  [(set (match_operand:HI 0 "register_operand") (match_operand:HI 1 "register_operand"))
+   (set (match_operand:HI 2 "register_operand") (call (mem:HI (match_dup 0))(const_int 0)))
+  ]
+  "peep2_regno_dead_p (2, REGNO (operands[0]))
+   && REGNO (operands[1]) < 8"
+  [(set (match_dup 2) (call (mem:HI (match_dup 1))(const_int 0)))
+  ]
+)
+
 (define_insn "*cbranchqi4_real_signed"
   [(set (pc) (if_then_else
 	      (match_operator 0 "rl78_cmp_operator_signed"
Index: gcc/config/rl78/rl78.c
===================================================================
--- gcc/config/rl78/rl78.c	(revision 224011)
+++ gcc/config/rl78/rl78.c	(working copy)
@@ -678,10 +678,12 @@
 
       /* If the handler is a non-leaf function then it may call
 	 non-interrupt aware routines which will happily clobber
-	 any call_used registers, so we have to preserve them.  */
-      if (!crtl->is_leaf && call_used_regs[regno])
+	 any call_used registers, so we have to preserve them.
+         We do not have to worry about the frame pointer register
+	 though, as that is handled below.  */
+      if (!crtl->is_leaf && call_used_regs[regno] && regno < 22)
 	return true;
-
+      
       /* Otherwise we only have to save a register, call_used
 	 or not, if it is used by this handler.  */
       return df_regs_ever_live_p (regno);