mips-protos.h (mips_expand_before_return): Declare.

gcc/
	* config/mips/mips-protos.h (mips_expand_before_return): Declare.
	* config/mips/mips.c (mips_expand_before_return): New function.
	(mips_expand_epilogue): Call it.
	* config/mips/mips.md (return): Turn into a define_expand.
	(*return): New insn.

From-SVN: r136252

gcc/ChangeLog

 2008-06-01  Richard Sandiford  <rdsandiford@googlemail.com>
 
+	* config/mips/mips-protos.h (mips_expand_before_return): Declare.
+	* config/mips/mips.c (mips_expand_before_return): New function.
+	(mips_expand_epilogue): Call it.
+	* config/mips/mips.md (return): Turn into a define_expand.
+	(*return): New insn.
+
+2008-06-01  Richard Sandiford  <rdsandiford@googlemail.com>
+
 	* rtl.h (emit_clobber, gen_clobber, emit_use, gen_use): Declare.
 	* emit-rtl.c (emit_clobber, gen_clobber, emit_use, gen_use): New
 	functions.  Do not emit uses and clobbers of CONCATs; individually

gcc/config/mips/mips-protos.h

@@ -257,6 +257,7 @@ extern HOST_WIDE_INT mips_initial_elimination_offset (int, int);
 extern rtx mips_return_addr (int, rtx);
 extern enum mips_loadgp_style mips_current_loadgp_style (void);
 extern void mips_expand_prologue (void);
+extern void mips_expand_before_return (void);
 extern void mips_expand_epilogue (bool);
 extern bool mips_can_use_return_insn (void);
 extern rtx mips_function_value (const_tree, enum machine_mode);

gcc/config/mips/mips.c

@@ -8633,6 +8633,24 @@ mips_restore_reg (rtx reg, rtx mem)
     mips_emit_move (reg, mem);
 }
 
+/* Emit any instructions needed before a return.  */
+
+void
+mips_expand_before_return (void)
+{
+  /* When using a call-clobbered gp, we start out with unified call
+     insns that include instructions to restore the gp.  We then split
+     these unified calls after reload.  These split calls explicitly
+     clobber gp, so there is no need to define
+     PIC_OFFSET_TABLE_REG_CALL_CLOBBERED.
+
+     For consistency, we should also insert an explicit clobber of $28
+     before return insns, so that the post-reload optimizers know that
+     the register is not live on exit.  */
+  if (TARGET_CALL_CLOBBERED_GP)
+    emit_clobber (pic_offset_table_rtx);
+}
+
 /* Expand an "epilogue" or "sibcall_epilogue" pattern; SIBCALL_P
    says which.  */
 
@@ -8775,6 +8793,7 @@ mips_expand_epilogue (bool sibcall_p)
 	regno = GP_REG_FIRST + 7;
       else
 	regno = GP_REG_FIRST + 31;
+      mips_expand_before_return ();
       emit_jump_insn (gen_return_internal (gen_rtx_REG (Pmode, regno)));
     }
 }

gcc/config/mips/mips.md

@@ -5739,7 +5739,12 @@
 ;; Trivial return.  Make it look like a normal return insn as that
 ;; allows jump optimizations to work better.
 
-(define_insn "return"
+(define_expand "return"
+  [(return)]
+  "mips_can_use_return_insn ()"
+  { mips_expand_before_return (); })
+
+(define_insn "*return"
   [(return)]
   "mips_can_use_return_insn ()"
   "%*j\t$31%/"