re PR target/47192 (m68k target - gcc uses stack frame after it has been…

re PR target/47192 (m68k target - gcc uses stack frame after it has been unlinked when compiling with -Os)

	PR target/47192
	* config/m68k/m68k.c (m68k_expand_epilogue): Emit a scheduling
	barrier prior to deallocating the stack.

	PR target/47192
	* gcc.target/m68k/pr47192.c: New test.

From-SVN: r242575

gcc/ChangeLog

+2016-11-17  Jeff Law  <law@redhat.com>
+
+	PR target/47192
+	* config/m68k/m68k.c (m68k_expand_epilogue): Emit a scheduling
+	barrier prior to deallocating the stack.
+
 2016-11-17  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* config/arc/arc.md (cmem bit/sign-extend peephole2): New peephole

gcc/config/m68k/m68k.c

@@ -1205,6 +1205,7 @@ m68k_expand_epilogue (bool sibcall_p)
 	     stack-based restore.  */
 	  emit_move_insn (gen_rtx_REG (Pmode, A1_REG),
 			  GEN_INT (-(current_frame.offset + fsize)));
+	  emit_insn (gen_blockage ());
 	  emit_insn (gen_addsi3 (stack_pointer_rtx,
 				 gen_rtx_REG (Pmode, A1_REG),
 				 frame_pointer_rtx));
@@ -1306,6 +1307,7 @@ m68k_expand_epilogue (bool sibcall_p)
 			 current_frame.fpu_mask, false, false);
     }
 
+  emit_insn (gen_blockage ());
   if (frame_pointer_needed)
     emit_insn (gen_unlink (frame_pointer_rtx));
   else if (fsize_with_regs)

gcc/testsuite/ChangeLog

+2016-11-17  Jeff Law  <law@redhat.com>
+
+	PR target/47192
+	* gcc.target/m68k/pr47192.c: New test.
+
 2016-11-17  Toma Tabacu  <toma.tabacu@imgtec.com>
 
 	* gcc.target/mips/branch-cost-1.c (dg-options): Use (HAS_MOVN)

gcc/testsuite/gcc.target/m68k/pr47192.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -mcpu=51qe -fdisable-ipa-pure-const -fdump-rtl-pro_and_epilogue" } */
+/* { dg-final { scan-rtl-dump-times "unspec_volatile" 1 "pro_and_epilogue"} } */
+
+
+char F(short *ty);
+
+short V(char cmd)
+{
+  static short st256;
+  static short stc;
+  short sc;
+  short scd;
+  short d;
+
+  F(&sc);
+
+  if (cmd == 4)
+  {
+    st256 = 0;
+    d = 0;
+  }
+  else
+  {
+    scd = sc - stc;
+    if (scd < -128)
+    {
+      scd += 256;
+    }
+    d = st256 >> 8;
+    st256 -= d << 8;
+  }
+  stc = sc;
+  return d;
+}
+