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Commit: MSP430: Fix detection of NOP and EINT

Nick Clifton nickc@redhat.com
Wed Apr 6 15:01:00 GMT 2016 
Hi Guys,

  I am checking in the patch below to fix a small problem with the
  MSP430 assemblers and its detection of NOP and EINT.  Prior to this
  patch the assembler would warn if an EINT instruction was not followed
  by a NOP, but the actual specification is that the EINT instruction
  should be preceded by a NOP instruction.  The patch makes this change.

Cheers
  Nick

gas/ChangeLog
2016-04-06  Nick Clifton  <nickc@redhat.com>

	* config/tc-msp430.c (msp430_operands): Check for a NOP preceding
	an EINT instruction.  Warn/fix as necessary.
	* testsuite/gas/msp430/bad.s: Add test of EINT without preceding NOP.
	* testsuite/gas/msp430/bad.l: Update expected messages.

Index: gas/config/tc-msp430.c
===================================================================
RCS file: /cvs/cvsfiles/gnupro/gas/config/tc-msp430.c,v
retrieving revision 1.24.2.3
diff -u -3 -p -r1.24.2.3 tc-msp430.c
--- gas/config/tc-msp430.c	17 Feb 2016 09:04:16 -0000	1.24.2.3
+++ gas/config/tc-msp430.c	6 Apr 2016 11:15:58 -0000
@@ -2480,6 +2480,7 @@ msp430_operands (struct msp430_opcode_s 
   bfd_boolean addr_op;
   const char * error_message;
   static signed int repeat_count = 0;
+  static bfd_boolean prev_insn_is_nop = FALSE;
   bfd_boolean fix_emitted;
 
   /* Opcode is the one from opcodes table
@@ -2679,7 +2680,24 @@ msp430_operands (struct msp430_opcode_s 
       switch (opcode->insn_opnumb)
 	{
 	case 0:
-	  if (is_opcode ("eint") || is_opcode ("dint"))
+	  if (is_opcode ("eint"))
+	    {
+	      if (! prev_insn_is_nop)
+		{
+		  if (gen_interrupt_nops)
+		    {
+		      frag = frag_more (2);
+		      bfd_putl16 ((bfd_vma) 0x4303 /* NOP */, frag);
+		      dwarf2_emit_insn (2);
+
+		      if (warn_interrupt_nops)
+			as_warn (_("inserting a NOP before EINT"));
+		    }
+		  else if (warn_interrupt_nops)
+		    as_warn (_("a NOP might be needed before the EINT"));
+		}
+	    }
+	  else if (is_opcode ("dint"))
 	    check_for_nop |= NOP_CHECK_INTERRUPT;
 
 	  /* Set/clear bits instructions.  */
@@ -3866,6 +3884,11 @@ msp430_operands (struct msp430_opcode_s 
       as_bad (_("Illegal instruction or not implemented opcode."));
     }
 
+  if (is_opcode ("nop"))
+    prev_insn_is_nop = TRUE;
+  else
+    prev_insn_is_nop = FALSE;
+	    
   input_line_pointer = line;
   return 0;
 }
Index: gas/testsuite/gas/msp430/bad.l
===================================================================
RCS file: /cvs/cvsfiles/gnupro/gas/testsuite/gas/msp430/bad.l,v
retrieving revision 1.3
diff -u -3 -p -r1.3 bad.l
--- gas/testsuite/gas/msp430/bad.l	18 Sep 2015 08:42:41 -0000	1.3
+++ gas/testsuite/gas/msp430/bad.l	6 Apr 2016 11:15:58 -0000
@@ -5,11 +5,13 @@
 [^:]*:9: Error: junk found after instruction: mov.cd r1,r2
 [^:]*:10: Warning: no size modifier after period, .w assumed
 [^:]*:11: Error: instruction bis.a does not exist
-[^:]*:19: Warning: a NOP might be needed here because of successive changes in interrupt state
-[^:]*:20: Warning: a NOP might be needed here because of successive changes in interrupt state
-[^:]*:23: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:16: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:16: Warning: a NOP might be needed before the EINT
 [^:]*:25: Warning: a NOP might be needed here because of successive changes in interrupt state
-[^:]*:26: Warning: a NOP might be needed here because of successive changes in interrupt state
-[^:]*:27: Warning: a NOP might be needed here because of successive changes in interrupt state
-[^:]*:28: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:25: Warning: a NOP might be needed before the EINT
+[^:]*:29: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:31: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:32: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:33: Warning: a NOP might be needed here because of successive changes in interrupt state
+[^:]*:34: Warning: a NOP might be needed here because of successive changes in interrupt state
 [^:]*: Warning: assembly finished without a possibly needed NOP instruction
Index: gas/testsuite/gas/msp430/bad.s
===================================================================
RCS file: /cvs/cvsfiles/gnupro/gas/testsuite/gas/msp430/bad.s,v
retrieving revision 1.2
diff -u -3 -p -r1.2 bad.s
--- gas/testsuite/gas/msp430/bad.s	11 Apr 2014 09:37:16 -0000	1.2
+++ gas/testsuite/gas/msp430/bad.s	6 Apr 2016 11:15:58 -0000
@@ -11,6 +11,12 @@
 	bis.a	#8, r2
 
 ;;; FIXME: Add more tests of assembler error detection here.
+
+	;;  A NOP is needed *before* an EINT instruction.
+	eint
+	nop
+	;; And *after* a DINT instruction.
+	dint
 	
 	;;  Changing interrupt states in two successive instructions
 	;;  might cause an interrupt to be missed.  The assembler
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