Index: inssel.brg
===================================================================
--- inssel.brg	(revision 116003)
+++ inssel.brg	(working copy)
@@ -781,6 +781,10 @@
 stmt: OP_NOP "0" {
 }
 
+stmp: OP_HARD_NOP "0" {
+	mono_bblock_add_inst (s->cbb, tree);
+}
+
 stmt: OP_BREAK "0" {
 	mono_bblock_add_inst (s->cbb, tree);
 }
Index: mini.c
===================================================================
--- mini.c	(revision 116003)
+++ mini.c	(working copy)
@@ -5233,6 +5233,7 @@
 	MonoDeclSecurityActions actions;
 	GSList *class_inits = NULL;
 	gboolean dont_verify, dont_verify_stloc, readonly = FALSE;
+	gboolean use_hard_nops = FALSE;
 	int context_used;
 
 	/* serialization and xdomain stuff may need access to private fields and methods */
@@ -5276,6 +5277,9 @@
 	if (!dont_verify && mini_method_verify (cfg, method_definition))
 		goto exception_exit;
 
+	if (mono_debug_using_mono_debugger ())
+		use_hard_nops = TRUE;
+
 	if (sig->is_inflated)
 		generic_context = mono_method_get_context (method);
 	else if (generic_container)
@@ -5683,7 +5687,10 @@
 
 		switch (*ip) {
 		case CEE_NOP:
-			MONO_INST_NEW (cfg, ins, OP_NOP);
+			if (use_hard_nops)
+				MONO_INST_NEW (cfg, ins, OP_HARD_NOP);
+			else
+				MONO_INST_NEW (cfg, ins, OP_NOP);
 			ip++;
 			MONO_ADD_INS (bblock, ins);
 			break;
Index: mini-amd64.c
===================================================================
--- mini-amd64.c	(revision 116003)
+++ mini-amd64.c	(working copy)
@@ -3347,6 +3347,9 @@
 			x86_prefix (code, X86_REP_PREFIX);
 			x86_nop (code);
 			break;
+		case OP_HARD_NOP:
+			x86_nop (code);
+			break;
 		case OP_NOP:
 		case OP_DUMMY_USE:
 		case OP_DUMMY_STORE:
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 116003)
+++ ChangeLog	(working copy)
@@ -1,3 +1,12 @@
+2008-10-16  Martin Baulig  <martin@ximian.com>
+
+	* mini-ops.h, cpu-amd64.md, cpu-x86.md: Added new `debugger_nop' opcode.
+
+	* inssel.brg: Add `OP_DEBUGGER_NOP'.
+
+	* mini.c: In `CEE_NOP': generate a `OP_DEBUGGER_NOP' instruction
+	when running inside the debugger.
+
 2008-10-15  Rodrigo Kumpera  <rkumpera@novell.com>
 
 	* simd-intrinsics.c (get_simd_vreg): Using sreg1 of OP_XMOVE
Index: cpu-x86.md
===================================================================
--- cpu-x86.md	(revision 116003)
+++ cpu-x86.md	(working copy)
@@ -310,6 +310,7 @@
 memory_barrier: len:16
 
 relaxed_nop: len:2
+hard_nop: len:1
 
 # Linear IR opcodes
 nop: len:0
Index: mini-x86.c
===================================================================
--- mini-x86.c	(revision 116003)
+++ mini-x86.c	(working copy)
@@ -2375,6 +2375,9 @@
 			x86_prefix (code, X86_REP_PREFIX);
 			x86_nop (code);
 			break;
+ 		case OP_HARD_NOP:
+			x86_nop (code);
+			break;
  		case OP_NOP:
  		case OP_DUMMY_USE:
  		case OP_DUMMY_STORE:
Index: mini-ops.h
===================================================================
--- mini-ops.h	(revision 116003)
+++ mini-ops.h	(working copy)
@@ -5,6 +5,7 @@
 MINI_OP(OP_OBJADDR,	"objaddr", NONE, NONE, NONE)
 MINI_OP(OP_VTADDR,	"vtaddr", NONE, NONE, NONE)
 MINI_OP(OP_NOP,     "nop", NONE, NONE, NONE)
+MINI_OP(OP_DEBUGGER_NOP,    "debugger_nop", NONE, NONE, NONE)
 MINI_OP(OP_RELAXED_NOP,     "relaxed_nop", NONE, NONE, NONE)
 MINI_OP(OP_PHI,		"phi", IREG, NONE, NONE)
 MINI_OP(OP_FPHI,	"fphi", FREG, NONE, NONE)
Index: cpu-amd64.md
===================================================================
--- cpu-amd64.md	(revision 116003)
+++ cpu-amd64.md	(working copy)
@@ -383,6 +383,7 @@
 int_ble_un: len:8
 
 relaxed_nop: len:2
+hard_nop: len:1
 
 # Linear IR opcodes
 nop: len:0