diff --git a/compiler/aoptobj.pas b/compiler/aoptobj.pas
index 792906d44d..9cc84c212d 100644
--- a/compiler/aoptobj.pas
+++ b/compiler/aoptobj.pas
@@ -1182,12 +1182,10 @@ Unit AoptObj;
         removedSomething := false;
         firstRemovedWasAlloc := false;
 {$ifdef allocregdebug}
-        hp := tai_comment.Create(strpnew('allocating '+std_regname(newreg(R_INTREGISTER,supreg,R_SUBWHOLE))+
-          ' from here...'));
-        insertllitem(asml,p1.previous,p1,hp);
-        hp := tai_comment.Create(strpnew('allocated '+std_regname(newreg(R_INTREGISTER,supreg,R_SUBWHOLE))+
-          ' till here...'));
-        insertllitem(asml,p2,p2.next,hp);
+        hp := tai_comment.Create(strpnew('allocating '+std_regname(reg)+' from here...'));
+        insertllitem(p1.previous,p1,hp);
+        hp := tai_comment.Create(strpnew('allocated '+std_regname(reg)+' till here...'));
+        insertllitem(p2,p2.next,hp);
 {$endif allocregdebug}
         { do it the safe way: always allocate the full super register,
           as we do no register re-allocation in the peephole optimizer,
diff --git a/compiler/fpcdefs.inc b/compiler/fpcdefs.inc
index c7ca6c5a5e..b4ec8a6dbc 100644
--- a/compiler/fpcdefs.inc
+++ b/compiler/fpcdefs.inc
@@ -32,6 +32,31 @@
   {$define USEINLINE}
 {$endif EXTDEBUG}
 
+{$ifdef DEBUG_ALL_OPT}
+  { for aopt unit }
+  {$define DEBUG_OPTALLOC}
+  {$define DEBUG_INSTRUCTIONREGISTERDEPENDENCIES}
+  {for CPU/aoptcpu unit }
+  {$define DEBUG_AOPTCPU}
+  {$define DEBUG_PREREGSCHEDULER (arm specific) }
+  { for aoptobj unit }
+  {$define DEBUG_AOPTOBJ}
+  {$define ALLOCREGDEBUG}
+  { for optconstprop unit }
+  {$define DEBUG_CONSTPROP}
+  { for optcse unit }
+  {$define CSEDEBUG}
+  { for optdeadstore unit }
+  {$define DEBUG_DEADSTORE}
+  { for optdfa unit }
+  {$define DEBUG_DFA}
+  { for optloop unit }
+  {$define DEBUG_OPTFORLOOP}
+  {$define DEBUG_OPTSTRENGTH}
+  { for optvirt unit }
+  {$define DEBUG_DEVIRT}
+{$endif}
+
 {$define USEEXCEPT}
 
 { This fake CPU is used to allow incorporation of globtype unit