Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi	(revision 136946)
+++ gcc/doc/tm.texi	(working copy)
@@ -2242,6 +2242,16 @@
 allocation.
 @end defmac
 
+@deftypefn {Target Hook} bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int @var{regno})
+This target hook should return 'true' if it is OK to use a hard register 
+@var{regno} as scratch reg in peephole2.
+
+One common use of this macro is to prevent using of a register that 
+is not saved by a prologue in an interrupt handler.
+
+TThe default version of this hook always returns 'true'.
+@end deftypefn
+
 @defmac AVOID_CCMODE_COPIES
 Define this macro if the compiler should avoid copies to/from @code{CCmode}
 registers.  You should only define this macro if support for copying to/from
Index: gcc/targhooks.c
===================================================================
--- gcc/targhooks.c	(revision 136946)
+++ gcc/targhooks.c	(working copy)
@@ -703,4 +703,10 @@
   return true;
 }
 
+bool 
+default_hard_regno_scratch_ok (unsigned int regno ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
 #include "gt-targhooks.h"
Index: gcc/targhooks.h
===================================================================
--- gcc/targhooks.h	(revision 136946)
+++ gcc/targhooks.h	(working copy)
@@ -97,3 +97,5 @@
 extern tree default_mangle_decl_assembler_name (tree, tree);
 extern tree default_emutls_var_fields (tree, tree *);
 extern tree default_emutls_var_init (tree, tree, tree);
+
+extern bool default_hard_regno_scratch_ok (unsigned int);
Index: gcc/target.h
===================================================================
--- gcc/target.h	(revision 136946)
+++ gcc/target.h	(working copy)
@@ -866,6 +866,10 @@
      but will be later.  */
   void (* instantiate_decls) (void);
 
+  /* Return true if is OK to use a hard register REGNO as scratch register 
+     in peephole2.  */
+  bool (* hard_regno_scratch_ok) (unsigned int regno);
+
   /* Functions specific to the C family of frontends.  */
   struct c {
     /* Return machine mode for non-standard suffix
Index: gcc/recog.c
===================================================================
--- gcc/recog.c	(revision 136946)
+++ gcc/recog.c	(working copy)
@@ -40,6 +40,7 @@
 #include "basic-block.h"
 #include "output.h"
 #include "reload.h"
+#include "target.h"
 #include "timevar.h"
 #include "tree-pass.h"
 #include "df.h"
@@ -2898,6 +2899,9 @@
       /* Don't allocate fixed registers.  */
       if (fixed_regs[regno])
 	continue;
+      /* Don't allocate global registers.  */
+      if (global_regs[regno])
+	continue;
       /* Make sure the register is of the right class.  */
       if (! TEST_HARD_REG_BIT (reg_class_contents[cl], regno))
 	continue;
@@ -2907,6 +2911,9 @@
       /* And that we don't create an extra save/restore.  */
       if (! call_used_regs[regno] && ! df_regs_ever_live_p (regno))
 	continue;
+      if (! targetm.hard_regno_scratch_ok (regno))
+	continue;
+
       /* And we don't clobber traceback for noreturn functions.  */
       if ((regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM)
 	  && (! reload_completed || frame_pointer_needed))
Index: gcc/target-def.h
===================================================================
--- gcc/target-def.h	(revision 136946)
+++ gcc/target-def.h	(working copy)
@@ -617,6 +617,10 @@
 #define TARGET_INSTANTIATE_DECLS hook_void_void
 #endif
 
+#ifndef TARGET_HARD_REGNO_SCRATCH_OK
+#define TARGET_HARD_REGNO_SCRATCH_OK default_hard_regno_scratch_ok
+#endif
+
 /* C specific.  */
 #ifndef TARGET_C_MODE_FOR_SUFFIX
 #define TARGET_C_MODE_FOR_SUFFIX default_mode_for_suffix
@@ -842,6 +846,7 @@
   TARGET_SECONDARY_RELOAD,			\
   TARGET_EXPAND_TO_RTL_HOOK,			\
   TARGET_INSTANTIATE_DECLS,			\
+  TARGET_HARD_REGNO_SCRATCH_OK,			\
   TARGET_C,					\
   TARGET_CXX,					\
   TARGET_EMUTLS,				\