target.h (struct gcc_target): Add hard_regno_scratch_ok field.

* target.h (struct gcc_target): Add hard_regno_scratch_ok field.
	* target-def.h (TARGET_HARD_REGNO_SCRATCH_OK): New.
	(TARGET_INITIALIZER): Use TARGET_HARD_REGNO_SCRATCH_OK.
	* targhooks.c (default_hard_regno_scratch_ok): New function.
	* targhooks.h (default_hard_regno_scratch_ok): Declare function.
	* doc/tm.texi: Document TARGET_HARD_REGNO_SCRATCH_OK hook.
	* recog.c:  Include "target.h".
	(peep2_find_free_register): Add check for global regs. Add target
	specific check.
	* Makefile.in (recog.o): Depend on target.h.

From-SVN: r137657

gcc/ChangeLog

@@ -1,3 +1,16 @@
+2008-07-09  Anatoly Sokolov  <aesok@post.ru>
+
+	* target.h (struct gcc_target): Add hard_regno_scratch_ok field.
+	* target-def.h (TARGET_HARD_REGNO_SCRATCH_OK): New.
+	(TARGET_INITIALIZER): Use TARGET_HARD_REGNO_SCRATCH_OK.
+	* targhooks.c (default_hard_regno_scratch_ok): New function.
+	* targhooks.h (default_hard_regno_scratch_ok): Declare function.
+	* doc/tm.texi: Document TARGET_HARD_REGNO_SCRATCH_OK hook.
+	* recog.c:  Include "target.h".
+	(peep2_find_free_register): Add check for global regs. Add target
+	specific check.
+	* Makefile.in (recog.o): Depend on target.h.
+
 2008-07-09  Kaz Kojima  <kkojima@gcc.gnu.org>
 
 	* config/sh/sh.c (sh_canonical_va_list_type): New.

gcc/Makefile.in

@@ -2868,7 +2868,7 @@ recog.o : recog.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
    $(FUNCTION_H) $(BASIC_BLOCK_H) $(REGS_H) $(RECOG_H) $(EXPR_H) \
    $(FLAGS_H) insn-config.h $(INSN_ATTR_H) toplev.h output.h reload.h \
    addresses.h $(TM_P_H) $(TIMEVAR_H) tree-pass.h hard-reg-set.h $(REAL_H) \
-   $(DF_H) $(DBGCNT_H)
+   $(DF_H) $(DBGCNT_H) $(TARGET_H)
 reg-stack.o : reg-stack.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(RTL_H) $(TREE_H) $(RECOG_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) \
    insn-config.h toplev.h reload.h $(FUNCTION_H) $(TM_P_H) $(GGC_H) \

gcc/doc/tm.texi

@@ -2242,6 +2242,16 @@ possible since doing so will allow GCC to perform better register
 allocation.
 @end defmac
 
+@deftypefn {Target Hook} bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int @var{regno})
+This target hook should return @code{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.
+
+The default version of this hook always returns @code{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

gcc/recog.c

@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.  If not see
 #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 @@ peep2_find_free_register (int from, int to, const char *class_str,
       /* 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 @@ peep2_find_free_register (int from, int to, const char *class_str,
       /* 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))

gcc/target-def.h

@@ -619,6 +619,10 @@
 #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
@@ -846,6 +850,7 @@
   TARGET_SECONDARY_RELOAD,			\
   TARGET_EXPAND_TO_RTL_HOOK,			\
   TARGET_INSTANTIATE_DECLS,			\
+  TARGET_HARD_REGNO_SCRATCH_OK,			\
   TARGET_C,					\
   TARGET_CXX,					\
   TARGET_EMUTLS,				\

gcc/target.h

@@ -872,6 +872,10 @@ struct gcc_target
      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

gcc/targhooks.c

@@ -703,4 +703,10 @@ default_builtin_vector_alignment_reachable (const_tree type, bool is_packed)
   return true;
 }
 
+bool
+default_hard_regno_scratch_ok (unsigned int regno ATTRIBUTE_UNUSED)
+{
+  return true;
+}
+
 #include "gt-targhooks.h"

gcc/targhooks.h

@@ -97,3 +97,5 @@ extern int default_reloc_rw_mask (void);
 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);