regs.h (HARD_REGNO_CALLER_SAVE_MODE): New macro.

        * regs.h (HARD_REGNO_CALLER_SAVE_MODE): New macro.
        * caller-save.c (init_caller_save): Use it.
        * tm.texi: Document HARD_REGNO_CALLER_SAVE_MODE.

From-SVN: r22682

gcc/ChangeLog

-Wed Sep 30 12:57:30 1998Zack Weinberg  <zack@rabi.phys.columbia.edu>  
+Wed Sep 30 18:19:27 1998  Michael Hayes  <m.hayes@elec.canterbury.ac.nz>
+
+	* regs.h (HARD_REGNO_CALLER_SAVE_MODE): New macro.
+	* caller-save.c (init_caller_save): Use it.
+	* tm.texi: Document HARD_REGNO_CALLER_SAVE_MODE.
+
+Wed Sep 30 12:57:30 1998 Zack Weinberg  <zack@rabi.phys.columbia.edu>  
 
 	* configure.in: Add --enable-cpplib option which uses cpplib
 	for cpp, but doesn't link cpplib into cc1.  Make help text

gcc/caller-save.c

@@ -115,7 +115,7 @@ init_caller_save ()
 	{
 	  for (j = 1; j <= MOVE_MAX / UNITS_PER_WORD; j++)
 	    {
-	      regno_save_mode[i][j] = choose_hard_reg_mode (i, j);
+	      regno_save_mode[i][j] = HARD_REGNO_CALLER_SAVE_MODE (i, j);
 	      if (regno_save_mode[i][j] == VOIDmode && j == 1)
 		{
 		  call_fixed_regs[i] = 1;

gcc/regs.h

@@ -211,6 +211,12 @@ extern int caller_save_needed;
 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 #endif
 
+/* Select a register mode required for caller save of hard regno REGNO.  */
+#ifndef HARD_REGNO_CALLER_SAVE_MODE
+#define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS) \
+  choose_hard_reg_mode (REGNO, NREGS)
+#endif
+
 /* Allocated in local_alloc.  */
 
 /* A list of SCRATCH rtl allocated by local-alloc.  */

gcc/tm.texi

@@ -3174,6 +3174,14 @@ this is worth doing, and 0 otherwise.
 
 If you don't define this macro, a default is used which is good on most
 machines: @code{4 * @var{calls} < @var{refs}}.
+
+@findex HARD_REGNO_CALLER_SAVE_MODE
+@item HARD_REGNO_CALLER_SAVE_MODE (@var{regno}, @var{nregs})
+A C expression specifying which mode is required for saving @var{nregs}
+of a pseudo-register in call-clobbered hard register @var{regno}.  If
+@var{regno} is unsuitable for caller save, @code{VOIDmode} should be
+returned.  For most machines this macro need not be defined since GCC
+will select the smallest suitable mode.
 @end table
 
 @node Function Entry