integrate.c (get_hard_reg_initial_reg): New.

* integrate.c (get_hard_reg_initial_reg): New.
* integrate.h (get_hard_reg_initial_reg): Prototype.
* local-alloc.c (block_alloc): Don't tie pseudos that
represent call-saved hard regs' initial values.

From-SVN: r47037

gcc/ChangeLog

+2001-11-14  DJ Delorie  <dj@redhat.com>
+
+	* integrate.c (get_hard_reg_initial_reg): New.
+	* integrate.h (get_hard_reg_initial_reg): Prototype.
+	* local-alloc.c (block_alloc): Don't tie pseudos that
+	represent call-saved hard regs' initial values.
+
 2001-11-14  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* m68k/linux.h: Include <linux.h> not "linux.h" to avoid infinite

gcc/integrate.c

@@ -2964,6 +2964,24 @@ output_inline_function (fndecl)
    the function.  */
 
 rtx
+get_hard_reg_initial_reg (fun, reg)
+     struct function *fun;
+     rtx reg;
+{
+  struct initial_value_struct *ivs = fun->hard_reg_initial_vals;
+  int i;
+
+  if (ivs == 0)
+    return NULL_RTX;
+
+  for (i = 0; i < ivs->num_entries; i++)
+    if (rtx_equal_p (ivs->entries[i].pseudo, reg))
+      return ivs->entries[i].hard_reg;
+
+  return NULL_RTX;
+}
+
+rtx
 has_func_hard_reg_initial_val (fun, reg)
      struct function *fun;
      rtx reg;

gcc/integrate.h

@@ -140,6 +140,9 @@ extern rtx get_func_hard_reg_initial_val	PARAMS ((struct function *, rtx));
 extern rtx has_func_hard_reg_initial_val	PARAMS ((struct function *, rtx));
 /* Likewise, but for common cases.  */
 extern rtx has_hard_reg_initial_val		PARAMS ((enum machine_mode, int));
+/* If a pseudo represents an initial hard reg (or expression), return
+   it, else return NULL_RTX.  */
+extern rtx get_hard_reg_initial_reg		PARAMS ((struct function *, rtx));
 /* This is for GC.  */
 extern void mark_hard_reg_initial_vals		PARAMS ((struct function *));
 /* Called from rest_of_compilation.  */

gcc/local-alloc.c

@@ -74,6 +74,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "output.h"
 #include "toplev.h"
 #include "except.h"
+#include "integrate.h"
 
 /* Next quantity number available for allocation.  */
 
@@ -1216,7 +1217,7 @@ block_alloc (b)
 {
   int i, q;
   rtx insn;
-  rtx note;
+  rtx note, hard_reg;
   int insn_number = 0;
   int insn_count = 0;
   int max_uid = get_max_uid ();
@@ -1340,6 +1341,18 @@ block_alloc (b)
 		    while (GET_CODE (r1) == PLUS || GET_CODE (r1) == MULT)
 		      r1 = XEXP (r1, 0);
 
+		  /* Avoid making a call-saved register unnecessarily
+                     clobbered.  */
+		  hard_reg = get_hard_reg_initial_reg (cfun, r1);
+		  if (hard_reg != NULL_RTX)
+		    {
+		      if (GET_CODE (hard_reg) == REG
+			  && REGNO (hard_reg) >= 0
+			  && REGNO (hard_reg) < FIRST_PSEUDO_REGISTER
+			  && ! call_used_regs[REGNO (hard_reg)])
+			continue;
+		    }
+
 		  if (GET_CODE (r0) == REG || GET_CODE (r0) == SUBREG)
 		    {
 		      /* We have two priorities for hard register preferences.