re PR tree-optimization/91109 ([arm] gcc.c-torture/execute/20040709-1.c fails since r273135)

2019-08-16  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR tree-optimization/91109
        * lra-int.h (lra_need_for_scratch_reg_p): Declare.
        * lra.c (lra): Use lra_need_for_scratch_reg_p.
        * lra-spills.c (lra_need_for_scratch_reg_p): New function.

From-SVN: r274573

gcc/ChangeLog

+2019-08-16  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	PR tree-optimization/91109
+	* lra-int.h (lra_need_for_scratch_reg_p): Declare.
+	* lra.c (lra): Use lra_need_for_scratch_reg_p.
+	* lra-spills.c (lra_need_for_scratch_reg_p): New function.
+
 2019-08-16  Uroš Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/mmx.md (mmxdoublemode): New mode attribute.

gcc/lra-int.h

@@ -396,6 +396,7 @@ extern bool lra_coalesce (void);
 
 /* lra-spills.c:  */
 
+extern bool lra_need_for_scratch_reg_p (void);
 extern bool lra_need_for_spills_p (void);
 extern void lra_spill (void);
 extern void lra_final_code_change (void);

gcc/lra-spills.c

@@ -549,6 +549,19 @@ spill_pseudos (void)
     }
 }
 
+/* Return true if we need scratch reg assignments.  */
+bool
+lra_need_for_scratch_reg_p (void)
+{
+  int i; max_regno = max_reg_num ();
+
+  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
+    if (lra_reg_info[i].nrefs != 0 && lra_get_regno_hard_regno (i) < 0
+	&& lra_former_scratch_p (i))
+      return true;
+  return false;
+}
+
 /* Return true if we need to change some pseudos into memory.  */
 bool
 lra_need_for_spills_p (void)

gcc/lra.c

@@ -2567,8 +2567,12 @@ lra (FILE *f)
 	  lra_create_live_ranges (lra_reg_spill_p, true);
 	  live_p = true;
 	  if (! lra_need_for_spills_p ())
+	    {
+	      if (lra_need_for_scratch_reg_p ())
+		continue;
 	      break;
 	    }
+	}
       lra_spill ();
       /* Assignment of stack slots changes elimination offsets for
 	 some eliminations.  So update the offsets here.  */