arm.c (arm_compute_save_reg0_reg12_mask): Add special case for noreturn functions.

2009-11-23  Paul Brook  <paul@codesourcery.com>

	gcc/
	* config/arm/arm.c (arm_compute_save_reg0_reg12_mask): Add special
	case for noreturn functions.
	(arm_compute_save_reg_mask): Remove special noreturn handling.

From-SVN: r154441

gcc/ChangeLog

+2009-11-23  Paul Brook  <paul@codesourcery.com>
+
+	* config/arm/arm.c (arm_compute_save_reg0_reg12_mask): Add special
+	case for noreturn functions.
+	(arm_compute_save_reg_mask): Remove special noreturn handling.
+
 2009-11-23  Richard Guenther  <rguenther@suse.de>
 
 	* tree-dfa.c (get_ref_base_and_extent): Adjust maximum access

gcc/config/arm/arm.c

@@ -12831,6 +12831,20 @@ arm_compute_save_reg0_reg12_mask (void)
 	  && crtl->uses_pic_offset_table)
 	save_reg_mask |= 1 << PIC_OFFSET_TABLE_REGNUM;
     }
+  else if (IS_VOLATILE(func_type))
+    {
+      /* For noreturn functions we historically omitted register saves
+	 altogether.  However this really messes up debugging.  As a
+	 compromise save just the fame pointers.  Combined with the link
+	 register saved elsewhere this should be sufficient to get
+	 a backtrace.  */
+      if (frame_pointer_needed)
+	save_reg_mask |= 1 << HARD_FRAME_POINTER_REGNUM;
+      if (df_regs_ever_live_p (ARM_HARD_FRAME_POINTER_REGNUM))
+	save_reg_mask |= 1 << ARM_HARD_FRAME_POINTER_REGNUM;
+      if (df_regs_ever_live_p (THUMB_HARD_FRAME_POINTER_REGNUM))
+	save_reg_mask |= 1 << THUMB_HARD_FRAME_POINTER_REGNUM;
+    }
   else
     {
       /* In the normal case we only need to save those registers
@@ -12917,11 +12931,6 @@ arm_compute_save_reg_mask (void)
       | (1 << LR_REGNUM)
       | (1 << PC_REGNUM);
 
-  /* Volatile functions do not return, so there
-     is no need to save any other registers.  */
-  if (IS_VOLATILE (func_type))
-    return save_reg_mask;
-
   save_reg_mask |= arm_compute_save_reg0_reg12_mask ();
 
   /* Decide if we need to save the link register.