[COMMIT] Add DWARF2_FRAME_REG_RA_OFFSET support

[Mark Kettenis]

Preparation for SPARC DWARF unwinder support.  Proposed this some
weeks ago.  Daniel liked DWARF2_FRAME_REG_RA_OFFSET; thanks for
helping me decide.

Committed,

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>

	* dwarf2-frame.h: Update copyrigh year.
	(enum dwarf2_frame_reg_rule): Add DWARF2_FRAME_REG_RA_OFFSET.
	* dwarf2-frame.c: Update copyright year.
	(struct dwarf2_frame_cache): Add member `retaddr_reg'.
	(dwarf2_frame_cache): Deal with DWARF2_FRAME_REG_RA_OFFSET.
	(dwarf2_frame_prev_register): Handle DWARF2_FRAME_REG_RA_OFFSET.

Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.48
diff -u -p -r1.48 dwarf2-frame.c
--- dwarf2-frame.c 11 Feb 2005 18:13:49 -0000 1.48
+++ dwarf2-frame.c 25 Mar 2005 16:50:26 -0000
@@ -1,6 +1,6 @@
 /* Frame unwinder for frames with DWARF Call Frame Information.
 
-   Copyright 2003, 2004 Free Software Foundation, Inc.
+   Copyright 2003, 2004, 2005 Free Software Foundation, Inc.
 
    Contributed by Mark Kettenis.
 
@@ -588,6 +588,9 @@ struct dwarf2_frame_cache
   /* Saved registers, indexed by GDB register number, not by DWARF
      register number.  */
   struct dwarf2_frame_state_reg *reg;
+
+  /* Return address register.  */
+  struct dwarf2_frame_state_reg retaddr_reg;
 };
 
 static struct dwarf2_frame_cache *
@@ -717,13 +720,15 @@ incomplete CFI data; unspecified registe
       }
   }
 
-  /* Eliminate any DWARF2_FRAME_REG_RA rules.  */
+  /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
+     we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules.  */
   {
     int regnum;
 
     for (regnum = 0; regnum < num_regs; regnum++)
       {
-	if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
+	if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA
+	    || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET)
 	  {
 	    struct dwarf2_frame_state_reg *retaddr_reg =
 	      &fs->regs.reg[fs->retaddr_column];
@@ -733,16 +738,29 @@ incomplete CFI data; unspecified registe
                what GCC does on some targets.  It turns out that GCC
                assumes that the return address can be found in the
                register corresponding to the return address column.
-               Incidentally, that's how should treat a return address
-               column specifying "same value" too.  */
+               Incidentally, that's how we should treat a return
+               address column specifying "same value" too.  */
 	    if (fs->retaddr_column < fs->regs.num_regs
 		&& retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED
 		&& retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE)
-	      cache->reg[regnum] = *retaddr_reg;
+	      {
+		if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
+		  cache->reg[regnum] = *retaddr_reg;
+		else
+		  cache->retaddr_reg = *retaddr_reg;
+	      }
 	    else
 	      {
-		cache->reg[regnum].loc.reg = fs->retaddr_column;
-		cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
+		if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
+		  {
+		    cache->reg[regnum].loc.reg = fs->retaddr_column;
+		    cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
+		  }
+		else
+		  {
+		    cache->retaddr_reg.loc.reg = fs->retaddr_column;
+		    cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG;
+		  }
 	      }
 	  }
       }
@@ -864,6 +882,21 @@ dwarf2_frame_prev_register (struct frame
 	}
       break;
 
+    case DWARF2_FRAME_REG_RA_OFFSET:
+      *optimizedp = 0;
+      *lvalp = not_lval;
+      *addrp = 0;
+      *realnump = -1;
+      if (valuep)
+        {
+          CORE_ADDR pc = cache->reg[regnum].loc.offset;
+
+          regnum = DWARF2_REG_TO_REGNUM (cache->retaddr_reg.loc.reg);
+          pc += frame_unwind_register_unsigned (next_frame, regnum);
+          store_typed_address (valuep, builtin_type_void_func_ptr, pc);
+        }
+      break;
+
     default:
       internal_error (__FILE__, __LINE__, _("Unknown register rule."));
     }
Index: dwarf2-frame.h
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.h,v
retrieving revision 1.7
diff -u -p -r1.7 dwarf2-frame.h
--- dwarf2-frame.h 7 Nov 2004 21:16:11 -0000 1.7
+++ dwarf2-frame.h 25 Mar 2005 16:50:26 -0000
@@ -1,6 +1,6 @@
 /* Frame unwinder for frames with DWARF Call Frame Information.
 
-   Copyright 2003, 2004 Free Software Foundation, Inc.
+   Copyright 2003, 2004, 2005 Free Software Foundation, Inc.
 
    Contributed by Mark Kettenis.
 
@@ -54,6 +54,7 @@ enum dwarf2_frame_reg_rule
   /* These aren't defined by the DWARF2 CFI specification, but are
      used internally by GDB.  */
   DWARF2_FRAME_REG_RA,		/* Return Address.  */
+  DWARF2_FRAME_REG_RA_OFFSET,	/* Return Address with offset.  */
   DWARF2_FRAME_REG_CFA		/* Call Frame Address.  */
 };