[RFA] Rewrite mips_get_saved_register()

[Kevin Buettner]

This patch depends on the following (as of yet) unapproved patches:

    http://sources.redhat.com/ml/gdb-patches/2002-08/msg00189.html
    http://sources.redhat.com/ml/gdb-patches/2002-08/msg00195.html
    http://sources.redhat.com/ml/gdb-patches/2002-08/msg00196.html

Okay to commit?

	* mips-tdep.c (mips_get_saved_register): Rewrite to use
	frame_register_unwind() instead of find_saved_register().

Index: mips-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-tdep.c,v
retrieving revision 1.93
diff -u -p -r1.93 mips-tdep.c
--- mips-tdep.c	8 Aug 2002 23:32:52 -0000	1.93
+++ mips-tdep.c	9 Aug 2002 00:26:00 -0000
@@ -4241,53 +4246,48 @@ mips_get_saved_register (char *raw_buffe
 			 int regnum,
 			 enum lval_type *lval)
 {
-  CORE_ADDR addr;
+  int realnum;
+  int scratch_optimized;
+  enum lval_type scratch_lval;
+  CORE_ADDR scratch_addr;
 
   if (!target_has_registers)
     error ("No registers.");
 
-  /* Normal systems don't optimize out things with register numbers.  */
-  if (optimized != NULL)
-    *optimized = 0;
-  addr = find_saved_register (frame, regnum);
-  if (addr != 0)
-    {
-      if (lval != NULL)
-	*lval = lval_memory;
-      if (regnum == SP_REGNUM)
-	{
-	  if (raw_buffer != NULL)
-	    {
-	      /* Put it back in target format.  */
-	      store_address (raw_buffer, REGISTER_RAW_SIZE (regnum),
-			     (LONGEST) addr);
-	    }
-	  if (addrp != NULL)
-	    *addrp = 0;
-	  return;
-	}
-      if (raw_buffer != NULL)
-	{
-	  LONGEST val;
-	  if (regnum < 32)
-	    /* Only MIPS_SAVED_REGSIZE bytes of GP registers are
-               saved. */
-	    val = read_memory_integer (addr, MIPS_SAVED_REGSIZE);
-	  else
-	    val = read_memory_integer (addr, REGISTER_RAW_SIZE (regnum));
-	  store_address (raw_buffer, REGISTER_RAW_SIZE (regnum), val);
-	}
-    }
-  else
-    {
-      if (lval != NULL)
-	*lval = lval_register;
-      addr = REGISTER_BYTE (regnum);
-      if (raw_buffer != NULL)
-	read_register_gen (regnum, raw_buffer);
+  /* frame_register_unwind() requires ``optimized'', ``lval'',  ``addrp'',
+     and ``realnum'' to be non-NULL.  So use the scratch variables, if
+     necessary.  (Note that realnum isn't a problem since we pass the
+     address of local storage directly.)  */
+  if (optimized == NULL)
+    optimized = &scratch_optimized;
+  if (addrp == NULL)
+    addrp = &scratch_addr;
+  if (lval == NULL)
+    lval = &scratch_lval;
+
+  /* Fetch register REGNUM from an inner (callee) frame.  */
+  frame_register_unwind (get_next_frame (frame), regnum, optimized,
+                         lval, addrp, &realnum, raw_buffer);
+
+  /* Only MIPS_SAVED_REGSIZE bytes of GP registers are saved on the
+     stack.  If this differs from the raw size, then frame_register_unwind()
+     fetched too much.  Adjust value fetched and save back into the buffer.  
+     (The excess is thus discarded.)
+     
+     The SP register is handled specially.  Its value will have been
+     set correctly by frame_register_unwind(), so don't attempt to adjust
+     it.  */
+  if (*addrp != 0 			/* Register must be saved on stack,  */
+      && regnum < 32			/* must be a GP register,  */
+      && regnum != SP_REGNUM		/* but not SP.  */
+      && MIPS_SAVED_REGSIZE < REGISTER_RAW_SIZE (regnum))
+    {
+      LONGEST val;
+      
+      val = extract_signed_integer (raw_buffer, MIPS_SAVED_REGSIZE);
+      store_signed_integer (raw_buffer, REGISTER_RAW_SIZE (regnum),
+                            val);
     }
-  if (addrp != NULL)
-    *addrp = addr;
 }
 
 /* Immediately after a function call, return the saved pc.